UNITED STATES ENVIRONMENTAL PROTECTION AGENCY WASHINGTON, D. C. 20460 OFFICE OF PREVENTION, PESTICIDES AND TOXIC SUBSTANCES MEMORANDUM Date: March 21, 2006 Subject: Agency Responses to Phase 3 Public Comments Related to Methyl Bromide's Uses in Enclosures, Chambers, and Structural Food Processing/ Storage Facilities From: Steven Weiss, Chemical Review Manager Special Review Branch, Special Review and Reregistration Division To: Methyl Bromide Docket ( EPA HQ OPP 2005 0123)

The Environmental Protection Agency ( EPA) is developing a Reregistration Eligibility Decision ( RED) for the uses of Methyl Bromide through a 6 phase public participation process that the Agency uses to involve the public in developing pesticide reregistration and tolerance reassessment decisions. During Phase 3 of the process, the Agency received 52 separate public comment entries on the methyl bromide risk assessments and supporting documents that are summarized in Table 1. These 52 entries were merged into a matrix of 96.

As part of the Phase 5 revised risk assessment uses in enclosures, chambers, and structural food processing/ storage facilities, the Agency has prepared responses related to comments on commodity uses and human toxicity endpoints ( see Table 2). Responses from Biological and Economic Analysis Division ( BEAD) are also attached ( March 15, 2006 memo from BEAD/ B. Chism to SRRD/ S. Weiss). Responses to comments related to methyl bromide's other uses ( e. g. pre plant soil applications) will be released later this year along with the Phase 5 revised risk assessment for the soil uses. Table 1. Summary of Phase 3 Public Comments 1 OPP 2005 0123 0052 Comments Submitted by Barbara Sachau 2 OPP 2005 0123 0053 Comments from Various Private Citizens ( Campaign Letters). A Total of 837 Letters were Received. 3 OPP 2005 0123 0054 Comments from the Al FLEX Exterminators, Inc. 4 OPP 2005 0123 0056 Comments from the Association of Floral Importers 5 OPP 2005 0123 0057 Comments submitted by the Peruvian Asparagus Industry 6 OPP 2005 0123 0058 Comments submitted by Lee Murphy, President/ CEO California Cut Flower Commission 7 OPP 2005 0123 0076 Comments from the Lassen Canyon Nursery, Inc. 8 OPP 2005 0123 0077 Comments from the International Paper Company 9 OPP 2005 0123 0083 Comments from the Smurfit Stone Rock Creek Nursery 10 OPP 2005 0123 0084 Comments from the La Department of Agriculture and Forestry   Oberlin Nursery 11 OPP 2005 0123 0085 Comments from the Associated Oregon Hazelnut Industry 12 OPP 2005 0123 0086 Comments from the Association of Floral Importers of Florida 13 OPP 2005 0123 0087 Comments from the Georgia Forestry Commission's Flint River Nursery 14 OPP 2005 0123 0088 Comments from the Southern Forest Nursery Management Cooperative 15 OPP 2005 0123 0089 Comments from the Louisiana Department of Agriculture & Forestry 16 OPP 2005 0123 0090 Comments from the Texas Forest Service 17 OPP 2005 0123 0091 Comments from the South California Forestry Commission 18 OPP 2005 0123 0092 Comment from the Tennessee Department of Agriculture 19 OPP 2005 0123 0093 Comments from the Sunrise Growers Inc. 20 OPP 2005 0123 0094 Comments from the Sunrise Growers, Inc. ( repeat of previous comment) 21 OPP 2005 0123 0095 Comments from the Peruvian Asparagus Importers Association 22 OPP 2005 0123 0096 Comments from the FJ Pugliese Company Inc. 23 OPP 2005 0123 0097 Comments submitted by Don Stringfield 24 OPP 2005 0123 0101 Comments from the Warren Co. Ag. Extension Service 25 OPP 2005 0123 0102 Comment submitted by Plum Creek 26 OPP 2005 0123 0103 Comments from the California Carrot Board 27 OPP 2005 0123 0104 Comments from the California Pepper Commission 28 OPP 2005 0123 0105 Comments from the Fumigation Service & Supply, Inc. 29 OPP 2005 0123 0106 Comments from the California Tomato Commission 30 OPP 2005 0123 0107 Comments from the California Tomato Growers Association 31 OPP 2005 0123 0108 Comments from the California Pistachio Industry 32 OPP 2005 0123 0109 Comments from the University of Hawaii 33 OPP 2005 0123 0110 Comments from the Royal Fumigation Inc. 34 OPP 2005 0123 0111 Comments from California Minor Crops Council 35 OPP 2005 0123 0112 Comments from the Pesticide Action Network ( these comments were re submitted, see below) 36 OPP 2005 0123 0113 Comments from the Pesticide Action Network ( these comments were re submitted, see below) 37 OPP 2005 0123 0114 Comments from the Western Industries North, Inc. 38 OPP 2005 0123 0115 Comments from the National Pest Management Association Inc. 39 OPP 2005 0123 0116 Comments from the Golf Course Superintendents Association of America 40 OPP 2005 0123 0116 Comments from the Golf Course Superintendents Association of America 41 OPP 2005 0123 0117 Comments from Fumigation Service & Supply, Inc. 42 OPP 2005 0123 0118 Comments from Fred Leitz, Leitz Farms LLC 43 OPP 2005 0123 0119 Comments from the Plant Protection and Quarantine Program/ US Department of AHHIS 44 OPP 2005 0123 0121 Comments submitted by Bayer Corporate and Business Services, LLC 45 OPP 2005 0123 0122 Comments submitted by the Natural Resources Defense Council 46 OPP 2005 0123 0123 Comments on Methyl Bromide from Private Citizen Carol Fisher 47 OPP 2005 0123 0124 Comments from John Kepner, Beyound Pesticides ( re submitted version of OPP 2005 0112) 48 OPP 2005 0123 0125 Comment from Private Citizen RL McKay 49 OPP 2005 0123 0126 Comments from Chava McKeel of GCSA 50 OPP 2005 0123 0127 Comments of the MBIP of the ACC 51 OPP 2005 0123 0128 Comments from Pesticide Action Network 52 OPP 2005 0123 0129 Comment submitted by Almond Hullers & Processors Association Table 2. Responses to Phase 3 Public Comments OPP 2005 0123 Document ID Public Comment Agency Response 1 0056, 0076, 0077,

0083, 0084, 0085,

0086, 0087, 0088,

0089, 0090, 0091,

0092, 0093, 0102,

0110, 0111, 0118 The Agency makes a number of assumptions on the rates of application, methods of use and other use practices for methyl bromide. These assumptions do not reflect typical use practices. The Agency assessed risk based on a range of application rates and other parameters such as field/ chamber size, weather conditions, etc. Data submitted by stakeholders on typical rates, methods and other practices throughout the risk assessment process has been reviewed and incorporated into the revised risk assessment as appropriate. The Agency has also worked with USDA APHIS to refine the risk assessment.

2 0056, 0058, 0077,

0083, 0084, 0086,

0087, 0089, 0090 0091, 0092, 0093,

0102, 0110, 0111,

0118 Based on the errors in EPA's assumptions about use practices, we are concerned that EPA has neither reviewed nor incorporated any of the usage information previously provided by the grower community. The Agency's inaccurate assumptions have resulted in risk assessments that grossly overestimate exposure and potential risks. Given the importance of methyl bromide as a crop protection tool, EPA's risk determinations must be accurate. Thus, it is imperative that the Agency refine its occupational and bystander risk assessments to reflect accurate data on use patterns, rates, and methods applications. See response to comment # 1 3 0056, 0076, 0077,

0083, 0084, 0086,

0087, 0089, 0090,

0091, 0092, 0093 We have found the 60 day comment period to be insufficient given the amount of information made public, the complexity of the analyses involved and the voluminous level of material placed in the supporting dockets. The Agency extended the comment period another 30 days, from September 12, 2005 to October 12, 2005.

4 0054 On page 45 50 on the assumptions for commodity fumigations: we disagree with the application rate stated here should be 3lb/ 1000 ft. Also loss rate should be a minimum of 2 3 lb/ 1000 ft. And loss during aeration should be aeration completed when tacted with drager tubes less than 5ppm. We are an exterminating company dealing with tenting and fumigation of crates and pallets. See response to comment # 1 5 0077 EPA's assumed typical application rate is overstated. International Paper's typical rate is 23% less averaging just over 330 pound of active ingredient per acre ( 350 pounds/ acre of Mbr/ Chloropicrin at the 98/ 2 formulation) . Fields are typically fumigated every fourth year either in the fall or early spring . A crop is grown in a field for two years after fumigation and then rotated " out" for the next two growing season See response to comment # 1 6 0083 According to EPA's Preliminary Human Health Risk Assessment on page 5, they state that typical usage rates are around 430 1bs/ ai. Are actual usage rate averages around 300 1bs/ ai . On page 37, the agency assumes a field size of 40 acres. We are averaging around 20 to 25 acres per year. Other usage issues have been researched by the Auburn Coop and the Fumigator. See response to comment # 1 7 0084   the Agency makes a number of assumptions on the rates of application,

methods of use and other use practices for methyl bromide. These assumptions do not reflect typical use practices. The typical size of fields treated at the Oberlin Nursery are anywhere from 12 to 15 acres See response to comment # 1 8 0085   the Agency makes a number of assumptions on the rates of application,

methods of use and other use practices for methyl bromide . These assumptions do See response to comment # 1 Table 2. Responses to Phase 3 Public Comments OPP 2005 0123 Document ID Public Comment Agency Response not all reflect typical use practices. Hazelnut handlers typically use approximately 3 pounds ai methyl bromide per 1,000 cu ft . The assessment has the rate at 9 pounds. If other assessment data is also overstated, it is imperative that the correct data be collected and used in the risk assessment. An extension of the comment period may help industries collect more information that can be used to justify or to change the actual use figures. Or, perhaps the project should be put on hold until more correct information is collected .

9 0087   the Agency makes a number of assumptions on the rates of application,

methods of use and other use practices for methyl bromide. These assumptions do not reflect typical use practices. [ Here at Flint River Nursery we typically fumigate 30 acres . Each field fumigated is 10 acres in size. The rate of use is 400 lbs ai per acre in a 67/ 33 or a 98/ 2 mixture of Methyl Bromide and Chloropicorin.] See response to comment # 1 10 0088 As mentioned previously, use surveys conducted by the Nursery Cooperative for its members for 2000 2005 indicate that, on average, the pre plant use of MBr for 34 nurseries was 270 lbs MBr ai per acre. This is significantly less than what is reported in EPA's use patterns which reports 430 lbs/ ai of MBr per acre.

Use surveys conducted by the Nursery Cooperative for its members for 2000 2005 indicate that approximately 23 acres were treated per year in each nursery. Many of these treated areas were in small blocks, 10 acres or less in size, scattered throughout the nursery. Requiring multiple buffer areas for these small blocks would be impractical and cost prohibitive . This is significantly less than what is reported in EPA's use patterns which assumes a maximum field size of 40 acres.

Based on the errors in EPA's assumptions about use for forest tree nursery practices, I am concerned that EPA has not incorporated any of the usage information previously provided by the forest seedling industry. These inaccurate assumptions have resulted in risk assessments that grossly overestimate exposure and potential risks. Given the importance of methyl bromide as a standard seedling protection tool, EPA's risk determinations must be accurate. See response to comment # 1 11 0090   the Agency makes a number of assumptions on the rates of application,

methods of use and other use practices for methyl bromide . These assumptions do not reflect typical use practices.

° We typically contract to have between 350 and 400 pounds of methyl bromide applied per acre under plastic tarps that stay down at least 49 hours prior to removal and aeration of soil .

° In a typical year we will contract to have between 5 and 25 acres of methyl bromide fumigation performed on our nursery property at the above described application rates. See response to comment # 1 12 0091 .. the Agency makes a number of assumptions on the rates of application, methods of use and other use practices for methyl bromide . These assumptions do not reflect typical use practices .

° At Taylor Nursery, we currently use only 350 lbs./ acre of Mbr 33%. We inject it 8" into properly prepared soil and immediately tarp it with 1 mil plastic . The tarp remains for 72 hours and then is removed and disposed of at our local approved See response to comment # 1 Table 2. Responses to Phase 3 Public Comments OPP 2005 0123 Document ID Public Comment Agency Response waste disposal center. I believe this is less than reported as typical. This is the rate we have been suing for over 25 years .

° We have 125 production acres under irrigation and out of this acreage, we will only fumigate 20 acres this year . This is broken up into 20 small fields, which averages between 6 6.5 acres each. Our entire nursery property is surrounded by large trees, wind breaks or pine plantations that act as buffers for wind, noise,

visual screens and pesticide applications to surrounding property owners.

13 0092 Apparently, the Agency assumes that a typical application rate for methyl bromide is 430 lbs/ ai per acre . However, this rate is not typical for our nursery. For several years we have used 343 lbs/ ai of methyl bromide per acre as our standard rate . In addition, the Agency apparently assumes a maximum field size of 40 acres;

however this size field is also not typical for our nursery. Our fields range from 2.5 to 9.0 acres in size, with an average size of 5 acres . In a typical year, we would fumigate no more than 3 of these fields. See response to comment # 1 14 0093 Sunrise rarely, if ever, uses the maximum rate of Methyl Bromide allowable by law. The typical maximum rate of application is 325 pounds per acre, not the 430 pounds the EPA has suggested.

Sunrise has no typical field size . Our fields range from 3 acres up to 80 100 acres . There are many growers in California whose fields are well below the EPA's typical field of 40 acres. See response to comment # 1 15 0094 As more fully explained below, we are concerned that EPA's preliminary risk assessments are based on assumptions regarding use rates and application methodologies that do not reflect actual use practices. These errors appear to have distorted the Agency's assessments.

Typical rates of application will vary from 1  1.5 lbs per 1000 cubic feet.

Effective sealing can reduce additional bump up and provide effective treatment. See response to comment # 1 16 0110 The use rate assumed by EPA for both commodity and industrial structural fumigation with methyl bromide is 9 lbs./ 1,000 cubic feet. The most common application rate that Royal uses is 4 lbs./ 1,000 cubic feet. The application rates we use range from 1.5 lbs. to 3 lbs./ 1,000 cubic feet for most commodities, 3 lb./ 1,000 cubic feet for wood packing material and 5 lbs./ 1,000 cubic feet for most log fumigations. EPA's assumption of 9 lbs. is therefore more than twice the norm.

EPA also assumes loss rates of approximately 33% during commodity fumigations and 45% during industrial structural fumigations. Royal experiences negligible loss during fumigation. EPA also assumes that during aeration, methyl bromide is specifically channeled away only in the case of venting the gas through a stack. Royal directs the path of the gas in all its fumigations by the use of powerful evacuation fans to which are attached collapsible ducts. With this equipment, the stream of exhaust from a fumigation can be directed hundreds of feet. In addition, even in the case of a stack, Royal can utilize ventilation systems that mix air with the stream from fumigation to dilute the stream, thus enabling it to compensate for stacks that are short. Royal controls bystander presence, which See response to comment # 1 Table 2. Responses to Phase 3 Public Comments OPP 2005 0123 Document ID Public Comment Agency Response does not appear to be contemplated by EPA. In Royal's largest fumigations, those of Chilean fruit, all operations take place at night in a secured port warehouse and with the cooperation of port security to keep bystanders from being in the area.

Aeration generally takes place at midnight or later, when few people are likely to be in the area surrounding the fumigation. Other fumigations are also performed at night for precisely the same control and safety goals.

17 0110 Finally, with respect to worker exposure EPA mentions the use of " respirators."

Royal's personnel use self contained breathing apparatus ( SCBA) for any aspect of a methyl bromide fumigation where they might be exposed to the gas. Since EPA does not define what it includes in the category of " respirator" the distinction should be drawn, as SCBA greatly decreases the degree of worker risk. The risk assessment does estimate risk for workers with no respirator, negative pressure respirators with a protection factor of 10, and SCBAs with a protection factor of 10,000.

18 0114 As has been pointed out by various commenters, certain assumptions, which EPA has made do not appear to reflect actual use practices. Our focus is primarily on perishable commodity fumigations, which in the largest part, are carried out under PPQ regulations. The highest application rate that we are required to apply to perishables is 4 lbs/ 1000 cubic feet and depending on the temperature of the commodity that application rate may be as low as 1.5 lbs/ 1000 cubic feet ( PPQ T101 a 1 or equivalent). EPA assumption puts application rate for commodity fumigation at 9 lbs/ 1000 cubic feet with a loss rate during treatment of 3 lbs/ 1000 cubic feet and 6 lbs/ 1000 cubic feet during aeration.

Question: In conjunction with the above how does EPA determine the loss rate and how does that relate to the risk assessment? Based on the EPA figures, at an application rate of 4 lbs/ 1000 cubic feet would we expect a loss rate of 1.33 lbs/ 1000 cubic feet during treatment and 2.66 lbs/ 1000 cubic feet during aeration? The Agency has based its assumptions for loss rates on CDPR's 1994 Suggested Permit Conditions for Methyl Bromide Fumigation and also the USDA APHIS PPQ treatment handbook as well as other sources of information ( e. g., MBAO. ORG presentations).

19 0115 We are concerned, however, that the Agency has not included post harvest stakeholders in the methyl bromide reregistration process as effectively as it did during the reregistration of aluminum and magnesium phosphide. In fact,

documents the Agency has released continually use the term " soil fumigant" and generally mislead readers into thinking that structural or commodity uses of methyl bromide are not covered or impacted by these assessments. Moreover, at a July 13 technical briefing on the risk assessments for methyl bromide and the other fumigants, EPA noted on sixth slide of a 239 slide presentation, that commodity and structural fumigation were not included. Obviously, the future use of methyl bromide in commodity or structural fumigation would be impacted by the final methyl bromide Reregistration Eligibility Decision document, and we want to make sure that only the most up to date and accurate information is used to make regulatory decisions. Much of the focus thus far has been on soil uses since the majority of use in the US is from soil uses.

However, the Agency recognizes the importance and impact of the other uses such as post harvest commodity fumigation. Furthermore, the risk assessment that is being released in April 2006 is based on commodity uses. The Agency values the input of post harvest stakeholders and encourages comments all aspects of the documents included in the docket 20 0117 Phosphine fumigants have recently gone through an extensive RED process . MB product labels need to be amended and submitted to the Agency with cautions to protect applicators, bystanders, and the community's environment. The 15 RMMs that phosphine registrants and stakeholders worked through should also apply to MB : Fumigation Management Plan, Incident Reporting, Monitoring Studies,

Worker Exposure Limits, Training / Certification. We at Fumigation Service & The Agency is considering a similar process for methyl bromide. The Agency is asking all stakeholders to comment on risk mitigation options paper for commodity uses that was released along with the revised risk assessment. Table 2. Responses to Phase 3 Public Comments OPP 2005 0123 Document ID Public Comment Agency Response Supply, Inc . were part of the Phosphine Coalition that worked through this RED for phosphine and believe that there is a workable standard for Methyl Bromide too . We ask that you hold Methyl Bromide to the same standard as phosphine and sulfuryl fluoride when it is evaluated . We believe that the new phosphine and sulfuryl fluoride labels have helped us to better steward these products 21 0118 EPA's Human Health Risk Assessment assumes a typical rate of 4301bs/ ai of methyl bromide per acre. On all the vegetable crops we use methyl bromide on the recommendation is 400 lbs of 67% methyl bromide and 33% chloropicrin or 67/ 33. Assuming this percentage of use we would use only 268 lb/ ai of methyl bromide per acre . This is not a typical use in vegetable production either . We use plasticulture as the preferred method of growing. By doing this we cut down on fertilizer, water and fumigant. The width of the row and how far apart the rows are determine the square footage of application. We have two foot wide rows and 5 feet between row centers. In other words 2 out of 5 feet is being used or 40% of the ground . Using 67/ 33 at the recommended rate gives us 1081bs/ ai of methyl bromide per acre. This is typical usage for fruit and vegetable farms in the Midwest . The size of our fields is variable. I have fields that are 8 acres to 40 acres in size on the same farm. We have multiple locations in the same county.

We size fields to meet planting schedules, water availability, soil and wind erosion, and proximity to neighbors when we plan . See response to comment # 1 22 0119 APHIS is concerned that EPA may not have a complete understanding of how commodity fumigation is conducted at our nation's ports of entry, and this may be affecting some of the assumptions that EPA has made in developing their risk assessments. The Agency has been working closely with USDAAPHIS to better understand the commodity fumigation process has incorporated information from meetings,

conference calls, and written comments into the revised risk assessment. It should be noted that the Agency risk assessment covers APHIS and non APHIS supervised facilities.

23 0119 EPA's assumptions regarding treatment and flux rates described in the preliminary risk assessments on commodity fumigation exceed actual treatment and flux rates for imported commodities fumigated under APHIS supervision. The Agency has based its assumptions for loss rates on CDPR's 1994 Suggested Permit Conditions for Methyl Bromide Fumigation. The Agency has attempted to estimate risk for a wide range of conditions. It should be noted that the Agency risk assessment covers APHIS and non APHIS supervised facilities.

24 0119 APHIS has analyzed all treatments conducted under a variety of treatment schedules and has determined that, for imported commodities, the decrease in methyl bromide concentrations are much smaller than that estimated in EPA's Draft Risk Assessment ( Figure 5). The observed, minimal decrease in fumigant is attributable to absorption/ adsorption of the fumigant by commodities and particularly by wood packing which absorbs large amounts of fumigant; the decrease is not attributable to loss of gas from the enclosure to the outside ( flux). See response to comment # 23 25 0119 APHIS does not believe that a model which requires a flux input to estimate bystander risks during the treatment phase of fumigations is appropriate. Any decrease in methyl bromide concentrations during the treatment period is attributable to absorption by the commodity or wood packing. In the event that EPA considers this decrease as treatment flux, APHIS respectfully requests that the estimate of loss be significantly reduced, and the by stander risk model,

including the Human Equivalent Concentration, be re assessed to reflect an average treatment time of 3 hours rather than 24 hours. The Agency is now using PERFUM model and is incorporating a range of % loss rates.

26 0119 APHIS appreciates the difficulty in modeling the dispersal of methyl bromide but has difficulty in understanding how the use of the ISCST3 model, a smokestack simulation used to estimate the concentration of air pollutants emitted over a 24

hour period, estimates the dispersal of methyl bromide following commodity fumigation. It is not clear whether the chemical methyl bromide disperses from an aeration vent in the same way as particulate matter emitted from an incinerator's smokestack. Secondly, EPA's model estimates of treatment rates and treatment/ aeration flux are grossly exaggerated compared to what occurs during APHIS supervised commodity fumigation. The Agency is now using PERFUM model and is assessing 1, 4, and 24 hr periods. This allows for a closer approximation of actual emissions and for better characterization of risks compared to the available HECs for commodity uses.

27 0119 EPA's model assumes a commodity treatment rate of 9 lb of methyl bromide per 1,000 cubic feet. A graph depicting APHIS fumigation rates is presented in Figure 6. Nearly 100% of imported commodities are treated at rates less than 9 lb/ 1,000 cubic feet; most imported commodities are treated at 3 or 4 lb/ 1,000 cubic feet.

Three quarters of all APHIS supervised treatments, including both imports and exports, are conducted at 4 lb/ 1000 cubic feet or less. Only 21% of APHISsupervised treatments are at rates of 9 lb/ 1,000 cubic feet or more; although a small portion of these treatments may be for imported tiles, most of these treatments are for exported logs, which are not APHIS regulated commodities. In an effort to fulfill the second prong of the Congressional mandate ( facilitate agricultural trade), APHIS, as a courtesy to other countries, has agreed to supervise certain fumigations according to those countries' requirements, which,

for logs, involve a treatment rate of 15 lb of methyl bromide/ 1,000 cubic feet. This information along with other data provided to the Agency by USDA APHIS has been incorporated into the assessment as appropriate.

28 0119 During a treatment period, there is minimal, if any emission ( flux) from a fumigation enclosure, as it must be sealed to hold the gas. Besides having to bear the high cost of loosing fumigant, a fumigator who lost 2 or 3 lb/ 1,000 cubic feet during a treatment period, as assumed by EPA in the Draft Risk Assessment,

stands to lose APHIS certification to operate at U. S. ports of entry. See response to comment # 25. A wide range of loss rates were considered in order to evaluate the possible range of conditions across the country.

29 0119 APHIS is concerned about the manner in which the by stander risk model is calculated, since the Human Equivalent Concentration used to calculate bystander risk, was developed based on a 24 hour exposure of the expelled stream of methyl bromide, not a 15 30 minute exposure. Furthermore, the assumption that the entire amount is carried in a single direction to a model human being standing at various distances from the aeration site is unrealistic and overconservative;

consequently, it greatly overestimates risks to bystanders. See response to comment # 26 30 0119 APHIS is concerned about the amount released during aeration. The total amount of fumigant released during aeration can be no more than the total amount introduced into the enclosure. EPA's model assumes that 6 lb/ 1,000 cubic feet is released during aeration. Since most import fumigations are at 4 lb/ 1,000 cubic feet or less ( the amount expected to be expelled during aeration) this model clearly overestimates the release of fumigant. See response to comments # 1 & 25 31 0119 APHIS is concerned about the use of this model in general. EPA had to use a variety of enclosure sizes to estimate by stander risk, and use various assumptions about flux, aeration, and stack height. In reality many of the largest APHISsupervised enclosures are fumigated at no more than 2 or 3 lb/ 1,000 cubic feet.

These large enclosures, however, release much larger quantities of gas than do the smaller enclosures, typically used to fumigate a small proportion of imported commodities at the higher rates of 8 or 9 lb/ 1,000 cubic feet or greater. It would seem to be more appropriate to investigate by stander risk as a function of the quantity of gas introduced into an enclosure, rather than as a function of enclosure size, treatment rates and flux rates. See response to comment # 27 32 0119 APHIS notes that no APHIS supervised enclosure reaches the 250,000 cubic foot size as used in EPA modeling; the largest enclosure supervised by APHIS is 136,000 cubic feet. APHIS also notes that, unlike EPA's model, which evaluates exposure to non active aeration events, all APHIS supervised enclosures are actively aerated using fans, which are required according to the label. See response to comment # 27 33 124 We do not agree with the choice of study and dose selection for the assessment of short term and intermediate methyl bromide exposure and human health risks. We conclude that an estimated NOAEL of 0.5 ppm ( 0.14 mg/ kg day) should be used for assessing short term and intermediate risk of methyl bromide exposure. This NOAEL is estimated by dividing the LOAEL of 5 ppm for decreased responsiveness in dogs observed after 34 exposure days ( Newton 199439) by a factor of ten. The use of a ten fold uncertainty factor to extrapolate from a LOAEL to a NOAEL using these data is consistent with the ten fold uncertainty factor applied by US EPA when extrapolating from a LOAEL to a NOAEL, where a true NOEL ( no observable effect level) is not evident from available data. The Agency has evaluated two subchronic inhalation studies in dogs and has conducted a weight of evidence evaluation in establishing the point of departure for this risk assessment. While in MRID 43386802 unresponsiveness and/ or depressed appearance was reported for 2/ 8 females exposed to 5.3 ppm after 32 days of exposure, the Agency has concluded that these observations are spurious given that no effects were observed after 5 weeks of exposure at 11 ppm.

Moreover, in a non guideline inhalation toxicity study in dogs ( MRID 45722801) no effects were seen at the 5.3 ppm exposure concentration after 6 weeks of exposure. Thus, the Agency reaffirms its conclusions that the NOAEL for these studies should be established at 5 ppm and that no additional uncertainty factor ( UF)

for lack of a NOAEL is required.

34 124 The selection of the chronic inhalation toxicity endpoint also presents a problem.

Although it is understandable that US EPA desires to use the chronic rat study because the study design meets US EPA guidelines for conducting chronic and carcinogenicity inhalation studies in rodents, the scientific evidence supports the determination that dogs are the most sensitive test species to methyl bromide exposure. In 2003, US EPA50 had recommended using the Newton ( 1994) dog study for chronic inhalation exposure risk assessment. This would be an acceptable approach. If US EPA insists on using the basal cell hyperplasia toxicity The Agency has concluded that use of the inhalation chronic toxicity study in rats is appropriate for the chronic inhalation risk assessment. This study is of the appropriate duration for this risk assessment and yield the lowest HEC ( 0.13 pmm) for this risk assessment.

Since a NOAEL for the effects of concern was not identified in this study, the Agency has retained a 3X uncertainty factor ( due to the limited severity of the endpoint in rats51 ( LOAEL = 3 ppm) as the endpoint for chronic inhalation toxicity, then an additional uncertainty should be included ( see discussion below).

This use of the rat endpoint is consistent with CDPR, 52 which used an estimated NOAEL of 0.3 ppm in its 2002 risk assessment for inhalation exposures to methyl bromide. There is also a discrepancy between CDPR and US EPA in the selection of the study, critical endpoint, and dose for chronic dietary risk assessment. In its 2002 risk characterization document for dietary methyl bromide exposure, 53 CDPR selected the 1996 chronic oral dog study conducted by Newton, and a NOAEL of 1.5 ppm for decreased hemoglobin and/ or hematocrit levels in male dogs. US EPA's decision to use a NOAEL of 50 ppm from a rat study is: a)

inconsistent with the widely accepted methodology to select a toxicity endpoint from the more sensitive species when there are adequate toxicity data available in more than one species, b) does not result in the lowest human equivalent concentration, and c) is inconsistent with CDPR, something that US EPA stated it was trying to avoid. We recommend that the more health protective toxicity endpoint and dose level of concern ( 1.5 ppm) from the dog study be used in the dietary exposure risk assessment. effect, HED concluded a 3X UF would be sufficient to extrapolate from the LOAEL to the NOAEL). As it pertains to the Agency's selection of a point of departure for the chronic dietary, the Agency notes that given the conduct of the study ( using fumigated feed) it is not feasible to accurately determine the concentration level at which the animals were exposed.

Given the limitations of this study, the Agency has concluded that it is not appropriate for selection of a point of departure for risk assessment. Consequently,

the Agency has selected the chronic dietary toxicity study in rats to establish a chronic reference dose ( cRfD). In this study, rats were exposed to microencapsulated methyl bromide thus allowing for a more appropriate quantification of the exposure concentration. The Agency also notes that HECs are not calculated for dietary exposures as the commenter implies in part ( b) of its comments. In conclusion, the Agency considers the use of the Chronic Dietary Toxicity Study in Rats in the risk assessment is appropriate and justified.

35 124 We find it particularly troubling that after almost 20 years of intensive evaluation of the health effects and risks of methyl bromide exposures, there is still a data gap for a developmental neurotoxicity study, a key study for evaluating effects on what is probably the most vulnerable subpopulation for methyl bromide toxicity.

We understand that the Registrant has finally initiated the study, however it may take months to years for US EPA to evaluate the findings, validate the results, and decide how the data should be used. When the study results are available, we urge US EPA to release them to the public to allow for further discussion and analysis of methyl bromide toxicity and risk. Furthermore, we request that any changes made to the risk assessment for methyl bromide based on the results of this study be disseminated for public review and comment. An inhalation DNT study has been submitted to the Agency. The Agency has reviewed the study and incorporated into the revised risk assessment. A review of the study is available to the public by contacting the Chemical Review Manager for Methyl Bromide ( Steven Weiss, 703 308 8293 or weiss. steven@ epa. gov). The selected endpoints from the previous risk assessment have not changed based on DNT results. The 10x factor that was previously applied for lack of a DNT has been removed in the current assessment.

36 124 According to both US EPA and CDPR, methyl bromide is highly toxic by both the dermal and ocular routes of exposure ( Toxicity Category I). However, based on a flawed assumption that one or both of these exposure routes would not be expected for humans, a risk assessment for dermal/ ocular exposure was not included in the assessment. There are enough occurrences of spills and whole body exposures described in the methyl bromide toxicity incident reports to warrant a risk determination via dermal/ ocular exposure. In fact, on August 29,

2005, a Modesto Bee newspaper article described a worker who was sprayed in the face and eyes with methyl bromide, the result of faulty equipment. We urge US EPA to include this analysis in the risk assessment, especially for workers.

Furthermore, an aggregate exposure/ risk assessment must include dermal exposures along with all other routes of exposure. The Agency agrees that workers may be exposed via the dermal and inhalation route. Risk mitigation measures ( including PPE) focus on all routes of exposure. Bystander exposure is limited to the inhalation route. However, inhalation is the main route of exposure in terms of the Agency's risk assessment focus. The Agency believes that dermal exposure worker studies and toxicity studies are not feasible or practical. Incident reports such as the one described in August 29, 2005 have been incorporated to the Agency's risk assessment. 37 124 In general, the discussion and justification for the use of uncertainty factors in the methyl bromide risk assessment is difficult to follow and the rationale for selecting uncertainty factors so unclear as to appear as if US EPA's decisions were subjective and arbitrary. We recommend that US EPA adopt the more widely used and recognized methodology in risk assessment for deriving levels of concern for humans from toxicity data. That is, dividing NOAELs by factors of ten ( or factors of three only when adequate data and scientific support are available and a complete discussion provided) to correct for interspecies and intraspecies variation, converting LOAELs to NOAELs, and for addressing adequacy or uncertainty in the database. In the methyl bromide risk assessment, the Agency has used the RfC Methodology developed by the USEPA Office of Research and Development ( ORD) and published in 1994. The RfC methodology applies a dosimetric adjustment that takes into consideration not only the differences in ventilation rate ( MV) but also the physicochemical properties of the inhaled compound, the type of toxicity observed ( e. g. systemic vs. port of entry) and the pharmacokinetic ( PK) but not pharmacodynamic ( PD) differences between animals and humans. As a result, the interspecies UF is reduced from 10X to 3X ( a 3X is retained to account for the pharmacodynamic differences between animals and humans). For a more detailed discussion of the use of the RfC methodology and uncertainty factors the reader is referred to the website http:// cfpub. epa. gov/ ncea/ cfm/ recordisplay. cfm? deid= 7 1993 38 124 In 2001, US EPA concluded that an additional uncertainty factor of ten should be " retained" for methyl bromide 54 as required by the Food Quality Protection Act of 1996 to address weight of evidence considerations and the differential toxicity between infants and children and adults. In 2003, US EPA reversed its decision and concluded that no additional uncertainty factor was warranted because the database is complete. At that time, the only new data to be submitted to US EPA was the Schaefer ( 2002) dog study previously addressed in these comments. In other words, there were no additional or new data available to US EPA specifically addressing developmental neurotoxicity or the differential effects of methyl bromide on the developing fetus, infants, and children. This apparently arbitrary decision was not discussed in the 2005 risk assessment. Nevertheless, if this change remains in the risk assessment, the result is that the developing fetus,

infants, and children will not be afforded additional protection compared to adults when exposed to regulatory levels considered acceptable to US EPA. There are several scientific and public health policy arguments to justify additional protection for children and infants, as presented below. From a regulatory perspective, there is a data gap for a developmental neurotoxicity data. This is a key missing study because the available data from generic developmental toxicity studies do not specifically address the most sensitive endpoint of concern for methyl bromide, which is neurotoxicity. The observed developmental toxicity,

neurotoxicity, and genotoxicity of methyl bromide in experimental studies are other factors, as is the observed difference in sensitivity for the developing fetus and newborn with methyl bromide exposure, when compared to adults.

Furthermore, there is a wide variation in responses to methyl bromide toxicity observed in exposed adults. Therefore, the conventional ten fold uncertainty factor applied for human variability might only account for adult variation, and The Agency notes that a 10X UF for lack of the DNT was retained in the 2005 risk assessment. Since then,

an acceptable DNT has been submitted and reviewed by the Agency. The results of this study have been considered in the revised risk assessment. Based on the availability of this study and the Agency's review,

the 10X UF has been reduced to 1X. not for differences between adults and infants and children. Some, but not all, of the observed differences in sensitivity among fetuses, newborn infants, developing young, and adults are overlapping. Nevertheless, we conclude that the scientific evidence supports that an additional uncertainty factor of ten be used in calculating the target concentrations in air, water, and the diet for methyl bromide that are fully protective of infants and children. Therefore, we recommend that US EPA apply the default 1,000 fold uncertainty factor to the rat study LOAEL in order to define the chronic, non carcinogenicity level of concern for the risk assessment.

39 124 The preliminary risk assessment for chronic inhalation risks defines the level of concern as the LOAEL from a chronic toxicity/ carcinogenicity in rats divided by an uncertainty factor of 100. The universal risk assessment default is to apply a 1,000 fold uncertainty factor when no NOAEL is identified from a toxicity study in animals. However, in its risk assessment US EPA assumes: a) their RfC methodology already accounts for a three fold interspecies difference, and b) the toxicity endpoint, basal cell hyperplasia, is not severe enough effect to warrant the full default uncertainty factor value of ten fold for the extrapolation of a NOAEL from a LOAEL. This logic is flawed on three grounds. First, as mentioned above,

rats are less sensitive to methyl bromide toxicity than dogs. This could mean that the interspecies differences between humans and experimental animals are underestimated. One solution is to use the intermediate term toxicity study results of Newton ( 1994) for chronic toxicity as proposed by US EPA in 2003. However,

the studies in dogs were not designed to be chronic toxicity/ carcinogenicity studies. A more practical solution is to use a larger uncertainty factor in deriving the levels of concern. See response to comment # 34 40 124 Methyl bromide is a direct acting mutagen, especially in in vitro systems. It was found positive in Salmonella typhimurium strains TA 100 and TA 1535,

Escherichia coli strains Sd 4 and WP2hcr, and in Saccharomyces cerevisiae. It also produced a dose dependent induction of sex linked recessive lethality in Drosophila melanogaster. In in vivo assays, methyl bromide was found to cause dominant lethal mutations, an increase of micronuclei, and a dose related increase in the frequency of sister chromatid exchanges in bone marrow. DNA adducts were detected in liver, lung, stomach, and forestomach of rats exposed to high concentration of methyl bromide by inhalation. Although there is no clear evidence of oncogenicity in the currently available chronic/ carcinogenicity studies in animals, CDPR in its Summary of Toxicological Data for Methyl Bromide,

does describe some data that are suggestive of carcinogenic potential. This is a significant biological contradiction. The lack of correlation between the strong mutagenic activity and the largely negative results in cancer bioassays for methyl bromide is significant enough to warrant discussion in the risk assessment as well as some added degree of uncertainty in the results. Finally, there is recent evidence that methyl bromide increases the incidence of prostate cancer in male agricultural workers ( applicators). 62 The Agency's classification of methyl bromide as " not likely to be carcinogenic in humans" fails to encompass a growing body of epidemiology. A recent large prospective cohort study conducted by the National Cancer Institute of 55,332 male pesticide handlers in two states The Agency acknowledges the positive findings in the genotoxicity testing battery. However, no indication of carcinogenesis is evident in the rat or mouse cancer bioassays. The Agency also recognizes the findings from the Agricultural Health Study ( AHS) suggesting a link between prostate cancer and MeBr use. In 2003,

methyl bromide was among a small numbers of pesticides linked with an overall 14% excess of prostate cancer. The study was of 566 new cases of prostate cancers between 1993 and 1999, among 55,332 farmers and commercial pesticide applicators.

Cumulative exposure increased risk to 3 fold for methyl bromide. Lead by the National Cancer Institute ( NCI) and other Federal Agencies, including US EPA,

this study is being followed by a second study that is designed to confirm the previous findings, since a family history of prostate cancer increased risk.

The second study is of men diagnosed with prostate cancer since the completion of the first study. The second study when completed will be published, and so ( Iowa and North Carolina) found use of methyl bromide significantly associated with heightened risk of prostate cancer. The association had an exposure related trend with odds ratios of 2.73 ( 95% CI 1.18, 6.33) and 3.47 ( 95% CI: 1.37, 8.76)

in the two highest exposure categories. 63 Moreover, a study of California farmworkers ( ecological epidemiology study design) found a suggestion of elevated risk of prostate cancer among farmworkers judged to have high exposures to methyl bromide as assessed from pesticide use records for crops,

counties and time periods of work. The Odds Ratio was 1.16 ( 95% CI: 0.77,

1.75). 64 Virtually no discussion of this study is included in the 2005 risk assessment or any of the post 2003 memoranda and documents produced by US EPA staff. This is an important oversight that must be corrected.

The new human evidence linking methyl bromide exposures with increased risk of cancer coupled with the strong evidence of genotoxic and mutagenic potential of methyl bromide supports our determination that EPA needs to conduct a thorough and transparent scientific reassessment of the cancer risk associated with methyl bromide. This assessment should undergo public review by a Scientific Advisory Panel that includes authors of the main epidemiology and ecological studies of methyl bromide cancer risks. Presuming that a risk of cancer is found to be associated with methyl bromide, EPA should conduct a quantitative risk estimate ( Q*) presuming linearity at low exposures. The EPA 2005 Cancer Guidelines Supplemental65 are clear that when infants or children may be exposed, the default assumption is to assume no safe level of exposure, and use a linear low dose extrapolation for mutagens. The EPA assessment of methyl bromide cancer risks will have no credibility or scientific defense if EPA fails to conduct a thorough and transparent review of the cancer risks for methyl bromide consistent with the 2005 Cancer Guidelines. far it reportedly has found no excess risk associated with methyl bromide exposure. At this time, there is no definitive explanation for the differences in these two studies and further investigations are being conducted. When the results of these evaluations become available, the Agency will reevaluate the carcinogenic classification for methyl bromide.

41 124 Chloropicrin is combined with methyl bromide as a warning agent and also as an active ingredient. Chloropicrin is used with methyl bromide in various products at ratios varying from approximately 1: 400 to 1: 1. In California, 4.93 million pounds of chloropicrin were reported used in 1997, compared to 7.38 million pounds of methyl bromide ( Pesticide Use Report, CDPR, 2003). This is particularly relevant in applications to strawberries, for which reported methyl bromide use in 2003 was 3.67 million pounds, and reported chloropicrin use was 3.28 million pounds presumably applied together). US EPA includes a brief discussion of the public health data regarding chloropicrin/ methyl bromide formulations in its risk assessment. However, there is not enough information to adequately convey the impact of combining these two active ingredients on human health. We have provided general comments regarding US EPA's methods to evaluate cumulative risks of the soil fumigants ( see Section 1.5). It is essential that US EPA quantify the health risks of the exposure to the combination of methyl bromide and chloropicrin, including a complete toxicological evaluation of combined toxicity,

exposure, and interaction between chloropicrin and methyl bromide to address the risk of using these formulations. When US EPA completes its assessment for chloropicrin as an active ingredient, we believe that the findings will demonstrate that chloropicrin is much more acutely toxic than methyl bromide ( up to about 50 times more potent as an irritant). Therefore, we believe that the effects of Soil Uses  Phase 5 of The Agency's risk assessment for methyl bromide's soil uses along with the Phase 3 risk assessment for chloropicrin is planned to begin this summer. Since the focus of this comment is on soil uses, a response will be included with the release of Phase 5 risk assessment for methyl bromide's soil uses. chloropicrin, and not methyl bromide will dominate the acute toxicity hazard from the use of chloropicrin/ methyl bromide mixtures. In addition, because the volatility and evaporation rate of chloropicrin is lower than that of methyl bromide, it is likely that chloropicrin persists longer in the environment.

Therefore, measured levels of methyl bromide in ambient air would not accurately predict chloropicrin levels based on the initial mixture ratio. It appears that the longer duration inhalation exposures from use of the combined products could be essentially chloropicrin exposure. We have already alluded to the polymorphism of glutathione S transferase ( GST) enzymes in humans and the role of GST in mediating methyl bromide toxicity. Because GST also activates chloropicrin66 there is clearly a need for US EPA to research the association between the mechanism of action and the cumulative toxicity of these two agents. In looking toward the future for assuring worker and public health and safety related to fumigants, we remain concerned about the absence of regulatory controls specific to chloropicrin, an agent with high acute toxicity, and chloropicrin used in combination with methyl bromide and other fumigants. Some registered methyl bromide products currently contain up to 50% chloropicrin, thereby increasing our concern regarding this agent. Even if methyl bromide use continues, or if its use declines or is phased out altogether, it is likely that some growers will choose to use other fumigant that also utilize chloropicrin as an active ingredient and warning agent. Since products containing chloropicrin are being re evaluated for registration purposes at this time, it seems appropriate and timely that US EPA initiate rule making for chloropicrin, as it is used in combination with other soil fumigants, in particular methyl bromide and Telone. We believe that when assessed together, the combination of the toxicity levels of concern and the exposure risks for residents and workers will require even more stringent mitigation and control measures than the use of either of these chemicals alone. It is quite possible that the data will demonstrate that there is no acceptable means to handle mixtures of methyl bromide and chloropicrin.

42 124 For methyl bromide, there are four distinct sources of exposure in the environment and workplace ( air, water, diet, and direct contact) and three important exposure routes ( inhalation, ingestion, and dermal contact). An appropriate aggregate risk assessment for a single chemical considers all routes of exposure together to characterize short term ( acute), intermediate ( subchronic) and long term ( chronic)

risks. Although the toxicity endpoint often differs in animal studies depending on the route and duration of exposure, for methyl bromide there are common endpoints for which aggregate risks can be estimated. At a minimum, these toxicity endpoints include neurotoxicity, weight loss, and developmental effects.

The sections referring to aggregate risk assessment are so poorly written that is not clear what approach US EPA has taken in deriving aggregate risks for methyl bromide. The document does not present a useful characterization of risks from exposure through multiple exposure routes. Therefore, the risk assessment is incomplete in this regard. Most likely, inhalation risks would dominate an aggregate risk assessment, especially for subchronic and chronic toxicity.

However, dermal exposure is especially critical for acute exposures in workers,

but was completely ignored by US EPA. We recommend the authors revise the The Agency believes that its aggregate assessment is appropriate. It is the Agency's policy not to aggregate worker exposure with dietary exposure.

Nonoccupational exposure to methyl bromide via the dermal route is not expected. In terms of the acute, sub chronic, and chronic aggregate risk, the Agency's estimates that the contribution of dietary and drinking water exposure is negligible (< 14%) in comparison to exposure from bystander inhalation exposure.

Additionally, it should also be noted that in the current assessment neither dietary nor combined dietary and water exposures were of concern. risk assessment document to include a full quantitative analysis of all three exposure routes and all four exposure sources and provide a table showing aggregate risks for acute, subchronic and chronic exposure to methyl bromide.

43 0122 Would OPP consider in all its risk assessments placing the Data Evaluation Reports ( DER) into the Docket for the studies that EPA relies on as the basis for derivation of the reference dose and toxicological assessment? Without access to the underlying data it is impossible for the public to do much more than rely on the OPP risk assessment document. It is a logical impossibility to evaluate the reliability of the risk assessment by relying only on the information provided in the risk assessment itself. Even public access to the EPA DER's would be very helpful, since this provides some additional detail about the study design and findings, along with the expert opinion of EPA technical staff. For copies of DERs not included in the docket, contact the Chemical Review Manager for Methyl Bromide ( Steven Weiss, 703 308 8293 or weiss. steven@ epa. gov).

44 0122 How will EPA consider the toxicity data suggesting that different species have varying sensitivities to methyl bromide, and therefore that humans are likely to also have varying sensitivities? For example, in the developmental toxicity study ( MRID 41580401), pregnant rabbits ( 26 animals/ dose) were exposed by whole body inhalation. In the high dose treatment group ( 80 ppm) 3/ 26 adult exposed rabbits were reported by EPA to exhibit signs of toxicity ( lethargy, ataxia, etc.),

and exhibited a treatment related but not dose related decrease in body weight.

This suggests that there may be individual differences in response to MeBr toxicity, likely mediated through differences in glutathione activity. Thus, even a full 10X adjustment for variation within species is likely inadequate. Has EPA fully considered the implications of glutathione differences across individuals? The Agency has considered the variation that is likely to occur within a species and has therefore retained a 10X UF for the intraspecies variation in keeping with the Agency's policy and standard practices.

45 0122 Acute dietary ( all exposure scenarios) and acute inhalation: How does EPA justify eliminating the 10X FQPA based on the expected receipt of the required inhalation DNT study, without having received and reviewed the study, and given data in two species indicating juveniles are more sensitive than adults? The 10X FQPA is meant to adjust for increased sensitivity of the juvenile, compared with the adult, and not to simply check off whether or not data has been received. How is EPA intending to evaluate and incorporate the findings of the DNT? What will EPA do if the results indicate that juveniles are likely to be more than 10X sensitive than adults to MeBr toxicity? Does EPA intend to simply waive the 10X FQPA factor if a test is received, no matter what the data indicate? See response to comment # 38 46 0122 Acute dietary ( all exposure scenarios) and acute inhalation: How does EPA justify reducing the FQPA factor from 10X to 1X, given the rabbit developmental toxicity data in rabbits ( MRID41580401) used by EPA reports much more severe and irreversible effects in the offspring, compared with the exposed mothers? This study reports that at the high dose ( 80 ppm; 28mg/ kg/ day) mothers experienced toxicity including ataxia, lethargy, decreased apetite, etc., whereas in the exposed offspring toxicity effects included fused vertebrae, failure to develop a gall bladder, and decreased body weight. The number of fused sternebrae in fetallyexposed offspring was statistically significantly increased in the high dose group ( 12.6%) compared to the control group ( 0%). These data demonstrate that the effects in the offspring, fused vertebrae and failure to develop a gall bladder, are considerably more severe than the observations in the mother animals ( lethargy ataxia) at the same dose. Yet, the EPA has determined that both the mothers and In the developmental toxicity study in rabbits both maternal and developmental NOAELs were established at 40 ppm. The Agency concludes from this data that no quantitative sensitivity differences exist between adult and young animals and that use of a 40 ppm NOAEL as a point of departure would be protective of the effects noted in both maternal animals and the developing fetus. As a result, no additional uncertainty factor is required for this risk assessment. the offspring show the same NOAEL ( 40 ppm) and the same LOAEL ( 80 ppm).

In contrast, the FQPA Safety Factor Committee ( June 21, 2001; 0035)

recommended retaining a full 10X FQPA factor based on both the qualitative and quantitative effects in the rabbit study and also " qualitative and quantitative evidence of increased susceptibility following pre and postnatal exposure to methyl bromide in the 2 generation reproduction study in rats" ( June 21, 2001;

0035). A factor of 10X is supported by the reproduction rat study ( MRID 00160477), for which EPA reports a parental NOAEL of 30 ppm, and an offspring NOAEL of 3 ppm.

47 0122 Short and Intermediate term inhalation ( occ and non occ): Why has EPA not considered and discussed the dog study by Newton ( 1994), which has a lower and therefore more protective LOAEL of 5 ppm, than the dog study used by EPA with a NOAEL of 5 ppm? Since there are two available non guideline methyl bromide inhalation studies conducted in dogs ( Newton, 1994; Schaefer, 2002), why has EPA only discussed and evaluated one for this assessment? Both studies have been reviewed by California EPA and the National Academies review in 2000.

The Newton study reports a LOAEL of 5 ppm based on decreased responsiveness in dogs after 34 days of exposure, and does not determine a NOAEL. In its 2003 review, EPA determined that the Newton study was most appropriate to derive a toxicity endpoint for subchronic and chronic inhalation, but changed its determination in its 2005 assessment. Given the importance of this decision,

would EPA explain why it selected the less protective endpoint rather than the more protective value? Why has EPA not selected the more protective study, and then applied a 10X UF to extrapolate from a LOAEL of 5 ppm to a NOAEL of 0.5 ppm, because the study did not identify a true " no effect" level? How does EPA explain the inconsistency between its own earlier determination and this more recent less protective one? How does EPA explain its inconsistency between its more recent assessment and that done by California EPA? See response to comment # 33 48 0122 Short and Intermediate term inhalation ( occ and non occ): How does EPA justify selecting a NOAEL of 5 ppm from the dog study ( MRID 43386802), rather than the lower and therefore more protective NOAEL of 3 ppm ( LOAEL of 30 ppm)

from the multi generation rat reproduction study ( Appendix B)? The nonoccupational HEC value resulting from the offspring in the rat study is 0.54 ppm,

significantly lower than the HEC value derived from the dog study of 1.0 ppm.

The occupational HEC value derived from the rat study is 2.3 ppm, lower than the 4.4 ppm value derived from the dog study ( Appendix B). How does EPA justify choosing the less protective study NOAEL? Has EPA fully considered that pregnant women work in agriculture fields and may be involved in fumigation activities, and in addition children are legally allowed to do agriculture work and may be involved in fumigation activities? Does EPA not think that a NOAEL derived from the offspring of a multigenerational reproduction rat study is as relevant to inhalation risks as a NOAEL derived from an adult dog study? In addition, the selection of the NOAEL from the dog study should also be more protective. The Agency has selected the subchronic inhalation dog study for this risk assessment. This study is of the appropriate duration for these risk assessments.

Though a lower HEC was identified for the offspring toxicity in the multigeneration toxicity study in rats,

this study was not used since the effects noted occurred after a longer period of exposure than the ones considered for these risk assessments 49 0122 Short and Intermediate term inhalation ( occupational and non occupational):

How does EPA resolve the discrepancy between its toxicity profile determination The Agency notes the discrepancy in the document and will change the toxicity profile to reflect its most recent for the dog study ( Appendix A) and its use of the data in the human health inhalation risk assessment? EPA reports that it has used a 5 7 wk inhalation study in dogs ( MRID 43386802) as a basis for its HED/ HEC's. Yet, the Appendix A toxicity profile reports that the NOAEL=< 5ppm and the LOAEL= 5 ppm ( 0.21 mg/ L) based on decreased responsiveness in females. However, in its final Human Health Inhalation Risk Assessment, EPA has reported a NOAEL= 5 ppm and a LOAEL= 10 ppm, based on the same toxicity endpoint of decreased responsiveness in females, and also fecal effects and eye irritation ( MRID 45722801). If EPA did not determine a true NOAEL for females from the study,

why has EPA not used an UF of at least 3X and preferable 10X, as is its normal practice? determination that the 5 ppm is a NOAEL.

50 0122 Subchronic inhalation: How does EPA justify making a determination that findings of unresponsiveness in female dogs exposed to methyl bromide ( MRID 43386802) are not treatment related " because these effects did not show clear dose response relationship" ( Appendix A) when only 4 dogs / sex/ dose were used in the study? Has EPA calculated the power of the study to find a dose response relationship with so few animals? Has EPA considered the clear dose response trend in the 5 wk data, where 2/ 8 dogs at 53.1 ppm showed decreased activity by day 14, 3/ 8 dogs at 102.7 ppm by day 9, and all dogs by sacrifice. Can EPA justify dismissal of toxicity simply because a dose response isn't evident from such a small and underpowered study? Has EPA considered the more likely interpretation that the effect is treatment related and suggests that there are sensitive individuals within the same species that respond variably to MeBr exposure? See response to comment # 33 51 0122 Inhalation endpoints: How does EPA justify reducing the interspecies UF from 10X to 3X, based on pharmacokinetic species extrapolation data that has only been validated in rats, and not in the species used by EPA for its assessment,

rabbits or dogs? EPA has used only a 3X interspecies adjustment for acute,

subchronic and chronic inhalation determinations. However, this reduction has only been validated in rats and mice. EPA used dog and rabbit studies for its inhalation toxicity endpoints. Since there are no data to guide the extrapolation from rodent metabolism to either dogs, rabbits, or humans, how can EPA justify reduction in the protection factor? This is especially unscientific given the evidence from both the dog and rabbit studies ( see points 2 and 7) suggesting that there is significant variability within species, and therefore likely also between species and within humans, in response to MeBr toxicity. California DPR used a 10X interspecies extrapolation factor in its assessment of MeBr, and this was reviewed and supported by the National Academies in its review. See response to question # 37. More specifically, for the case where a dog study is used the effects of concern are systemic. In the case of systemic effects,

the RGDR is defined as the ratio of the blood: gas partition coefficient of the chemical for the test species to humans ( Hb/ g animal/ Hb/ g human). When this ratio is unknown or when the Hb/ g animal > Hb/ g human a default value of 1.0 is used as the RGDR. Thus the calculations used in the risk assessment are consistent with the recommendations put forth in the RfC methodology document available at the website cited in the response to comment # 37 52 0122 Why has EPA failed to fully consider the implications of glutathione polymorphisms in humans as an indication of diverse intraspecies sensitivities?

The National Academies recommended that this issue be more fully considered in its review. Fully understanding the mechanism of toxicity of MeBr will involve consideration of the human polymorphic GST catalysing conjugation following MeBr inhalation. Inter individual variations in xenobiotic metabolism capacities may be due to polymorphisms of the genes coding for the enzymes themselves or of the genes coding for the receptors or transcription factors which regulate the See response to comment # 44 expression of the enzymes. Also, polymorphisms in several regions of genes may cause altered ligand affinity, transactivation activity or expression levels of the receptor subsequently influencing the expression of the downstream target genes. ii A medical case report noted that genotyping of the glutathione S transferase TI enzyme in erthyrocytes characterized a predisposition to the neurotoxic effects of methyl bromide. iii How will OPP consider its evaluation to be complete if these intraspecies variations are not fully considered and discussed, and the magnitude of such variations evaluated?

53 0122 How does EPA intend to incorporate the risks related to continued MeBr use from skin cancer and other illnesses resulting from ozone depletion ? Assessment of health risks under FIFRA must include the full range of such risks, including methyl bromide's adverse effects on public health and the environment through ozone depletion. See, for example, ICF, Inc, " Economic Impact Analysis for Methyl Bromide Allocation in the United States, Chapter 4 ( Revised Draft Report,

Dec. 2, 2003) and Chapter 8 ( Revised Draft Report, Oct. 9, 2003). ( NRDC will submit copies of these two documents to the docket by hand on October 20,

2005.) This report assessed the risks of skin cancer and other illnesses from an assumed schedule of critical use exemptions in the United States for a 13 year period running from 2005 through 2017 ( Chapter 4, p. 45, Exh. 4.1.1). The table shows that the total amount of critical use exemptions in the U. S. assumed over this period is approximately 193 million pounds. ( This figure is derived as follows: The annual exemption percentages presented in Table 4.1.1. total 343 percent of the U. S. 1991 baseline level of methyl bromide production and consumption, which was 25,528 metric tons. Multiplying by 3.43 yields 87,561 metric tonsm or approximately 193 million pounds.) Chapter 8 of the report applies a model developed by ICF, known as the Atmospheric and Health Effects Framework (" AHEF"), to produce estimates of the likely increases in skin cancer mortality, non fatal skin cancer incidence, and cataract incidence resulting from emissions of ozone depleting chemicals, including methyl bromide. Using the AHEF model, the health impacts of methyl bromide exemptions totaling 193 million pounds are estimated. Exhibit 8.3.1 summarizes the results:

o 125 skin cancer deaths ( 83 from cutaneous malignant melanoma and 42 from basal and squamous cell carcinoma);

o 24,221 non fatal skin cancer cases ( 660 from cutaneous malignant melanoma and 23, 561 from basal and squamous cell carcinoma); and o 8,105 cataract cases.

( Exhibit 8.3.1 also presents uncertainty ranges reflecting a variety of factors. For example, the range for skin cancer deaths extends from 9,689 to 38,753. The range for cataract cases extends from 3,242 to 12,968.)

How does EPA intend to incorporate these risks into the methyl bromide risk assessment and comparisons conducted in the cluster rule? The Agency has included an assessment of UV related skin cancer incidents and deaths from methyl bromide uses conducted by the Office of Atmospheric Programs ( OAP) in the methyl bromide docket. Stakeholders are encouraged submit comments on this assessment. The results of this assessment will be considered in conjunction with the current OPP assessment in determining any regulatory action related to methyl bromide.

54 127 Application Rates and Field Sizes for Soil Fumigation  Human Health Risk Assessment, Pages 5 and 37 In the Human Health Risk Assessment, EPA incorrectly assumes a rate of 430 lbs of ai/ acre for pre plant soil fumigation for all uses. However, actual application rates for the vast majority of current uses are considerably lower than that. For example, typical application rates for soil uses See response to comment # 1 are below 200 lb/ acre. Rates above this amount may be used, but only in rare cases. Moreover, beginning in 2005, the vast majority of methyl bromide used in the U. S. will fall under Critical Use Exemptions that are regulated under the Federal Clean Air Act and an international environmental treaty known as the Montreal Protocol. The Methyl Bromide Technical Options Committee, an international technical body that is responsible for reviewing all Critical Use Exemptions recently reviewed and compiled standard use presumptions for Critical Uses. The standard presumption for use rate for soil applications was 20g methyl bromide per m or 178 lbs of methyl bromide per acre in standard mixtures of methyl bromide  chloropicrin ( 67: 33). The vast majority of soil applications in the United States utilize these same 67: 3 3 mixtures. Other mixtures with lower amounts of methyl bromide ( methyl bromide/ chioropicrin 57: 43) are utilized for a significant portion of the remaining soil applications. Because of the standards set by the Methyl Bromide Technical Options Committee, future allocations of Critical Use Exemptions under the Montreal Protocol will be contingent upon a use rate less than 200 lb/ acre. Thus, it is wrong for EPA to assume an application rate of more than double that amount   430 lb/ acre   when assessing future risks of exposure from methyl bromide soil applications.

Similarly, EPA continues to assume a maximum soil application block size of up to 40 acres. However, the typical size of a treated field is 10 acres. Collected data on actual application rates and field sizes in California ( the State with the highest use of methyl bromide) confirm that typical rates are well below EPA assumption.

The MBIP queried the California Pesticide Use Reporting ( PUR) Database for the years 2001 2003 for all soil fumigations in which methyl bromide was used. For this time period, the average application rate for methyl bromide was 140 lb./ acre,

and the median fumigation block size was 9.7 acres. Rates and application block sizes reported by commercial applicators are also consistent with these values.

The PRA should assess risks on the basis of typical rates of application and field sizes for soil fumigation. Correction factors should be utilized to account for the rare use of higher or lower rates.

55 127 Application Rates for Commodity Fumigation   Human Health Risk Assessment, Pages 49 50 EPA continues to assume an application rate for post harvest fumigation of 9 lb/ I 000 ft Actual application rates for the vast majority of commodity fumigation scenarios are much lower, ranging from 0.75 2.5 lb/ 1000 ft These rates are specified in criteria set by the Technology and Economic Assessment Panel ( TEAP), an international technical body affiliated with the Montreal Protocol. The TEAP criteria for post harvest commodity fumigations call for a maximum dosage of 20 g/ m or 1.25 lb/ 1000 ft In California, actual rates of application reported in the PUR database range from 2 to 2.5 lb methyl bromide/ 1000 ft for fresh commodities. Rates for fumigation of structures/ storage areas were reported as 0.75 to 1.5 lb methyl bromide/ 1000 ft As in the case of soil applications, the PRA should be based on typical application rates. Correction factors should be utilized to account for the relatively small fraction of commodity applications are conducted at higher rates. See response to comment # 1 Given the importance of methyl bromide as a crop protection tool, EPNs risk determinations must be accurate. The MBIP urges EPA to consider the data presented here and in user comments submitted on the PRA, and revise its risk assessments to reflect actual use practices and rates of application.

56 127 10X Uncertainty Factor For Lack of DNT Study  Pages 10 12 EPA continues to add a TOX uncertainty factor for the lack of a DNT study in the calculation of the Human Equivalent Concentration ( HEC) for the acute dietary and inhalation exposure scenarios. The MBIP has completed a DNT study, which eliminates the need for the additional lox factor. The HEC used in the PRA increases from 0.033 ppm to 0.33 ppm without the factor. This translates into buffer zone estimates that are dramatically different than those presented in the PRA. An interim report of the in life phase of the DNT study was submitted to EPA on June 8, 2005. A meeting to discuss the preliminary results of the study with EPA staff was held on June 15, 2005. The final report for the study,

including neuropathological evaluations, was submitted to EPA on October 5,

2005. The MBIP urges EPA to review the results of the DNT study and adjust the HEC in PRA to account for the removal of the tox uncertainty factor. See response to comment # 35 57 127 Endpoints for Short and Intermediate Term Inhalation Exposures  Pages 10 11 EPA continues to use a sub chronic inhalation study in dogs   MRID 45722801 ( Schaefer Study)   to derive the endpoint for the short and intermediate term inhalation exposures. As noted in the MBIFs prior comments, the Schaefer Study establishes a NOAEL of 20 ppm. The Agency continues to utilize a different NOAEL   5.3 ppm for male dogs and 10 ppm for female dogs. The MBIP incorporates its previous comments and submissions on this issue ( see Attachments 1 and 2), and reiterates its request that EPA reconsider its position on the NOAEL for this study. The Agency concludes that the effects seen at the 10 and 20 ppm concentrations represent part of the doseresponse curve for the endpoint identified in the study ( i. e., lack of proprioceptive placing). Thus the Agency reaffirms its conclusions regarding the endpoint and point of departure for the risk assessments.

Ecological risks will be addressed later in 2006/ 2007 along with the pre plan soil uses of methyl bromide.

58 127 Bystander Exposure and Risk From Pre Plant Agricultural Use   PERFUM Model  Estimation of Flux Rates   Pages 32 45 The MBJP supports EPA's use of the PERFUM Model to estimate nonoccupational exposures. Using this approach leads to more accurate exposure estimates than applying the ISCST3 model. However, there is a serious technical flaw in the way EPA has calculated the flux rates that were used in the PERFUIVI modeling. Compared to the other soil fumigants, methyl bromide has an extensive array of field studies from which flux rates can be estimated. In the PRA, EPA relies on work done by the California Department of Pesticide Regulation ( CDPR)

to generate composite flux rate profiles ( i. e., flux rate versus time since application) for each type of field application ( see Johnson, 19992; Johnson and Segawa, 2000 Johnson, 2004 This work was not intended to be used for developing flux rate profiles and certain aspects of CDPR's procedure for calculating the profiles are problematic and lead to the overestimation of risk.

Under CDPR's approach, a mean " emission ratio" is estimated for each application type based on all of the field study data. The emission ratio is defined as the percentage of methyl bromide mass that volatilizes in the first 24 hours after the application. This part of the procedure is scientifically sound and acceptable.

CDPR then develops a composite decline profile for methyl bromide that is meant See response to comment # 41 to reflect the proportion of mass that volatilizes over each hour since the start of the application. There is a significant technical flaw in the manner in which EPA is using this aspect of CDPR's analysis, the result of which is an overestimation of buffer zones.

The technical flaw arises from the decline curves developed by CDPR. Those curves were based on the average downwind concentration as opposed to the flux rate. While there is a correlation between these two parameters, it is not perfect.

For example, a higher flux rate is needed during the daytime to achieve the same concentrations near the field as during the nighttime, due to the more conducive dispersion conditions during the daytime.

The problem with using the concentration to develop a decline curve for the flux rate is illustrated by the following example. Using data from a study at Seal Beach, California, CDPR developed a decline curve for the bedded tarp application using the shank ahead method The application occurred on June 24,

1999. The decline curve is reported in Johnson, 1999 ( see Figure A9). Figure 1 below reproduces the decline curve in the original CDPR report and plots the concentrations and flux rates using the mid point of the measurement interval. The concentration values ( triangle symbol) fall very close to the decline curve. This is expected since the concentration values were used to estimate the decline curve.

The flux rate is in different units. Therefore, it was plotted on a separate axis and the peak value at hour 3 was matched to approximately fall on the decline curve.

The second flux rate point falls substantially below the decline curve. The result is that the flux rate estimated with the CDPR decline curve is much higher during the nighttime period than actually occurred during the study.

To illustrate the effect of the poorly specified flux rate decline curve, the MBIP modeled the actual flux rate data from the Seal Beach shank ahead study to compare the results with the composite curve used by EPA. Table 1 summarizes the flux rates for the Seal Beach study and the composite flux rate used by EPA,

both scaled to an application rate of 430 lbs/ acre. Using the actual data, the flux rates are generally higher in the daytime following the application. However,

during the nighttime period, the smoothed flux rates are several fold higher than the actual flux rates. This is problematic and scientifically unsound because the atmosphere is less conducive to dispersion at night, and placing more mass in the nighttime period than actually occurred results in an overestimation of the buffer zones as shown in Figure 2.

Figure 2 presents the 95 percentile buffer distances for both the whole field and maximum concentration approaches using both the datasets summarized in Table 1. The buffer zones using the actual flux rates are about 20% lower than with the smoothed flux rates. The reason, as noted above, is that the smoothed flux rates artificially place more mass in the nighttime period than actually occurred in the volatility study. In the PRA, EPA should correct this issue by either: ( 1) using the actual flux rates in the modeling as was done for all of the other fumigants, or ( 2)

developing a smoothing method based on the flux rates, and not raw concentration values.

59 127 Bystander Exposure and Risk From Pre Plant Agricultural Use   PERFUM Model   Whole Field v. Maximum Concentration Approach  Pages 36 46 See response to comment # 41. These issues have also been considered characterization of the risks for methyl The Human Health Risk Assessment presents results from the PERFUM model based on twenty five combinations of flux and meteorological data for field (

preplant agricultural) applications. The PERFUM model generates two statistical distributions of buffer zones in its output   one based on the maximum concentration approach and the other based on the whole field approach. Both are presented in the PRA. For the maximum concentration approach, the direction from the field with the highest concentration is selected for each simulated day and the values for all of the simulated days are assembled into a distribution.

Essentially, this represents a variability distribution around the maximally exposed individual ( MEI), except that in this case, it is not necessarily known that there is an individual at the maximally exposed location. In fact, given the sparse population near many applications, the odds are against someone being right at the maximum concentration location ( and for all 24 hours after the application as EPA assumed for methyl bromide).

By contrast, the whole field distribution expands upon the maximum concentration distribution by including locations in every direction around the field, not just the direction that produces the maximum concentration. Therefore,

the whole field distribution is essentially a population distribution at the buffer zone. It represents the variability in exposure at the perimeter of the buffer zone.

The debate between using the whole field versus the maximum concentration approach largely falls towards what is meant by probabilistic risk assessment.

EPA recently explained what " probabilistic analysis" means in its Risk Assessment Principals & Practices. There it stated that probabilistic analysis is " a means for describing the uncertainty in risk estimates by characterizing the uncertainty and population variability in the individual steps by probability distributions." Only the whole field approach represents a " population variability." The maximum concentration approach only represents the variability in exposure of a single individual, the ME In fact, the whole purpose of probabilistic risk assessment was to move away from just focusing on the MEl. In other OPP assessments such as for dietary exposure, the percentiles used for regulation define population variability. Furthermore, in the OP cumulative assessment of all exposure pathways, the percentiles also referred to a population variability. For all of these reasons, EPA should utilize the whole field approach in assessing risks of exposure to methyl bromide.

The MBIP believes that exposure should be assessed on the basis of a population,

not a single individual. Although specification of the exposed population is not entirely straightforward given the nature of field fumigation, the PERFUM model defines the population in the most constrained way possible. The population only includes the locations around the buffer zone perimeter. As one moves away from the perimeter, the concentrations fall and defining the population as alternatively being some distance from the field beyond the buffer zone would have resulted in smaller values. Going the other way, it is clearly inappropriate to include those locations inside the buffer zone, as these locations will be protected from exposures while the buffer zone is in place. Therefore, the PERFUM model ( using the whole field approach) defines the population in the most conservative manner possible. bromide and other fumigant chemicals and they will be given due consideration in any regulatory action. 60 127 Bystander Exposures from Greenhouse, Commodity, Industrial Facility and Residential Use   Pages 46 56 The PRA includes an assessment of bystander exposures and risks from industrial uses ( i. e., greenhouse, commodity, industrial and residential applications). The Agency acknowledges that the PERFUM model provides the most refined,

scientifically defensible approach for calculating and characterizing risks.

However, it was unable to utilize the PERFUM mode! for the industrial uses because the version of the model available to EPA was only capable of providing results for pre plant agricultural field scenarios. Thus, by default, the Agency ran the ISCST3 model for these industrial scenarios using data from methyl bromide studies conducted by the California Department of Pesticide Regulation ( CDPR).

The PERFUM model has been updated to include the capability to model these types of application scenarios. PERFUM 2.0 allows mode! ing of raised area and point sources using the PERFUM framework. In the remainder of this section, the MBIP demonstrates how PERFUM 2.0 can be used to estimate buffer zones for the industrial application scenarios using the assumptions made by HED in the PRA. The MBIP urges EPA to consider these results in assessing potential exposures associated with the use of methyl bromide for fumigation of greenhouses, potting soil, commodities, residential buildings and industrial buildings. The Agency revised assessment for commodity uses is now based on the PERFUM model and has incorporated these comments as appropriate.

61 127 In reviewing the EPA modeling files, the MBIP identified several issues:

° EPA's Model Does Not Account for 24 hour Toxicity Averaging Time. The most significant issue with EPA's modeling in the PRA is that it does not account for the 24 hour toxicity averaging time for methyl bromide for the commodity aeration scenarios. For emission periods less than 24 hours ( e. g., 15 minutes or 1 hour), EPA calculated a result for that smaller time period, but did not adjust the result to match the toxicity averaging period of 24 hours. This mismatch results in a 100 fold underestimation of the MOE's ( i. e., overestimation of risk) for the " Commodity Aeration with No Stack" and " Commodity Aeration with Minimal Stack" scenarios.

° EPA Assumes the Wrong Release Height. For the commodity fumigation scenarios, EPA used 3 feet as the release height for all of the building area sources. According to the dimensions of the 250,000 ft building used by EPA, the building should be 25 feet tall given the lOOxlOO' base assumed by EPA.

Therefore the release height does not match the building dimensions ( although CDPR found that lower heights worked better). According to CDPR ( CDPR 1994), using a release height of 3 feet overestimated the concentrations when attempting to model a building fumigation. Therefore, a release height equal to half of the building height ( based on area and volumes used in EPA' s modeling)

was used, to account for the fact that not all of the fumigant will be released from the top of the building.

° EPA Assumptions on Building Downwash are Unexplained and Unwarranted.

EPA used an ISC algorithm for modeling building downwash for the aeration with stack scenario, which is when a nearby building influences the air dispersion from a source by altering the airflow pattern in the vicinity of the source. Inexplicably,

EPA's downwash building height was higher than the stack. There is no See response to comment # 25, 26, 60. In the updated assessment a variety of inputs have been considered.

Complete modeling inputs and output files can be provided for consideration by stakeholders. Much of the factors considered in this comment have been updated based on newly available use information and the modification of the PERFUM model for use in commodity assessments. discussion in the risk assessment of this assumption, and it appears unwarranted.

The MBIP disputes the inclusion of building downwash in the modeling.

62 Although there are several issues to be resolved, the MBIP urges EPA to step back and carefully consider the PERFUM 2.0 approach to estimating potential exposures from building fumigations. The MBIP is committed to work with the Agency to develop an adequate solution to these complex problems so that PERFUM 2.0 can be utilized to improve the accuracy of assessments for these application scenarios. See response to comment # 25, 26, 60 63 127 HUMAN HEALTH RISK ASSESSMENT  Occupational Exposure   Pre Plant and Field Fumigation In the PRA at pages 69 71 and Appendix T, EPA presents the results of its assessment of potential occupational exposures and risks associated with pre plant agricultural field fumigation. In the PRA, all of the data on worker exposures are taken from studies performed in the State of California. Thus, the Agency's entire analysis of risk for these workers rests solely on California exposure data. As a result, it is critical that the exposure data be placed in the historical framework of the use of methyl bromide in California.

The Agency has not done this and has in fact treated all measurements of exposure with absolutely no consideration of the historical context of the studies in which they were reported. This failure to properly interpret the California data is the primary reason for the Agency's conclusion that current exposures pose unacceptable risks. A proper evaluation using corrected data leads to the conclusion that current exposures are safe. The PRA also presents a risk characterization that is fraught with errors. These errors occurred in both the exposure and risk characterization processes. These errors have further obscured the context of the exposures. See response to comment # 41. Stakeholders are also encouraged to submit additional data which better aligns with their current situation which would allow for a more refined risk assessment. At this time, the vast majority of all methyl bromide data have been generated in California so it is not possible to more accurately represent conditions in other geographic regions such as the mid atlantic or upper midwest.

64 127 Overview of Errors and Flaws In EPA's Analysis of Pre plant and Field Fumigation Workers Available data on worker exposure and the proper use of methyl bromide toxicity data indicate that current risks are significantly lower than the estimates given in the PRA. As a threshold issue, the MOE calculations presented in Table 6 of the Agency's " Overview" document and Table 20 in the Revised Human Health Risk Assessment ( June 13, 2005) appear to be incorrect. It appears that the Agency applied a Human Equivalent Concentration ( HEC) of 10 ppm to calculate the MOE for both the acute and the short and intermediate term scenarios. However, this HEC value does not match the HEC concentrations for these occupational scenarios that are presented in Table 2 in the " Overview"

document ( Table 4 in the Revised Human Health Risk Assessment). For acute occupational exposure, the HEC is reported as 30 ppm ( not 10 ppm) and the required MOE is 30. In essence, this is equivalent to an acceptable acute human exposure concentration of 1 ppm. It also appears that the acute and the short and intermediate term exposure concentrations for " All Workers at Field Application"

are in error.

As stated in the introduction of this section, the Agency's analysis is based solely on data from workers in the State of California. Based on that data, the Agency concludes that all of the job classifications evaluated in the assessment fail the 1 ppm risk criterion. However, in California, soil applications are currently being See response to comment # 41 conducted to meet a 210 ppb 24 hour TWA standard. This standard has been set by the California Department of Pesticide Regulation ( CDPR) and is applicable to all workers. The standard has the effect of placing a cap on the exposures that occur in any 8 hour period. The highest amount of exposure that can occur in this shorter period is three times the 24 hour standard or 630 ppb ( 0.63 ppm). Methyl bromide applications in California currently meet this standard. Therefore, EPA should expect that data from California would support a finding that current exposures do not exceed 0.63 ppm, and as a result, that current exposures also will not exceed the higher health criterion of 1 ppm.

Despite the fact that the soil fumigation industry is meeting the more stringent standard, EPA has determined in the PRA that the available data indicate that all seven jobs classifications associated with soil fumigation pose unacceptable risks.

The Agency is led to this conclusion because it has failed to account for current practices that control exposure. The root of this error is the Agency's use of monitoring data that dates back to 1981. Prior to 1992, the standards for exposure were 15 ppm and as a result, levels of exposure above I ppm were permitted in the 1980s. Application practices have changed since the 1 980s and current exposures are lower. Modifications currently in place in California that reduce current exposures include:

° Reduction of the application rates;

° Changes in applications methods ( improved injection designs, rapid closure of injection shank furrows, and separation of tarp cutting and tarp removal processes)

that minimize the amount of methyl bromide that is released;

° Use of high barrier tarps;

° Modification of tractors; and ° Use of ventilation fans in the tractor cabs.

Because the worker monitoring data from the 1990s is more recent and because of the documented changes in engineering practices data from the 1 980s, the studies performed in the 1980s should not be used in the PRA. A second problem with the Agency's analysis is that it has included all of the data from studies of engineering controls where the above technologies have been demonstrated. These data included the " control" data where the technology was not applied. If EPA had limited measurements used in these studies to the data that reflect the current controls, the results would indicate that workers are not exposed to unsafe levels.

While the decision to include monitoring data that do not reflect current practices is the major reason for EPA's finding of unacceptable risk, the PRA also contains a large number of factual errors in the compilation of monitoring data from the California studies. These errors include:

° Errors in the citation of studies;

° Failure to include all of the data in a given study;

° Duplicative citations of the same data;

° Inclusion of studies for pests that are not supported by current labels ( ground squirrels);

° Misapplying data to the wrong job classifications.

These errors are outlined below. In preparing these comments, the MBIP has sought to correct the data and to provide a more accurate characterization of the currently available studies. A corrected data set is presented in Attachment 4.

Aside from these errors, EPA has failed to interpret properly the available monitoring data in several respects. These errors include:

1. EPA does not give equal weight to data from studies from the early 1980s that are not representative of current exposures and data from more recent studies.

2. EPA incorrectly gives equal weight to samples taken with and without controls.

3. EPA incorrectly gives equal weight to short term measurements ( 30 mm. and less in duration) and measurements over an entire working day.

4. EPA assessment fails to consider the impact of reduced application rates and other mitigation measures already in use in California on current exposures.

These points are discussed in detail below.

Finally, this assessment has focused on the impacts of a proper interpretation of the toxicity and exposure for acute risks, specifically whether workers in 2005 will be exposed to levels above 1 ppm 8 h TWA on any given day. The comments have focused on the acute risks because these are the risks that the PRA identified as being of the greatest concern. However, the proper evaluation of the exposure studies described below will also result in lower estimates of short/

intermediateterm and long term exposures. These lower estimates also result in acceptable risks for these toxicological endpoints without the need for respirators.

65 127 Errors and Data Related Issues in the PRA Analysis The MBIP found numerous errors in the data underlying the Agency's analysis.

These errors were not evident in the prior rounds of the error correction phase because the underlying data have only now been made available. Thus, this is the first opportunity that the MBIP has had to discover them.

As more fully detailed below, the errors in the data are numerous. For ease of reference, the errors are organized based on the study names as listed in the bibliography to the PRA ( Appendix C). In the tables provided in Appendix T, 16 studies are listed as contributing data to the PRA ( Field 3, 4, 5, 7, 16, 18, 20, 21,

21, 23, 38, 39, 49, and 50). Three studies have duplicate listings ( Field 22 is also Field 40, Field 38 is also Field 41, and Field 49 is also Field 50). Thus there are actually only 13 named studies, not 16. In addition, as the following indicates, the names on the actual documents do not necessarily match up with the names in the bibliography.

° Field 4. Siemer and Associates, Inc. ( 1992c) AMBI: Shallow Shank Tarped Bed Fumigation Assessment ( Interim Report No. SM924096C, M).

This " study" consists of two reports. The EPA analysis omits data from the second of the two reports. In this analysis these data are included. This adds 19 additional measurements to the database. As discussed below, the missing data also provide information on how commonly used controls reduce worker exposures in the fumigation of beds.

In addition, the data from Siemer and Associates, Inc. ( 1992c) on Shovelman ( Table 4 of the study) were not used in the EPA analysis. The MBIP used these data in the assessment summarized below. Data on the job that EPA labeled as " Plastic Truck Driver" are included in the " Second Driver" job. However, the " Second Driver" appears to be intended to cover workers in vehicles that follow See response to comment # 41 the tractor pulling the methyl bromide injection equipment. These vehicles can include tractors laying tarps and pulling cultipackers, but they do not include the " Plastic Truck Drivers". These drivers bring the tarps to the work site but do not enter the fields. Therefore these workers should not be included in the " Second Driver" job. The data in this study is also reported under Field 39.

° Field 5. Maddy, K.; Lowe, J.; Fredrickson, S. ( 1984) Employee Exposure To Methyl Bromide Used For Ground Squirrel Control: HS 1238. Unpublished study prepared by California Dept. of Food & Agriculture, l3p.

This study reports on exposures that occur from the control of ground squirrels.

The registrants no longer support this use. In addition, the method of application is so different from soil fumigation ( squirting methyl bromide down a burrow by hand) that the data are not a relevant measure of agricultural worker exposures from soil fumigants. The data from this study should not be included in the PRA.

° Field 18. Maddy, K.; Gibbons, D.; Lowe, S.; et al ( 1984) A Study Of the Inhalation Exposure of Workers to Methyl Bromide during Preplant Soil Fumigation ( Shallow Injection) in 1980 and 1981: HS 900. Unpublished study prepared by California Dept. of Food and Agriculture, Div. of Pest Management,

Environmental Protection and Worker Safety, Worker Health and Safety Unit.

37p.

The name of the studies that provide the data listed under Field 18a e in the Tables in Appendix I is incorrectly listed in Appendix C. The data in Field 18 are taken from three sources. Two, and possibly three of these sources are from studies other than the one cited for Field 18. The first set of data listed as 18a comes from a 1982 Study by Maddy ( A Study of the Inhalation Exposure of Workers to Methyl Bromide During Preplant Soil Fumigants ( Shallow injection)

in 1980 and 1981.) The second set of data, listed as I 8b comes from an unreferenced table described as " preliminary results   for review and discussion only." The table does not include any supporting information on the origin of the data or the date that it was collected. The third set of data, listed as 1 8c e, is a series of internal studies from TriCal Inc. collected by Donald Richmond of the State of California. This set of data is presented later as part of the data entered as Field 49.

The data from the first two sources ( labeled 1 8a and 1 8b) are used to evaluate the Driver, Co pilot, and Shovelman job classifications. The data from all three sources ( labeled 1 8a, 1 8b, 1 8c, 1 8d, and 1 8e) are used in the determination of " All Workers at Field Application." In the corrected analysis presented below,

only the data from the first source is used. The data from the second source, the 1984 table, should not be used since the table lacks any description on where the data originates, how it was collected, and how the values were calculated. Finally these data are described as preliminary. The data from the third source appear to be a subset of the data presented in Field 49 and are entered under that Field number.

° Field 19. Gillis M. Becker ( 1994 c) Report on New High Barrier Film Evaluation Studies, TC233 1, TC233 2 and TC233 3, TRICAL Inc.

This study is not listed in Appendix C but is listed in Appendix T.

° Field 20. TriCal, Inc. ( 1993a) Tarp Removal Worker Exposure Vol. 1 2 ( TC211).

EPA used a measurement of Tarp Puller exposure that reflects a technical problem in the field and is not representative of typical tarp remover exposures. This data point should be removed from EPA analysis.

° Field 22 ( Also listed as Field 40). Siemer and Associates, Inc. ( 1993b) Deep Shank, Nontarped Fumigation Mitigation of Methyl Bromide Worker Exposure and Offsite Drift ( Interim Report No. SM934104, 1 2, Report No.

SM934104.2 1, Vol. 1 2).

Data from this study are listed under Fields 22 and 40 in the RED. Thus the data are double counted in the EPA analysis. In the MBIP's corrected analysis, these data are entered only once under the heading of Field 22.

° Field 39. Siemer and Associates, Inc. ( 1992b) Nontarp Deep Injection for Measurement of Methyl Bromide Exposure to the Applicator, Applicator Assistant, and Cultipacker Tractor Driver ( Interim Report No. SM924096B).

This Field is mislabeled in Appendix C. The data for Field 39 actually comes from the study, Siemer and Associates, Inc. ( 1992c) AMBI: Shallow Shank Tarped Bed Fumigation Assessment ( Interim Report No. SM924096C, M). The data from Siemer and Associates, Inc ( 1992c) is already entered into the PRA analysis under Field 4.

In the corrected analysis presented below, the data from Siemer and Associated,

Inc ( 1 992c) is removed from the Field 39 entry and is replaced with the data from Siemer and Associates, Inc. ( 1992b).

° Field 49 ( Also listed as Field 50). TriCal, Inc. ( 1987) Response/ California Notice 87 5: Risk Assessment/ Methyl Bromide. DPN 123 099. Record No. 64748 to 64753.

Field 49 is incorrectly listed in Appendix C. It is actually an interoffice memo dated 1981 ( Great Lakes Chemical Corporation, ( 1981) Interoffice Memorandum From D. L. McAllister to R. J. McKeand, Subject Methyl Bromide   Applicator Exposures) and is composed of a series of data sheets on worker monitoring.

A number of errors were identified in the transcription of the data. The EPA analysis failed to use data labeled " Swamper." This is an alternative name for copilot These data have been included in the corrected data as part of the co pilot data. The data on tarp cutters was also omitted. These data are also included in the MBIFs analysis.

Field 50 is also incorrectly listed in Appendix C and differs from the TriCal Inc.

( 1987) reference. The data actually come from a document defined as " Results of Worker Monitoring of Deep Tarpless Application at Various Sites in CA, by Rick Stange Sponsored by TriCal, 04/ 03/ 1986."

A measurement point from a grab sample taken when an applicator fixed a connection is listed as an applicator exposure. This measurement is too short a duration ( 1 minute) to be indicative of the 8 hr TWA exposures. This data point should not be used EPA's analysis.

Finally it is unclear why a " Shovelman" exposure is reported when the study is described as Tarpless.

° Additional Errors  Miscellaneous In Appendix T, EPA Lists the same data from Field 4 under both the " Second Tractor Driver" and " Irrigation Worker" job classifications. This is incorrect. In the MBIP's reanalysis, the data have been listed under " Irrigation Worker."

66 Temporal Trends in Worker Exposures Due to Improved Technology The available monitoring data on worker exposure levels present a strong case that technological changes in California have greatly reduced exposure to methyl bromide over the period of 1981 to 1994. The following figure presents the maximum values for each of the seven job classifications as given by each of the available monitoring studies. Where a study demonstrates the use of a technology that is now in common use in California, only the data from the samples that reflect the use of that technology are presented. Thus, in Field 4 only data from the fields that used the rapid closure technology ( closing shoes followed by a roller that compacts the soil prior to tarp placement) are used'. In Field 23 only data from the fields treated with a noble plow are used. As the figure shows there is a strong trend of reduced exposure over time. Data from the early 1990s indicates that when controls are used, most of the jobs are below 1 ppm. This finding is expected because CDPR lowered the permissible exposure to Methyl Bromide to a 24 hour TWA of 210 ppb in the early 1990' s. See response to comment # 41 67 127 Changes in Engineering and Practice In the 1980s a number of engineering practices in soil fumigation were modified to reduce exposures. Some of these practices were captured in s guidance on the use of methyl bromide When methyl bromide is injected into soil the injection is performed by a series of injections at the bottom of the shanks of plows pulled behind a tractor. The tractor pulls the application equipment across a field. Once the equipment reached the end of the field, the plows and injection equipment must be raised to allow the tractor to swing around and begin plowing the next section of the field. In the early 1980s the practice was to shut off the supply of methyl bromide into the injection equipment prior to raising the plows. This was done using a " shut off valve." This prevented the spraying of methyl bromide into the air when the injection shanks were in a raised position. However, a substantial amount of methyl bromide remained in the tubes leading down to the shanks. This residual methyl bromide in the injection equipment would escape during the time the tractor repositioned itself and began plowing the next portion of the field. These releases occurred each time the tractor reached the end of the field and resulted in increased exposures to all employees at the site.

In the mid 1980s, the injection equipment was modified to allow compressed air to flush the methyl bromide from the shanks prior to lifting the shanks from the soil. This flushing was performed after the cutoff valve was closed and before the shanks were raised from the soil. As a result, methyl bromide is not released to the air.

A second modification that also occurred during this period was the requirement that engine fans of the tractor blow back towards the injection equipment. Prior to this modification certain types of tractors used to pull the injection equipment ( Caterpillar tractors) had fans that pulled air from the rear of the tractor over the engine and blew the air out of the front of the vehicle. This practice " pulled" air See response to comment # 41 over the injection equipment and carried the methyl bromide towards the driver and co pilot. In the mid 1980s, this mechanism of exposure was identified and the tractors were modified to blow air from the front of the tractor back across the engine to the rear of the tractor. This caused any methyl bromide released from the injection equipment to be blown away from the driver and co pilot and resulted in reduced exposures to these jobs.

In addition to these changes, in the early 1 990s CDPR required the use of tarps with low permeability to Methyl Bromide' Specifically these regulations require that tarps used for methyl bromide soil fumigations in California shall have a permeability factor between 5 and 8 milliliters per hour per square meter per 1000 ppm of methyl bromide at 30 degrees Celsius and be approved by the Department.

Tarps used prior to this time had much higher permeability and as a result general air levels at treated fields were higher in the 1980s than after the 1990s.

68 127 Decreased Application Rates will Reduce Occupational Exposures The existing monitoring data are all more than 12 years old. Typical application rates of Methyl Bromide are now significantly lower then the levels in the monitoring studies performed in the 1980s and 1990s. As discussed in Section II above, typical rate for soil fumigation are now below 200 lb/ acre. As the data in Attachment 4 shows, almost all of the monitoring data utilized by EPA in the PRA reflects usage rates from greater than 200 lbs/ acre and includes data from fields where the application rates were as high as 400 lbs/ acre.

The role of application rates as a factor in methyl bromide exposure has been discussed by a number of authors ( Maddy et al. Abdalla et al.' and higher levels of exposure are believed to occur when application rates are high. Quantitative evidence of the role of application rate and air concentrations can be seen in the monitoring data.

In Field 23 ( Siemer and Associates, Inc., 1992a), First Tractor Drivers, Co Pilots,

and Shovelman were monitored. The purpose of the study was to demonstrate the reduction of exposure from the use of the Nobel plow. However, as the following three figures show the exposures to all three jobs declines as the application rates decline. This decline occurs for both types of plow. These data show that as the application rates approach 200 lbs/ acre, the measured exposures to methyl bromide drop to less than 0.5 ppm for all three jobs.

Similar patterns can be seen in other studies. The finding that concentrations drop with application rates indicates that the current use rates of methyl bromide result in lower exposures than the studies from the 1980s and 1990s indicate. Since the studies from the 1990s indicate that uses in the range of 200 400 lbs can meet the current 1 ppm criterion, future levels of exposure are likely to be well below 1 ppm. See response to comment # 41 69 127 Use of Short Term Data to Predict 8 hour TWA In the PRA, EPA has assumed that the air concentrations reported by the authors of the various studies can be assumed to be predictors of 8 hr TWA. This is incorrect. The range of sampling times for these measurements has ranged from less than 30 minutes up to six hours with the majority of the samples less than three hours in duration. Since short term sampling is taken at those times where the potential for exposure is the highest, the values reported may be higher than See response to comment # 41 the 8 hour TWA exposure received by the worker. This occurs for two reasons.

First, if the sample was taken over a period of relatively high exposure ( correction of a malfunction of a piece of equipment) then the measurement could over estimate the average exposure during the time of injection.

Second, any measure of exposure taken during the time of actual injection of methyl bromide will overestimate the 8 hr TWA, since methyl bromide is not injected for 8 hours a day. Soil fumigation requires that large pieces of equipment be transported to the site of the soil fumigation. Once there, equipment preparation and set up requires approximately 1  1.5 hours. Application of methyl bromide must cease during lunch. At the end of the day shut down and removal processes require approximately 1 hour. Thus in a nine hour working day only 5.5 hours of injection occurs ( personal communication Tom Dufala, 2005).

Evidence that applications occur for less than 8 h per day can be seen in the sampling times from a number of the recent surveys where workers were monitored for an entire injection period. The durations in these surveys are typically in the range of 4 5 hours. Additional evidence for a 5.5 h injection time is seen in a 1998 study that investigated the temporal patterns of worker exposure in the methyl bromide soil fumigation industry ( MBIP, 1998' s). In this study, data on the number of acres treated by each of 47 workers in each month of a 1 2

month period ( May 1997 April 1998) was analyzed. The time necessary to treat an acre and the assumption the injection time will be limited to 5.5 hrs per day were used to solve for how many days in the month the worker was injecting methyl bromide. In every case, the total number of acres treated in a given month by a worker did not exceed the number that could be treated in a 5.5 hr workday ( given a 5 6 day workweek).

For both of these reasons the finding that a specific sample is greater than 1 ppm cannot be taken as evidence that the worker has had an 8 hour TWA exposure of greater than 1 ppm.

70 127 Comments on Specific Job Classifications in the PRA EPA establishes seven job classifications in its assessment of soil fumigation exposures. The following section presents the specific comments on these seven job classifications. As the comments indicate, two of the jobs classes ( second tractor, and irrigation worker) should be dropped. As the comments indicate MIBP believes that the available data indicate that the current exposures for the remaining five jobs are not likely to exceed 1 ppm.

° First Tractor Driver There is a large amount of data for the First Tractor Driver or Applicator. As data on historical trends indicates, the exposures to methyl bromide for this job have been reduced to levels below 1 ppm in the early 1990s. This reduction was achieved by improved injection methods, use of high barrier films, modifications in the engine fans, and the introduction of ventilation fans in the driver's cabin.

Moreover, current levels are expected to be lower than the levels in the studies from the early 1 990s since application rates have declined over the last 10 years.

° Co pilot The co pilot's exposure tends to be more variable than the driver's reflecting the wider range of tasks performed by the co pilot. However, the co pilots exposures See response to comment # 41 have been reduced over time by the use of better injection methodologies,

improved barrier films, and modifications in the engine fans of the tractors. As in the case of the tractor driver and applicator, current levels are expected to be lower than the levels in the studies from the early 1990s since application rates have declined over the last 10 years.

° Shovelman Exposures to these workers are controlled by improved injection techniques and by use of high barrier films. Current levels are expected to be lower than the levels in the studies from the early 1 990s since application rates have declined over the last 10 years.

° Tarp Cutter and Tarp Remover Tarp cutters and tarp removers have a potential for exposure that is potentially increased by the use of high barrier films ( tmpping more methyl bromide).

However as the study listed as Field 20 indicates, these exposures can be greatly minimized if the cutting of the tarps is performed on one day and the tarps are removed on a subsequent day. Cutting the tarps allows the residual methyl bromide to dissipate prior to removal of the tarps. Current levels are expected to be lower than the levels in the studies from the early 1990s since application rates have declined over the last 10 years.

° Second Tractor Driver MBIP recommends that EPA drop this classification for the following reasons.

First, the Pipe Layer and Pipe Tractor workers are listed under the " Irrigation Workers" job category and should not be considered under this category. Second,

the classification includes measurements at are no longer common practice. The reference to " Tarp Layer" occurs in the study listed as " Field 3". In this study, a second tractor applied the tarp following the tractor that injected the Methyl Bromide. This practice is not common today. The reference to " Cultipacker Driver" occurs in the study listed as " Field 22". In this study, a second tractor pulls a cultipacker that closes the soil furrows following injection of Methyl Bromide. Again this practice is not common today. Under current practices, a single tractor pulls equipment that both injects the Methyl Bromide, and lays the tarp in one operation.

Third, the remaining workers, " Drip Tape", and " Plastic Truck Driver" represent two very different jobs. The " Drip Tape Layer" is the driver of a tractor lays a drip line, or drip tape, in the field prior to the injection of the Methyl Bromide and tarp placement. The " Plastic Truck Driver" delivers the rolls of plastic tarp to the tractor but does not enter the treated field. The differences between these two tasks makes the grouping useless in characterizing occupational exposures.

Fourth, there is only a single measurement for each of the categories. This is too limited a data set to reach any conclusions.

Finally, the various jobs occur at locations that are farther from the soil injection process than the locations of the First Tractor Driver, Co pilot, and Shovelman and are likely to have exposures that are lower than those jobs. Mitigations that protect these three exposure categories will also protect the more distant workers.

° Irrigation Worker The irrigation workers are the pipe layers and the pipe tractor drivers. Data on these workers comes from two studies of raised bed tarped applications ( Fields 4 and 22). These workers were involved in placing water on top of the tarp as a means of forcing the tarp to remain on the ground. In these instances, the tarp remains on the field as mulch. This practice is not commonly performed today.

Because of this change in practices there is no need to evaluate this job classification. 71 127 Overall Conclusions on Occupation Exposures for Pre plant Soil Fumigation In short, the available data on methyl bromide exposures resulting from soil fumigation indicate that the current exposures are significantly lower than the estimates given in the PRA. The MBIP urges EPA to take the foregoing comments into account and reconsider its conclusions on potential occupational risks from soil applications. See response to comment # 41 72 127 Acute exposure The Agency identified a potential acute risk concern for avian species. Exposure modeling was performed using the ISCST3 model and risk assessments performed. Under these conditions, the Agency showed that the acute inhalation risks to birds do not exceed even the lowest of the LOCs, including endangered species. The avian acute RQ was 0.03. Based on the conservative exposure concentrations generated by the ISCST3 model, conducting acute inhalation testing in avian species is considered a waste of animal resources and the study requirement should be waived. The avian inhalation risk assessment is based on extrapolation from mammals. The extrapolation uses acute oral data for mammals and birds, mammal inhalation data, and a mammal to bird conversion factor. Acute avian inhalation data will reduce any uncertainty associated with this extrapolation.

73 127 Chronic exposure In its risk assessment, the Agency indicated that a chronic avian inhalation study " will enable the Agency to address chronic exposure to birds". The Agency concern relates to the potential for wild birds to be exposed repeatedly as a result of treatment of multiple fields over multiple days in the birds' home range or territory.

Chronic ( long term) exposure testing of avian species is covered by guideline OPPTS 850.2300, Avian Reproduction study. This data requirement is for assessing dietary risk. The study design entails initial exposure of adult male and females birds for a period of 10 weeks. During that period, the light cycle is gradually increased ( photostimulation) to induce egg laying. Any significant stress or disruption to the birds would have significant impact on the study. For inhalation exposure, the birds would need to be moved each day to confined cages within the inhalation chamber. Such movement and confinement alone would significantly stress the birds leading to deficits in body weight, food consumption and survival. Addition of chemical exposure would most likely add to the stress on the birds. Stress also may lead to production of infertile eggs.

The second phase of the study is the egg laying phase in which eggs are collected for at least 10 weeks, incubated and hatched. OPPTS 850.2300 specifically states that " taking of body weights during egg laying is discouraged because of possible adverse effects on egg production." During the egg laying phase, the physical handling and placement of the birds into the inhalation chambers alone would be expected to lead to ruptured yolks and broken eggs within the female reproductive tract and ultimately lead to death of those birds.

Clearly, long term exposure of avian species is not a practical consideration. No meaningful results would be achieved given the way the study is required to be designed, and there would be no scientific benefit to running it. In short, it would amount to a waste of test animals and resources. As an aside, it also is evident that there are no laboratories equipped to conduct long term avian inhalation studies yet alone attempt a reproductive study by this route of exposure. EFED envisions an inhalation study longer than the typical ( e. g., mammal) acute study ( 4 hours), not a full reproduction study. 74 ( EFED) 127 Terrestrial Risks  Risks to Non Target Terrestrial Plants   Page 28 The Agency has requested that terrestrial plant guideline toxicity data are needed to evaluate risks to non target plants off site. The terrestrial plant guideline studies are designed to evaluate the effect of pesticide products on seedling emergence ( 850.4100) and vegetative vigor ( 850.4150). The general concern is related to either overspray or spray drift of pesticide products from the treated area.

Methyl bromide is directly injected/ applied to field areas that are tarped. The treated area is defined so that off site applications will not occur.

The seedling emergence study is not appropriate for methyl bromide because the method of application is such that overspray and/ or drift will not occur in nontarget areas.

The vegetative vigor study is designed to evaluate phytotoxicity from direct spraying on nontarget plants. Generally several concentrations are used spanning the field application rate and level above and below that rate. Methyl bromide is not directly applied to plants. There is no evidence that methyl bromide vapors would plate on plant surfaces in areas outside of the treated area. Thus, this study is not appropriate to methyl bromide and its requirement must be reconsidered. Seedling emergence and vegetative vigor study protocols have been submitted by another registrant for another fumigant. The goal is to evaluate the toxicity of the volatilized vapors to plants. Protocols for methyl bromide should also be submitted.

75 ( EFED) 127 Aquatic Risks  Page 29 On page 29 of the " Overview of the Preliminary Methyl Bromide Risk Assessment ( July 13, 2005)" it is stated that: Acute and chronic LOCs for freshwater fish are not exceeded, but the analysis is based on supplemental data ( acute) and on open literature ( chronic) only. Core acute and chronic fish data on methyl bromide are needed to more fully evaluate risk to fish.

LOCs for aquatic plants are not exceeded based on available data, but additional toxicity data are needed to complete this assessment.

Although these statements appear in the ` Revised Draft Methyl Bromide Environmental Fate and Ecological Risk Assessment following the review of 30

Day Error Correction Comments ( June 6, 2005)', it is important to note that the document also states in the Executive Summary age 4 of 92) that:

Toxicity databases for acute exposure of mammals, birds, fish, aquatic invertebrates and algae and chronic exposure of mammals and fish are adequate to estimate risk using a RQ approach."

The MBIP concurs with the conclusion that the current databases above are adequate. Conducting further testing would not be fruitful or relevant to potential environmental exposures related to the actual uses of methyl bromide.

The Environmental Fate and Ecological Risk Assessment states that " the Henry's law constant of 744 Pa m3/ mol suggests that it will be volatized from surface water, thus chronic exposure to methyl bromide is expected to be low." Because of the volatility of methyl bromide from water, artificial test systems were developed to permit evaluation of short term exposures of aquatic organisms to methyl bromide.