Following this future species specific analysis, a determination that there is a likelihood of potential impact to a listed species or its critical habitat may result in: limitations on the use of sodium chlorate, other measures to mitigate any potential impact; or consultations with the Fish and Wildlife Service or the National Marine Fisheries Service as necessary. If the Agency determines use of sodium chlorate " may affect" listed species or their designated critical habitat, EPA will employ the provisions in the Services regulations ( 50 CFR Part 402). Until that species specific analysis is completed, the risk mitigation measures being implemented through this RED will reduce the likelihood that endangered and threatened species may be exposed to sodium chlorate at levels of concern. EPA is not requiring specific sodium chlorate label language at the present time relative to threatened and endangered species. If, in the future, specific measures are necessary for the protection of listed species, the Agency will implement them through the Endangered Species Protection Program. 44 D. Tolerance Reassessment Summary Table 24 summarizes the reassessment of the sodium chlorate tolerance exemptions pending a safety finding can be made for sodium chlorite. 40 CFR must be updated to reflect the tolerance exemptions in the table below. The tolerance exemptions listed in 40 CFR must be reorganized in order to: ( i) incorporate the recommendations made by the Agency concerning the sodium chlorate residues of concern that need to be regulated for plant and animal commodities; ( ii) include tolerance exemptions that are needed to cover sodium chlorate residues of concern in/ on the raw agricultural commodities and processed commodities of rotational crops; and ( iii) conform with the requirements of FQPA.

Table 24. Tolerance Reassessment Summary for Sodium Chlorate Listed under 40 CFR 180.1020( a)

Commodity Current Tolerance ( ppm) Tolerance Reassessment ( ppm) [ Correct Definition] Comments Beans, dry, edible Exempt Exempt [ Bean, dry, seed]

Corn, fodder Exempt Corn, forage Exempt Corn, grain Exempt Exempt [ Corn, field, stover; Corn, field, forage; Corn, field, grain; Corn, sweet, stover; Corn, pop, stover; Corn, pop, grain; Corn, sweet, forage]

Cottonseed Exempt Exempt [ Cotton, undelinted seed]

Flaxseed Exempt Exempt [ Flax, seed]

Flax, straw Exempt Revoke Flax straw is not listed in Table 1 of OPPTS 860.1000 Guar beans Exempt Exempt [ Guar, seed]

Peas, southern Exempt Exempt [ Pea, southern, seed]

Potatoes Exempt Exempt [ Potato]

Peppers, chili Exempt Exempt [ Pepper, nonbell]

Rice Exempt Rice, straw Exempt Exempt [ Rice, grain; Rice, straw]

Safflower, grain Exempt Exempt [ Safflower, seed]

Sorghum, grain Exempt Sorghum, fodder Exempt Sorghum, forage Exempt Exempt [ Sorghum grain, grain; Sorghum, grain, stover; Sorghum, grain, forage]

Soybeans Exempt Exempt [ Soybean, seed] 45 Table 24. Tolerance Reassessment Summary for Sodium Chlorate Listed under 40 CFR 180.1020( a)

Sunflower seed Exempt Exempt [ Sunflower, seed]

Wheat None Exempt [ Wheat, grain]

Listed under 40 CFR 180.1020( b)

Wheat Exempt Revoke [ Wheat, grain] Time limited exemption currently expires on 12/ 31// 2006 Existing Exemptions Sodium chlorate is currently registered for preharvest and foliar applications as a defoliant or desiccant to the following food/ feed crops: beans, corn, cotton, flax, guar, chili peppers, potatoes, rice, safflower, sorghum ( grain), southern peas ( i. e., cowpeas), soybeans, and sunflowers.

Sodium chlorate exemptions under 40 CFR 180.1020( a) from the requirement of a tolerance should be amended as follows to: ( 1) specify defoliant and desiccant use only, ( 2) specify use on crops rather than raw agricultural commodities, and ( 3) include an exemption for wheat ( grain).

40 CFR 180.1020( a) Sodium chlorate is exempt from the requirement of a tolerance for residues when used as a defoliant or desiccant in accordance with good agricultural practice on the following crops: Bean ( dry, seed), Corn ( field, stover), Corn ( field, forage), Corn ( field, grain), Corn ( sweet, stover), Corn ( pop, stover), Corn ( pop, grain); Corn ( sweet, forage), Cotton ( undilented seed), Flax ( seed), Guar ( seed), Peas ( southern, seed), Peppers ( nonbell), Potatoes, Rice ( grain), Rice ( straw), Safflower ( seed), Sorghum ( grain, grain), Sorghum ( grain, stover), Sorghum ( grain, forage), Soybean ( seed), and Sunflower ( seed).

Under 40 CFR 180.1020( b), a time limited exemption from the requirement of a tolerance is established for residues of the defoliant/ desiccant in connection with use of the pesticide under section 18 emergency exemptions granted by EPA. This exemption was granted for wheat and expires 12/ 31/ 06. The use of sodium chlorate on wheat is also addressed herein with the intention to convert the time limited exemption status to a permanent exemption from the requirement of a tolerance under 40 CFR. 1020 ( a). The proposed use rate is for a single application of sodium chlorate to wheat at 6 lbs ai/ A with a 3 day PHI.

Needed Exemptions Sodium chlorate ( 873301) as an inert ingredient in herbicide formulation products can be applied professionally to agricultural ( corn, guava, macadamia nuts, sorghum grain, sugarcane, wheat), commercial ( non agricultural), and residential sites. These conventional pesticide products contain < 1 % sodium chlorate and can be applied at rates no greater than 0.07 lb ( as sodium chlorate) per acre. 46 Potassium chlorate ( 900583) as an inert ingredient in fungicide products can be applied in poultry premises. These conventional pesticide products contain < 20% potassium chlorate and can be applied at rates not greater than 0.01 lb ( as potassium chlorate) per 500 ft3. See Table 25 below for the tolerance exemptions needed for sodium chlorate.

Table 25. Tolerance Exemptions Needed for sodium chlorate Tolerance Exemption Expression PC Code CAS Reg No. 40 CFR § Use ( Pesticidal) List Classification Sodium chlorate 873301 7775 09 9 180.920 1 Stabilizer 3 Potassium chlorate 900583 3811 04 9 180.930 2 Oxidizer 3 1. Residues listed in 40 CFR § 180.920 [ formerly 40 CFR § 180.100( d)] are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert ( or occasionally active) ingredients in pesticide formulations applied to growing crops only. 2. Residues listed in 40 CFR § 180.930 [ formerly 40 CFR § 180.100( e)] are exempted from the requirement of a tolerance when used in accordance with good agricultural practice as inert ( or occasionally active) ingredients in pesticide formulations applied to animals.

Codex/ International Harmonization There are no Codex maximum residue limits ( MRLs) for sodium chlorate.

E. Regulatory Rationale The following is a summary of the rationale for managing risks associated with the use of sodium chlorate for sodium chlorate products to be eligible for reregistration. Where labelling revisions are warranted, specific language is set forth in Table 28 of Section V.

1. Human Health Risk Management a. Dietary ( Food) Risk Mitigation Acute Dietary ( Food) Risk No acute dietary endpoint was selected for sodium chlorate, because effects attributable to a single dose were not seen in the available data. Therefore, dietary acute risk is not of concern to the Agency, and no mitigation measures are required to address acute risk.

Chronic Dietary ( Food) Risk The chronic dietary risk assessment for food only is below the Agency's level of concern ( LOC) for the general US population and all population subgroups. The most highly exposed population subgroup, children 1 2 years of age, was at 28% of the chronic Population Adjusted Dose ( cPAD). Since this is less than 100% of the cPAD, no mitigation is needed. 47 b. Residential Risk Mitigation All residential ( non occupational) handler and post application risk estimates for inorganic chlorates, as active or inert ingredients in conventional pesticide products used in residential environments, are below the Agency's LOC ( i. e., MOEs are greater than the LOC of 100). The handler inhalation MOEs ranged from 370 to 710,000. The post application combined MOE ( for inert ingredients) was 23,000 for all potential routes of exposure to children; therefore, no residential mitigation is necessary.

c. Aggregate Risk Mitigation As discussed in Section III of this RED, aggregate risk refers to the combined risk from food, drinking water, and residential exposures. Aggregate risk can result from one time ( acute), short term and/ or chronic exposures.

Acute Aggregate Risk For sodium chlorate, acute aggregate risk was not assessed, because effects attributable to a single dose were not seen in the available data. Therefore, acute aggregate risk is not of concern to the Agency.

Short Term Aggregate Risk Short term aggregate risk was quantitatively assessed for adults only, using the highest exposure scenario ( inhalation exposure while applying granules by hand) resulting in an MOE of 324. Short term aggregate risk for children was qualitatively assessed and not of concern to the Agency because the short term residential risk to children from the use of sodium chlorate as an inert is minimal ( MOE of 23,000). All short term aggregate risks are below the Agency's LOC ( i. e., MOEs are greater than 100); therefore, no mitigation is necessary.

Chronic Aggregate Risk Since no chronic residential ( non dietary) exposure scenarios have been identified for sodium chlorate, the chronic aggregate risk assessment considers exposure only through food and drinking water. The Agency believes there is no chronic risk of concern, for the US general population or any subpopulation group, for the reasons described below.

The chronic dietary ( water only) risk assessment for chlorate in drinking water, using the highest annual average concentration from ICR data of 0.69 mg/ L, is below the Agency's level of concern for the general US population and all subgroups except all infants < 1 year of age. The highest exposed population subgroup, all infants < 1 year of age, was 159% of the cPAD. Using the 90th percentile annual average concentration of 0.24 mg/ L, the chronic dietary ( water only) risk for all infants < 1 year of age was < 55% of the cPAD; using the median annual average concentration estimated at 0.11 mg/ L, estimated chronic risk from drinking water was 25% of the cPAD. The contribution of exposure from food sources increases total dietary risk ( food + drinking water) to 174% of the cPAD for infants < 1 year of age at the highest annual average, 48 but remains below EPA's level of concern at the 90th percentile ( 70% of the cPAD).

Data on the occurrence of chlorate ion in drinking water were available from two primary sources: the Information Collection Rule ( ICR) Auxiliary 1 Database, Version 5.0, and the AwwaRF research study on the control of chlorate ion in hypochlorite solutions. The most extensive data are from the ICR where source water and drinking water were monitored for chlorate ion between July 1997 and December 1998. Water systems serving a population of at least 100,000 were required to monitor for chlorate ion at treatment plants using chlorine dioxide or hypochlorite solutions in the treatment process. Although the ICR water systems represent roughly one percent of the total number of drinking water systems in the United States, these systems serve almost 60% of the population. Under the ICR, plants using chlorine dioxide collected monthly samples of the source water entering the plant, the finished water leaving the plant, and at three sample points in the distribution system ( near the first customer, an average residence time, and a maximum residence time). Samples were taken throughout the distribution systems for plants using chlorine dioxide, since the concentration of chlorate is expected to change within the system due to the conversion of chlorine dioxide to chlorate that occurs in the presence of chlorine. Plants using hypochlorite solutions were required to collect quarterly samples of the water entering and leaving the plant.

The AwwaRF data consists of samples collected in 1993 by 111 water treatment plants using hypochlorite. The majority of the systems in the AwwaRF project serve populations less than 100,000, and a large subset of those serve populations less than 10,000. Samples of source water, hypochlorite solution, and finished drinking water from 111 of water systems were analyzed for chlorate. Only one set of samples was collected for each system, and samples were not collected at plants using chlorine dioxide. Furthermore, the background information on the 111 water systems that participated in the project was not linked to the samples they provided; therefore, the chlorate concentrations can not be directly related to the size of the water system or type of hypochlorite solution in use.

The AwwaRF samples were typically found to have higher concentrations of chlorate than the samples collected from the larger ICR systems. The difference in chlorate concentrations could be the result of a number of factors, such as: 1) The AwwaRF data represents a single point in time, while the ICR data reflects an average over 18 months; 2) most of the AwwaRF samples were collected from utilities that served populations of less that 100,000, while all of the ICR samples were from utilities serving at least 100,000; and 3) hypochlorite treatment plant practices may have changed between when the AwwaRF samples were collected ( 1993) and the ICR samples were collected ( 1997 1998). When the AwwaRF study was conducted, utilities were just becoming aware of the formation of chlorate ion in hypochlorite solutions. The AwwaRF project was funded in order to provide water treatment facilities with information on how to minimize the formation of chlorate byproduct; it is possible that facilities consequently revised their treatment practices.

The ICR Database was considered the more appropriate source for estimating exposure averages from individual water treatment plants, primarily because the AwwaRF study is a less robust data set consisting of only one sample per utility, whereas the ICR database collected multiple samples over an 18 month period, from plants using both hypochlorite and chlorine 49 dioxide. Both the AwwaRF study and the ICR data reveal high concentrations of chlorate ion to be a local situation affecting a relatively small number of systems. Of the ICR data set, only four water treatment plants had average chlorate ion concentrations that exceeded the Agency's level of concern ( i. e., 370 ppb or 0.37 mg/ L, for the infant subpopulation) including one treatment plant serving 218,000 people that had the highest annual average ( 0.69 mg/ L). Of the four plants that exceeded, two treatment plants used chlorine dioxide, and two used hypochlorite. The total number of people served by the four water treatment plants exceeding 0.37 mg/ L represents 0.5% of the ICR population, or 621,000 people. All three exposure ranges ( highest average, 90th percentile, and median) are presented in Section III. Only the " highest average" exposures resulted in potential chronic risk estimates that were above the Agency's LOC, and only for infants. Over 99% of the ICR population receives finished water below the Agency's LOC of 0.37 mg/ L.

The chlorate ion ( ClO 3 ) is a disinfection byproduct ( DBP) of water treatment which can be formed during the on site generation of chlorine dioxide ( ClO 2 ), the decomposition of chlorine dioxide in the water treatment system, the decomposition of hypochlorite ( OCl) during storage, and the interaction of chlorite ion and free chlorine. Treatment of public water supplies is necessary to kill pathogens that may exist in the drinking water, such as cholera, typhoid, and dysentery. Outbreaks of these diseases decreased significantly when disinfection of the water systems was introduced in the early 1900s. While there are many important public functions of water treatment, the Agency is taking steps to limit the exposure of chlorate ion as a DBP to the public.

In order to help reduce potential exposure to chlorate, the Agency's Office of Pesticide Programs ( OPP), in conjunction with the Office of Water ( OW), is working with the American Water Works Association ( AWWA), the Chlorine Institute, and individual water communities to provide community water systems with information on Best Management Practices ( BMPs) for use in drinking water treatment. BMPs may include measures such as production modifications, operational changes, materials substitution, materials and water conservation, and other such measures. For example, water systems that use hypochlorite solutions can minimize the levels of chlorate ion by purchasing high quality hypochlorite solutions and through careful storage during use. While decomposition of hypochlorite solutions cannot be avoided, the rate of decomposition can be managed. Among the major factors affecting stability are the following: concentration of the hypochlorite solution, temperature of the solution, pH of the solution, and exposure to light sources. The pH of the solution should be in the 12 to 13 range to minimize decomposition. Hypochlorite solutions should be protected from high temperatures and sunlight, and storage time should be minimized, both from the time of manufacture to delivery, and from the time of delivery to use. The solutions can also be diluted to control decomposition as long as the proper pH is maintained and high quality dilution water is used. The primary ways in which water systems using chlorine dioxide can control the levels of chlorate in the finished water is through high efficiency operation of their chlorine dioxide generators and by reducing chlorite ion concentrations prior to the addition of free chlorine. The BMPs could also include additional training of the water systems employees on the proper handling of these chemicals.

The Agency believes that sodium chlorate does not constitute a risk of concern to the general population or any population subgroups, since the LOC exceedances are associated with 50 a small number of water treatment facilities and inappropriate treatment practices. Furthermore, the Agency anticipates that the community water system outreach strategy previously discussed will greatly reduce potential drinking water byproduct exposure.

d. Occupational Risk Mitigation With the consideration of mitigation measures proposed by registrants and the use of engineering controls ( enclosed cockpits or cabs), all occupational handler risks for the use of inorganic chlorates as an active or inert ingredient in conventional pesticides are below the Agency's LOC ( i. e., MOEs are greater than the LOC of 100). For sodium chlorate, occupational exposure durations are short ( 1 30 days) and intermediate term ( 1 6 months) only. Long term (> 6 months) exposure is not expected based on the use pattern for sodium chlorate. Postapplication dermal and inhalation exposures are negligible due to the chemical's physical and chemical characteristics as an inorganic salt. No significant amount of sodium chlorate is expected to be absorbed through the skin and the vapor pressure is negligible; therefore, a postapplication exposure assessment was not conducted.

Antimicrobial Uses of Sodium Chlorate Risks to handlers treating water systems are below the Agency's LOC; therefore, no mitigation measures are necessary.

Agricultural Uses of Sodium Chlorate With the exception of aerial applications, for which enclosed cockpits are required, the handler and flagger MOEs for sodium chlorate's agricultural uses are below the Agency LOC at baseline level of protection ( long sleeve shirt, long pants, shoes, and socks). MOEs range from 190 ( mixing/ loading liquids for aerial application on cotton, corn, et al.) to 3600 ( mixing/ loading liquids for groundboom application on ornamental gourds and cucurbits). Further, the maximum application rate for use on cotton will be reduced from 7.5 lbs ai/ A to 6 lbs ai/ A, with a limitation of one application ( except for California, where two applications will be allowed). No additional mitigation is required for occupational risk resulting from the agricultural uses of sodium chlorate.

Non agricultural Uses of Sodium Chlorate The Agency's review of sodium chlorate labels, in addition to discussions with registrants, indicates that the current non agricultural use labels are not reflective of actual use practices. The non agricultural use labels currently allow for larger application rates than are necessary for efficacy, as well as allow for unlimited treatment areas, although sodium chlorate's non agricultural formulations are typically used as spot treatments.

Mitigation measures for sodium chlorate's non agricultural uses to be included on product labels will reduce risk from the occupational and ecological exposures to sodium chlorate. The registrants have agreed to the following non agricultural use mitigation measures for sodium chlorate: 51   All non agricultural uses will be limited to spot treatments only ( with the exception of the granular formulation for use under asphalt, although this use will be limited to an 8000 ft2 treatment area). The uses limited to spot treatments include, but are not limited to: building perimeters ( including farm buildings), driveways, parking lots, fence rows, military installations, pipelines, railroads, lumberyards, industrial sites ( transformers, generators, utility poles, etc.), tennis court perimeters, picnic areas, bleachers, cemeteries, fuel tanks, airport runways, helo pads, wood decks, guard rails, highway medians, sidewalks/ walkways, vacant lots, fire hydrants, recreational areas, and other similar areas.

  Use on rights of way and ditch banks will be cancelled.

  The label will specify a maximum application rate of 0.9 lb ai/ 100 ft2 The Agency generally converts application rates to a per acre basis for assessment purposes; therefore, the rate of 0.9 lb ai/ 100 ft2 is referred to as 392 lb ai/ A in this document. However, because all non agricultural uses will be limited to spot treatment applications only, all 392 pounds of a. i. will not be applied on any one given acre. Assuming only one acre is considered for treatment, sodium chlorate can only be applied to up to 8000 ft2, which equates to up to approximately 78 lbs ai being applied to any given acre. It is assumed that more than one acre will be treated.

Risk calculations have been developed to better represent the current, actual use pattern for sodium chlorate, and occupational risk was reassessed based on the revised use pattern discussed above ( i. e., application rates, target sites, and amount treated). Following is a summary of the Inorganic Chlorates: Addendum to the Occupational and Residential Exposure Assessment for the Reregistration Eligibility Decision ( RED) Document, dated May 18, 2006.

All data, factors, and assumptions used in the addendum are the same as those used in the previous occupational risk assessment. These include, but are not limited to:

  body weight ( 70 kg representing adult handlers);   toxicological endpoints ( short/ intermediate term oral NOAEL of 30 mg/ kg/ day) and uncertainty factors ( Level of Concern ( LOC) for the MOE is 100);   application rates ( in lb ai/ A   presented as a range to encompass the various registered products); and,   unit exposures ( from PHED and/ or ORETF database, both of which have undergone appropriate review by the Human Studies Review Board).

However, factors regarding application equipment used and daily area treated were revised based on updated use pattern information and proposed product label revisions. The previous assessment, summarized in Section III, was based on applications with larger, industrial equipment such as tractor spreaders or groundboom sprayers. As a result of mitigation measures agreed to by the technical registrants, sodium chlorate applications to non agricultural areas ( i. e., building perimeters, ditch banks, bleachers, airport runways, vacant lots, fire hydrants, or as a pre paving treatment) will be limited to " handheld" equipment such as rotary spreaders and 52 pump or power sprayers. In addition, the standard Agency assumptions for the amount applied per work day is based on the application equipment used to determine exposure and risk. Since submitted information indicates that no more than 8,000 ft2 of an acre ( approximately 20%) will be treated with sodium chlorate, the Agency has adjusted the standard assumptions for acres treated per day to reflect this spot treatment type scenario.

Based on the revised assumptions for the daily area treated and on application methods suitable for spot treatments ( low pressure handwand sprayers, belly grinders, push type spreaders), the risks for all non agricultural uses, even at the currently labeled application rate ( 523 lbs ai/ A instead of 392 lb ai/ A), are below the Agency LOC. The higher application rate of 523 lb ai/ A was used, because at the time the Inorganic Chlorates: Addendum to the Occupational and Residential Exposure Assessment for the Reregistration Eligibility Decision ( RED) Document, dated May 18, 2006, was prepared, the 392 lb ai/ A maximum application rate mitigation measure was not yet finalized. The mitigation measures outlined above reduce the occupational risk from all of sodium chlorate's non agricultural uses to below the Agency's level of concern at baseline level of protection ( long sleeve shirt, long pants, shoes, and socks). The risks based on the revised non agricultural use patterns for sodium chlorate are summarized in Table 26 below.

Table 26: Sodium Chlorate: Short and Intermediate Term Occupational Inhalation Exposure Exposure Scenario Daily Area Treated ( Acres/ day) Crop/ Target Application Rate ( lbs ai/ Acre) a Inhalation MOE ( at baseline)

Mixer/ Loader/ Applicators & Loader/ Applicators 523 330 Mixing/ Loading/ Applying liquids with a lowpressure handwand sprayer 0.4 Industrial/ Non Crop Sites 132 1300 523 2200 M/ L/ A liquids with a handgun sprayer 1 Industrial/ Non Crop Sites 132 8800 523 320 240 710 L/ A granules with a belly grinder 0.2 Industrial/ Non Crop Sites 161 1100 523 550 240 1200 L/ A granules with a pushtype spreader 1 Industrial/ Non Crop Sites 161 1800 a. Application rate will be reduced to 0.9 lb ai/ 100 ft2 ( 392 lb ai/ A).

2. Non Target Organism ( Ecological) Risk Management Chlorate is a strong oxidizer and may be reduced to other chemically related species under some environmental conditions. The extent and rate to which this occurs will depend on the redox chemical species ( including organic matter) in the water or soil. Extensive spatial and 53 temporal variability is expected for the reactions of chlorate in the environment. However, the currently available simulation models do not allow for a quantitative evaluation of the potential exposure levels of each the reduced products of chlorate ( i. e., speciation and predominance) and how fast these chemical species may form. Therefore, there is a high degree of uncertainty in the ecological exposure and risk assessment. This is important because a reduction product of chlorate ( chlorite) is expected to be more toxic to most aquatic and terrestrial species, particularly aquatic invertebrates.

a. Terrestrial Organisms 1. Birds and Mammals EPA's screening level risk assessment, based on currently labelled maximum application rates, for both agricultural and non agricultural uses for sodium chlorate, suggests potential acute and chronic risk for birds Avian Acute Risk Avian acute risk was not calculated, since no mortality or signs of toxicity were observed in the submitted subacute or acute toxicity studies at concentrations that are above the limit for these types of studies; therefore, acute risk to birds is not expected. However, the Agency cannot preclude acute or subacute risk from the non agricultural uses. Some labels have maximum application rates up to 1032 lbs ai/ A, and the ecological assessment for risk from nonagricultural uses was based on rates ranging from 52 to 523 lbs ai/ A, with corresponding EECs from 12,500 and 125,000 ppm, respectively. These EECs are approximately 2.5 to 25 fold higher than the highest concentration tested in the subacute bird toxicity studies. The nonagricultural use mitigation outlined above, including the reduction of the maximum application rate to 392 lbs ai/ A, and a limitation to spot treatments only ( except for use under asphalt, although this use is limited to no more than an 8000 ft2 area). Reducing the maximum application rate from 520 lbs ai/ A to 392 lbs ai/ A will reduce the estimated environmental concentrations of chlorate by approximately 25%. Further, to the extent that there is any potential acute risk to birds from the non agricultural uses, the fact that these uses will result in small contiguously treated areas could limit avian exposure.

Avian Chronic Risk Maximum chronic RQs, based on EECs derived with 90th percentile residue estimates from the Kenaga nomogram, exceed the Agency's avian LOC of 1.0 for all agricultural uses assessed for birds eating short grass, tall grass, broadleaf forage, and small insects. Chronic RQs based on EECs derived with mean residue estimates from the Kenaga nomogram, although not presented in Section III, would be approximately three times lower for any single application of sodium chlorate. The highest agricultural use chronic RQ was 11 ( chili peppers/ white, Irish potatoes and the short grass food category). The second highest RQs were for cotton ( ranging from 10.0 for the short grass food category, to 0.63 for fruits, pods, seeds, and small insects). Cotton is also by far the most common agricultural use of sodium chlorate, with approximately 1,900,000 lbs ai applied annually. 54 To address the chronic risk to birds from use on cotton, the maximum application rate will be reduced from 7.5 lbs ai/ A to 6 lbs ai/ A, and applications will be limited to a single applications in all states except California, where a second application will be allowed. This mitigation measure will reduce chronic risk to birds from use on cotton by approximately onehalf with RQs ranging from 5.31 ( on the short grass food category), to 0.33 ( on fruits, pods, seeds, and small insects) for all states except California. In California, the chronic avian RQs based on the reduced maximum application rate of 6 lbs ai/ A, and two applications, will be reduced to a range of 8.25 ( on the short grass food category) to 0.52 ( on fruits, pods, seeds, and small insects).

Chronic avian RQs for sodium chlorate were based on a NOAEC of 271 ppm from the bobwhite quail chronic reproductive toxicity test. However, maximum EECs for a majority of the uses and classes of food items were also higher than the LOAEC in bobwhite quail of 964 ppm. At the LOAEC, reproductive effects occurred, including a 67% reduction in eggs laid and 64% reduction in number of hatchlings per egg laid. Therefore, if actual exposure is equivalent to the maximum values calculated with the T REX model, there is a greater certainty that frank reproductive effects in birds might occur.

However, the duration of exposure needed to produce reproductive effects in birds is an uncertainty. This uncertainty is significant in the case of sodium chlorate, because as a broadspectrum herbicide, its toxic effects on plants are visible within several days. Since the vegetation in the treated area will die, it is uncertain whether or not this vegetation will be attractive to birds as a feed item long enough for the chronic effects to occur.

Chronic RQs were not calculated for sodium chlorate's non agricultural uses. However, based on the high application rates and resulting high potential EECs, risks from sodium chlorate's non agricultural uses could be considerably higher than those described in Section III for the agricultural uses. The non agricultural use mitigation outlined above, including a reduction in the maximum labeled application rate to 0.9 lbs ai/ 100 ft2 ( 392 lbs ai/ A), would reduce the EECs of chlorate by approximately 25% in the areas treated. Furthermore, the limitation of most non agricultural uses to spot treatments only is expected to reduce the likelihood that a terrestrial organism will come into contact and consume all of its diet from a treated area. However, RQs still exceed the chronic LOC for birds ( 1.0). See the Analysis of proposed changes to sodium chlorate's application rates and maximum treated area on potential ecological risks presented in EFED's reregistration eligibility decision ( RED) document, dated June 13, 2006 for further detail.

Mammalian Acute Risk Acute RQs were not calculated for mammals. The LD50 from a core acute oral toxicity study in rats was > 5000 mg/ kg bw. In this study, 10% ( 1/ 10) of the rats administered 5000 mg/ kg died. Mortality was not observed at any other dose. Therefore, the data were not sufficient to allow for characterization of the dose response relationship and the proximity of the LD50 to 5000 mg/ kg bw is uncertain. Although RQs were not calculated for mammals, Tables 17, 18 and 19 in Section III present a comparison of the body weight adjusted LD50s to EECs for 55 agricultural spray, and the non agricultural spray and granular, formulations, respectively. These ratios can be used to estimate high end risk to exposed mammals. Risk quotients would be lower than the values in Section III.

For sodium chlorate's agricultural uses, all of the mammalian acute risk estimates are below the Agency's acute and endangered species LOC of 1.0 and 0.1, respectively, with the exception of small mammals eating short grass. The highest exceedence is for 15 gram mammals eating short grass ( risk ratio = 0.26); therefore, no mitigation is necessary.

For sodium chlorate's non agricultural uses, the ratios indicate a potential acute concern to mammals for both spray and granular formulations, with the highest ratios calculated for small mammals ( ratios = 11 and 33 for spray and granular formulations, respectively). While the ratios presented in Section III suggest that there could be acute risk to mammals of all sizes that forage in the area where sodium chlorate is applied to non agricultural use sites, the risk was likely over estimated, since an LD50 has not been established. Furthermore, as previously explained, a reduction in the maximum application rate for the non agricultural uses to 392 lbs ai/ A would reduce the EEC's of chlorate in treated areas by approximately 25%. Limitation of the treatments to spot treatments only would be expected to further reduce the likelihood that a terrestrial organism will come into contact and consume all of its diet from that area.

Mammalian Chronic Risk For mammals, the Agency typically evaluates the mammalian reproductive effects for exposures greater than 30 days. The interpretation of the effects seen in the 2 generation rat reproduction toxicity study, used to derive the mammalian reproduction toxicity endpoint for sodium chlorate, is difficult in this respect. While effects were observed at 70 mg/ kg bw and above, the effects are not clearly associated with reduced reproductive success or survival. The mammalian reproductive NOAEC is based on the highest dose tested in this study ( 500 mg/ kgbw although no toxic or reproductive effects were observed at this level. Therefore, the NOAEC could be higher than 500 mg/ kg bw, which would result in lower mammalian reproduction risk estimates. However, the Agency calculated risk ratios based on the 500 mg/ kgday NOAEL as a conservative estimate of risk, as presented in Section III. For the agricultural uses of sodium chlorate, the chronic mammalian LOC of 1.0 was only slightly exceeded for the smallest weight classes of mammals for most food items and the largest weight class of mammals feeding on short grass ( RQs range from 2.6 to 0.07). The mitigation measures previously outlined for sodium chlorate use on cotton ( maximum application rate reduced from 7.5 lbs ai/ A to 6 lbs ai/ A, with the limitation of a single application, except in California, where a second application will be allowed), will further reduced chronic mammalian risk. Furthermore, based on the lack of observed reproductive effects in the chronic study and the slight LOC exceedances for agricultural uses, the Agency does not anticipate a chronic risk of concern to mammals from these uses.

As with the agricultural uses, mammalian reproduction RQs were not calculated for sodium chlorate's non agricultural uses. However, the higher application rates for the nonagricultural uses, and the resulting higher EECs, suggest that the risk for these uses would be higher than the risk estimates presented for the agricultural uses. Note that the mammalian 56 reproduction RQs for the agricultural uses of sodium chlorate, presented in Section III, are a conservative estimate of risk. Furthermore, as previously explained, to reduce risk from sodium chlorate's non agricultural uses, the maximum application rate will be reduced to 0.9 lb ai/ 100 ft2. This mitigation measure will reduce the EECs by approximately 25%. In addition, the limitation to spot treatments will reduce the likelihood that mammals will come into contact and consume all of its diet from a treated area. See the Analysis of proposed changes to sodium chlorate's application rates and maximum treated area on potential ecological risks presented in EFED's reregistration eligibility decision ( RED) document, dated June 13, 2006, for further detail.

2. Non Target Insects EPA currently does not estimate RQs for terrestrial non target insects. In addition, the Agency has no toxicity data for sodium chlorate. Therefore, EPA will require data to address this uncertainty.

3. Non Target Terrestrial Plants Based on chlorate's non selective mode of action and lack of adequate toxicity data, the Agency presumes risk to non target terrestrial plants at levels above the Agency's level of concern for all uses. The risks to plants cannot be quantified at this time due to lack of data; however, the Agency will require data to address this uncertainty.

b. Aquatic Organisms 1. Fish There is no acute risk of concern, from either the agricultural or non agricultural uses of sodium chlorate, to freshwater or estuarine/ marine fish. All risk ratios are less than 0.05, which is below the Agency's acute LOC of 0.5 and below the acute endangered species LOC of 0.05. However, some data suggest that brown trout ( freshwater fish) could be substantially more sensitive than other fish species tested to chlorate's toxicity. It is uncertain if these data are reliable; therefore, the Agency will require additional testing in brown trout to address this area of uncertainty.

No chronic fish toxicity studies are available to allow for chronic risk to fish to be quantified. Therefore, the Agency will require data to address this uncertainty.

2. Aquatic Invertebrates For freshwater invertebrates, acute RQs are below the acute LOC of 0.5 and the endangered species acute LOC of 0.05, for both agricultural and non agricultural uses of sodium chlorate. Therefore, acute risk to freshwater invertebrates is not of concern to the Agency, and no mitigation is required.

For saltwater invertebrates, the acute risk ratios for sodium chlorate's agricultural and nonagricultural uses were below the Agency's acute LOC of 0.5, in addition to the endangered species acute LOC of 0.05 ( highest ratio = 0.04 for non agricultural uses). Therefore, acute risk 57 to saltwater invertebrates is not of concern to the Agency.

Chronic risk to invertebrates ( freshwater and saltwater) was not assessed, since treatmentrelated effects were not observed at any concentration in available studies.

3. Aquatic Plants For non endangered aquatic plants, the Agency's LOC of 1.0 was not exceeded for either the agricultural or nonagricultural uses of sodium chlorate ( highest RQ = 0.91 for nonagricultural uses). Therefore, risk to non endangered aquatic plants is not of concern to the Agency.

For endangered aquatic plants, the Agency's LOC of 1.0 was not exceeded for sodium chlorate's agricultural uses ( highest RQ = 0.29), but the LOC was exceeded for sodium chlorate's nonagricultural uses ( highest RQ = 12.6). However, the mitigation measures listed above for the non agricultural uses of sodium chlorate, including a reduction in the application rate and treated area, result in a reduction of the endangered vascular plant RQ from 12.6 to 1.5. While this is a significant improvement, it is still above the Agency's endangered plant LOC of 1.0. Furthermore, because of a lack of submitted data, there is uncertainty remaining on sodium chlorate's toxicity to aquatic plants. The Agency will require data to address this area of uncertainty.

3. Summary of Mitigation Measures The following mitigation measures are necessary for sodium chlorate to be eligible for reregistration. These include use restrictions, voluntary cancellations and/ or use deletions, and personal protective equipment.

Agricultural use mitigation:

  Engineering controls ( enclosed cockpits) for aerial applications on agricultural crops.   For cotton, the maximum application rate will be reduced from 7.5 lbs ai/ A to 6 lbs ai/ A, and applications will be limited to a single applications in all states except California, where a second application will be allowed.

Non agricultural use mitigation:

  All non agricultural uses will be limited to spot treatments only ( with the exception of the granular formulation for use under asphalt, although this use will be limited to an 8000 ft2 treatment area). The uses limited to spot treatments include, but are not limited to: building perimeters ( including farm buildings), driveways, parking lots, fence rows, military installations, pipelines, railroads, lumberyards, industrial sites ( transformers, generators, utility poles, etc.), tennis court perimeters, picnic areas, bleachers, cemeteries, fuel tanks, airport runways, helo pads, wood decks, guard rails, highway medians, sidewalks/ walkways, vacant lots, fire hydrants, recreational areas, and other similar areas. 58   Use on rights of way and ditch banks will be cancelled.

  The label will specify a maximum application rate of 0.9 lb ai/ 100 ft2.

F. Other Labeling Requirements To be eligible for reregistration, various use and safety information will be included in the labeling of all end use products containing sodium chlorate. For the specific labeling statements and a list of outstanding data, refer to Section V of this RED document.

1. Endangered Species Considerations The Agency's screening level assessment results in the determination that sodium chlorate will have no acute risks to birds, no acute risks to fish ( freshwater and estuarine/ marine), and no acute or chronic risks to aquatic invertebrates ( freshwater and estuarine/ marine).

However, the preliminary risk assessment for endangered species indicates that RQs exceed endangered species LOCs for chronic risks to birds ( RQs up to 11 for agricultural uses and greater for non agricultural uses); acute risks to mammals ( RQs up to 33); chronic risks to mammals ( RQs up to 1.2 for agricultural uses and greater for non agricultural uses); and risks to aquatic plants ( RQs up to 13). Risks could not be calculated for terrestrial plants and for chronic risks to fish; however, the Agency will be requiring data.

Further, potential indirect effects to any species dependent upon a species that experiences effects from use of sodium chlorate can not be precluded based on the screening level ecological risk assessment. These findings are based solely on EPA's screening level assessment and do not constitute " may affect" findings under the Endangered Species Act.

The Agency has developed the Endangered Species Protection Program to identify pesticides whose use may cause adverse impacts on endangered and threatened species, and to implement mitigation measures that address these impacts. The Endangered Species Act ( ESA) requires federal agencies to ensure that their actions are not likely to jeopardize listed species or adversely modify designated critical habitat. To analyze the potential of registered pesticide uses that may affect any particular species, EPA uses basic toxicity and exposure data developed for the REDs and considers it in relation to individual species and their locations by evaluating important ecological parameters, pesticide use information, geographic relationship between specific pesticide uses and species locations, and biological requirements and behavioral aspects of the particular species, as part of a refined species specific analysis. When conducted, this species specific analysis will take into consideration any regulatory changes recommended in this RED that are being implemented at that time.

Following this future species specific analysis, a determination that there is a likelihood of potential impact to a listed species or its critical habitat may result in: limitations on the use of sodium chlorate, other measures to mitigate any potential impact, or consultations with the Fish and Wildlife Service or the National Marine Fisheries Service as necessary. If the Agency determines use of sodium chlorate " may affect" listed species or their designated critical habitat, 59 EPA will employ the provisions in the Services regulations ( 50 CFR Part 402). Until that species specific analysis is completed, the risk mitigation measures being implemented through this RED will reduce the likelihood that endangered and threatened species may be exposed to sodium chlorate at levels of concern. EPA is not requiring specific sodium chlorate label language at the present time relative to threatened and endangered species. If, in the future, specific measures are necessary for the protection of listed species, the Agency will implement them through the Endangered Species Protection Program.

2. Spray Drift Management The Agency has been working closely with stakeholders to develop improved approaches for mitigating risks to human health and the environment from pesticide spray and dust drift. As part of the reregistration process, EPA will continue to work with all interested parties on this important issue.

From its assessment of sodium chlorate, as summarized in this document, the Agency concludes that certain drift mitigation measures are needed to address the risks from off target drift for sodium chlorate, including a requirement for medium to coarse droplet size. Label statements implementing these measures are listed in the " spray drift management" section of the label table ( Table 28 in Section V of this RED document. In the future, sodium chlorate product labels may need to be revised to include additional or different drift label statements. 60 V. What Registrants Need to Do A. Manufacturing Use Products 1. Generic Data Requirements The generic data base supporting the reregistration of sodium chlorate has been reviewed and determined to be substantially complete. However, there are a few data gaps remaining, and these data, presented in Table 27, must be submitted or the Agency may take regulatory action on registrations of pesticide products containing sodium chlorate.

Table 27. Guideline Requirements for Sodium Chlorate Data Requirement Old Guideline Number New OPPTS Guideline No.

Magnitude of the Residue Meat/ Milk/ Poultry/ Eggs 171 4j 860.1480 Submittal of Analytical Reference Standards 171 13 860.1650 28 Day Inhalation Toxicity 82 4 870.3465 Terrestrial Field Dissipation or Retrospective Monitoring Study 164 1 835.6100 Freshwater Fish Early Life Stage 72 4 ( a) 850.1400 Avian Reproduction ( 1 Generation, Duck) 71 4b 850.2300 Seedling Emergence ( Tier II only) 123 1 ( a) 850.4225 Vegetative Vigor ( Tier II only) 123 1 ( b) 850.4250 Aquatic Plant Toxicity, using Lemna spp. ( Tier II) 123 2 850.4400 Honey Bee Acute Contact Toxicity 141 1 850.3020 While the terrestrial field dissipation ( 835.6100) guideline study may not be appropriate for sodium chlorate, the Agency is still concerned about the prolonged use of sodium chlorate on cotton ( about 50 years). Terrestrial field dissipation data are not available for sodium chlorate, and the guideline requirement for this study was never waived. There are some reports that sodium chlorate can be persistent in the field ( ranging from 6 months to 5 years, depending on application rate, soil type, fertility, organic matter, moisture, and weather conditions). Also, several labels report that sodium chlorate is effective for the control of weeds for up to a year, which indicates that chlorate may persist for up to a year. Therefore, the range of persistence of sodium chlorate in the field remains a major uncertainty in the environmental fate behavior of this chemical. Use of sodium chlorate in the field requires that it be applied in conjunction with a fire retardant to minimize fire incidents. It is unclear how the fire retardant could influence the persistence in the field. Even though the persistence of chlorate in the field is uncertain, a terrestrial field dissipation data from a study conducted as per guideline 835.6100 may not provide adequate data because of the complexity of the chlorine oxyanion system and analytical chemistry methodology. Given that chloride is the end chemical species of chlorate, it poses the 61 question of increased chloride from year after year usage ( i. e., salinization), and leaching of chloride to ground water, particularly in areas where chloride is not a significant, natural component in soil and/ or ground water. Therefore, the Agency recommends a retrospective monitoring study ( soil; ground water) aimed to address the effect of prolong use of sodium chlorate on cotton. The study must be conducted upon agreement of a protocol, but monitoring sites in coastal areas should not be included.

2. Labeling for Manufacturing Use Products To ensure compliance with FIFRA, manufacturing use product ( MUP) labeling should be revised to comply with all current EPA regulations, PR Notices, and applicable policies. The MUP labeling should bear the labeling contained in Table 28.

B. End Use Products 1. Additional Product Specific Data Requirements Section 4( g)( 2)( B) of FIFRA calls for the Agency to obtain any needed product specific data regarding the pesticide after a determination of eligibility has been made. The registrant must review previous data submissions to ensure that they meet current EPA acceptance criteria and if not, commit to conduct new studies. If a registrant believes that previously submitted data meet current testing standards, then the study MRID numbers should be cited according to the instructions in the Requirement Status and Registrants Response Form provided for each product. The Agency intends to issue a separate product specific data call in ( PDCI) outlining specific data requirements.

2. Labeling for End Use Products To be eligible for reregistration, labeling changes are necessary to implement measures outlined in Section IV above. Specific language to incorporate these changes is provided in Table 28. Generally, conditions for the distribution and sale of products bearing old labels/ labeling will be established when the label changes are approved. However, specific existing stocks time frames will be established case by case, depending on the number of products involved, the number of label changes, and other factors.

C. Labeling Changes Summary Table For sodium chlorate to be eligible for reregistration, all sodium chlorate labels must be amended to incorporate the risk mitigation measures outlined in Section IV. Table 28 describes how language on the labels should be amended.

D. Existing Stocks Registrants may generally distribute and sell products bearing old labels/ labeling for 18 months after the date of approval of revised labels implementing the changes described in this RED. Registrants and all other persons remain obligated to meet pre existing label requirements 62 and existing stocks requirements applicable to stocks they sell or distribute.