UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
                         WASHINGTON, D.C. 20460

                                                     	OFFICE OF CHEMICAL SAFETY
                                                      	AND POLLUTION PREVENTION

Date:	8/30/18

Subject:	BROMOXYNIL.  Occupational and Residential Exposure Assessment for the Registration Review of Bromoxynil, Bromoxynil Phenyl and Bromoxynil Octanate

PC Code: 035301, 035302, 035303,128920
DP Barcode:  D448609
Decision No.: 535851
Registration No.: See Tables 4.1
Petition No.: NA
Regulatory Action: Registration Review
Risk Assessment Type: Occupational/Residential Exposure Assessment
Case No.: 1689-84-5, 1689-99-2, 3861-41-4, 56634-95-8
TXR No.: NA
CAS No.: 1689-84-5, 1689-99-2
MRID No.: NA
40 CFR: §180.324

FROM:	Seyed Tadayon, Chemist
      Risk Assessment Branch III
		Health Effects Division (HED, 7509P)

THROUGH	Thomas Moriarty, Branch Chief
		Risk Assessment Branch III
		Health Effects Division (7509P)

and

		Shalu Shelat, ExpoSAC Designated Reviewer
		Monica Hawkins, ExpoSAC Designated Reviewer
		Exposure Science Advisory Committee (ExpoSAC) / HED

TO: 		Nicole Zinn, Chemical Review Manager
      Pesticide Reevaluation Division (PRD) (7508P)

Introduction

The Pesticide Re-evaluation Division (PRD) has requested that the Health Effects Division (HED) conduct an exposure and risk assessment to estimate the risk to human health that will result from the currently registered uses of bromoxynil in support of registration review. This memorandum serves as HED's assessment of the occupational and residential exposure and risk from existing uses of bromoxynil.

It is HED policy to use the best available data to assess exposure.  Several sources of generic data were used in this assessment as surrogate data in the absence of chemical-specific data, including Pesticide Handlers Exposure Database Version 1.1 (PHED 1.1); the Agricultural Handler Exposure Task Force (AHETF) database; the Outdoor Residential Exposure Task Force (ORETF) database; the Agricultural Reentry Task Force (ARTF) database; and other registrant-submitted exposure monitoring studies (MRIDs 49884502 and 49884501).  Some of these data are proprietary, and subject to the data protection provisions of the Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA).

Note:  This memorandum was reviewed by the Exposure Science Advisory Committee (ExpoSAC) on 8/30/2018.
                               Table of Contents

1.0 Executive Summary	4
2.0 Risk Assessment Conclusions and Recommendations	6
2.1 Summary of Risk Estimates	6
2.2 Label Recommendations from Occupational Assessment	8
2.3 Data Deficiencies and Requirements	8
3.0 Hazard Characterization	8
4.0 Use Profile	11
5.0 Residential Exposure and Risk Estimates	13
6.0 Non-Occupational Spray Drift Exposure and Risk Estimates	13
7.0 Non-Occupational Bystander Post-Application Inhalation Exposure and Risk Estimates	17
8.0 Occupational Exposure and Risk Estimates	17
8.1 Occupational Handler Exposure/Risk Estimates	17
8.2 Occupational Post-application Exposure/Risk Estimates	30
8.2.1 Occupational Post-application Inhalation Exposure/Risk Estimates	30
8.2.2 Occupational Post-application Dermal Exposure/Risk Estimates	30
Appendix A.  Summary of Occupational Non-cancer Algorithms	38
Appendix B.  Summary of Occupational and Residential Cancer Algorithms	41
Appendix C.  Summary of Spray Drift Algorithms	42
Appendix D.  Summary of Directions for Agricultural Occupational Uses of Bromoxynil	46

1.0 Executive Summary

HED has conducted an occupational and residential exposure assessment for Registration Review uses of the active ingredient (ai), bromoxynil.  Bromoxynil is a contact herbicide which is registered for application as the octanoic and/or heptanoic acid esters for control of broadleaf weeds. Since the bromoxynil octanoic and heptanoic esters are rapidly converted to the bromoxynil phenol, the exposure and tolerances are based on bromoxynil phenol (referred to as bromoxynil in the remainder of this document).

This memorandum contains HED's exposure and risk estimates to occupational pesticide handlers (i.e., mixers, loaders, applicators) and post-application exposure to re-entry workers.  There are no registered residential uses. However, a spray drift assessment for off-target movement of pesticides into residential settings was conducted for existing registered uses.

Based on the Agency's current practices, a quantitative non-cancer occupational post-application inhalation exposure assessment was not performed for bromoxynil at this time.  If new policies or procedures are put into place, the Agency may revisit the need for a quantitative occupational post-application inhalation exposure assessment for bromoxynil.

Use Pattern
Bromoxynil is currently formulated as a liquid, registered for use on agricultural food crops including garlic and onions; food and feed crops including mint, flax, spearmint, peppermint, barley, oats, rye, triticale, wheat, sorghum, cotton, and corn (field and pop); and feed crops including alfalfa, forage/hay, and grass.  Current, non-food uses include outdoor industrial areas, non-agricultural uncultivated areas/soil, non-residential commercial/industrial lawns, shrubs/bushes/vines, and sod farms.

Bromoxynil registered products are applied either via aerial, groundboom, or chemigation equipment. The use of a backpack or any type of handheld equipment is prohibited on all the registered labels.  Spot treatments should be applied only with a calibrated boom. Most of the bromoxynil product labels direct mixers, loaders, applicators, and other handlers to wear baseline attire (i.e., long-sleeved shirt, long pants, shoes and socks), coveralls, chemical resistant apron, gloves, protective eyewear, and respirators. The restricted entry intervals (REIs) range from 12 to 24 hours for most labels.

Exposure Profile
Occupational handler and post-application exposure is expected to be both short- (1 to 30 days) and intermediate-term (1 to 6 months).  Exposures from spray drift are expected to be short-term only.  For occupational use patterns, dermal and inhalation exposures are anticipated for occupational handlers and post application workers.

Hazard Characterization
Bromoxynil phenol has moderate acute toxicity (Toxicity Category II) via the oral and inhalation routes and low acute toxicity (Toxicity Category III) via the dermal route. It is a moderate eye irritant (Toxicity Category II) and is not a dermal irritant (Toxicity Category IV) or skin sensitizer.  Bromoxynil octanoate has moderate acute toxicity via the oral and dermal routes (Toxicity Category II) and low acute toxicity (Toxicity Category III) via the inhalation route.  It is a moderate eye irritant (Toxicity Category II) and is not a dermal irritant (Toxicity Category IV).  Bromoxynil octanoate is a skin sensitizer.

Estimated short- and intermediate-term dermal exposures were compared to the no observed adverse effect level (NOAEL) of 10 mg/kg/day from a dermal developmental study in which increased incidence of supernumerary ribs were seen.  Estimated short- and intermediate-term inhalation exposures were compared to the NOAEL of 4 mg/kg/day from an oral developmental toxicity study in the rat based on increased incidence of supernumerary ribs.

Short-term incidental oral NOAEL of 5 mg/kg/day has been selected to protect infants and children from the subchronic dog study. The Food Quality Protection Act (FQPA) Safety Factor (SF) was reduced from 10X to 1X.

The dermal, inhalation and oral level of concern (LOC) is equal to 100 based on an uncertainty factor (UF) of 100 to account for interspecies extrapolation (10X); intraspecies variation (10X); and the FQPA SF of 1X.

Bromoxynil is classified as a "possible human carcinogen" based on the presence of hepatocellular tumors in male mice.  The unit risk, Q1[*], of bromoxynil based upon male mouse hepatocellular tumors rates is 0.103 (mg/kg/day)[-1] in human equivalents (TXR 0050045, E. Budd and E. Rinde. 03/12/1997).  Mutagenicity tests were largely negative and did not raise a concern.

Residential Exposure and Risk Assessment
There are no registered residential uses associated with bromoxynil; therefore, a quantitative handler and post-application assessment was not performed.

Spray Drift Exposure and Risks
Adult dermal risk estimates from aerial and groundboom applications are not of concern at the field edge.

Dermal and hand-to-mouth risk estimates for children 1 < 2 years old from groundboom applications are not of concern at the field edge For aerial applications, hand-to-mouth risks are not of concern at the field edge; however, dermal risk estimates are of concern for several scenarios.
Occupational Handler Exposure and Risk Assessment

Non-Cancer Exposure and Risk Estimates
Dermal MOEs range from 5.2 to 23,000, inhalation MOEs range from 2,100 to 1,800,000, and total MOEs range from 5.2 to 23,000 at baseline. All occupational handler inhalation risk estimates are not of concern at baseline attire (no respirator), while about a third of the dermal risks estimates are of concern at baseline (single layer, no gloves).  Of the eleven scenarios with dermal risks of concern at baseline, all but two are not of concern with consideration of increasing levels of dermal protection (e.g., double layer + gloves).  Two of the occupational handler exposure scenarios result in estimated risks of concern despite the addition of dermal protection (e.g., double layer + gloves). These two scenarios are not of concern with the use of engineering controls which result in dermal MOEs of 230 and 130 for mixing/loading liquids for applications to fallow land and mixing/loading liquids for applications to high-acreage field crops respectively.

Cancer Exposure and Risk Estimates
Occupational cancer risks were estimated for both private/farmer and contract/commercial handlers.  Cancer risks at baseline (single layer, no gloves, no respirator) range from 6E-07 to 4E[-]04 for private/farmer and 2E-06 to 1E-03 for contract/commercial handlers. With the addition of dermal and inhalation protection (double layer, gloves, P10 respirator), cancer risks range from 9E-08 to 5E-05 for private/farmer and 3E-07 to 1E-04 or contract/commercial handlers.

Occupational Post-application Dermal Exposure and Risk Assessment

Non-Cancer Exposure and Risk Estimates
Several dermal post-application exposure scenarios resulted in MOEs lower than the LOC (100) on the day of treatment (i.e., day 0) and are of concern. These scenarios resulted in MOEs ranging from 14 to 310.

Cancer Exposure and Risk Estimates
Cancer risks based on a 30-day average dose range from 1E-07 to 1E-05 .

Human Studies Review

This risk assessment relies in part on data from studies in which adult human subjects were intentionally exposed to a pesticide or other chemical.  These data, which include studies from PHED 1.1; the AHETF database; the Outdoor Residential Exposure Task Force (ORETF) database and the ARTF database; are (1) subject to ethics review pursuant to 40 CFR 26, (2) have received that review, and (3) are compliant with applicable ethics requirements.  For certain studies, the ethics review may have included review by the Human Studies Review Board.  Descriptions of data sources, as well as guidance on their use, can be found at the Agency website.

2.0 Risk Assessment Conclusions and Recommendations

2.1 Summary of Risk Estimates
Exposure and Risk Assessment
A residential handler exposure assessment was not conducted since bromoxynil is only applied to use sites that are not treated by residential handlers (e.g., grass grown for seed only, sod farms, non-residential turf, and non-cropland industrial sites).

Spray Drift Exposure and Risks
Adult dermal risks from groundboom and aerial  applications are not of concern at the field edge.
Dermal and hand-to-mouth risk estimates for children 1 < 2 years old from groundboom applications are not of concern at the field edge. Hand-to-mouth risk estimates resulting  from aerial application, are not of concern at the field edge; however, dermal risks is of concern for the following scenarios:

 Aerial applications using fine to medium spray up to 10 feet from the field
 Aerial applications using medium to coarse spray at edge
 Aerial applications using coarse to very coarse spray at edge
 Aerial applications using very fine to fine spray up to 100 feet from the field
 Aerial applications using AT401, M, 10 mph, 37% SD configuration at edge and up to 10 feet from field Aerial applications using WASP, M, 10 mph, 37% SD and AT401, C, 10 mph, 25% SD at edge.

Occupational Handler Exposure and Risk Assessment

Non-Cancer Exposure and Risk Estimates
Dermal MOEs range from 5.2 to 23,000, inhalation MOEs range from 2,100 to 1,800,000, and total MOEs range from 5.2 to 23,000 wearing baseline attire. Occupational handler inhalation risk estimates are not of concern at baseline (no respirator), while about a third of the dermal risks estimates were of concern at baseline (single layer, no gloves).  Of the eleven scenarios with dermal risks of concern at baseline, all but two scenarios are not of concern with consideration of increasing levels of dermal protection.  The following two mixer/loader  exposure scenarios result in estimated risks of concern despite the addition of dermal protection (double layer + gloves):

 Mixer/loader of liquid formulation for aerial applications to fallow land at 1.0 lb ai/A (Dermal MOE = 68, Total MOE = 67)
 Mixer/loader of liquid formulation for aerial applications to high-acreage field crop at 0.5 lb ai/A (Dermal MOE = 39, Total MOE = 38).

These two mixer/loader scenarios are not of concern with the use of engineering controls. The mixing/loading of liquids for applications to fallow land resulted in a dermal MOE of 230; while  mixing/loading liquids for applications to high-acreage field crops resulted in a dermal MOE of
130.

Cancer Exposure and Risk Estimates
Occupational cancer risks were estimated for both private/farmer and contract/commercial handlers.  Cancer risks at baseline (single layer, no gloves, no respirator) range from 6E-07 to 4E-04 for private/farmer and 2E-06 to 1E-03 contract/commercial handlers. With the addition of dermal and inhalation protection (double layer, gloves, P10 respirator), cancer risks range from 9E-08 to 5E-05 for private/farmer and 3E-07 to 1E-04 or contract/commercial handlers

Occupational Post-application Dermal Exposure and Risk Assessment

Non-Cancer Exposure and Risk Estimates
Several dermal post-application exposure scenarios resulted in MOEs lower than the LOC (MOE < 100) on the day of treatment (i.e., day 0) and are of concern. Risks were of concern (MOE < 100) for the following scenarios:

 Irrigating (hand set) alfalfa, grasses grown for seed, and mint up to 1 day after application at 0.5 lb ai/A
 Scouting barley and wheat on the day of treatment at 0.5 lb ai/A
 Scouting flax on the day of treatment at 0.25 lb ai/A
 Irrigating (hand set) corn (field and pop) up to 1 days after application at 0.5 lb ai/A
 Hand weeding onion (green and bulb) up to 1 days after application at 0.375 lb ai/A
 Hand weeding garlic up to 3 days after application at 0.5 lb ai/A

Cancer Exposure and Risk Estimates
Cancer risks based on a 30-day average dose range from from 7E-07 to 3E-05.

2.2 Label Recommendations from Occupational Assessment

None.

2.3 Data Deficiencies and Requirements
There are no data deficiencies or outstanding data requirements for the registered uses of bromoxynil

3.0 Hazard Characterization

Acute Toxicity
Bromoxynil phenol has moderate acute toxicity (Toxicity Category II) via the oral and inhalation routes and low acute toxicity (Toxicity Category III) via the dermal route. It is a moderate eye irritant (Toxicity Category II) and is not a dermal irritant (Toxicity Category IV) or skin sensitizer.

Bromoxynil octanoate has moderate acute toxicity via the oral and dermal routes (Toxicity Category II) and low acute toxicity (Toxicity Category III) via the inhalation route.  It is a moderate eye irritant (Toxicity Category II) and is not a dermal irritant (Toxicity Category IV).  Bromoxynil octanoate is a skin sensitizer.

Table 3.1.  Acute Toxicity of Bromoxynil Phenol and Bromoxynil Octanoate
                                   Guideline
                                     Study
                                    Species
                                    Results
                                 Tox. Category
                                   MRID No.
                          Bromoxynil Phenol Technical
870.1100
Acute oral toxicity
Rat
LD50 = 81 mg/kg  M
LD50 = 93 mg/kg  F
                                      II
                                   00124758
870.1200
Acute dermal toxicity
Rat
LD50 >= 2000 mg/kg (M, F)
                                      III
                                   00124758
870.1300
Acute inhalation toxicity
Rat
LC5O = 0.269 mg/L M
LC5O = 0.150 mg/L F
                                      II
                                   43014701
870.2400
Primary eye irritation
Rabbit
Corneal opacity resolved within 3 days; iritis resolved within 4 days; conjunctival irritation persisted for 10 days.
                                      II
                                   00124758
870.2500
Primary skin irritation
Rabbit
Not an irritant
                                      IV
                                   00124758
870.2600
Dermal sensitization
Guinea Pig
Not a sensitizer
                                   Negative
                                   42718701
                        Bromoxynil Octanoate Technical
870.1100
Acute oral toxicity
Rat
LD50 = 400 mg/kg  M
LD50 = 238 mg/kg  F
                                      II
                                   00124112
870.1100
Acute dermal toxicity
Rabbit
LD50> 2000 mg/kg  M
  abraded skin.
LD50 1310 mg/kg  F
  with intact skin.
LD50 = 1660 mg/kg  F
  with abraded skin.
                                      II
                                   00124112
870.1300
Acute inhalation toxicity
Rat
LC5O = 0.810 mg/L  M
LC5O = 0.720 mg/L  F
                                      III
                                   42167101
870.2400
Primary eye irritation
Rabbit
Corneal opacity and irritation lasting 24-72 hrs. Cleared by 96 hrs.
                                      II
                                   00124112
870.2500
Primary skin irritation
Rabbit
Erythema for 72 hrs. No edema,
                                      IV
                                   00124112
870.2600
Dermal sensitization
Guinea Pig
Contact sensitizer in modified Draize test.
                                   Positive
                                   41879801

Toxicological PODs Used for Risk Assessment
Estimated short- and intermediate-term dermal exposures were compared to the NOAEL of 10 mg/kg/day from a dermal developmental study in which increased incidence of supernumerary ribs were seen.  Estimated short- and intermediate-term inhalation exposures were compared to the NOAEL of 4 mg/kg/day from an oral developmental toxicity study in the rat based on increased incidence of supernumerary ribs.  Short- and intermediate-term incidental oral POD has been selected to protect infants and children. The NOAEL of 5 mg/kg/day was selected from the subchronic dog study and was considered the most appropriate oral POD.

The dermal, inhalation and incidental oral LOC is based on an uncertainty factor (UF) of 100 (interspecies extrapolation (10X) x  intraspecies variation (10X) x  FQPA Safety Factor (1X).

Bromoxynil is classified as a "possible human carcinogen" based on the presence of hepatocellular tumors in male and female mice.  The unit risk, Q1[*], of bromoxynil based upon male mouse hepatocellular tumors rates is 0.103 (mg/kg/day)[-1] in human equivalents.  (TXR 0050045, E. Budd and E. Rinde. 03/12/1997)  Mutagenicity tests were largely negative and did not raise a concern.

Table 3.2 Summary of Toxicological Doses and Endpoints for Bromoxynil for Use in Non-Occupational Human Health Risk Assessments
Exposure/
Scenario
                              Point of Departure
                        Uncertainty/FQPA Safety Factors
                RfD, PAD, Level of Concern for Risk Assessment
                        Study and Toxicological Effects
Dermal Short- (1-30 days) and Intermediate- Term (1-6 months)
NOAEL= 10 mg/kg/day
UFA= 10 x
UFH=10 x

Occupational LOC = 100
Dermal developmental toxicity study  -  Rats
The LOAEL of 15 mg/kg/day based on increased incidence of supernumerary (14th) ribs.
Incidental Oral
Short-Term
(1-30 days)

NOAEL= 5 mg/kg/day
UFA= 10 x
UFH=10 x
FQPA SF=1x

LOC = 100
Subchronic Study in Dogs
The LOAEL for effects attributed to a single dose was 8 mg/kg based on panting.  In addition to panting, elevated rectal temperatures occurred at 16 mg/kg and above, and death occurred at 30 mg/kg and above after a single dose on day 1
Cancer (oral, dermal, inhalation)
Bromoxynil phenol has been classified by the HED Carcinogenicity Peer Review Committee (E. Budd and E. Rinde, 3/12/1997, TXR 0050045) as a Group C, possible human carcinogen, based on male mouse hepatocellular tumors.  The committee also recommended that a low dose extrapolation model (Q1*) be applied to the experimental animal tumor data for quantification of human risk.  Q1* = 0.103 (mg/kg/day)[-1]
Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures.  NOAEL = no observed adverse effect level.  LOAEL = lowest observed adverse effect level.  UF = uncertainty factor.  UFA = extrapolation from animal to human (interspecies).  UFH = potential variation in sensitivity among members of the human population (intraspecies).  FQPA SF = FQPA Safety Factor. LOC = Level of Concern

Table 3.3 Summary of Toxicological Doses and Endpoints for Bromoxynil for Use in Occupational Human Health Risk Assessments
Exposure/
Scenario
Point of Departure
Uncertainty Factors
Level of Concern for Risk Assessment
Study and Toxicological Effects
Dermal Short- (1-30 days) and Intermediate- Term (1-6 months)
NOAEL= 10 mg/kg/day
UFA= 10 x
UFH=10 x

Occupational LOC = 100
Dermal developmental toxicity study  -  Rats
The LOAEL of 15 mg/kg/day based on increased incidence of supernumerary (14th) ribs.
Inhalation Short- (1-30 days) and Intermediate-Term (1-6 months)
NOAEL= 4 mg/kg/day
UFA= 10 x
UFH=10 x

Occupational LOC = 100
Oral developmental toxicity study in rats. NOAEL of 4 mg/kg/day was selected from one study (MRID 40466802, LOAEL =   mg/kg/day) and the LOAEL of 5 mg/kg/day was selected from another study (MRID 00116558, NOAEL not established).  Both studies showed a dose-related increased incidence of supernumerary ribs at the LOAEL.
Cancer (oral, dermal, inhalation)
Bromoxynil phenol has been classified by the HED Carcinogenicity Peer Review Committee (E. Budd and E. Rinde, 3/12/1997, TXR 0050045) as a Group C, possible human carcinogen, based on male mouse hepatocellular tumors.  The committee also recommended that a low dose extrapolation model (Q1*) be applied to the experimental animal tumor data for quantification of human risk.  Q1* = 0.103 (mg/kg/day)[-1]
Point of Departure (POD) = A data point or an estimated point that is derived from observed dose-response data and used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human exposures.  NOAEL = no observed adverse effect level.  LOAEL = lowest observed adverse effect level.  UF = uncertainty factor.  UFA = extrapolation from animal to human (interspecies).  UFH = potential variation in sensitivity among members of the human population (intraspecies).   LOC = level of concern.  . LOC = Level of Concern

Absorption
Since the short- and intermediate-term dermal POD was based on a route-specific toxicity study, no absorption factor was necessary to estimate dermal exposure in the non-cancer assessment. For the cancer assessment, the Q1* is based on an oral study; a dermal absorption factor of 17% was used.

Since no inhalation absorption data are available, toxicity by the inhalation route is considered to be equivalent to the estimated toxicity by the oral route of exposure for both the non-cancer and cancer assessments.

Body Weight
For the occupational non-cancer assessment, the dermal and inhalation PODs are based on developmental and/or fetal effects, therefore, the body weight appropriate for dermal and inhalation assessments is 69 kg.  For purposes of performing a spray drift assessment an adult body weight of 69 kg and child (1 < 2 yrs old) body weight of 11 kg was used.  Finally, in order to perform the occupational cancer assessment, a  standard body weight for the general population (80 kg) was used since the cancer endpoint was not based on developmental and/or fetal effects.

4.0 Use Profile

Bromoxynil is currently formulated as a liquid formulation, and registered for use on agricultural food crops including garlic and onions; food and feed crops including mint, flax, spearmint, peppermint, barley, oats, rye, triticale, wheat, sorghum, cotton, and corn (field and pop); and feed crops including alfalfa, forage/hay, and grass.  Current, non-food uses include outdoor industrial areas, nonagricultural uncultivated areas/soil, non-residential commercial/industrial lawns, shrubs/bushes/vines, and sod farms.

Bromoxynil registered products are applied either via aerial, groundboom, or chemigation equipment. Most of the bromoxynil product labels direct mixers, loaders, applicators, and other handlers to wear baseline attire (i.e., long-sleeved shirt, long pants, shoes and socks), coveralls, chemical resistant apron and gloves, protective eyewear, and respirators. The restricted entry intervals (REIs) range from 12 to 24 hours for registered labels.

A summary of the representative registered commercial end-use products and use sites with the highest application rates provided by PLUS report (4/12/18) is provided in Table D.1 in appendix D.

5.0 Residential Exposure and Risk Estimates

A residential handler and post-application exposure assessment is not required for bromoxynil since there are no registered direct residential uses at this time

6.0 Non-Occupational Spray Drift Exposure and Risk Estimates

Spray drift is a potential source of exposure to those nearby pesticide applications.  This is particularly the case with aerial application, but, to a lesser extent, spray drift can also be a potential source of exposure from the ground application methods (e.g., groundboom) employed for bromoxynil.  The Agency has been working with the Spray Drift Task Force (a task force composed of various registrants which was developed as a result of a Data Call-In issued by EPA), EPA Regional Offices and State Lead Agencies for pesticide regulation and other parties to develop the best spray drift management practices (see the Agency's Spray Drift website for more information).   The Agency has also developed a policy on how to appropriately consider spray drift as a potential source of exposure in risk assessments for pesticides.  The potential for spray drift will be quantitatively evaluated for each pesticide during the Registration Review process which ensures that all uses for that pesticide will be considered concurrently.  The approach is outlined in the revised (2012) Standard Operating Procedures For Residential Risk Assessment (SOPs) - Residential Exposure Assessment Standard Operating Procedures Addenda 1: Consideration of Spray Drift.  This document outlines the quantification of indirect non-occupational exposure to drift.

Off-target movement of pesticides can occur via many types of pathways and it is governed by a variety of factors.  Sprays that are released and do not deposit in the application area end up off-target and can lead to exposures to those it may directly contact.  They can also deposit on surfaces where contact with residues can eventually lead to indirect exposures (e.g., children playing on lawns where residues have deposited next to treated fields).  The potential risk estimates from these residues can be calculated using drift modeling coupled with methods employed for residential risk assessments for turf products.

The approach to be used for quantitatively incorporating spray drift into risk assessment is based on a premise of compliant applications which, by definition, should not result in direct exposures to individuals because of existing label language and other regulatory requirements intended to prevent them.  Direct exposures would include inhalation of the spray plume or being sprayed directly.  Rather, the exposures addressed here are thought to occur indirectly through contact with impacted areas, such as residential lawns, when compliant applications are conducted.  Given this premise, exposures for children (1 to 2 years old) and adults who have contact with turf where residues are assumed to have deposited via spray drift thus resulting in an indirect exposure are the focus of this analysis analogous to how exposures to turf products are considered in risk assessment.

In order to evaluate the drift potential and associated risks, an approach based on drift modeling coupled with techniques used to evaluate residential uses of pesticides was utilized. Essentially, a residential turf assessment based on exposure to deposited residues has been completed to address drift from the agricultural applications of bromoxynil.  In the spray drift scenario, the deposited residue value was determined based on the amount of spray drift that may occur at varying distances from the edge of the treated field using the AgDrift (v2.1.1) model and the Residential Exposure Assessment Standard Operating Procedures Addenda 1: Consideration of Spray Drift Policy. Once the deposited residue values were determined, the remainder of the spray drift assessment was based on the algorithms and input values specified in the recently revised (2012) Standard Operating Procedures for Residential Risk Assessment (SOPs).

A screening approach was developed based on the use of the AgDrift model in situations where specific label guidance that defines application parameters is not available. AgDrift is appropriate for use only when applications are made by aircraft, airblast orchard sprayers, and groundboom sprayers.  When AgDrift was developed, a series of screening values (i.e., the Tier 1 option) were incorporated into the model and represent each equipment type and use under varied conditions.  The screening options specifically recommended in this methodology were selected because they are plausible and represent a reasonable upper bound level of drift for common application methods in agriculture.  These screening options are consistent with how spray drift is considered in a number of ecological risk assessments and in the process used to develop drinking water concentrations used for risk assessment.  In all cases, each scenario is to be evaluated unless it is not plausible based on the anticipated use pattern (e.g., herbicides are not typically applied to tree canopies) or specific label prohibitions (e.g., aerial applications are not allowed).  The screening level drift related risk estimates are presented below.  In many cases, risks are of concern when the screening level estimates for spray drift are used as the basis for the analysis.  In order to account for this issue and to provide additional risk management options additional spray drift deposition fractions were also considered.  These drift estimates represent plausible options for pesticide labels.

The spray drift risk estimates are based on an estimated deposited residue concentration as a result of the screening level agricultural application scenarios.  Bromoxynil is applied on fallow land via aerial and groundboom equipment at a maximum application rate of 1.0 lb ai/A. Exposures were considered for 50 feet wide lawns where the nearest side of the property was directly adjoining the treated field (at field edge) and at varied distances up to 300 feet downwind of a treated field.

Furthermore, spray drift risk estimates were refined by using chemical-specific turf transferable residue (TTR) data submitted for bromoxynil (MRID 49884501). The study has been reviewed by HED and was found to be acceptable for risk assessment. The predicted DAT-0 residue value of 0.041 ug/cm2 from the Georgia site (non-irrigated plot) was used in the assessment, adjusted for differences in application rates between study and label.  Adjusted TTR value of 0.080 ug/cm2 was used to estimate risks. For a more detailed summary of the study, see Section 8.2.2.

Dermal risks were estimated for adults and children; incidental oral risk estimates were calculated for children 1 < 2 years old. The level of concern (LOC) is 100 so MOEs < 100 would be of concern.  Results are presented in Tables 6.1 (adults) and 6.2 (children 1 < 2 years old).

For adults (Table 6.1), dermal risks from groundboom applications are not of concern at the field edge. Most dermal risks are not of concern for aerial applications. Aerial applications using very fine to fine spray type resulted in dermal MOEs ranging from 85 at the field edge and 93 at a distance of 10 feet. Dermal MOEs did not reach 100 until 25 feet.

For children 1 < 2 years old (Table 6.2), dermal and hand-to-mouth risk estimates from groundboom applications are not of concern at the field edge. For aerial applications, hand-to-mouth risks are not of concern at the field edge; however, dermal risk estimates is of concern for the following scenarios:

 Aerial applications using fine to medium spray up to 10 feet from the field
 Aerial applications using medium to coarse spray at edge
 Aerial applications using very fine to fine spray up to 100 feet from the field
 Aerial applications using AT401, M, 10 mph, 37% SD configuration at edge risks)
 Aerial applications using WASP, M, 10 mph, 37% SD and AT401, C, 10 mph, 25% SD at edge

Table 6.1. Residential Exposure due to Agricultural Drift - Adults
                                Crop/Rate Group
                       Spray Type/ Nozzle Configuration
                                    At Edge
                                    10 Feet
                                   25 Feet
                                    50 Feet
                                    75 Feet
                                   100 Feet
                                   125 Feet
                                   150 Feet
                                   200 Feet
                                   250 Feet
                                   300 Feet
Fallow land (Application Rate = 1.0 lb ai/A; Adjusted TTR = 0.0804 ug/cm[2])
                                 Dermal MOE[1]
                                    Aerial
                                Fine to Medium
                                      120
                                      150
                                      190
                                      250
                                      320
                                      420
                                      500
                                      590
                                      780
                                      930
                                     1,100

                               Medium to Coarse
                                      150
                                      200
                                      280
                                      390
                                      550
                                      720
                                      910
                                     1,100
                                     1,500
                                     2,000
                                     2,400

                             Coarse to Very Coarse
                                      170
                                      260
                                      390
                                      600
                                      860
                                     1,100
                                     1,400
                                     1,800
                                     2,400
                                     3,200
                                     4,000

                               Very Fine to Fine
                                      85
                                      93
                                      100
                                      120
                                      140
                                      160
                                      180
                                      210
                                      250
                                      290
                                      330

                           AT401, M, 10 mph, 37% SD
                                      140
                                      170
                                      220
                                      300
                                      410
                                      530
                                      650
                                      760
                                      990
                                     1,200
                                     1,500

                            WASP, M, 10 mph, 37% SD
                                      150
                                      190
                                      250
                                      370
                                      500
                                      650
                                      790
                                      930
                                     1,200
                                     1,500
                                     1,800

                           AT401, C, 10 mph, 25% SD
                                      160
                                      230
                                      320
                                      470
                                      680
                                      880
                                     1,100
                                     1,300
                                     1,900
                                     2,400
                                     2,900

                            WASP, C, 10 mph, 25% SD
                                      190
                                      260
                                      380
                                      600
                                      840
                                     1,100
                                     1,400
                                     1,800
                                     2,400
                                     3,200
                                     3,500

                           AT401, VC, 10 mph, 20% SD
                                      180
                                      280
                                      440
                                      720
                                     1,000
                                     1,400
                                     1,800
                                     2,300
                                     3,200
                                     4,000
                                     5,300

                           WASP, VC, 10 mph, 20% SD
                                      230
                                      360
                                      560
                                      880
                                     1,300
                                     1,700
                                     2,300
                                     2,600
                                     4,000
                                     4,500
                                     5,300
                                  Groundboom
                          High Boom Very fine to Fine
                                      170
                                      340
                                      570
                                      910
                                     1,300
                                     1,600
                                     1,900
                                     2,300
                                     2,900
                                     4,000
                                     4,500

                          Low Boom Very fine to Fine
                                      370
                                      990
                                     1,600
                                     2,400
                                     3,200
                                     4,000
                                     4,500
                                     5,300
                                     6,400
                                     7,900
                                    11,000

                        High Boom Fine to Medium/Coarse
                                      650
                                     1,700
                                     2,400
                                     3,500
                                     4,500
                                     5,300
                                     6,400
                                     6,400
                                     7,900
                                    11,000
                                    11,000

                        Low Boom Fine to Medium/Coarse
                                      960
                                     2,600
                                     4,000
                                     5,300
                                     6,400
                                     7,900
                                    11,000
                                    11,000
                                    16,000
                                    16,000
                                    16,000
1	Dermal MOE = Dermal POD (10 mg/kg/day) / Dermal Dose (mg/kg/day).

Table 6.2. Residential Exposure due to Agricultural Drift - Children 1<2 years old
                                Crop/Rate Group
                       Spray Type/ Nozzle Configuration
                                    At Edge
                                    10 Feet
                                   25 Feet
                                    50 Feet
                                    75 Feet
                                   100 Feet
                                   125 Feet
                                   150 Feet
                                   200 Feet
                                   250 Feet
                                   300 Feet
Fallow land (Application Rate = 1.0 lb ai/A; Adjusted TTR = 0.0804 ug/cm[2])
                                 Dermal MOE[1]
                                    Aerial
                                Fine to Medium
                                      72
                                      89
                                     110
                                     140
                                     190
                                      240
                                     300
                                     340
                                     450
                                     550
                                     660

                               Medium to Coarse
                                             88
                                            120
                                            160
                                            230
                                            320
                                            420
                                            530
                                            640
                                            890
                                           1,200
                                           1,400

                             Coarse to Very Coarse
                                            100
                                            150
                                            230
                                            350
                                            500
                                            660
                                            850
                                          1,000
                                          1,400
                                           1,900
                                           2,300

                               Very Fine to Fine
                                             50
                                              55
                                              61
                                              71
                                              82
                                              94
                                            110
                                            120
                                            150
                                              170
                                              200

                           AT401, M, 10 mph, 37% SD
                                             80
                                            100
                                            130
                                            180
                                            240
                                            310
                                            380
                                            440
                                            580
                                              720
                                              890

                            WASP, M, 10 mph, 37% SD
                                             85
                                            110
                                            140
                                            220
                                            300
                                            380
                                            470
                                            550
                                            720
                                              890
                                           1,000

                           AT401, C, 10 mph, 25% SD
                                             94
                                            130
                                            190
                                            280
                                            400
                                            520
                                            640
                                            780
                                          1,100
                                           1,400
                                           1,700

                            WASP, C, 10 mph, 25% SD
                                            110
                                            150
                                            220
                                            350
                                            490
                                            660
                                            810
                                          1,000
                                          1,400
                                           1,900
                                           2,100

                           AT401, VC, 10 mph, 20% SD
                                            110
                                            160
                                            260
                                            420
                                            600
                                            810
                                          1,000
                                          1,300
                                          1,900
                                           2,300
                                           3,100

                           WASP, VC, 10 mph, 20% SD
                                            130
                                            210
                                            330
                                            520
                                            740
                                            980
                                          1,300
                                          1,600
                                          2,300
                                           2,700
                                           3,100
                                  Groundboom
                          High Boom Very fine to Fine
                                            100
                                            200
                                            330
                                            530
                                            740
                                            930
                                          1,100
                                          1,300
                                          1,700
                                           2,300
                                           2,700

                          Low Boom Very fine to Fine
                                            220
                                            580
                                            930
                                          1,400
                                          1,900
                                          2,300
                                          2,700
                                          3,100
                                          3,700
                                           4,700
                                           6,200

                        High Boom Fine to Medium/Coarse
                                            380
                                            980
                                          1,400
                                          2,100
                                          2,700
                                          3,100
                                          3,700
                                          3,700
                                          4,700
                                           6,200
                                           6,200

                        Low Boom Fine to Medium/Coarse
                                            560
                                          1,600
                                          2,300
                                          3,100
                                          3,700
                                          4,700
                                          6,200
                                          6,200
                                          9,300
                                           9,300
                                           9,300
                                   HtM MOE2
                                    Aerial
                                Fine to Medium
                                         1,800
                                         2,200
                                         2,700
                                         3,500
                                         4,600
                                         6,000
                                         7,200
                                         8,400
                                       11,000
                                       13,000
                                       16,000

                               Medium to Coarse
                                         2,200
                                         2,900
                                         3,900
                                         5,500
                                         7,800
                                       10,000
                                       13,000
                                       16,000
                                       22,000
                                       28,000
                                       35,000

                             Coarse to Very Coarse
                                         2,500
                                         3,700
                                         5,500
                                         8,600
                                       12,000
                                       16,000
                                       21,000
                                       25,000
                                       35,000
                                       45,000
                                       57,000

                               Very Fine to Fine
                                         1,200
                                         1,300
                                         1,500
                                         1,700
                                         2,000
                                         2,300
                                         2,600
                                         2,900
                                         3,600
                                         4,200
                                         4,800

                           AT401, M, 10 mph, 37% SD
                                         1,900
                                         2,500
                                         3,200
                                         4,300
                                         5,800
                                         7,600
                                         9,300
                                       11,000
                                       14,000
                                       17,000
                                       22,000

                            WASP, M, 10 mph, 37% SD
                                         2,100
                                         2,700
                                         3,500
                                         5,300
                                         7,200
                                         9,300
                                       11,000
                                       13,000
                                       17,000
                                       22,000
                                       25,000

                           AT401, C, 10 mph, 25% SD
                                         2,300
                                         3,200
                                         4,600
                                         6,800
                                         9,700
                                       13,000
                                       16,000
                                       19,000
                                       27,000
                                       35,000
                                       41,000

                            WASP, C, 10 mph, 25% SD
                                         2,700
                                         3,800
                                         5,400
                                         8,600
                                       12,000
                                       16,000
                                       20,000
                                       25,000
                                       35,000
                                       45,000
                                       50,000

                           AT401, VC, 10 mph, 20% SD
                                         2,600
                                         3,900
                                         6,300
                                       10,000
                                       15,000
                                       20,000
                                       25,000
                                       32,000
                                       45,000
                                       57,000
                                       76,000

                           WASP, VC, 10 mph, 20% SD
                                         3,300
                                         5,200
                                         8,000
                                       13,000
                                       18,000
                                       24,000
                                       32,000
                                       38,000
                                       57,000
                                       65,000
                                       76,000
                                  Groundboom
                          High Boom Very fine to Fine
                                         2,400
                                         4,900
                                         8,100
                                       13,000
                                       18,000
                                       23,000
                                       27,000
                                       32,000
                                       41,000
                                       57,000
                                       65,000

                          Low Boom Very fine to Fine
                                         5,300
                                       14,000
                                       23,000
                                       35,000
                                       45,000
                                       57,000
                                       65,000
                                       76,000
                                       91,000
                                      110,000
                                      150,000

                        High Boom Fine to Medium/Coarse
                                         9,300
                                       24,000
                                       35,000
                                       50,000
                                       65,000
                                       76,000
                                       91,000
                                       91,000
                                      110,000
                                      150,000
                                      150,000

                        Low Boom Fine to Medium/Coarse
                                       14,000
                                       38,000
                                       57,000
                                       76,000
                                       91,000
                                      110,000
                                      150,000
                                      150,000
                                      230,000
                                      230,000
                                      230,000
1	Dermal MOE = Dermal POD (10 mg/kg/day) / Dermal Dose (mg/kg/day).
2	Hand to Mouth MOE = Incidental Oral POD (5 mg/kg/day) / Hand to Mouth Dose (mg/kg/day).3

7.0 Non-Occupational Bystander Post-Application Inhalation Exposure and Risk Estimates

The Agency has also developed a preliminary bystander volatilization inhalation exposure assessment for bromoxynil utilizing the currently available inhalation toxicity and air monitoring data.  There is one air monitoring studies available for bromoxynil that was conducted at the request of California Department of Pesticide Regulation (CDPR) http://www.cdpr.ca.gov/docs/emon/pubs/tac/bromoxynil.pdf "Ambient Air Monitoring after an
Application of Bromoxynil in Imperial County during January 1995."

At the request of California Department of Pesticide Regulation, the Air Resources Board (ARB) conducted a three-day source impacted ambient monitoring for an application of bromoxynil (end-use product: Buctril) to an onion field in program Imperial County during January of 1995.

This monitoring was a follow-up to similar sampling conducted in January of 1992
which found low (0.02 to 2.34 ug/m[3]), but measurable levels of bromoxynil.

The results from the 1992 data were found to be not representative due to the placement of the monitors and unusual wind patterns. At that time, samplers were located upwind and downwind of the field based on prevailing winds. With the approval of the DPR, ARB conducted a second study by placing four samplers, one placed on each side of the field. No field conditions were observed to explain the lower levels found in this second study, although a lower application rate (one pint per acre versus 1.3 pints per acre) and a different crop (onions versus wheat) may have affected the levels detected. There is no route specific inhalation study available for conducting a bystander post-application inhalation exposure assessment.  Also no sample analyzed contained bromoxynil above the detection limit (0.04 ug/sample). Therefore, a bystander post-application inhalation exposure assessment was not conducted.

8.0 Occupational Exposure and Risk Estimates

8.1 Occupational Handler Exposure/Risk Estimates

HED uses the term handlers to describe those individuals who are involved in the pesticide application process.  HED believes that there are distinct job functions or tasks related to applications and exposures can vary depending on the specifics of each task.  Job requirements (amount of chemical used in each application), the kinds of equipment used, the target being treated, and the level of protection used by a handler can cause exposure levels to differ in a manner specific to each application event.

Based on the registered use patterns and current labeling, types of equipment and techniques that can potentially be used, occupational handler exposure is expected from the registered uses.  The quantitative exposure/risk assessment developed for occupational handlers is based on the scenarios listed in Table 8.1.1.

Occupational Handler Exposure Data and Assumptions

A series of assumptions and exposure factors served as the basis for completing the occupational handler risk assessments.  Each assumption and factor is detailed below on an individual basis.

Application Rate:  The registered application rates for bromoxynil are listed in Table 4.1.

Unit Exposures:  It is the policy of HED to use the best available data to assess handler exposure.  Sources of generic handler data, used as surrogate data in the absence of chemical-specific data, include PHED 1.1, the AHETF database, the Outdoor Residential Exposure Task Force (ORETF) database, or other registrant-submitted occupational exposure studies.  Some of these data are proprietary (e.g., AHETF data), and subject to the data protection provisions of FIFRA.  The standard values recommended for use in predicting handler exposure that are used in this assessment, known as "unit exposures", are outlined in the "Occupational Pesticide Handler Unit Exposure Surrogate Reference Table", which, along with additional information on HED policy on use of surrogate data, including descriptions of the various sources, can be found at the Agency website.

Area Treated or Amount Handled:  The area treated/amount handled are based on ExpoSAC Policy 9.1.

Exposure Duration: HED classifies exposures from 1 to 30 days as short-term and exposures 30 days to six months as intermediate-term.  Exposure duration is determined by many things, including the exposed population, the use site, the pest pressure triggering the use of the pesticide, and the cultural practices surrounding that use site.  For most agricultural uses, it is reasonable to believe that occupational handlers will not apply the same chemical every day for more than a one-month time frame; however, there may be a large agribusiness and/or commercial applicators who may apply a product over a period of weeks (e.g., completing multiple applications for multiple clients within a region).

For bromoxynil, based on the existing uses, both short- and intermediate-term exposures are expected for occupational handlers because it could be applied multiple times per season to many registered use sites.

Mitigation/Personal Protective Equipment:  Estimates of dermal and inhalation exposure were calculated for various levels of personal protective equipment (PPE).  Results are presented for "baseline," defined as a single layer of clothing consisting of a long sleeved shirt, long pants, shoes plus socks, no protective gloves, and no respirator, as well as baseline with various levels of PPE as necessary (e.g., gloves, respirator, etc).  The bromoxynil product labels direct mixers, loaders, applicators, and other handlers to wear baseline attire (i.e., long-sleeved shirt, long pants, shoes and socks), coveralls, chemical resistant apron and gloves, protective eyewear, and respirators.

Occupational Handler Non-Cancer Exposure and Risk Estimate Equations
The algorithms used to estimate non-cancer exposure and dose for occupational handlers can be found in Appendix A.

Combining Exposures/Risk Estimates:
Dermal and inhalation risk estimates were combined in this assessment, since the toxicological effects for these exposure routes were similar.  Dermal and inhalation risk estimates were combined using the following formula:

 Total MOE = 1 / (1/Dermal MOE) + (1/Inhalation MOE)

Summary of Occupational Handler Non-Cancer Exposure and Risk Estimates
Dermal MOEs range from 5.2 to 23,000, inhalation MOEs range from 2,100 to 1,800,000, and Total MOEs range from 5.2 to 23,000 at baseline. All occupational handler inhalation risk estimates are not of concern at baseline attire (no respirator), while about a third of the dermal risks estimates were of concern at baseline (single layer, no gloves).  Of the eleven scenarios with dermal risks of concern at baseline, all but two are not of concern with consideration of lable recommended dermal PPE (double layer clothing + gloves).  The following occupational handler exposure scenarios result in estimated risks of concern despite the addition of dermal protection (double layer clothing + gloves):

 Mixer/loader of liquid formulation for aerial applications to fallow land at 1.0 lb ai/A (Dermal MOE = 68, Total MOE = 67)
 Mixer/loader of liquid formulation for aerial applications to high-acreage field crop at 0.5 lb ai/A (Dermal MOE = 39, Total MOE = 38).

These two mixer/loader scenarios are not of concern with the use of engineering controls; the dermal MOEs are 230 for mixing/loading liquids for applications to fallow land and 130 for mixing/loading liquids for applications to high-acreage field crops.

The Agency matches quantitative occupational exposure assessment with appropriate characterization of exposure potential. While HED presents quantitative risk estimates for human flaggers where appropriate, agricultural aviation has changed dramatically over the past two decades. According the 2012 National Agricultural Aviation Association (NAAA) survey of their membership, the use of GPS for swath guidance in agricultural aviation has grown steadily from the mid 1990's. Over the same time period, the use of human flaggers for aerial pesticide applications has decreased steadily from ~15% in the late 1990's to only 1% in the most recent (2012) NAAA survey. The Agency will continue to monitor all available information sources to best assess and characterize the exposure potential for human flaggers in agricultural aerial applications.

HED has no data to assess exposures to pilots using open cockpits.  The only data available is for exposure to pilots in enclosed cockpits.  Therefore, risks to pilots are assessed using the engineering control (enclosed cockpits) and baseline attire (long-sleeve shirt, long pants, shoes, and socks); per the Agency's Worker Protection Standard stipulations for engineering controls, pilots are not required to wear protective gloves for the duration of the application.  With this level of protection, there are no risk estimates of concern for applicators.

Table 8.1.1.  Occupational Handler Non-Cancer Exposure and Risk Estimates for Bromoxynil
                               Exposure Scenario
                                Crop or Target
                     Dermal Unit Exposure[1]
(μg/lb ai)
                    Inhalation
Unit
Exposure[1]
(μg/lb ai)
                          Maximum
Application Rate[2]
                    Area Treated /
Amount Handled Daily[3]
                                    Dermal
                                  Inhalation
                                     Total

                              Dose (mg/kg/day)[4]
                                    MOE[5]
                              Dose (mg/kg/day)[6]
                                    MOE[7]
                                    MOE[8]
                                 Mixer/Loader
                Mixing/Loading Liquids for Aerial Applications
                    Roads, parking lots, etc. (pre-paving)
                                      220
                                     0.219
                               0.522 lb ai/acre
                                   60 acres
                                    0.0999
                                      100
                                   0.0000994
                                     40000
                                      100

                         Field-grown ornamental crops
                                      220
                                     0.219
                               0.368 lb ai/acre
                                   40 acres
                                     0.047
                                      210
                                    0.00322
                                     86000
                                      210

                                      Sod
                                      220
                                     0.219
                               0.522 lb ai/acre
                                   350 acres
                                     0.583
                                      17
                                    0.00058
                                     6900
                                      17

                                  37.6 (SL/G)

                                    0.0996
                                      100

                                      99

                              Field crop, typical
                                      220
                                     0.219
                                0.5 lb ai/acre
                                   350 acres
                                     0.558
                                      18
                                   0.000555
                                     7200
                                      18

                                  37.6 (SL/G)

                                    0.0954
                                      100

                                      100

                                  Fallow land
                                      220
                                     0.219
                                 1 lb ai/acre
                                   350 acres
                                     1.12
                                      8.9
                                    0.00111
                                     3600
                                      8.9

                                  37.6 (SL/G)

                                     0.191
                                      52

                                      51

                                  29.1 (DL/G)

                                     0.148
                                      68

                                      67

                                   8.6 (EC)
                                  0.083 (EC)

                                    0.0436
                                      230
                                   0.000422
                                     9500
                                      220

                           Field crop, high-acreage
                                      220
                                     0.219
                                0.5 lb ai/acre
                                  1200 acres
                                     1.91
                                      5.2
                                    0.0019
                                     2100
                                      5.2

                                  37.6 (SL/G)

                                     0.328
                                      30

                                      30

                                  29.1 (DL/G)

                                     0.254
                                      39

                                      38

                                   8.6 (EC)
                                  0.083 (EC)

                                    0.0748
                                      130
                                   0.000722
                                     5500
                                      130
              Mixing/Loading Liquids for Chemigation Applications

                                      Sod
                                      220
                                     0.219
                                0.5 lb ai/acre
                                   350 acres
                                     0.558
                                      18
                                   0.000555
                                     7200
                                      18

                                  37.6 (SL/G)

                                    0.0954
                                      100

                                      99

                              Field crop, typical
                                      220
                                     0.219
                                0.5 lb ai/acre
                                   350 acres
                                     0.558
                                      18
                                   0.000555
                                     7200
                                      18

                                  37.6 (SL/G)

                                    0.0954
                                      100

                                      100

                           Field crop, high-acreage
                                      220
                                     0.219
                                0.5 lb ai/acre
                                   350 acres
                                     0.558
                                      18
                                   0.000555
                                     7200
                                      18

                                  37.6 (SL/G)

                                    0.0954
                                      100

                                      99
              Mixing/Loading Liquids for Groundboom Applications
                    Roads, parking lots, etc. (pre-paving)
                                      220
                                     0.219
                               0.523 lb ai/acre
                                    5 acres
                                    0.00833
                                     1200
                                   0.0000083
                                    480000
                                     1200

                         Field-grown ornamental crops
                                      220
                                     0.219
                               0.368 lb ai/acre
                                   40 acres
                                     0.047
                                      210
                                   0.0000467
                                     86000
                                      210

                                      Sod
                                      220
                                     0.219
                               0.523 lb ai/acre
                                   80 acres
                                     0.133
                                      75
                                   0.000133
                                     30000
                                      75

                                  37.6 (SL/G)

                                    0.0228
                                      440

                                      430

                              Field crop, typical
                                      220
                                     0.219
                                0.5 lb ai/acre
                                   80 acres
                                     0.128
                                      78
                                    0.00876
                                     31000
                                      78

                                  37.6 (SL/G

                                    0.0217
                                      460

                                      450

                                  Fallow land
                                      220
                                     0.219
                                 1 lb ai/acre
                                   80 acres
                                     0.255
                                      39
                                   0.000254
                                     16000
                                      39

                                  37.6 (SL/G)

                                    0.0436
                                      230

                                      230

                           Field crop, high-acreage
                                      220
                                     0.219
                                0.5 lb ai/acre
                                   200 acres
                                     0.319
                                      31
                                   0.000317
                                     13000
                                      31

                                  37.6 (SL/G)

                                    0.0545
                                      180

                                      180
                                  Applicator
               Applying Sprays with Aerial Application Equipment
                    Roads, parking lots, etc. (pre-paving)
                                   2.08 (EC)
                                    0.0049
                                     (EC)
                               0.522 lb ai/acre
                                   60 acres
                                   0.000943
                                     11000
                                  0.00000222
                                    1800000
                                     11000

                         Field-grown ornamental crops
                                   2.08 (EC)
                                    0.0049
                                     (EC)
                               0.368 lb ai/acre
                                   40 acres
                                   0.0000443
                                     23000
                                  0.00000104
                                    380000
                                     23000

                                      Sod
                                   2.08 (EC)
                                    0.0049
                                     (EC)
                               0.522 lb ai/acre
                                   350 acres
                                    0.00551
                                     1800
                                   0.000013
                                    310000
                                     1800

                              Field crop, typical
                                   2.08 (EC)
                                    0.0049
                                     (EC)
                                0.50 lb ai/acre
                                   350 acres
                                    0.00528
                                     1900
                                   0.0000124
                                     32000
                                     1900

                                  Fallow land
                                   2.08 (EC)
                                    0.0049
                                     (EC)
                                 1 lb ai/acre
                                   350 acres
                                    0.0106
                                      940
                                   0.0000249
                                    160000
                                      930

                           Field crop, high-acreage
                                    No Data
                                    No Data
                                0.5 lb ai/acre
                                  1200 acres
                                    0.0181
                                      550
                                   0.0000426
                                     94000
                                      550
             Applying Sprays with Groundboom Application Equipment
                    Roads, parking lots, etc. (pre-paving)
                                     78.6
                                     0.34
                               0.523 lb ai/acre
                                    5 acres
                                    0.00299
                                     3300
                                   0.0000129
                                    310000
                                     3300

                         Field-grown ornamental crops
                                     78.6
                                     0.34
                               0.368 lb ai/acre
                                   40 acres
                                    0.0168
                                      600
                                   0.0000725
                                     55000
                                      590

                                      Sod
                                     78.6
                                     0.34
                               0.523 lb ai/acre
                                   80 acres
                                    0.0477
                                      210
                                   0.000206
                                     19000
                                      210

                              Field crop, typical
                                     78.6
                                     0.34
                                0.5 lb ai/acre
                                   80 acres
                                    0.0455
                                      220
                                   0.000197
                                     2000
                                      220

                                  Fallow land
                                     78.6
                                     0.34
                                 1 lb ai/acre
                                   80 acres
                                    0.0912
                                      110
                                   0.000394
                                     10000
                                      110

                           Field crop, high-acreage
                                     78.6
                                     0.34
                                0.5 lb ai/acre
                                   200 acres
                                     0.114
                                      88
                                   0.000493
                                     8100
                                      87

                                  16.1 (SL/G)

                                    0.0233
                                      430

                                      410
                                    Flagger
                   Flagging for Aerial Applications (Sprays)
                         Field-grown ornamental crops
                                      11
                                     0.35
                               0.368 lb ai/acre
                                   350 acres
                                    0.0203
                                      490
                                   0.0000654
                                     6100
                                      450

                                      Sod
                                      11
                                     0.35
                               0.522 lb ai/acre
                                   350 acres
                                    0.0291
                                      340
                                   0.000926
                                     4300
                                      320

                              Field crop, typical
                                      11
                                     0.35
                                0.5 lb ai/acre
                                   350 acres
                                     0.028
                                      360
                                   0.000888
                                     4500
                                      330

                                  Fallow land
                                      11
                                     0.35
                                 1 lb ai/acre
                                   350 acres
                                    0.0558
                                      180
                                    0.00178
                                     2200
                                      170

                           Field crop, high-acreage
                                      11
                                     0.35
                                0.5 lb ai/acre
                                   350 acres
                                     0.028
                                      360
                                   0.000888
                                     4500
                                      330
1	Based on the "Occupational Pesticide Handler Unit Exposure Surrogate Reference Table" (https://www.epa.gov/pesticide-science-and-assessing-pesticide-risks/occupational-pesticide-handler-exposure-data); Level of mitigation: Baseline unless shown otherwise. G = gloves, DL= double layer, EC = engineering control..
2	Based on registered labels.
3	Exposure Science Advisory Council Policy #9.1.
4	Dermal Dose = Dermal Unit Exposure (μg/lb ai) x Conversion Factor (0.001 mg/μg) x Application Rate (lb ai/acre or gal) x Area Treated or Amount Handled (A or gal/day)  / BW (69 kg).
5	Dermal MOE = Dermal POD (mg/kg/day) / Dermal Dose (mg/kg/day). Bold MOEs represent estimates of concern (LOC = 100).
6	Inhalation Dose = Inhalation Unit Exposure (μg/lb ai) x Conversion Factor (0.001 mg/μg) x Application Rate (lb ai/acre or gal) x Area Treated or Amount Handled (A or gal/day) / BW (69 kg).
7	Inhalation MOE = Inhalation POD (mg/kg/day) / Inhalation Dose (mg/kg/day).
8	Total MOE = 1 / (1/Dermal MOE + 1/Inhalation MOE).

Occupational Handler Cancer Exposure and Risk Equations
Cancer risk estimates were calculated using a linear low-dose extrapolation approach in which a Lifetime Average Daily Dose (LADD) is first calculated and then compared with a Q1* that has been calculated for bromoxynil based on dose response data in the appropriate toxicology study (Q1* = 0.103 (mg/kg/day)[-1]).  Absorbed average daily dose (ADD) levels were used as the basis for calculating the LADD values.  Dermal and inhalation ADD values were first added together to obtain combined ADD values.  LADD values were then calculated and compared to the Q1* to obtain cancer risk estimates.  The algorithms used to estimate the LADD and cancer risk for occupational handlers can be found in Appendix B.

Days per Year of Exposure: To assess cancer risk, it is assumed that private growers would be exposed 10 days per year and commercial applicators would be exposed 30 days per year.  The term "private grower" means that the grower or one of the workers would apply the pesticides to land owned or operated by the grower.  Commercial applicators means the applicators are completing multiple applications for multiple clients.

Years per Lifetime of Exposure: It is assumed that handlers would be exposed for 35 years out of a 78 year lifespan.

Lifetime Expectancy: Life expectancy values are from the Exposure Factors Handbook 2011 Edition Table 18-1 (U.S. EPA, 2011).  The table shows that the overall life expectancy is 78 years based on life expectancy data from 2007.  In 2007, the average life expectancy for males was 75 years and 80 years for females.  Based on the available data, the recommended value for use in cancer risk assessments is 78 years.

Summary of Occupational Handler Cancer Exposure and Risk Estimates
Occupational cancer risks were estimated for both private/farmer and contract/commercial handlers.  Cancer risks at baseline (single layer, no gloves, no respirator) range from 6E-07 to 4E-04 for private/farmer and 2E[-06] to 1E[-03] contract/commercial handlers. With the addition of lable recommended PPE , dermal and inhalation protection (double layer, gloves, P10 respirator), cancer risks range from 9E[-08] to 5E[-05] for private/farmer and 3E[-07] to 1E[-04] or contract/commercial handlers

A summary of occupational cancer risks as estimated at all levels of personal protection and with use of engineering controls is presented in Tables 8.1.2 and 8.1.3.  Table 8.1.2 presents cancer risks for private/farmer handlers and Table 8.1.3 presents risks for contract/commercial handlers.

Table 8.1.2.  Bromoxynil Occupational Handler Cancer Risk Estimates  -  Private/Farmer
                               Exposure Scenario
                                Crop or Target
                                 App. Rate[1]
                                Area Treated[2]
                                 (units/ day)
                               Private/Farmer[3]

                                SL/No G + No-R
                                  SL/G + No-R
                                  DL/G + No-R
                               SL/No G + PF10 R
                                 SL/G + PF10 R
                                 DL/G + PF10 R
                               SL/No G + PF50 R
                                 SL/G + PF50 R
                                 DL/G + PF50 R
                                      EC
                                 Mixer/Loader
                Mixing/Loading Liquids for Aerial Applications
                    Roads, parking lots, etc. (pre-paving)
                               0.522 lb ai/acre
                                   60 acres
                                     2E-05
                                     3E-06
                                     3E-06
                                     2E-05
                                     3E-06
                                     2E-06
                                     2E-05
                                     3E-06
                                     2E-06
                                     8E-07

                         Field-grown ornamental crops
                               0.368 lb ai/acre
                                  40 acres
                                     9E-06
                                     2E-06
                                     1E-06
                                     9E-06
                                     1E-06
                                     1E-06
                                     9E-06
                                     1E-06
                                     1E-06

                                     4E-07

                                      Sod
                               0.522 lb ai/acre
                                   350 acres
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     4E-06

                              Field crop, typical
                                0.5 lb ai/acre
                                   350 acres
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     4E-06

                                  Fallow land
                                1.0 lb ai/acre
                                   350 acres
                                     2E-04
                                     4E-05
                                     3E-05
                                     2E-04
                                     4E-05
                                     3E-05
                                     2E-04
                                     4E-05
                                     3E-05
                                     9E-06

                           Field crop, high-acreage
                               0.500 lb ai/acre
                                  1200 acres
                                     4E-04
                                     6E-05
                                     5E-05
                                     4E-04
                                     6E-05
                                     5E-05
                                     4E-04
                                     6E-05
                                     5E-05
                                     1E-05
              Mixing/Loading Liquids for Chemigation Applications

                                      Sod
                               0.500 lb ai/acre
                                   350 acres
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     4E-06

                              Field crop, typical
                                0.5 lb ai/acre
                                   350 acres
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     4E-06

                           Field crop, high-acreage
                               0.500 lb ai/acre
                                   350 acres
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     1E-04
                                     2E-05
                                     1E-05
                                     4E-06
              Mixing/Loading Liquids for Groundboom Applications
                    Roads, parking lots, etc. (pre-paving)
                               0.523 lb ai/acre
                                    5 acres
                                     2E-06
                                     3E-07
                                     2E-07
                                     2E-06
                                     3E-07
                                     2E-07
                                     2E-06
                                     3E-07
                                     2E-07
                                     6E-08

                         Field-grown ornamental crops
                               0.368 lb ai/acre
                                   40 acres
                                     9E-06
                                     2E-06
                                     1E-06
                                     9E-06
                                     1E-06
                                     1E-06
                                     9E-06
                                     1E-06
                                     1E-06
                                     4E-07

                                      Sod
                               0.523 lb ai/acre
                                   80 acres
                                     2E-05
                                     4E-06
                                     3E-06
                                     2E-05
                                     4E-06
                                     3E-06
                                     2E-05
                                     4E-06
                                     3E-06
                                     1E-06

                              Field crop, typical
                                0.5 lb ai/acre
                                   80 acres
                                     2E-05
                                     4E-06
                                     3E-06
                                     2E-05
                                     4E-06
                                     3E-06
                                     2E-05
                                     4E-06
                                     3E-06
                                     1E-06

                                  Fallow land
                                 1 lb ai/acre
                                   80 acres
                                     5E-05
                                     8E-06
                                     7E-06
                                     5E-05
                                     8E-06
                                     6E-06
                                     5E-05
                                     8E-06
                                     6E-06
                                     2E-06

                           Field crop, high-acreage
                               0.500 lb ai/acre
                                   200 acres
                                     6E-05
                                     1E-05
                                     8E-06
                                     6E-05
                                     1E-05
                                     8E-06
                                     6E-05
                                     1E-05
                                     8E-06
                                     2E-06
                                  Applicator
               Applying Sprays with Aerial Application Equipment
                    Roads, parking lots, etc. (pre-paving)
                               0.522 lb ai/acre
                                   60 acres
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                     2E-07

                         Field-grown ornamental crops
                               0.368 lb ai/acre
                                   40 acres
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                     8E-08

                                      Sod
                               0.522 lb ai/acre
                                   350 acres
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                     1E-06

                              Field crop, typical
                                0.5 lb ai/acre
                                   350 acres
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                     1E-06

                                  Fallow land
                                 1 lb ai/acre
                                   350 acres
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                     2E-06

                           Field crop, high-acreage
                               0.500 lb ai/acre
                                  1200 acres
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                    No Data
                                     3E-06
             Applying Sprays with Groundboom Application Equipment
                    Roads, parking lots, etc. (pre-paving)
                               0.523 lb ai/acre
                                    5 acres
                                     6E-07
                                     1E-07
                                     1E-07
                                     6E-07
                                     1E-07
                                     9E-08
                                     6E-07
                                     1E-07
                                     9E-08
                                     4E-08

                         Field-grown ornamental crops
                               0.368 lb ai/acre
                                   40 acres
                                     3E-06
                                     7E-07
                                     6E-07
                                     3E-06
                                     6E-07
                                     5E-07
                                     3E-06
                                     6E-07
                                     5E-07
                                     2E-07

                                      Sod
                               0.523 lb ai/acre
                                   80 acres
                                     9E-06
                                     2E-06
                                     2E-06
                                     9E-06
                                     2E-06
                                     1E-06
                                     9E-06
                                     2E-06
                                     1E-06
                                     6E-07

                              Field crop, typical
                                0.5 lb ai/acre
                                   80 acres
                                     9E-06
                                     2E-06
                                     2E-06
                                     8E-06
                                     2E-06
                                     1E-06
                                     8E-06
                                     2E-06
                                     1E-06
                                     6E-07

                                  Fallow land
                                 1 lb ai/acre
                                   80 acres
                                     2E-05
                                     4E-06
                                     3E-06
                                     2E-05
                                     4E-06
                                     3E-06
                                     2E-05
                                     3E-06
                                     3E-06
                                     1E-06

                           Field crop, high-acreage
                               0.500 lb ai/acre
                                   200 acres
                                     2E-05
                                     5E-06
                                     4E-06
                                     2E-05
                                     4E-06
                                     3E-06
                                     2E-05
                                     4E-06
                                     3E-06
                                     1E-06
                                    Flagger
                   Flagging for Aerial Applications (Sprays)
                                  Fallow land
                                 1 lb ai/acre
                                   350 acres
                                     1E-05
                                     1E-05
                                     1E-05
                                     1E-05
                                     1E-05
                                     1E-05
                                     1E-05
                                     1E-05
                                     1E-05
                                    No Data

                         Field-grown ornamental crops
                               0.368 lb ai/acre
                                   350 acres
                                     5E-06
                                     5E-06
                                     4E-06
                                     4E-06
                                     4E-06
                                     4E-06
                                     4E-06
                                     4E-06
                                     4E-06
                                    No Data

                                      Sod
                               0.522 lb ai/acre
                                   350 acres
                                     6E-06
                                     7E-06
                                     6E-06
                                     6E-06
                                     6E-06
                                     5E-06
                                     5E-06
                                     6E-06
                                     5E-06
                                    No Data

                              Field crop, typical
                                0.5 lb ai/acre
                                   350 acres
                                     6E-06
                                     7E-06
                                     6E-06
                                     5E-06
                                     6E-06
                                     5E-06
                                     5E-06
                                     6E-06
                                     5E-06
                                    No Data

                           Field crop, high-acreage
                               0.500 lb ai/acre
                                   350 acres
                                     6E-06
                                     7E-06
                                     6E-06
                                     5E-06
                                     6E-06
                                     5E-06
                                     5E-06
                                     6E-06
                                     5E-06
                                    No Data
1	Based on registered labels.
2	Exposure Science Advisory Council Policy #9.1.
3	Cancer risk estimates = Total LADD x Q1[*], where Q1[*] = 0.103 (mg/kg/day)[-1]

Table 8.1.3.  Bromoxynil Occupational Handler Cancer Risk Estimates  -  Contract/Commercial Handler
                               Exposure Scenario
                                Crop or Target
                                 App. Rate[1]
                                Area Treated[2]
                                 (units/ day)
                        Contract/Commercial Handler[3]

                                SL/No G + No-R
                                  SL/G + No-R
                                  DL/G + No-R
                               SL/No G + PF10 R
                                 SL/G + PF10 R
                                 DL/G + PF10 R
                               SL/No G + PF50 R
                                 SL/G + PF50 R
                                 DL/G + PF50 R
                                      EC
                                 Mixer/Loader
                Mixing/Loading Liquids for Aerial Applications
                    Roads, parking lots, etc. (pre-paving)
                               0.522 lb ai/acre
                                   60 acres
                                     6E-05
                                     1E-05
                                     8E-06
                                     6E-05
                                     1E-05
                                     7E-06
                                     6E-05
                                     1E-05
                                     7E-06
                                     2E-06

                         Field-grown ornamental crops
                               0.368 lb ai/acre
                                   40 acres
                                     3E-05
                                     5E-06
                                     4E-06
                                     3E-05
                                     4E-06
                                     3E-06
                                     3E-05
                                     4E-06
                                     3E-06
                                    1E-06

                                      Sod
                               0.522 lb ai/acre
                                   350 acres
                                     3E-04
                                     6E-05
                                     4E-05
                                     3E-04
                                     6E-05
                                     4E-05
                                     3E-04
                                     6E-05
                                     4E-05
                                     1E-05

                              Field crop, typical
                                0.5 lb ai/acre
                                   350 acres
                                     3E-04
                                     6E-05
                                     4E-05
                                     3E-04
                                     5E-05
                                     4E-05
                                     3E-04
                                     5E-05
                                     4E-05
                                     1E-05

                                  Fallow land
                                1.0 lb ai/acre
                                   350 acres
                                     6E-04
                                     1E-04
                                     9E-05
                                     6E-04
                                     1E-04
                                     8E-05
                                     6E-04
                                     1E-04
                                     8E-05
                                     3E-05

                           Field crop, high-acreage
                               0.500 lb ai/acre
                                  1200 acres
                                     1E-03
                                     2E-04
                                     1E-04
                                     1E-03
                                     2E-04
                                     1E-04
                                     1E-03
                                     2E-04
                                     1E-04
                                     4E-05
              Mixing/Loading Liquids for Chemigation Applications

                                      Sod
                               0.500 lb ai/acre
                                   350 acres
                                     3E-04
                                     6E-05
                                     4E-05
                                     3E-04
                                     5E-05
                                     4E-05
                                     3E-04
                                     5E-05
                                     4E-05
                                     1E-05

                              Field crop, typical
                                0.5 lb ai/acre
                                   350 acres
                                     3E-04
                                     6E-05
                                     4E-05
                                     3E-04
                                     5E-05
                                     4E-05
                                     3E-04
                                     5E-05
                                     4E-05
                                     1E-05

                           Field crop, high-acreage
                               0.500 lb ai/acre
                                   350 acres
                                     3E-04
                                     6E-05
                                     4E-05
                                     3E-04
                                     5E-05
                                     4E-05
                                     3E-04
                                     5E-05
                                     4E-05
                                     1E-05
              Mixing/Loading Liquids for Groundboom Applications
                    Roads, parking lots, etc. (pre-paving)
                               0.523 lb ai/acre
                                    5 acres
                                     5E-06
                                     8E-07
                                     6E-07
                                     5E-06
                                     8E-07
                                     6E-07
                                     5E-06
                                     8E-07
                                     6E-07
                                     2E-07

                         Field-grown ornamental crops
                               0.368 lb ai/acre
                                   40 acres
                                     3E-05
                                     5E-06
                                     4E-06
                                     3E-05
                                     4E-06
                                     3E-06
                                     3E-05
                                     4E-06
                                     3E-06
                                     1E-06

                                      Sod
                               0.523 lb ai/acre
                                   80 acres
                                     7E-05
                                     1E-05
                                     1E-05
                                     7E-05
                                     1E-05
                                     1E-05
                                     7E-05
                                     1E-05
                                     1E-05
                                     3E-06

                              Field crop, typical
                                0.5 lb ai/acre
                                   80 acres
                                     7E-05
                                     1E-05
                                     1E-05
                                     7E-05
                                     1E-05
                                     9E-06
                                     7E-05
                                     1E-05
                                     9E-06
                                     3E-06

                                  Fallow land
                                 1 lb ai/acre
                                   80 acres
                                     1E-04
                                     3E-05
                                     2E-05
                                     1E-04
                                     2E-05
                                     2E-05
                                     1E-04
                                     2E-05
                                     2E-05
                                     6E-06

                           Field crop, high-acreage
                               0.500 lb ai/acre
                                   200 acres
                                     2E-04
                                     3E-05
                                     2E-05
                                     2E-04
                                     3E-05
                                     2E-05
                                     2E-04
                                     3E-05