UNITED STATES ENVIRONMENTAL PROTECTION AGENCY 

WASHINGTON, D.C. 20460 

OFFICE OF 

CHEMICAL SAFETY AND 

POLLUTION PREVENTION 

MEMORANDUM 

DATE: September 30, 2014 

SUBJECT: Boscalid- Human Health Risk Assessment for a Section 3 Registration of New 

Uses on Herb Subgroup 19A and Dill Seed, Plus Crop Group Conversions on 

Stone Fruit Group 12-12 and Tree Nut Group 14-12. 

PC Code: 128008 DP Barcode: 0416695,0416696 

Decision No.: 484932, 484933 Registration No.: 7969-199 

Petition No.: 3E8215 Regulatory Action: Section 3 Registration 

Risk Assessment Type: Single ChemicaVAggregate Case No.: 7034 

TXRNo.: NA CAS No.: 188425-85-6 

MRID No.: NA 40 CFR: 180.589 

FROM: 

TO: 

Barry O'Keefe, Senior Biologist B. () 'Wuv j)n 

Myron S. Ottley: Senior ~iologist ~1)7~~ Steve Funk, Semor Chem1st (X,.fc:;::t?:..,:_ 

Cassi Walls, Senior Biologist ~~ t Wt/!h> 

Risk Assessment Branch III (RAB III) 

Health Effects Division (7509P) 

Andrew Ertman, Risk Manager 

Risk Integration, Minor Use and Emergency Response Branch (RIMUERB) 

Registration Division (7505P) 

This document and attachments provide an assessment of the human health risk resulting from 

the proposed and registered uses ofboscalid. The toxicology reevaluation was performed by 

Myron Ottley, the drinking water assessment was conducted by Katrina White (EPA 

Environmental Fate and Effects Division (EFED)), the review of the residue chemistry data and 

dietary exposure assessment were conducted by Steve Funk, the occupational and residential 

exposure assessment was conducted by Cassi Walls, and the human health risk assessment was 

conducted by Barry O'Keefe. 

Page 1 of45 
Table of Contents 

1.0 Executive Summary ........................................................................................................... 4 

2.0 HED Recommendations ........ ................................... ......................................................... 6 

2.1 Data Deficiencies ............................................................................................................ 7 

2.2.1 Enforcement Analytical Method ...................................................................... ......... 7 

2.2.2 Recommended Tolerances ........................................................... ........ ............. ......... 7 

2.2.3 Revisions to Petitioned-For Tolerances .................................................................... 8 

2.2.4 International Harmonization ....................... ............ .................................................. 8 

3.0 Introduction ........................................................................................................................ 8 

3.1 Chemical Identity ........................................................................................................... 9 

3.2 Physical/Chemical Characteristics .... ......................................................................... 10 

3.3 Pesticide Use Pattern .................................................................................................... 10 

3.4 Anticipated Exposure Pathways ................................................................................. 11 

3.5 Consideration of Environmental Justice ............................. ....................................... 11 

4.0 Hazard Characterization and Dose-Response Assessment.. ........................................ 12 

4.1 Summary of Toxicological Effects .............................................................................. 12 

4.2 Safety Factor for Infants and Children (FQP A Safety Factor) ............................... 13 

4.2.1 Completeness of the Toxicology Database .............................................................. 13 

4.2.2 Evidence of Neurotoxicity ....................................... ........ ........ ................................. 13 

4.2.3 Evidence of Sensitivity/Susceptibility in the Developing or Young Animal.. ...... 13 

4.2.4 Residual Uncertainty in the Exposure Database ................................................... 14 

4.3 Toxicity Endpoint and Point of Departure Selections .............................................. 15 

4.3.1 Dose-Response Assessment ........................................................ .............................. 15 

4.3.2 Recommendation for Combining Routes of Exposure for Risk Assessment ...... 16 

4.3.3 Cancer Classification and Risk Assessment Recommendation ............................ 16 

4.3.4 Summary of Points of Departure and Toxicity Endpoints Used in Human Risk 

Assessment ............................................................................................................ ................... 17 

5.0 Dietary Exposure and Risk Assessment.. ....................................................................... 18 

5.1 Residues of Concern Summary and Rationale ...... ......................................... ........... 18 

5.2 Food Residue Profile .................................................................................................... 19 

5.3 Water Residue Profile ............... ........ ........................................................................... 19 

5.4 Dietary Risk Assessment .............................................................................................. 20 

5.4.1 Description of Residue Data Used in Dietary Assessment .................................... 20 

5.4.2 Percent Crop Treated Used in Dietary Assessment .............................................. 21 

5.4.3 Acute Dietary Risk Assessment.. ............................................ ........ ......................... 21 

5.4.4 Chronic Dietary Risk Assessments ......................................................................... 22 

5.4.5 Summary Table ......................................................................................................... 22 

6.0 Residential (Non-Occupational) Exposure/Risk Characterization ................ ............. 22 

6.1 Residential Handler Exposure .................................................................................... 23 

6.2 Post-Application Exposure .................................................................... .... .... .... ..... ..... 23 

6.3 Combined Residential Risk Estimates (Multiple Exposure Scenarios) ................... 25 

6.4 Residential Risk Estimates for Use in Aggregate Assessment.. ................................ 25 

6.5 Residential Bystander Post-application Inhalation Exposure ................................. 26 

6.6 Spray Drift ............. ........................................... ............................................................ 26 

7.0 Aggregate Exposure/Risk Characterization .................................................................. 27 

Page 2 of45 
Page 3 of 45

7.1 Acute Aggregate Risk................................................................................................... 27

7.2 Short-Term Aggregate Risk ........................................................................................ 27

7.3 Chronic Aggregate Risk .............................................................................................. 28

8.0 Cumulative Exposure/Risk Characterization ............................................................... 28

9.0 Occupational Exposure/Risk Characterization ............................................................ 28

9.1 Short-/Intermediate-Term Handler Risk................................................................... 28

9.2 Short-and Intermediate-Term Post-Application Risk.............................................. 29

9.2.1 Dermal Post-Application Risk................................................................................. 30

9.2.2 Inhalation Post-Application Risk............................................................................ 31

10.0 References......................................................................................................................... 32

Appendix A. Toxicology Profile and Executive Summaries .................................................. 33

A.1 Toxicology Data Requirements................................................................................... 33

A.2 Toxicity Profiles............................................................................................................ 34

Appendix B. Physicochemical Properties of Boscalid. ........................................................... 40

Appendix C. Review of Human Research................................................................................ 40

Appendix D. Residential Handler and Post-application Exposure and Risk Estimates ..... 41

Appendix E. Occupational Handler and Post-application Exposure and Risk Estimates.. 43

Appendix F. Summaries of Field Residue Data ...................................................................... 44

Appendix G. International Residue Limits Status Sheet ....................................................... 45
Page 4 of 45

1.0 Executive Summary

Introduction

Boscalid, 3-pyridinecarboxamide, 2-chloro-N-(4'-chloro[1,1'-biphenyl]-2-yl), is a fungicide 

active ingredient (ai) that stops fungi from producing the energy they need to carry on basic 

functions. It works inside the mitochondria and binds to the enzyme succinate ubiquinone

reductase, preventing energy production. Boscalid is currently registered on numerous 

agricultural crops and on golf course turf, residential ornamentals, landscape gardens, residential 

fruit and nut trees, and greenhouse grown tomato transplants for the home consumer market.

Use Profile

The Interregional Research Project No. 4 (IR-4) is proposing new uses on herb subgroup 19A 

and dill as additions to the Pristine® Fungicide label (EPA Reg. No. 7969-199). Additionally,

IR-4 is proposing crop group conversions for the stone fruit group 12-12 and the tree nut group 

14-12. The Pristine® Fungicide label also includes the active ingredient pyraclostrobin. For 

pyraclostrobin, IR-4 is also proposing new uses on herb subgroup 19A and dill, and crop group 

conversions for the stone fruit group 12-12 and the tree nut group 14-12. Therefore, a separate 

HED exposure and risk assessment document will be completed for pyraclostrobin. The 

Pristine® label requires occupational handlers to wear the following personal protective 

equipment (PPE): long-sleeved shirts, long pants, shoes, socks, and chemical resistant gloves. 

The 12 hour restricted entry interval (REI) listed on the label is adequate to protect workers. 

Exposure Profile

Exposure pathways include dietary (food and drinking water), residential, and occupational 

exposure sources. Dietary exposures are expected for acute and chronic durations. Existing

residential uses result in short-term handler dermal and inhalation exposures for adults, and 

short-term post-application dermal exposures for adults, youths (11 to 16 years old), and children 

6 to 11 years old. Occupational handler and post-application exposures are expected via dermal 

and inhalation routes for short- and intermediate-term durations.

Hazard Assessment 

In subchronic and chronic feeding studies in rats, mice, and dogs, boscalid generally caused 

decreased body weights and effects on the liver as well as on the thyroid. While the dog appeared 

to be the most sensitive species in the subchronic studies, the sensitivity of the dog and the rat was 

similar in the chronic studies. Based on weak evidence of carcinogenic effects in male rats, 

boscalid is classified as, “suggestive evidence of carcinogenicity, but not sufficient to assess 

human carcinogenic potential.” Boscalid was negative in the mutagenicity battery, the 

neurotoxicity battery and the immunotoxicity study. There were no susceptibility concerns and 

no residual uncertainties regarding developing offspring, and the Food Quality Protection Act 

(FQPA) Safety Factor (SF) was reduced to 1X. Boscalid has low acute toxicity via the oral, 

dermal, and inhalation routes of exposure and is not a dermal sensitizer, primary eye irritant, or 

skin irritant. Endpoints and points of departure (PODs) were selected for chronic dietary, 

incidental oral (short- and intermediate-term), dermal (all durations) and inhalation (all durations) 

exposure scenarios. As there were no toxic effects attributable to a single dose, an endpoint for 

acute dietary was not identified. Note that the requirement for a subchronic inhalation study 

remains outstanding. 
Page 5 of 45

Dietary Exposure

The residue chemistry and environmental fate data are adequate to assess human dietary 

exposure. The assessments are based on reliable data and will not underestimate exposure or 

risk. Estimated drinking water concentrations (EDWCs) were incorporated directly into the 

dietary exposure assessments. 

Since no observed effects could be attributed to a single dose, an acute endpoint was not 

established. Therefore, an acute dietary exposure assessment was not conducted.

The results of the slightly refined chronic dietary (food and drinking water) analysis are below 

the Agency’s level of concern (LOC) for all population subgroups. The dietary exposure for 

food and drinking water for the general U.S. population is 12% of the chronic Population 

Adjusted Dose (cPAD) and 25.5% of the cPAD for all infants (<1 year old), the population 

subgroup with the highest estimated chronic dietary exposure to boscalid.

Residential Exposure

No new residential uses were requested in this action. However, boscalid is currently registered 

for use on golf course turf, residential ornamentals and landscape gardens, and residential fruit 

and nut trees. Residential exposures from existing residential uses were previously assessed 

using the updated 2012 HED Residential Standard Operating Procedures1(SOPs). Residential 

exposure is expected to be short-term only. Because the dermal and inhalation PODs are the 

same, but the uncertainty factors are different, the dermal and inhalation handler exposure 

estimates were combined using the aggregated risk index (ARI) approach. All residential 

handler dermal and inhalation exposure risk estimates were not of concern to HED (i.e. all ARIs 

>1), with ARI values ranging from 24 to 330. All residential post-application dermal exposure 

risk estimates were also not of concern to HED, with margins of exposure (MOEs) ranging from 

680 to 16,000. 

Aggregate Exposure

There is potential for short-term and chronic aggregate exposure to boscalid. The short-term 

aggregate exposure results from dietary (which is considered background exposure) and 

residential (which is considered primary) exposure pathways. The chronic aggregate exposure is 

the same as chronic dietary exposure from food and drinking water, which are all below the 

HED’s level of concern. The short-term aggregate MOEs are 460 for children 6 to 11 years old, 

1,100 for youths 11 to 16 years old, and 380 for adults. None of these short-term aggregate risk 

estimates are of concern to HED.

Occupational Exposure

Based on the proposed agricultural uses, there is potential for short- and intermediate-term 

occupational exposure during handling and post-application activities. The proposed labels 

require occupational handlers to wear the following PPE: long-sleeved shirts, long pants, shoes,

socks, and chemical resistant gloves. Because the dermal and inhalation PODs are the same, but 

the uncertainty factors are different, the dermal and inhalation handler exposure estimates were 

combined using the ARI approach. 

 

1 http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 6 of 45

All of the occupational handler ARIs are greater than 1.0 (range from 1.3 to 480) when assessed 

using labeled PPE (gloves), and are not a concern to HED.

All post-application scenarios resulted in dermal MOEs greater than 100 on day 0 (12 hours after 

application), and therefore, are not of concern to HED. The dermal MOEs ranged from 940 to 

26,000. Dislodgable foliar residue (DFR) studies are not required at this time for boscalid since 

the lowest dermal MOE (940) is greater than two times the LOC (100) based on default input 

values.

Based on the Agency's current practices, a quantitative non-cancer occupational post-application 

inhalation exposure assessment was not performed for boscalid 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 boscalid. The 12 hour restricted entry 

interval (REI) listed on the labels is adequate for worker protection. 

Review of Human Research

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 

the 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), and the Residential SOPs (lawns and turf) are subject to ethics review pursuant to 40 

CFR 26, have received that review, and are compliant with applicable ethics requirements. For 

certain studies that 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 

http://www.epa.gov/pesticides/science/handler-exposure-data.html and 

http://www.epa.gov/pesticides/science/post-app-exposure-data.html. 

Environmental Justice Considerations

Potential areas of environmental justice concerns, to the extent possible, were considered in this 

human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions 

to Address Environmental Justice in Minority Populations and Low-Income Populations," 

(http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf. 

2.0 HED Recommendations

HED has examined the toxicology, residue chemistry, and exposure databases for boscalid. 

Pending submission of revised Section F, there are no toxicology or residue chemistry issues that 

would preclude granting Section 3 registration for the requested uses of boscalid, or 

establishment of tolerances for residues of boscalid. Additional data are needed, as outlined 

below in Section 2.1. The specific tolerance recommendations are discussed in Section 2.2.
Page 7 of 45

2.1 Data Deficiencies

870.3465 Subchronic Inhalation Study

 A subchronic inhalation study is required because the use of an oral point of departure 

(POD) for inhalation exposure results in MOEs as low as 370 for occupational exposure, 

which does not meet the target of 1000 for a waiver (TXR0056585. K. Rury. 

03/04/2013). Therefore, a 10X database uncertainty factor has been added for inhalation 

exposures in the absence of the required inhalation toxicity study.

2.2 Tolerance Considerations

2.2.1 Enforcement Analytical Method

An adequate gas chromatography/mass spectrometry (GC/MS) method (Method D0008) is 

available for enforcing boscalid tolerances in plant commodities. Residues are extracted using 

an aqueous organic solvent mixture followed by liquid/liquid partitioning and column clean-up. 

Quantitation is by GC/MS, using selected ion monitoring (SIM) of major ions. The method lists 

monitoring ions of m/z 342, 142, or 140, and notes that any ion can be used for quantitation as 

appropriate to the situation. Quantitation is performed using an external calibration curve of 

boscalid standards. Adequate validation data were submitted, including independent laboratory 

validation (ILV) data (MRID 45405101). The validated LOQ is reported to be 0.05 ppm for 

residues of boscalid in plant matrices. The Analytical Chemistry Branch (ACB) of the 

Biological and Economic Analysis Division (BEAD) concluded that the method is acceptable for 

enforcement purposes in plants (D284510; D. Swineford and E. Kolbe, 8/12/2003, PMV memo).

2.2.2 Recommended Tolerances

Sufficient data are available to support tolerances for residues of the fungicide boscalid, 

including its metabolites and degradates, in or on dill seed and the herb subgroup 19A. 

Compliance with the tolerance levels is to be determined by measuring only boscalid, 3-

pyridinecarboxamide, 2-chloro-N-(4′-chloro[1,1'-biphenyl]-2-yl). The tolerance expression is 

aligned with the requirements of the S. Knizner memo dated 05/27/2009. Additionally, the 

proposed crop group conversions for fruit, stone, group 12-12 and nut, tree, group 14-12 are 

appropriate.

Table 2.2.2. Tolerance Summary for Boscalid

Commodity Proposed 

Tolerance (ppm)

Existing 

Tolerance

HED-Recommended 

Tolerance (ppm)

Comments 

(correct commodity 

definition)

Herb subgroup 19A 190 - 150

Dill, seed 300 - 100

Fruit, stone, group 12 - 3.5 Revoke Crop group conversion

Fruit, stone, group 12-12 3.5 - 3.5 Crop group conversion

Nut, tree, group 14 - 0.70 Revoke Crop group conversion

Nut, tree, group 14-12 0.70 - 0.70 Crop group conversion

Pistachio - 0.70 Revoke Crop group conversion. 

Member of group 14-12.
Page 8 of 45

2.2.3 Revisions to Petitioned-For Tolerances

The required stone fruit and tree nut crop group conversions occur without modification of the 

existing tolerances.

The recommended tolerance for the herb subgroup 19A is 150 ppm, based on the highest average 

field trial (HAFT) data for basil and the processing factor for drying. Dried basil had residues in 

excess of those found on dillweed, fresh basil, and chives. The petitioned for tolerance of 190 

ppm is not supported by the field trial data and the processing data.

The recommended tolerance for dill seed is 100 ppm, based on evaluation of the 0 day preharvest interval (PHI) data with the Organization for Economic Cooperation and Development 

(OECD) calculation procedure. It appears that the petitioned for tolerance of 300 ppm was based 

on data from an exaggerated application rate.

A revised Section F is needed for the herb subgroup 19A and for dill seed.

2.2.4 International Harmonization

Canada and Codex have not established maximum residue limits (MRLs)/tolerances for herbs or 

dill seed, and therefore there is no harmonization issue (see Appendix G).

For stone fruit, Canada has an MRL of 1.7 ppm and Codex has an MRL of 3 ppm. The US 

tolerance is 3.5 ppm, based on the evaluation of peach, plum, and cherry data (D364447, A. 

Acierto, 10/16/2009). The individual commodity tolerance estimates were 1.6 ppm for plum, 3.0 

ppm for peach, and 3.5 ppm for cherry. The Canada MRL of 1.7 ppm was the former US 

tolerance prior to the latest data review. The tolerance cannot be lowered to 3 ppm to harmonize 

with Codex, as the cherry data necessitate a higher value. The tree nut tolerance (0.7 ppm) is 

harmonized with Canada. The Codex tree nut MRL (0.05 ppm) is lower than the US tolerance, 

and harmonization is not possible.

3.0 Introduction

Boscalid, 3-pyridinecarboxamide, 2-chloro-N-(4'-chloro[1,1'-biphenyl]-2-yl), is a fungicide 

active ingredient that works inside the mitochondria of fungi and stops fungi from producing the 

energy that they need to carry on the basic functions such as obtaining food, growing and

reproducing. Boscalid prevents energy production by binding to the enzyme succinate 

ubiquinone reductase. 

Boscalid is currently registered on alfalfa, artichoke, beans, Belgium endive, berries, Brassica

vegetables (subgroups 5A and 5B), bulb vegetables, canola, carrots, celery, certain root 

vegetables, citrus, cotton, cucurbit vegetables, edible peas, fruiting vegetables, herbs (herbs 

subgroup 19A), grapes, lettuce, Leafy Greens Subgroup 4A, except head and leaf lettuce, and 

leaf petioles subgroup 4B, mint, peanuts, persimmon, pistachios, pome fruits, potatoes, soybeans, 

spinach, stone fruits, strawberries, tree nuts, tropical fruits (avocado, black sapote, canistel, 
Page 9 of 45

mamey sapote, mango, papaya, sapodilla, and star apple) sunflower, seed treatment of rapeseed,

greenhouse grown tomatoes, imported bananas, and imported coffee, as well as golf course turf,

residential fruit and nut trees, residential ornamentals and landscape gardens, and tomato 

transplants grown for the home consumer market.

With the current action, BASF is proposing new uses on herb subgroup 19A and dill seed as 

additions to the Pristine® Fungicide label (EPA Reg. No. 7969-199). Additionally, BASF is 

proposing crop group conversions for the stone fruit group 12-12 and the tree nut group 14-12. 

3.1 Chemical Identity

The chemical structure and nomenclature of boscalid and its hydroxyl metabolite are presented 

in Table 3.1.

Table 3.1. Nomenclature of Boscalid and its Hydroxy Metabolite.

Compound

Common name Boscalid; Nicobifen

Company experimental name BAS 510 F

IUPAC name 2-chloro-N-(4׳-chlorobiphenyl-2-yl)nicotinamide

CAS name 2-chloro-N-(4'-chloro[1,1'-biphenyl]-2-yl)-3-pyridinecarboxamide

Molecular weight 343.2

CAS registry number 188425-85-6

End-use product (EPs) 25.2% WDG (Pristine® Fungicide; EPA Reg. No. 7969-199, also contains 12.8% 

pyraclostrobin)

Hydroxy-metabolite

Common name Boscalid hydroxy metabolite

Company experimental name M510F01 (glucuronide conjugate – M510F02)

CAS name 2-chloro-N-(4'-chloro-5-hydroxy-biphenyl-2-yl)nicotinamide

Molecular weight 359.2

N

N

O

Cl

Cl

N

N

O

Cl

Cl

OH
Page 10 of 45

3.2 Physical/Chemical Characteristics

If released to air, a vapor pressure of 5.4 x 10-9 mm Hg at 20o C indicates boscalid will exist 

solely in the particulate phase in the atmosphere. Particulate-phase boscalid will be removed 

from the atmosphere by wet or dry deposition. Boscalid will not volatilize from dry soil surfaces 

based upon its vapor pressure. Boscalid is stable to direct photolysis by sunlight. If released to 

soil, boscalid is expected to have low mobility based upon an estimated Koc of 970. Boscalid is 

stable to hydrolysis. The physiochemical properties of boscalid are summarized in Appendix B. 

3.3 Pesticide Use Pattern

BASF is proposing new uses of boscalid on herb subgroup 19A and dill seed as additions to the 

Pristine® Fungicide label (EPA Reg. No. 7969-199). Pristine® Fungicide is a multiple active 

ingredient water dispersible granule (WDG) fungicide containing 12.8% pyraclostrobin and 

25.2% boscalid. Herbs and dill may be treated at a maximum single application rate of 0.292 lb 

ai/A (18.5 fl oz/A) using aerial, ground, or chemigation equipment. Pristine® Fungicide may be 

applied two times per year at a maximum yearly application rate of 0.584 lb ai/A (37 fl oz/A). 

The label requires occupational handlers to wear the following PPE: long-sleeved shirts, long 

pants, shoes and socks, and chemical resistant gloves. The 12 hour REI listed on the label is 

appropriate.

Additionally, BASF is proposing crop group conversions for the stone fruit group 12-12 and the 

tree nut group 14-12.

The proposed uses of boscalid are summarized in Table 3.3.

Table 3.3. Summary of Directions for the Proposed Uses of Boscalid.

Use Site Application 

Method

Maximum 

Single 

Application 

Rate

(lb ai/A)

Maximum 

Number of 

Applications/ 

Year

Maximum 

Application 

Rate/Acre/

Year

(lb ai/A/yr)

Minimum 

Retreatment 

Interval

(days)

PHI

(days)

Stone Fruit 

Group

Ground, 

Aerial, or 

Chemigation

0.229 5 1.15 7 0

Tree Nut 

Group 0.229 4 0.916

7

(10 for 

pistachio)

14

(25 days 

for almond)

Herb Subgroup 0.292 2 0.584 7 0

Dill Seed 0.292 2 0.584 7 0
Page 11 of 45

3.4 Anticipated Exposure Pathways

The Registration Division has requested an assessment of human health risk to support proposed 

new uses of boscalid on the herb subgroup 19A and dill seed. Humans may be exposed to 

boscalid in food and drinking water, since boscalid may be applied directly to growing crops and 

application may result in boscalid reaching surface and ground water drinking water sources. 

There are existing residential uses of boscalid so there is exposure to residential handlers and 

those entering treated areas following application. In occupational settings, applicators may be 

exposed while handling boscalid. There is a potential for post-application exposure for workers 

re-entering treated fields and residents re-entering treated areas. 

Risk assessments have been completed for proposed and existing uses of boscalid. This risk 

assessment considers all of the aforementioned exposure pathways based on the proposed new 

uses of boscalid, but also considers existing uses of boscalid, particularly in the dietary and 

residential exposure assessments. 

3.5 Consideration of Environmental Justice

Potential areas of environmental justice concerns, to the extent possible, were considered in this 

human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal Actions 

to Address Environmental Justice in Minority Populations and Low-Income Populations," 

(http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf). As a part of every pesticide risk 

assessment, OPP considers a large variety of consumer subgroups according to well-established 

procedures. In line with OPP policy, HED estimates risks to population subgroups from 

pesticide exposures that are based on patterns of that subgroup’s food and water consumption, 

and activities in and around the home that involve pesticide use in a residential setting. 

Extensive data on food consumption patterns are compiled by the U.S. Department of 

Agriculture’s National Health and Nutrition Examination Survey, What We Eat in America, 

(NHANES/WWEIA) and are used in pesticide risk assessments for all registered food uses of a 

pesticide. These data are analyzed and categorized by subgroups based on age and ethnic group. 

Additionally, OPP is able to assess dietary exposure to smaller, specialized subgroups and 

exposure assessments are performed when conditions or circumstances warrant. Whenever 

appropriate, non-dietary exposures based on home use of pesticide products and associated risks 

for adult applicators and for toddlers, youths, and adults entering or playing on treated areas 

post-application are evaluated. Further considerations are currently in development as OPP has 

committed resources and expertise to the development of specialized software and models that 

consider exposure to bystanders and farm workers as well as lifestyle and traditional dietary 

patterns among specific subgroups.
Page 12 of 45

4.0 Hazard Characterization and Dose-Response Assessment

4.1 Summary of Toxicological Effects

Boscalid is a carboxamide (anilide) fungicide that acts in the fungal cell by inhibiting 

mitochondrial respiration and subsequent production of adenosine triphosphate (ATP) and by 

inhibiting the succinate-ubiquinone oxidase reductase system in Complex II of the mitochondrial 

electron transport chain.

In mammals, the primary targets are the liver and the thyroid (indirectly from liver adaptive 

response). In subchronic and chronic feeding studies in rats, mice and dogs, boscalid generally 

caused decreased body weights (primarily in mice) and effects on the liver (increase in weights, 

changes in enzyme levels and histopathological changes) as well as on the thyroid (increase in 

weights and histopathological changes). Mode of action studies conducted in rats indicated that 

boscalid has a direct effect upon the liver and that the thyroid effects are secondary. A 

reversibility study in rats indicated that both liver and thyroid parameters returned to control 

values after the animals were placed on control diet. Absolute and/or relative thyroid weights 

were elevated in rats and dogs, but there were no histopathological changes observed in the 

thyroid in either mice or dogs.

In a developmental toxicity study in rats, no developmental toxicity was observed in the fetuses 

at the highest dose tested (limit dose). No effects were noted in the dams in this study. In a 

developmental toxicity study in rabbits, an increased incidence of abortions or early delivery was 

observed at the limit dose. There was quantitative evidence of increased susceptibility in the 

two-generation reproduction study in rats, where decreases in body weights in male offspring 

were seen at a dose that was lower than the dose that induced parental/systemic toxicity. There 

was quantitative evidence of increased susceptibility in the developmental neurotoxicity study in 

rats, where decreases in pup body weights on post natal day four (PND 4) and body weight gains 

(PND 1-4) were seen in the absence of any maternal toxicity. 

In a two-year chronic toxicity study and a two-year carcinogenicity study in male and female 

rats, the combined data showed an increased trend in thyroid follicular cell adenomas that 

appeared to be treatment-related in males. This was supported by thyroid hypertrophy and 

hyperplasia of follicular cells at the same dose as well as increased thyroid weights plus 

mechanistic data. The mouse carcinogenicity study was negative. Boscalid was negative in the 

mutagenicity battery.

There was no evidence of neurotoxicity in rats in the acute, subchronic or developmental studies 

up to the limit dose. No neurotoxic observations were noted in any of the other studies in any 

species. 

In acute studies, there is relatively low toxicity (Toxicity Categories III or IV for oral, dermal, 

inhalation, primary eye irritation and primary skin irritation).
Page 13 of 45

Dermal Absorption Based on the results of an available dermal absorption study in rats, the 

dermal absorption factor (DAF) of boscalid is determined to be 15%, as represented by 11% 

being absorbed plus 4% found as bound residue on the skin following a 24 hr exposure and 24 hr 

sacrifice.

4.2 Safety Factor for Infants and Children (FQPA Safety Factor)

The toxicity database is considered complete and adequate for risk assessment. There was no 

evidence of neurotoxicity in the database; there is low or no concern for developmental or 

reproductive toxicity, and for susceptibility in the developing or young animal. There are no 

residual uncertainties identified in the exposure databases. Therefore, the FQPA Safety Factor 

has been reduced to 1X.

4.2.1 Completeness of the Toxicology Database

The toxicity database is considered complete and adequate for risk assessment, with the 

exception of a subchronic inhalation study. All studies needed to assess susceptibility concerns, 

such as developmental and reproduction studies, have been submitted. Additional studies, such a 

developmental neurotoxicity study, acute and subchronic neurotoxicity studies and an 

immunotoxicity study are also available. The subchronic inhalation study is required because the 

use of an oral POD results in MOEs as low as 370 for occupational exposure, which is not 

sufficient to alleviate concern (TXR0056585. K.Rury. 03/04/2013). Therefore, a 10X database 

uncertainty factor has been added for inhalation exposure.

4.2.2 Evidence of Neurotoxicity

There was no evidence of neurotoxicity based on an acute neurotoxicity study, a 90-day 

neurotoxicity study and a developmental neurotoxicity study (all in rats). There was no evidence 

of neurotoxicity in the other subchronic and chronic studies in the database.

4.2.3 Evidence of Sensitivity/Susceptibility in the Developing or Young Animal

There is no evidence of susceptibility following in utero exposure to rats and there are low 

concern and no residual uncertainties in the developmental toxicity study in rabbits, in the 2-

generation reproduction study or in the developmental neurotoxicity study after establishing 

toxicity endpoints and traditional uncertainty factors to be used in the risk assessment. 

There was no evidence of increased susceptibility in the developmental rat study as no 

developmental toxicity was seen at the highest dose tested (limit dose).

There was evidence of qualitative (not quantitative) increased susceptibility in the developmental 

rabbit study as characterized by an increased incidence of abortions or early delivery at the limit 

dose. It could not be ascertained if the abortions were the result of a treatment-related effect on 

either the dams, the fetuses, or both. The degree of concern is low because the increased 

abortions or early delivery was seen only at the Limit Dose and the abortions may have been due 

to maternal stress.
Page 14 of 45

There was quantitative evidence of increased susceptibility in the two-generation reproduction 

study in rats, where decreases in body weights in male offspring were seen in the F2 generation at 

a dose that was lower than the dose that induced parental/systemic toxicity. However, the degree 

of concern is low because the dose selected for chronic dietary and non-dietary exposure risk 

assessments would address the concern for the body weight effects.

There also was quantitative evidence of increased susceptibility in the developmental 

neurotoxicity study in rats, where decreases in pup body weights on post-natal day four (PND 4) 

and body weight gains (PND 1-4) were seen in the absence of any maternal toxicity. However, 

the degree of concern is low because the decreases in pup body weights seen on PND 1- 4 (and 

not at any other time periods) were reversible, in that no treatment-related effects on body 

weight, body weight gain or any other parameter were noted at PND 21.

HED has concluded that there are no residual uncertainties for pre- and post-natal toxicity as the 

degree of concern is low for the susceptibility seen in the above studies, and the dose and 

endpoints selected for the overall risk assessments will address the concerns for the body weight 

effects seen in the offspring. Although the dose selected for overall risk assessments (21.8 

mg/kg/day) is higher than the NOAELs in the two-generation reproduction study (10.1 

mg/kg/day) and the developmental neurotoxicity study (14 mg/kg/day), these differences are 

considered to be an artifact of the dose selection process in these studies. For example, there is a 

10-fold difference between the LOAEL (106.8 mg/kg/day) and the NOAEL (10.1 mg/kg/day) in 

the two generation reproduction study. A similar pattern was seen with regard to the 

developmental neurotoxicity study, where there is also a 10-fold difference between the LOAEL 

(147 mg/kg/day) and the NOAEL (14 mg/kg/day). There is only a 2-3 fold difference between 

the LOAEL (57 mg/kg/day) and the NOAEL (21.8 mg/kg/day) in the critical study used for risk 

assessment. Because the gap between the NOAEL and LOAEL in the 2-generation reproduction 

and developmental neurotoxicity studies was large and the effects at the LOAELs were minimal, 

the true no-observed-adverse-effect-level was probably considerably higher. Therefore, the 

selection of the NOAEL of 21.8 mg/kg/day from the 1-year dog study is conservative and 

appropriate for the overall risk assessments. In addition, the endpoints for risk assessment are 

based on thyroid effects seen in multiple species (mice, rats and dogs) and after various exposure 

durations (subchronic and chronic exposures) which were not observed at the LOAELs in either 

the two-generation reproduction or the developmental neurotoxicity studies. Based on these 

data, it is concluded that there are no residual uncertainties for pre- and post-natal toxicity

(D290022 A. Levy. 09/08/2003).

4.2.4 Residual Uncertainty in the Exposure Database

There are no residual uncertainties identified in the exposure databases. The chronic dietary 

food exposure assessments were performed using tolerance-level residues, conservative average 

percent crop treated (CT) estimates for existing crops and 100% CT assumptions (for proposed 

crops). EPA made conservative (protective) assumptions in the ground and surface water 

modeling used to assess exposure to boscalid in drinking water. EPA used similarly 

conservative assumptions to assess post-application exposure of adults and children. In addition, 

the residential exposure assessment is based on the updated 2012 Residential SOPs employing 
Page 15 of 45

surrogate study data, including conservative exposure assumptions based on Day 0 contact to turf 

and surfaces treated at the maximum application rate. These data are reliable and are not 

expected to underestimate risks to adults or children. The Residential SOPs are based upon 

reasonable “worst-case” assumptions and are not expected to underestimate risk. Although some 

of the residue values used in the dietary exposure assessment were slightly refined, these 

assessments will not underestimate the exposure and risks posed by boscalid.

4.3 Toxicity Endpoint and Point of Departure Selections

4.3.1 Dose-Response Assessment

The endpoints and points of departure for this risk assessment as based on those of the previous 

risk assessment. The rationales for each selection, along with a detailed description of the 

toxicity studies used for various exposure scenarios are presented in that document (D290022. Y. 

Donovan 09/08/2003). Following is a summary:

Acute dietary endpoint: As there were no toxic effects attributable to a single dose, including 

the developmental toxicity studies, an endpoint of concern was not identified to quantify acutedietary risk to the general population or to the subpopulation females 13-49 years old. The 

changes in brain morphometrics seen in the developmental neurotoxicity study were not selected 

as they were observed only at a dose exceeding the limit dose (1442 mg/kg/day). Therefore, an 

acute RfD was not established for any population for boscalid.

Chronic dietary endpoint: HED selected the NOAEL of 21.8 mg/kg/day for establishing the 

chronic RfD based on the combined results of the following three studies: chronic rat, 

carcinogenicity rat and chronic dog. While this NOAEL is higher than the NOAELs in the 90-

day study in dogs (7.6 mg/kg/day), the two-generation reproduction study (10.1 mg/kg/day) and 

the developmental neurotoxicity study (14 mg/kg/day), these differences are considered an 

artifact of the dose selection process in these studies as shown below:

Study NOAEL

(mg/kg/day)

LOAEL

(mg/kg/day)

LOAEL:NOAEL

Ratio

90-day - dog 7.6 78.1 10.3

2-generation reproduction - rat 10.1 101.6 10.0

developmental neurotoxicity - rat 14.0 147 10.5

1-year - dog 21.8 57.4 2.6

Because the gap between the NOAEL and LOAEL in these studies was large and the effects at 

the LOAELs were minimal (dog: = increased alkaline phosphatase activity and hepatic weights; 

2-generation: = decreased body weights in offspring; developmental neurotoxicity: = decrease in 

pup body weight gains on post-natal days 1-4), the true no-observed-adverse-effect-level was 

probably considerably higher. Therefore, the selection of the NOAEL of 21.8 mg/kg/day from 

the 1-year dog study is conservative and appropriate for the overall risk assessments. In 

addition, the endpoints for risk assessment are based on thyroid effects seen in multiple species 

(mice, rats and dogs) and after various exposure durations (subchronic and chronic exposures) 
Page 16 of 45

which were not observed at the LOAELs in either the two-generation reproduction or the 

developmental neurotoxicity studies.

Occupational and Residential endpoints: All of the incidental oral, dermal, and inhalation 

endpoints are based on the co-critical chronic toxicity rat, carcinogenicity rat, and 1-year dog 

studies. Neither dermal nor systemic toxicity was seen at the limit dose (1000 mg/kg/day) in the 

28-day dermal toxicity study in rats. The oral NOAEL of 21.8 mg/kg/day was selected to be 

protective of the decreases in the body weight seen in the offspring in the two-generation 

reproduction and the developmental neurotoxicity studies. Additionally, this dose is protective 

of the thyroid and hepatotoxicity seen via the oral route in multiple species (mice, rats and dogs) 

after various exposure durations (90-day, 1-year and 2-years). There are no concerns that the 

effects will worsen following longer treatment.

For the dermal endpoints, a dermal study is available; however, the selected endpoint addresses 

potential effects on offspring, which are not normally examined in the dermal study. This 

endpoint is likely to be conservative because no systemic effects were observed in the dermal 

study up to the limit dose of 1000 mg/kg/day. In the reproduction study, the parental NOAEL is 

112.6/1180.8 mg/kg/day based on decreases in body weight as well as hepatocyte degeneration 

in males only. No such effects were observed in the 28-day dermal study.

The use of an oral POD for inhalation exposure results in MOEs as low as 370 for occupational 

exposure, which does not meet the target MOE of 1000 for a waiver (TXR0056585, K. Rury,

03/04/2013). Therefore, a 10X database uncertainty factor has been added for inhalation 

exposures.

4.3.2 Recommendation for Combining Routes of Exposure for Risk Assessment

When there are potential exposures to a pesticide, aggregate risk assessment must consider 

exposures from three major sources: oral, dermal and inhalation exposures. Since all endpoints 

are from the same studies, exposures from oral, dermal and inhalation exposure routes can be 

aggregated.

4.3.3 Cancer Classification and Risk Assessment Recommendation

The Cancer Assessment Review Committee (CARC) classified boscalid as “suggestive evidence 

of carcinogenicity, but not sufficient to assess human carcinogenic potential”, and, therefore, the 

quantification of human cancer risk is not recommended (TXR0051289, J. Kidwell, 11/14/2002). 

The classification was based on data which were combined from two 2-year rat studies where 

males had a significant increasing trend and significant differences in pair-wise comparison with 

the controls for thyroid follicular cell adenomas. The increased incidence of these adenomas 

exceeded the historical control mean and range. This was supported by thyroid hypertrophy and 

hyperplasia of follicular cells, increased thyroid weights and mechanistic data. Combined study 

data for female rats showed only a borderline significant increasing trend for thyroid follicular 

cell adenomas. No increase over controls was noted in males or females for carcinomas. There 

was no increase in the incidence of any tumors of either sex in the 18-month mouse study. All 

mutagenic studies were negative with or without activation. Based on the overall weak evidence 
Page 17 of 45

of carcinogenic effects, the CARC indicated that a dose-response assessment for cancer (either 

linear low-dose extrapolation or margin of exposure calculation) was not needed.

4.3.4 Summary of Points of Departure and Toxicity Endpoints Used in Human Risk 

Assessment

Table 4.3.4.1. Summary of Toxicological Doses and Endpoints for Boscalid for Use in Dietary and NonOccupational Human Health Risk Assessments.

Exposure/ 

Scenario

Point of 

Departure

Uncertainty/F

QPA Safety 

Factors

RfD, PAD, 

Level of 

Concern for 

Risk 

Assessment

Study and Toxicological Effects

Acute Dietary (All 

Populations, 

including Infants and 

Children and Females 

13-49 years of age)

NA NA NA No appropriate endpoint attributable to a 

single dose was not identified

Chronic Dietary 

(All Populations)

NOAEL= 

21.8 

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF= 1x

Chronic RfD = 

0.218

mg/kg/day

cPAD = 0.218 

mg/kg/day

Co-critical chronic rat, carcinogenicity rat, 

and 1-year dog studies

LOAEL = 57-58 mg/kg/day based on liver 

and thyroid effects

Incidental Oral 

Short-Term (1-30 

days) & 

Intermediate-Term 

(1-6 months)

NOAEL= 

21.8 

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF= 1x

Residential 

LOC for MOE 

= 100

Co-critical chronic rat, carcinogenicity rat, 

and 1-year dog studies

LOAEL = 57-58 mg/kg/day based on liver 

and thyroid effects

Dermal Short-Term 

(1-30 days) & 

Intermediate-Term 

(1-6 months)

NOAEL= 

21.8 

mg/kg/day

UFA= 10x

UFH=10x

FQPA SF= 1x

Residential 

LOC for MOE 

= 100

Co-critical chronic rat, carcinogenicity rat, 

and 1-year dog studies

LOAEL = 57-58 mg/kg/day based on liver 

and thyroid effects

Inhalationa ShortTerm (1-30 days)

& IntermediateTerm (1-6 months)

NOAEL= 

21.8 

mg/kg/day

UFA = 10x

UFH = 10x

UFDB = 10x

FQPA SF= 1x

Residential 

LOC for MOE 

= 1000

Co-critical chronic rat, carcinogenicity rat, 

and 1-year dog studies

LOAEL = 57-58 mg/kg/day based on liver 

and thyroid effects

Cancer (oral, 

dermal, inhalation)

Classification: “suggestive evidence of carcinogenicity, but not sufficient to assess human 

carcinogenic potential”; quantification of human cancer risk is not recommended. 

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). UFDB = to account for the absence of key data 

(i.e., lack of a critical study). FQPA SF = FQPA Safety Factor. PAD = population adjusted dose (a = acute, c = 

chronic). RfD = reference dose. MOE = margin of exposure. LOC = level of concern. N/A = not applicable. a =

Inhalation toxicity assumed to be equivalent to oral toxicity.
Page 18 of 45

Table 4.3.4.2. Summary of Toxicological Doses and Endpoints for Boscalid 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 ShortTerm (1-30 

days) and 

IntermediateTerm (1-6 

months) 

DAF = 15%

NOAEL= 

21.8 

mg/kg/day

UFA = 10x

UFH =10x

FQPA SF= 1x

Occupational 

LOC for MOE = 

100

Co-critical chronic rat, carcinogenicity rat, 

and 1-year dog studies

LOAEL = 57-58 mg/kg/day based on liver 

and thyroid effects

Inhalationa

Short-Term (1-

30 days) and 

Intermediateterm (1-6 

months)

NOAEL= 

21.8 

mg/kg/day

UFA = 10x

UFH=10x

UFDB = 10x

FQPA SF= 1x

Occupational 

LOC for MOE = 

1000

Co-critical chronic rat, carcinogenicity rat,

and 1-year dog studies

LOAEL = 57-58 mg/kg/day based on liver 

and thyroid effects

Cancer (oral, 

dermal, 

inhalation)

Classification: “suggestive evidence of carcinogenicity, but not sufficient to assess human 

carcinogenic potential”; quantification of human cancer risk is not recommended. 

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). UFDB = to account for the absence of key data 

(i.e., lack of a critical study). MOE = margin of exposure. LOC = level of concern. N/A = not applicable. . a = 

Inhalation toxicity assumed to be equivalent to oral toxicity.

5.0 Dietary Exposure and Risk Assessment 

5.1 Residues of Concern Summary and Rationale

The residues of concern for dietary risk assessment and the tolerance expression are summarized 

in Table 5.1 (HED MARC, D286786, M. Nelson, 01/09/2003). HED has concluded that the 

residue of concern in plants is boscalid for purposes of tolerance enforcement and risk 

assessment. The nature of boscalid residues in livestock is adequately understood, based upon 

acceptable 14C metabolism studies conducted on lactating goats and laying hens. In both goats

and hens, parent boscalid, M510F01 (hydroxy metabolite), and M510F02 (M510F01 

glucuronide) were identified as the major residues, each with ≥10% TRR. No amide bridge 

cleavage products were identified. Based on the structural similarity of boscalid and M510F 01, 

and the fact that the enzymatic hydrolysis step in the proposed enforcement method will release 

M510F 02 back to free M510F 01, HED concluded that the combined residues of parent 

boscalid, M510F 01 and M510F02 are the residues of concern in livestock matrices for purposes 

of risk assessment and the tolerance expression. 

For drinking water, the residue of concern for boscalid is the parent only.
Page 19 of 45

Table 5.1. Summary of Metabolites and Degradates to be included in the Risk Assessment and Tolerance

Expression.

Matrix Residues included in Risk 

Assessment

Residues included in Tolerance 

Expression

Plants

Primary Crop Boscalid Boscalid

Rotational Crop Boscalid Boscalid

Livestock (Ruminants and Poultry) Boscalid, M510F01 & M510F02 Boscalid, M510F01 & M510F02

Drinking Water Boscalid Not Applicable

5.2 Food Residue Profile

IR-4 submitted field trial data on basil (MRID 47014803), chives (MRID 47014802), and dill 

(MRID 47014801). The data reflect the proposed use patterns. The number of trials and 

geographic distribution are acceptable. The analytical method used is adequate for determination 

of the residue of concern, and the samples were stored frozen for intervals supported by the 

storage stability results. A summary of the residue data from the crop field trials is presented in 

Appendix F, Table F.1. The existing field trial data for the crop group conversions are adequate.

Processed Food and Feed

Basil from each of the four field trials was dried. The median processing factor for the 

conversion of fresh basil to dry basil is 6.0X. The four processing studies conducted for the 

production of dried basil are adequate to estimate a processing factor for the boscalid residue. In 

each of the trials, the fresh basil contained quantifiable residues of boscalid.

Livestock

There are no feed items associated with dill seed or herbs from the herb subgroup 19A. 

Therefore, the previous livestock dietary intake calculations and resulting tolerance 

recommendations are not changed.

Rotational Crops

Adequate limited and extensive field rotational crop studies are available supporting the existing 

tolerances for indirect residues in rotational crops. These data support the label-specific plantback interval of 14 days for crops without boscalid uses. No additional rotational crop data are 

required for purposes of this petition.

5.3 Water Residue Profile

EFED determined that a new drinking water assessment is not needed for the proposed new uses 

on herbs and dill (E. Arnold, Email to S. Funk, 07/08/2014), and the EDWC values determined 

with the last assessment (D409880, K. White, 04/17/2013) should be used in the current dietary 

risk assessment. These EDWCs were incorporated directly into the dietary assessment. Water 

residues were incorporated in the DEEM-FCID into the food categories “water, direct, all 

sources” and “water, indirect, all sources.”
Page 20 of 45

The drinking water assessment considered new uses and all existing uses. Surface water 

estimated drinking water concentrations (EDWC) were determined in previous assessments. See 

Tier I Drinking Water Exposure Assessment for the Section 3 New Use of Boscalid on Various 

Agricultural Crops Including Cranberries (White, 2012, D405064) for a discussion of modeling 

and estimating surface water concentrations. The EDWCs for boscalid in surface water were 

calculated using the screening model FIRST (FQPA Index Reservoir Screening Tool; v.1.1.1; 

dated 03/25/08). Screening Concentration in Ground Water (SCI-GROW v2.3, Jul. 29, 2003) is 

a regression model used as a screening tool to estimate pesticide concentrations found in ground

water used as drinking water. Tier 1 ground water EDWCs for boscalid were derived with 

PRZM-GW (Pesticide Root Zone Model for Ground Water, version 1.0, August 31, 2012), using 

the GW-GUI (Graphical User Interface, version 1.0, August 31, 2012). PRZM-GW is a onedimensional, finite-difference model that estimates the concentrations of pesticides in 

groundwater. It accounts for pesticide fate in the crop root zone by simulating pesticide transport 

and degradation through the soil profile after a pesticide is applied to an agricultural field. 

PRZM-GW permits the assessment of multiple years of pesticide application (up to 100 years) 

on a single site. Six standard scenarios, each representing a different region known to be 

vulnerable to ground water contaminations, are available for use with PRZM-GW for risk 

assessment purposes.

The maximum Tier 1 estimated chronic ground water EDWC is 697 ppb. The maximum Tier 1 

estimated chronic surface water EDWC is 26.4 ppb. This is based on turf use. The ground water 

value is higher than the surface water value and was therefore used in the assessment. The 

EFED models and their descriptions are available at the EPA internet site: 

http://www.epa.gov/oppefed1/models/water/. See Table 5.3.1.

Table 5.3.1. Tier I EDWCs Based on Boscalid Use on Turf.

1

Source of Drinking Water Acute

(μg/L)

Annual Average or Post 

Breakthrough Average

(μg/L)

Surface water 97.3 26.4

Ground water 773 697

1 These are the highest EDWCs for the proposed and relevant previously evaluated use scenarios.

5.4 Dietary Risk Assessment

5.4.1 Description of Residue Data Used in Dietary Assessment

The dietary exposure analysis incorporates all current and proposed tolerances for residues of 

boscalid, including its metabolites and degradates. 

Since no observed effects could be attributed to a single dose, an acute endpoint was not 

established. Therefore, an acute dietary exposure assessment was not conducted.

The chronic dietary assessment is slightly refined. The chronic dietary exposure and risk 

assessment is based on tolerance-level residues for all commodities. The data used in the 2013

dietary assessments were also used in this current analysis except for the addition of tolerances 

for herb subgroup 19A and dill seed. BEAD has provided %CT information for boscalid (S. 
Page 21 of 45

Haddad, BEAD, 02/19/2014). As a refinement, the weighted average %CT was incorporated. 

One hundred percent crop treated was assumed for commodities without % CT data. Note that 

%CT was not incorporated in the previous (2013) assessment, i.e., 100% CT was assumed for all 

commodities.

Crop group conversions included a consideration of harmonization of tolerances with Codex 

MRLs and/or Canadian MRLs. This resulted in no changes in tolerances.

A value of 0.5 ppm was used for honey, based on the existing tolerance in the European Union.

No new experimental processing data were incorporated into this analysis. The processing 

factors from earlier dietary assessments were derived as follows. For processed commodities 

where data were available to show no concentration (apple juice, dried plum prunes, rice bran, 

wheat flour, sunflower oil, mint oil, tomato puree, tomato juice, soybean oil, and cottonseed oil), 

the processing factor was set to 1. For processed commodities where the raw agricultural 

commodity (RAC) tolerance is adequate to cover the very slight concentration seen in the 

processing study (wheat germ, wheat bran, and tomato paste), the residue was set at the RAC 

level and the processing factor was reduced to 1. For processed commodities with established 

tolerances (raisin, peanut oil, and citrus oil), the processed commodity tolerance was used and 

the processing factor was set to 1.0. For all other processed commodities for which data were 

not available, DEEM (version 7.81) processing factors were used (DP336633, D. Davis, 

12/17/2007).

Boscalid is classified as “not likely to be carcinogenic to humans”. Therefore, a cancer dietary 

exposure assessment was not conducted.

5.4.2 Percent Crop Treated Used in Dietary Assessment

BEAD has provided percent crop treated information for boscalid (S. Haddad, BEAD, 

02/19/2014). As a refinement, the weighted average %CT was incorporated. One hundred 

percent crop treated was assumed for commodities with no % CT data. 

The following average percent crop treated estimates were used in the chronic dietary risk 

assessments for the crops that are currently registered for boscalid: almonds 40%; apples 15%; 

apricots 25%; green beans 5%; blueberries 35%; broccoli <2.5%; cabbage 5%; caneberries 45%; 

cantaloupes 5%; carrots 15%; cauliflower 5%; celery 5%; cherries 45%; cucumbers 5%; dry 

beans/dry peas <2.5%; garlic 5%; grapes 30%; hazelnuts 5%; lettuce 25%; nectarines 15%; 

onions 20%; oranges <1%; peaches 20%; peanuts <1%; pears 15%; green peas <1%; peppers 

<2.5%; pistachios 30%; plums/prunes 5%; potatoes 20%; pumpkins 10%; squash 5%; 

strawberries 60%; sugar beets <1%; tomatoes 5%; walnuts <1%; watermelons 25%.

5.4.3 Acute Dietary Risk Assessment

Since no observed effects could be attributed to a single dose, an acute endpoint was not 

established. Therefore, an acute dietary exposure assessment was not conducted.
Page 22 of 45

5.4.4 Chronic Dietary Risk Assessments

Boscalid exposure from the existing uses and the proposed new uses on dill seed and the herbs of 

crop subgroup 19A results in estimated risks that are below the Agency’s level of concern for 

food plus drinking water. The highest exposure and risk estimates for food plus drinking water 

utilized 12% of the chronic population adjusted dose (cPAD) for the U.S. population and 26% 

for all infants (<1 year old), the most highly exposed population subgroup.

5.4.5 Summary Table

Table 5.4.5. Summary of Dietary (Food and Drinking Water) Exposure and Risk for Boscalid1,2

Population Subgroup

Acute Dietary Chronic Dietary

Dietary Exposure 

(mg/kg/day) % aPAD Dietary Exposure(mg/kg/day) % cPAD

General U.S. Population

N/A N/A

0.025787 12

All Infants (< 1 year old) 0.055525 26

Children 1-2 years old 0.053267 24

Children 3-5 years old 0.041445 19

Children 6-12 years old 0.025564 12

Youth 13-19 years old 0.018134 8.3

Adults 20-49 years old 0.024325 11

Adults 50-99 years old 0.024330 11

Females 13-49 years old 0.024334 11

1The population subgroup with the highest estimated chronic dietary (food + drinking water) exposure and risk is indicated by 

bold text.

2NA = not applicable.

6.0 Residential (Non-Occupational) Exposure/Risk Characterization

There are no residential uses proposed for boscalid with this action. However, there are existing 

residential uses on golf course turf, ornamentals and garden landscapes, and on residential fruit 

and nut trees. These existing residential uses were assessed in the last HED exposure and risk 

assessment to reflect updates to HED’s 2012 Residential SOPs2along with policy changes for 

body weight assumptions (D405063, B. O’Keefe, 08/22/2013). Registered products do not lead 

to any residential handler or residential post-application risk estimates of concern. In order to 

incorporate residential exposure into the short-term aggregate risk assessment, a summary of the 

residential exposure and risk estimates resulting from the residential uses of boscalid are 

provided below.

 

2 Available: http://www.epa.gov/pesticides/science/residential-exposure-sop.html
Page 23 of 45

6.1 Residential Handler Exposure

The residential handler assessment included short-term exposures via the dermal and inhalation 

routes from treating gardens and trees (D405533, C. Walls, 04/30/13). Intermediate-term 

exposures are not likely because of the intermittent nature of applications by residential handlers.

The LOC for residential dermal exposure is an MOE of 100. For inhalation exposures, an 

additional 10X uncertainty factor is added because of the database gap for lack of an available 

subchronic inhalation toxicity study. Therefore, the total uncertainty factor that has been applied 

to the inhalation assessments of boscalid is 1000X for residential handler inhalation exposure 

(i.e., LOC is an MOE = 1000). 

Dermal and inhalation risk estimates were combined because the PODs are based on the same 

toxicological study, thus the effects for these exposure routes are the same. Dermal and 

inhalation risk estimates were combined using the total ARI methodology since the LOCs for 

dermal exposure (100) and inhalation exposure (1,000) are different. The LOC ARI is 1; 

therefore, ARIs of less than 1 are risk estimates of concern. 

Details of the inhalation and dermal exposure risk estimates for residential handlers are included 

in Appendix D. The maximum application rate for each exposure scenario is presented as the 

worst case scenario. The residential handler ARIs range from 24 to 330. Therefore, the dermal 

and inhalation risk estimates to residential handlers are not of concern to HED for any of the 

residential handler scenarios.

6.2 Post-Application Exposure

There is the potential for dermal post-application exposure for individuals as result of being in an 

environment that has been previously treated with boscalid. Short-term dermal exposures were 

previously assessed for adults, youth 11 to 16 years old, and children 6 to 11 years old. All the

short-term MOEs for each scenario are greater than the LOC of 100, ranging from 690 to 16,000, 

and therefore are not of concern (D405533, C. Walls, 04/30/13). Details of the residential 

dermal post-application exposure risk estimates are included in Appendix D. A TTR study is not 

required at this time for boscalid since the lowest dermal MOE (10,000) is greater than 10 times 

the LOC based on default values for the fraction of application rate available for transfer after a 

turf application. Additionally, DFR studies are not required at this time for boscalid since the 

lowest dermal MOE (690) is greater than two times the LOC based on default input values.

Turf Transferrable Residue (TTR) Data

In accordance with 40 CFR §158, TTR data are required for all occupational (e.g., sod farms, 

golf courses, parks, and recreational areas) or residential turf uses that could result in postapplication exposure to turf. In the absence of chemical-specific TTR data, EPA uses default 

values. The 2012 Standard Operating Procedures for Residential Pesticide Exposure 

Assessment includes an analysis of all TTR data, available at the time, which resulted in the 

selection of revised liquid and granular default values for the fraction of the application rate 

available for transfer after a turf application (FAR). These values are based on an analysis of 59 
Page 24 of 45

TTR studies performed with the Modified California Roller Method (36 studies using liquids, 11 

studies using wettable powders/water dispersible granules, and 12 studies using granules). The 

liquid results (N=131) indicate a range of FAR values from 0.0005% to 6.1% and the granular 

results (N=37) indicate a range of 0.00064% to 0.69%. In both the liquid and granular data, a 

large range of transferability is observed and this variability can potentially be attributable to 

many factors such as active ingredient; formulation; field conditions in the studies; weather 

conditions (e.g., humidity); or many other difficult to quantify factors. Although witnessed 

across multiple chemicals, this range in FAR values is not expected when considering TTR data 

for a single chemical. HED selected 1% and 0.2% as high-end default values for liquid and 

granular products, respectively. Because TTR data are not available for boscalid, EPA is using 

the default value of 1% for liquid boscalid products. Although there may be a small degree of 

uncertainty in the use of the default TTR value for boscalid (i.e., there is a small chance that the

FAR value may exceed the applicable default value), it is likely that the health-protective aspects 

of EPA’s residential post-application turf assessment methodology will more than compensate 

for this potential uncertainty (i.e., the methodology is likely to overestimate exposure by a factor 

greater than the factor than the highest measured FAR values exceed the defaults ). For example, 

when assessing residential post-application turf exposure, EPA assumes the following: exposures 

occur to zero-day (i.e., day of application ) residues every day of the assessed exposure duration 

(i.e., EPA assumes that no dissipation or degradation occurs, it doesn’t rain, the grass is not 

mowed, etc); individuals perform the same post-application activities performed in the turf 

transfer coefficient study day after day (e.g., tumbling, playing on turf with toys, etc.); and 

individuals engage in these post-application activities for a high-end amount of time every day 

that is represented by data reflecting time children spend outdoors and not specifically engaged 

in activities on turf, when in actuality children do not spend all of their outdoor time on turf and 

high-end levels of activity will not occur every day. 

Given the conservatisms discussed above and the potential compounding nature of these 

conservatisms, EPA is able to rely upon the calculated exposure estimates with confidence that 

exposure is not being underestimated. Since the estimated residential turf post-application 

exposure for golfers using default TTR values for boscalid is minimal in comparison to the level 

of concern (i.e., the calculated MOE is greater than 10 times higher than the level of concern, 

lowest dermal MOE = 10,000 compared to the LOC of 100); EPA is waiving the 40 CFR §158 

TTR data requirement. In this instance, it is unlikely that chemical-specific TTR data would be 

needed to further refine exposure assessments or would add appreciably to our general 

understanding of the availability of turf transferable pesticide residues for boscalid.

Dislodgeable Foliar Residue (DFR) Data

In accordance with 40 CFR §158, DFR data are required for all occupational (e.g., crop, nursery, 

greenhouse use sites) or residential (e.g., ornamental and vegetable gardens, pick your own 

farms, retail tree farms) uses that could result in post-application exposure to foliage. In the 

absence of chemical-specific DFR data, EPA uses default values. The 2012 Standard Operating 

Procedures for Residential Pesticide Exposure Assessment includes an analysis of a number of 

DFR studies, which resulted in the selection of a revised default values for the fraction of the 

application rate available for transfer after a foliar application (FAR). These values are based on 

an analysis of 19 DFR studies. Since that time, the Agricultural Re-entry Task Force has 

submitted information (MRID 49299201) that corrects an application rate error made in the 
Page 25 of 45

original submission of “ARF039 – Determination of Dermal and Inhalation Exposure to Reentry 

Workers During Chrysanthemum Pinching in a Greenhouse” (EPA MRID 45344501). As a 

result, the range of FAR values was revised from 2% - 89% to 2% - 47%. In the data, a large 

range of transferability is observed and this variability can potentially be attributable to many 

factors such as active ingredient; formulation; field conditions in the studies; weather conditions 

(e.g., humidity); or many other difficult to quantify factors. Although witnessed across multiple 

chemicals, this range in FAR values is not expected when considering DFR data for a single 

chemical. At this time, the ARTF submission did not alter the selection of 25% as the 

reasonable, high-end default value. Because DFR data are not available for boscalid, EPA is 

using the default value of 25%. Although there may be a small degree of uncertainty in the use 

of the default DFR value for boscalid (i.e., there is a small chance that the FAR value may exceed 

the applicable default value), it is likely that the health-protective aspects of EPA’s residential 

post-application assessment methodology will more than compensate for this potential 

uncertainty. For example, when assessing residential post-application exposure to gardens and 

ornamentals, EPA assumes the following: exposures occur to zero-day (i.e., day of application ) 

residues every day of the assessed exposure duration (i.e., EPA assumes that no dissipation or 

degradation occurs, it doesn’t rain, etc); individuals perform the same post-application activities 

performed in the transfer coefficient study day after day (e.g., weeding, harvesting, pruning, 

etc.); and individuals engage in these post-application activities for a high-end amount of time 

every day (represented by data reflecting time spent gardening based on survey data).

Given the conservatisms discussed above and the potential compounding nature of these 

conservatisms, EPA is able to rely upon the calculated exposure estimates with confidence that 

exposure is not being underestimated. Since the estimated residential post-application exposure 

for residential gardens using default DFR values for boscalid is minimal in comparison to the 

level of concern (i.e., the calculated MOE is greater than 2 times higher than the level of 

concern, MOE = 690 compared to the LOC of 100); EPA is waiving the 40 CFR §158 DFR data 

requirement. In this instance, it is unlikely that chemical-specific DFR data would be needed to 

further refine exposure assessments or would add appreciably to our overall understanding of the 

availability of dislodgeable foliar pesticide residues for boscalid. 

6.3 Combined Residential Risk Estimates (Multiple Exposure Scenarios)

Because dermal post-application exposures to treated gardens, fruit or nut trees, and turf could 

conceivably co-occur within the same day for adults and children 6 to 11 year olds, combined 

exposures from these scenarios were considered. However, all four of these use sites/scenarios 

are proposed on different labeled products containing boscalid; therefore, the probability of cooccurrence is considered improbable. Therefore, assessments of these combined exposures were 

not conducted. 

6.4 Residential Risk Estimates for Use in Aggregate Assessment

The scenarios with the highest exposures and corresponding lowest MOEs, provided in 

Appendix D, reflect the residential risk estimates that are recommended for use in the aggregate 

assessment for boscalid. Table 6.4 presents the residential risk estimates that are recommended 

for use in the aggregate assessment for boscalid.
Page 26 of 45

 The recommended residential dermal exposure for use in the adult aggregate assessment 

reflects dermal exposure from post-application activities on treated gardens.

 The recommended residential dermal exposure for use in the youth (11-16 yr) aggregate 

assessment reflects dermal exposure from post-application golfing on treated turf.

 The recommended residential dermal exposure for use in the child (6-11 yr) aggregate 

assessment reflects dermal exposure from post-application activities in treated gardens.

Table 6.4. Recommendations for the Residential Exposures for the Boscalid Short-term Aggregate Assessments.

Lifestage Route of 

Exposure Scenario Dose1(mg/kg/day) MOE2

Adult Dermal Post-application activities in treated gardens 0.032 680

Youth (11-16 yr old) Dermal Post-application golfing on treated turf 0.0018 12,000

Child (6-11 yr old) Dermal Post-application activities in treated gardens 0.022 990

1 Daily Dose = See Table D.2 in Appendix D for adult handler scenarios and Table 6.2 for post-application scenarios.

2 MOE = NOAEL (21.8 mg/kg/day) ÷ Daily Dose

6.5 Residential Bystander Post-application Inhalation Exposure

Volatilization of pesticides may be a source of post-application inhalation exposure to 

individuals nearby pesticide applications. The agency sought expert advice and input on issues 

related to volatilization of pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act 

Scientific Advisory Panel (SAP) in December 2009, and received the SAP’s final report on 

March 2, 2010 (http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The 

agency has evaluated the SAP report and has developed a Volatilization Screening Tool and a 

subsequent Volatilization Screening Analysis 

(http://www.regulations.gov/#!docketDetail;D=EPA-HQ-OPP-2014-0219). 

During Registration Review, the agency will utilize this analysis to determine if data (i.e., flux 

studies, route-specific inhalation toxicological studies) or further analysis is required for 

boscalid.

6.6 Spray Drift

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 and 

airblast) employed for boscalid. 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). 3 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 

 

3 Available: http://www.epa.gov/opp00001/factsheets/spraydrift.htm 
Page 27 of 45

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.

7.0 Aggregate Exposure/Risk Characterization

In accordance with FQPA, HED must consider and aggregate (add) pesticide exposures and risks 

from three major sources: food, drinking water, and residential exposures. In an aggregate 

assessment, exposures from relevant sources are added together and compared to quantitative 

estimates of hazard (e.g., a NOAEL or PAD), or the risks themselves can be aggregated. When 

aggregating exposures and risks from various sources, HED considers both the route and 

duration of exposure. For boscalid, potential exposures from food, drinking water, and 

residential scenarios were aggregated. 

7.1 Acute Aggregate Risk

The aggregate acute risk estimates include exposure to residues of boscalid in food and drinking 

water, and does not include dermal, inhalation, or incidental oral exposure. However, since no 

observed effects could be attributed to a single dose, an acute endpoint was not established. 

Therefore, an acute dietary exposure assessment was not conducted.

7.2 Short-Term Aggregate Risk

There is potential short-term exposure to boscalid via dietary (which is considered background 

exposure) and residential (which is considered primary) exposure pathways. For adults, these 

pathways lead to exposure via oral (background) as well as dermal and inhalation (primary) 

routes. The most conservative scenarios were chosen for each. For a description of the 

residential exposure scenarios considered in the aggregate assessment, see Section 6.4. 

The short-term aggregate MOEs are 460 for children 6 to 11 years old, 1,100 for youths 11 to 16 

years old, and 380 for adults. None of these aggregate risk estimates are of concern to HED.

Table 7.2.1. Short-Term Aggregate Risk Calculations 

Lifestage Residential Exposure 

Scenario

Dermal Exposure Oral Exposure Total 

Combined 

MOE2

NOAEL

mg/kg/day

Exposure

mg/kg/day MOE1 NOAEL mg/kg/day

Chronic Dietary 

(Food + Water) 

mg/kg/day

MOE1

Child 6-11 yrs Post-application activities 

in treated gardens 21.8 0.022 990 21.8 0.025564 850 460

Youth 11-16 yrs Post-application golfing on 

treated turf 21.8 0.0018 12,000 21.8 0.018134 1,200 1,100

Adult Post-application activities 

in treated gardens 21.8 0.032 680 21.8 0.025787 845 380

1 The Level of Concern MOE is 100.

2 Total Combined MOE = 1/ [(1/MOEDermal) + (1/MOEOral)]
Page 28 of 45

7.3 Chronic Aggregate Risk

Chronic exposure from the residential pathway is not anticipated based on the current boscalid

use pattern. The chronic aggregate risk (food and drinking water) is below HED’s LOC (i.e., 

<100% cPAD for the general U.S. population and all population subgroups). The dietary 

exposure is estimated at 0.025787 mg/kg/day for the general U.S. population (12% of the cPAD) 

and 0.055525 mg/kg/day (26% of the cPAD) for all infants <1 year old, the population subgroup 

with the highest estimated chronic dietary exposure to boscalid. See Section 5.4.4 for details.

8.0 Cumulative Exposure/Risk Characterization

Unlike other pesticides for which EPA has followed a cumulative risk approach based on a 

common mechanism of toxicity, EPA has not made a common mechanism of toxicity finding as 

to boscalid and any other substances and boscalid does not appear to produce a toxic metabolite 

produced by other substances. For the purposes of this tolerance action, therefore, EPA has not 

assumed that boscalid has a common mechanism of toxicity with other substances. For 

information regarding EPA’s efforts to determine which chemicals have a common mechanism 

of toxicity and to evaluate the cumulative effects of such chemicals, see the policy statements 

released by EPA’s Office of Pesticide Programs concerning common mechanism determinations 

and procedures for cumulating effects from substances found to have a common mechanism on 

EPA’s website at http://www.epa.gov/pesticides/cumulative/.

9.0 Occupational Exposure/Risk Characterization

Boscalid is proposed for new uses on dill seed and herb subgroup 19A. Application methods, 

maximum application rates, and use sites are summarized in Section 3.3 and Table 3.3. Based on 

the proposed use patterns, there is a potential for short- and intermediate-term occupational 

exposure to boscalid during handling (mixing, loading, and applying) and post-application 

activities. Boscalid use is proposed for up to two applications, with a minimum retreatment 

interval of 7 days. Additionally, for both dermal and inhalation exposures the same endpoint and 

point of departure were selected for short- and intermediate-term durations, and therefore, shortterm exposure and risk estimates are considered to be protective of intermediate-term exposure 

and risk estimates. The proposed label requires occupational handlers to wear the following 

PPE: long-sleeved shirts, long pants, chemical resistant gloves, and shoes plus socks. The 12 

hour REI listed on the label is appropriate. 

9.1 Short-/Intermediate-Term Handler Risk

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. 
Page 29 of 45

Based on the anticipated use patterns from the proposed label, types of equipment and techniques 

that can potentially be used, occupational handler exposure is expected from the proposed uses. 

HED’s LOC for the MOE is defined by the uncertainty factors that are applied to the assessment. 

HED applies a 10X factor to account for variability among species and a 10X factor to account 

for variability within species. The total uncertainty factor that has been applied to the boscalid 

occupational dermal exposure assessment is 100X. Occupational dermal exposure and risk 

resulting in MOEs greater than or equal to 100 will not be of concern to HED. 

For inhalation exposures, an additional 10X uncertainty factor is added because of the lack of an 

available subchronic inhalation toxicity study. Therefore, the total uncertainty factor that has 

been applied to the non-cancer inhalation assessments of boscalid is 1000X for residential 

handler exposure. Occupational inhalation exposure and risk resulting in MOEs greater than or 

equal to 1000 will not be of concern to HED (LOC = 1000). 

Dermal and inhalation risk estimates were combined in this assessment because the PODs are 

based on the same toxicological study, thus the effects for these exposure routes are the same. 

Dermal and inhalation risk estimates were combined using the total aggregated risk index (ARI) 

methodology since the LOCs for dermal exposure (100) and inhalation exposure (1,000) are 

different. The LOC ARI is 1; therefore, ARIs of less than 1 are risk estimates of concern. 

Summaries of the short- and intermediate-term risk estimates for occupational handlers applying 

boscalid are provided in Appendix E, Table E.1. The dermal MOEs range from 150 

(mixing/loading/applying of WDG formulation to support applications by mechanically 

pressurized handgun) to 5,500 (for applying with aerial equipment) at baseline PPE. All of the 

dermal MOEs are greater than the LOC of 100 when assessed using labeled PPE (baseline + 

gloves) and are not a concern to HED. 

The inhalation MOEs range from 1,900 (mixing/loading of WDG formulation to support aerial 

and chemigation applications) to 3,500,000 (applying with aerial equipment) at baseline PPE (no 

respirator). All of the inhalation MOEs are greater than the LOC of 1,000 when assessed at 

baseline PPE and are not a concern to HED. Furthermore, all of the ARIs for combined dermal 

and inhalation exposures all scenarios are greater than 1.0 (range from 1.3 to 480) when assessed 

using labeled PPE (baseline + gloves), and are not a concern to HED. 

9.2 Short-and Intermediate-Term Post-Application Risk

HED uses the term post-application to describe exposures that occur when individuals are 

present in an environment that has been previously treated with a pesticide (also referred to as reentry exposure). Such exposures may occur when workers enter previously treated areas to 

perform job functions, including activities related to crop production, such as scouting for pests 

or harvesting. Post-application exposure levels vary over time and depend on such things as the 

type of activity, the nature of the crop or target that was treated, the type of pesticide application, 

and the chemical’s degradation properties. In addition, the timing of pesticide applications, 

relative to harvest activities, can greatly reduce the potential for post-application exposure.
Page 30 of 45

9.2.1 Dermal Post-Application Risk

Based on the proposed use patterns, short- and intermediate-term post-application dermal 

exposures to workers re-entering treated areas is possible. Therefore, a post-application risk 

assessment for dermal exposures is needed

All post-application scenarios resulted in MOEs greater than 100 on day 0 (12 hours after 

application) and therefore are not of concern to HED. The MOEs for boscalid ranged from 940 

to 26,000. DFR studies are not required at this time for boscalid since the lowest dermal MOE 

(400) for all existing or proposed crops is greater than two times the LOC based on default input 

values. The short- and intermediate-term non-cancer post-application risk estimates for workers 

are provided in Appendix E, Table E.2. 

Turf Transferrable Residue (TTR) Data

In accordance with 40 CFR §158, TTR data are required for all occupational (e.g., sod farms, 

golf courses, parks, and recreational areas) or residential turf uses that could result in postapplication exposure to turf. In the absence of chemical-specific TTR data, EPA uses default 

values. As detailed in the Residential Post-Application section of this document for existing use 

of boscalid on golf course turf, the estimated occupational turf post-application exposure for 

workers using default TTR values for boscalid is minimal in comparison to the level of concern 

(i.e., the calculated occupational MOE is greater than 10 times higher than the level of concern, 

lowest dermal MOE = 3,900 compared to the LOC of 100); HED recommends waiving the 40

CFR §158 TTR data requirement. In this instance, it is unlikely that chemical-specific TTR data 

would be needed to further refine exposure assessments or would add appreciably to our general 

understanding of the availability of turf transferable pesticide residues for boscalid.

Dislodgeable Foliar Residue (DFR) Data

In accordance with 40 CFR §158, DFR data are required for all occupational (e.g., crop, nursery, 

greenhouse use sites) or residential (e.g., ornamental and vegetable gardens, pick your own 

farms, retail tree farms) uses that could result in post-application exposure to foliage. In the 

absence of chemical-specific DFR data, EPA uses default values. As explained in detail in the 

Residential Post-Application section of this document, and it is also the case for the highest 

estimated occupational post-application exposure from use on agricultural crops using default 

DFR values for boscalid the exposure is minimal in comparison to the level of concern (i.e., the 

calculated MOE is greater than 2 times higher than the level of concern, MOE = 400 compared 

to the LOC of 100); and therefore, HED recommends waiving the 40 CFR §158 DFR data 

requirement. In this instance, it is unlikely that chemical-specific DFR data would be needed to 

further refine exposure assessments or would add appreciably to our overall understanding of the 

availability of dislodgeable foliar pesticide residues for boscalid. 

Restricted Entry Interval

The REI specified on the proposed label is based on the acute toxicity of boscalid. Boscalid is 

classified as Toxicity Category III via the dermal route and Category IV for eye and for skin 

irritation potential. Short- and intermediate-term post-application risk estimates were not a 

concern on day 0 (12 hours following application) for all post-application activities. Under 40
Page 31 of 45

CFR 156.208 (c) (2) (iii), a.i.’s classified as Acute III or IV for acute dermal, eye irritation and 

primary skin irrigation are assigned a 12-hour REI. Therefore, the [156 subpart K] Worker 

Protection Statement interim REI of 12 hours is adequate to protect agricultural workers from 

post-application exposures to boscalid.

9.2.2 Inhalation Post-Application Risk

There are multiple potential sources of post-application inhalation exposure to individuals 

performing post-application activities in previously treated fields. These potential sources 

include volatilization of pesticides and resuspension of dusts and/or particulates that contain 

pesticides. The agency sought expert advice and input on issues related to volatilization of 

pesticides from its Federal Insecticide, Fungicide, and Rodenticide Act Scientific Advisory Panel 

(SAP) in December 2009, and received the SAP’s final report on March 2, 2010 

(http://www.epa.gov/scipoly/SAP/meetings/2009/120109meeting.html). The agency has 

evaluated the SAP report and has developed a Volatilization Screening Tool and a subsequent 

Volatilization Screening Analysis (http://www.regulations.gov/#!docketDetail;D=EPA-HQOPP-2014-0219). During Registration Review, the agency will utilize this analysis to determine 

if data (i.e., flux studies, route-specific inhalation toxicological studies) or further analysis is 

required for boscalid.

In addition, the Agency is continuing to evaluate the available post-application inhalation 

exposure data generated by the Agricultural Reentry Task Force. Given these two efforts, the 

Agency will continue to identify the need for and, subsequently, the way to incorporate 

occupational post-application inhalation exposure into the agency's risk assessments.

Although a quantitative occupational post-application inhalation exposure assessment was not 

performed, an inhalation exposure assessment was performed for occupational/commercial 

handlers. Handler exposure resulting from application of pesticides outdoors is likely to result in 

higher exposure than post-application exposure. Therefore, it is expected that these handler 

inhalation exposure estimates would be protective of most occupational post-application 

inhalation exposure scenarios.
Page 32 of 45

10.0 References

S. Funk, 06/30/2014, DP421150. Boscalid: Petition for the Establishment of Permanent 

Tolerances and Registration for Use on Herb Subgroup 19A and Dill Seed. Request for Crop 

Group Expansions/Revisions for Stone Fruit Group 12-12 and Tree Nut Group 14-12. Summary 

of Analytical Chemistry and Residue Data.

S. Funk, 07/16/2014, DP421151. Boscalid. Chronic Aggregate Dietary (Food and Drinking 

Water) Exposure and Risk Assessment for the Section 3 Registration For Herbs Subgroup 19A 

and Dill Seed and Crop Group Conversions for Stone Fruit Group and Tree Nut Group.

C. Walls, 07/31/2014, DP421152. Boscalid. Occupational and Residential Exposure 

Assessment for proposed new uses of boscalid on dill seed and the herb subgroup 19A.

C. Walls, 04/30/2013, DP405533. Boscalid. Occupational and Residential Exposure 

Assessment for proposed new uses of boscalid on globe artichoke, Belgium endive, persimmon, 

greenhouse grown tomato transplants grown for home consumer market, and residential 

ornamentals, landscape gardens, fruit trees and nut trees.

K. White, 04/17/2013, DP409880. Tier I Drinking Water Exposure Assessment for the Section 3 

New Uses of Boscalid on Various Agricultural Crops and Homeowner Uses.
Page 33 of 45

Appendix A. Toxicology Profile and Executive Summaries

A.1 Toxicology Data Requirements

The requirements (40 CFR 158.500) for food uses of boscalid are in the table below. Use of the 

new guideline numbers does not imply that the new (1998) guideline protocols were used.

Table A.1: Toxicology Studies Required Submitted Satisfied

870.1100 Acute Oral Toxicity ...................................................................................................

870.1200 Acute Dermal Toxicity...............................................................................................

870.1300 Acute Inhalation Toxicity ..........................................................................................

870.2400 Acute Eye Irritation....................................................................................................

870.2500 Acute Dermal Irritation..............................................................................................

870.2600 Skin Sensitization.......................................................................................................

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

yes

noa

870.3100 90-Day Oral Toxicity in Rodents...............................................................................

870.3150 90-Day Oral Toxicity in Non-Rodents.......................................................................

870.3200 21/28-Day Dermal Toxicity .......................................................................................

870.3250 90-Day Dermal Toxicity ............................................................................................

870.3465 90-Day Inhalation Toxicity ........................................................................................

yes

yes

yes

no (CR)

yes (CR)

yes

yes

yes

no

no

yes

yes

yes

---

no

870.3700 Prenatal Developmental Toxicity Study (Rodent)......................................................

870.3700 Prenatal Developmental Toxicity Study (Non-Rodent)..............................................

870.3800 Reproduction and Fertility Effects.............................................................................

yes

yes

yes

yes

yes

yes

yes

no

yes

870.4100 Chronic Toxicity (Rodent).........................................................................................

870.4100 Chronic Toxicity (Non-Rodent).................................................................................

870.4200 Carcinogenicity (Two Rodent Species; Rat and Mouse)............................................

870.4300 Combined Chronic Toxicity/Carcinogenicity ............................................................

yes

no

yes

no

yes

yes

yes

no

yes

---

yes

yes

870.5100 Bacterial Reverse Mutation Test ................................................................................

870.5300 in vitro Mammalian Cell Gene Mutation Test............................................................

870.5375 in vitro Mammalian Chromosome Aberration Test....................................................

870.5385 Mammalian Bone Marrow Chromosomal Aberration Test........................................

870.5395 Mammalian Erythrocyte Micronucleus Test ..............................................................

870.5550 Unscheduled DNA Synthesis in Mammalian Cells in Culture...................................

yes

yes

yes

---

yes

no

yes

yes

yes

no

yes

yes

yes

yes

yes

---

yes

---

870.6100 Delayed Neurotoxicity of Organophosphorus Substances (Acute, Hen)....................

870.6100 Delayed Neurotoxicity of Organophosphorus Substances (28-Day, Hen) .................

870.6200 Neurotoxicity Screening Battery (Acute, Rat) ...........................................................

870.6200 Neurotoxicity Screening Battery (Subchronic, Rat)...................................................

870.6300 Developmental Neurotoxicity Study ..........................................................................

no (CR)

no (CR)

yes

yes

no (CR)

no

no

yes

yes

no

---

---

yes

yes

---

870.7200 Companion Animal Safety.........................................................................................

870.7485 Metabolism and Pharmacokinetics.............................................................................

870.7600 Dermal Penetration ....................................................................................................

in vitro Dermal Penetration........................................................................................

870.7800 Immunotoxicity..........................................................................................................

no (CR)

yes

no (CR)

no

yes

no

yes

yes

no

yes

---

yes

---

---

---

a Submitted study was classified Unacceptable/Nonguideline

CR: Conditionally Required
Page 34 of 45

A.2 Toxicity Profiles

Table A.2.1. Acute Toxicity of Boscalid

Table A.2.1. Acute Toxicity Profile – Boscalid (BAS 510 F) Technical.

Test 

Material

Guideline 

No. Study Type MRID Results ToxicityCategory

Technical 870.1100 Acute Oral - rat 45404814 LD50 > 5000 mg/kg IV

Technical 870.1200 Acute Dermal -

rat 45404815 LD50 > 2000 mg/kg III

Technical 870.1300 Acute Inhalation 45404816 LC50 (M & F): > 6.7 mg/L IV

Technical 870.2400 Primary Eye 

Irritation 45404817 Not irritating to the eye IV

Technical 870.2500 Primary Dermal 

Irritation 45404818 Not irritating to the skin IV

Technical 870.2600 Dermal 

Sensitization 46270102 Not a dermal sensitizer N/A

Table A.2.2. Non-acute Toxicity Profile for Boscalid

Table A.2.2 Repeated Dose Toxicity Profile of Boscalid (BAS 510 F) Technical.

Guideline No. and 

Study Type

MRID (date)

Dose Levels

Study Classification

Results

870.3100

90-Day oral toxicity 

rodents (rat)

45404822 (2000)

0, 100, 500, 2000, 5000, 

15,000 ppm 

0, 7, 34, 137, 347, 1055 

mg/kg bw/day Males

0, 8, 40, 159, 395, or 1225 

mg/kg bw/day Females

Acceptable/Guideline

NOAEL: 34/159 mg/kg/day (M/F)

LOAEL: 137/395 mg/kg/day (M/F): M = increases in 

absolute and relative thyroid weights and increased 

incidence of thyroid hyperplasia as well as follicular 

epithelial hypertrophy; F = increases in absolute and 

relative thyroid weights.

870.3100

90-Day oral toxicity 

rodents (mouse)

45404821 (2000)

0, 150, 1000, 4000, 8000 ppm 

0, 29, 197, 788, and 1518 

mg/kg bw/day Males

0, 42, 277, 1184, and 2209 

mg/kg bw/day Females

Acceptable/Guideline

NOAEL: 197/2209 mg/kg/day (M/F)

LOAEL: 788/2209 mg/kg/day (M/F): M = increased liver 

weights and increased incidence of marked fatty change in 

the liver; F = not attained
Page 35 of 45

Table A.2.2 Repeated Dose Toxicity Profile of Boscalid (BAS 510 F) Technical.

Guideline No. and 

Study Type

MRID (date)

Dose Levels

Study Classification

Results

870.3150

90-Day oral toxicity 

in nonrodents (dog)

45404823 (2000)

0, 250, 2500, 25,000 ppm 

0, 7.6, 78.1, 728.9 mg/kg/day 

Males

0, 8.1, 81.7, 824.8 mg/kg/day 

Females

Acceptable/Guideline

NOAEL: 7.6/8.1 mg/kg/day (M/F)

LOAEL: 78.1/81.7 mg/kg/day (M/F): M = increased 

alkaline phosphatase activity and hepatic weights; F = 

increased alkaline phosphatase activity and hepatic 

weights.

870.3200

21/28-Day dermal 

toxicity

(rat)

45404824 (2000)

0, 100, 250, or 1000 mg/kg 

bw/day

Acceptable/Guideline

NOAEL: 1000 mg/kg/day (HDT)

LOAEL: >1000 mg/kg/day

870.3700

Prenatal 

developmental in 

rodents (rat)

45404904 (2000)

0, 100, 300, 1000 mg/kg 

bw/day

Acceptable/Guideline

Maternal NOAEL: 1000 mg/kg/day

Maternal LOAEL: cannot be established

Developmental NOAEL: 1000 mg/kg/day

Developmental LOAEL: cannot be established

870.3700

Prenatal 

developmental in 

nonrodents (rabbit)

45404905 (2000)

0, 100, 300, 1000 mg/kg 

bw/day

Acceptable/Guideline

Maternal NOAEL: 300 mg/kg/day

Maternal LOAEL: 1000 mg/kg/day based on abortions or 

early delivery.

Developmental NOAEL: 300 mg/kg/day 

Developmental LOAEL: 1000 mg/kg/day based on 

abortions or early delivery.

870.3800

Reproduction and 

fertility effects (rat)

45404906 (2001)

0, 100, 1000, 10,000 ppm

F0 parental animals 

10.1, 101.2, 1034.5 

mg/kg/day Males

10.7, 106.8, and 1062.0 

mg/kg/day Females

Acceptable/Guideline

Parental systemic NOAEL:112.6/1180.8 mg/kg/day 

(M/F)

Parental systemic LOAEL:1165.0/>1180.8 mg/kg/day 

(M/F) decreased body weight (F1) as well as hepatocyte 

degeneration F0 and F1) in males only.

Offspring systemic NOAEL:11.2/115.8 mg/kg/day (M/F)

Offspring systemic LOAEL:112.6/1180.8 mg/kg/day 

(M/F): decreased body weight for F2 pups in males and 

females of both generations.

Reproductive NOAEL:1165.0/1180.8 mg/kg/day (M/F)

Reproductive LOAEL:>1165.0/1180.8 (M/F)

870.4100a

Chronic toxicity 

rodents (rat)

45404827, 45723501 (2001)

0, 100, 500, 2500, 15,000 

ppm

0, 4.4, 21.9, 110.0, 739.0 

mg/kg bw/day for males and 

0, 5.9, 30.0, 150.3, 1000.4 

mg/kg bw/day for females

Acceptable/Guideline

NOAEL: 21.9/30.0 mg/kg/day (M/F)

LOAEL: 110.0/150.3 mg/kg/day (M/F): M = thyroid 

toxicity (weights and microscopic changes); F = thyroid 

toxicity (weights and microscopic changes). Thyroid 

follicular cell adenomas: M = 0/20, 0/20, 2/20,1/20; F = 

0/20, 0/20, 1/20,0/20.
Page 36 of 45

Table A.2.2 Repeated Dose Toxicity Profile of Boscalid (BAS 510 F) Technical.

Guideline No. and 

Study Type

MRID (date)

Dose Levels

Study Classification

Results

870.4100

Chronic toxicity (dog)

45404826 (2000)

0, 200, 800, 2000, 20,000 

ppm

0, 5.5, 21.8, 57.4, 544.0 

mg/kg bw/day Males

0, 5.8, 22.1, 58.3,592.9 mg/kg 

bw/day Females

Acceptable/Guideline

NOAEL: 21.8/22.1mg/kg/day (M/F)

LOAEL:57.4/58.3 mg/kg/day (M/F): M = elevated ALP 

activities and elevated hepatic weights; F = no effects

870.4200

Carcinogenicity

(rat)

45404828 (2001)

0, 100, 500, 2500, 15,000 

ppm

0, 4.6, 23.0, 116.1, 768.8 

mg/kg bw/day for males and 

0, 6.0, 29.7, 155.6, 1024.4 

mg/kg bw/day for females)

Acceptable/Guideline

NOAEL: 23.0/29.7 mg/kg/day (M/F)

LOAEL: 116.1/155.6 mg/kg/day (M/F): M = increased 

incidence of thyroid follicular cell hyperplasia and 

hypertrophy; F = decrease in increased incidence of 

thyroid follicular cell hyperplasia and hypertrophy. 

Thyroid follicular cell adenomas: M = 0/50, 0/50, 1/50, 

4/50; F = 0/50, 1/50, 0/50, 3/50.

870.4200

Carcinogenicity 

(mouse)

45404901 (2001)

0, 80, 400, 2000, 8000 ppm

0, 13, 65, 331, 1345 mg/kg 

bw/day Males

0, 18, 90, 443, 1804 mg/kg 

bw/day Females)

Acceptable/Guideline

NOAEL:65/443 mg/kg/day (M/F)

LOAEL: 331/1804 mg/kg/day (M/F): M = decreases in 

body weight; F = decreases in body weight. No evidence 

of carcinogenicity.

870.5100

Gene Mutation 

bacterial reverse 

mutation assay

45404913 (1998)

Initial concentrations: 22, 

110, 550, 2750, 5500 μg/plate

Repeat assay: 20, 100, 500, 

2500, 5000 μg/plate

Acceptable/Guideline

Negative without and with S-9 activation up to limit dose 

of 5000 μg/plate.

870.5300

In vitro mammalian 

cell forward gene 

mutation assay (CHO 

cells/HGPRT locus)

45404914 (2000)

Initial concentrations:

15.625, 31.25, 62.5, 125, 250 

or 500 μg/mL in the presence 

and absence of mammalian 

metabolic activation (S9-mix)

Repeat concentrations: 10.24, 

25.6, 64, 160, 400 1000 

μg/mL with and without S9-

mix with a repeat of the nonactivated test at 

concentrations of 3.125, 6.25, 

12.5, 25, 50, 100 μg/mL

Acceptable/Guideline

Negative without and with S-9 activation up to the limit of 

solubility of 25 μg/mL.
Page 37 of 45

Table A.2.2 Repeated Dose Toxicity Profile of Boscalid (BAS 510 F) Technical.

Guideline No. and 

Study Type

MRID (date)

Dose Levels

Study Classification

Results

870.5375

In vitro mammalian 

cytogenetics assay in 

Chinese hamster V79 

cells

45404915 (1999)

Initial exposure: 0, 20.0, 

100.0 500.0 μg/mL with and 

without metabolic activation

Second exposure: 0, 31.25, 

62.5, 125.0 μg/mL in the 

absence of S9-mix

Acceptable/Guideline

Negative without and with S-9 activation up to 3500 

μg/mL with precipitation showing at concentrations of 100 

μg/mL and higher.

870.5395

Cytogenetics -

mammalian 

erythrocyte 

micronucleus test in 

the mouse

45404916 (1999)

0, 500, 1000, 2000 mg/kg bw

Acceptable/Guideline

Negative at doses up to 2000 mg/kg.

870.5500

In vitro unscheduled 

DNA synthesis 

(primary rat 

hepatocytes)

45404917 (2000)

First: 0, 5, 10, 50, 100, 250, 

500, 750, 1000 μg/mL

Repeat due to excess 

cytotoxicity: 0, 0.5, 1.0, 5.0, 

10.0, 50.0, 100.0, 250.0, 

500.0 μg/mL 

A second experiment was 

conducted at 1.563, 3.125, 

6.250, 12.500, 25.000, 50.000 

μg/mL

Acceptable/Guideline

Negative response up to 50 μg/mL. Cytotoxicity at 100-

500 μg/mL.

870.6200a

Acute neurotoxicity 

screening battery (rat)

45404820 (2000)

0, 500, 1000 or 2000 mg/kg 

bw

Acceptable/Guideline

NOAEL:2000/1000 mg/kg/day (M/F)

LOAEL: >2000/2000 mg/kg/day (M/F): F = piloerection

870.6200b

Subchronic 

neurotoxicity 

screening battery (rat)

45404825 (2001)

0, 150, 1500, 15000 ppm 0, 

10.5, 103.1 1050.0 mg/kg 

bw/day for males 0, 12.7, 

124.5 or 1272.5 mg/kg 

bw/day for females

Acceptable/Guideline

NOAEL:1050.0/1272.5 mg/kg/day (M/F)

LOAEL: >1050.0/1272.5 mg/kg/day (M/F)
Page 38 of 45

Table A.2.2 Repeated Dose Toxicity Profile of Boscalid (BAS 510 F) Technical.

Guideline No. and 

Study Type

MRID (date)

Dose Levels

Study Classification

Results

870.6300

Developmental 

neurotoxicity (rat)

45404907 (2001)

45800101 (2002)

45800102 (2002)

0, 100, 1000 10000 ppm 0, 

14, 147 1442 mg/kg/day

Acceptable/Guideline

Maternal NOAEL:1442 mg/kg/day

Maternal LOAEL: >1442 mg/kg/day

Offspring NOAEL: 14 mg/kg/day

Offspring LOAEL: 147 mg/kg/day (decreased body 

weights on PND 4 and decreased body weight gain on 

PNDs 1-4)

870.7485

Metabolism and 

pharmacokinetics 

(rat)

45404918 (2001)

45404919 (2000)

45692401 (2002)

a single 50 or 500 mg/kg oral 

dose, or a 14-day repeated 

dose (500 mg/kg/day)

Acceptable/Guideline

BAS 510 F was readily absorbed and excreted following 

single oral 50 mg/kg; at single 500 mg/kg or 15 doses of 

500 mg/kg, absorption was saturated. Excretion mainly by 

feces (80-98%). Biliary excretion 40-50% of fecal activity 

at 50 mg/kg, 10% at 500 mg/kg. Urine, about 16% at 50 

mg/kg, 3-5% at 500 mg/kg. Absorption about 56% at 50 

mg/kg and 13-17% at 500 mg/kg. Excretory patterns 

similar by gender or radiolabel position. Metabolites 

(hydroxylation and conjugation products) were consistent 

with Phase I oxidation reactions followed by Phase II 

conjugation with glucuronic acid or sulfate, or by 

conjugation of the parent with glutathione with cleavage to 

sulfate metabolites.

870.7600

Dermal Penetration 

(rat)

45404920 (2001)

0.01, 0.10, 1.0 mg/cm2for 1, 

4, 10, or 24 hours

Acceptable/Guideline

Maximum % absorption:

0.01 mg/cm2 = 10.93 (24 hour exposure, 24 hour sacrifice)

0.10 mg/cm2 = 3.76 (24 hour exposure, 24 hour sacrifice)

1.00 mg/cm2 = 1.48 (10 hour exposure, 72 hour sacrifice)

870.7800

Immunotoxicity

MRID 48203801 (2003)

0, 100, 1000, or 10000 ppm 

0, 7.45, 73.1, or 736.2 

mg/gk/day

Acceptable / Guideline

NOAEL = 736.2 mg/kg/day

LOAEL = not established

Non-guideline

Hepatic enzyme 

induction (rat)

45404902 (1999)

0 or 15,000 ppm (equivalent 

to 0 or ~1500 mg/kg bw/day) 

for two weeks

Acceptable/Non-guideline

1. hypertrophy of zone III hepatocytes

2. >20% increase in liver weight

3. increase in CYP450 activity

4. slight to extensive microscopic SER proliferation

5. not a peroxisome proliferator

6. enzymes in CYP450 subfamily not induced

7. no notable microscopic increase in size or number of 

peroxisomes

CONCLUSION: inducer of total CYP450 activity
Page 39 of 45

Table A.2.2 Repeated Dose Toxicity Profile of Boscalid (BAS 510 F) Technical.

Guideline No. and 

Study Type

MRID (date)

Dose Levels

Study Classification

Results

Non-guideline

Hormone and enzyme 

induction (rat)

45404903 (2001)

0 or 15,000 ppm

0 or ~1000 mg/kg bw/day 

For four weeks

Acceptable/Non-guideline

1. slight (statistically significant) decrease in circulating T3

and T4 only in males

2. increase in circulating TSH levels both sexes

3. increase in all 3 liver microsomal 

glucuronyltransferases

CONCLUSION: disruption of thyroid homoeostasis by 

decreasing circulating T3 and T4 and increasing TSH; 

likely the result of hepatic microsomal 

glucuronyltransferase induction

Non-guideline

Reversibility study 

(dietary): 4-week 

administration 

followed by 4 weeks 

recovery or 13 weeks 

recovery (rat)

45550601 (2001)

0, 100, 2500, 15000 ppm

0, 7.7, 190.3, 1137.4 

mg/kg/day)

Acceptable/Non-guideline

4 weeks dosing: at 2500 and 15000 ppm: increase in TSH 

(68% and 87%); increase in absolute and relative thyroid 

weights, hypertrophy of thyroid follicular epithelial cells 

and diffuse follicular hyperplasia, increase in absolute and 

relative liver weights and centrilobular hypertrophy as 

well as liver portal fatty changes.

4 weeks dosing + 4 weeks recovery: no increases in TSH; 

increase in absolute and relative thyroid weights; thyroid 

hypertrophy and hyperplasia decreased to control values; 

all liver effects reversed to control.

4 weeks dosing + 13 weeks recovery: no increases in TSH; 

increase in absolute and relative thyroid weights; thyroid 

hypertrophy and hyperplasia decreased to control values; 

all liver effects reversed to control.

CONCLUSION: induction of liver microsomal enzyme 

system resulting in increased glucuronidation of thyroxine, 

resulting in an increase in TSH secretion as a 

compensatory response of the physiological negative 

feedback system; increased TSH resulted in increased 

thyroid weight.
Page 40 of 45

Appendix B. Physicochemical Properties of Boscalid.

Table B. Physicochemical Properties of Boscalid.

Parameter Value References

Melting point/range 142.8-143.8 C MRIDs 45404802 and 

pH NA (does not dissociate in water) 45404804-45404809

Relative Density (20oC) 1.381g/cm3

Water solubility (20oC) 4.64 mg/L at pH 6

Solvent solubility (g/100 mL at 20oC) acetone 16-20 ethyl acetate 6.7-8.0 

methanol 4-5 2-propanol <0.01 

acetonitrile 4-5 dichloromethane 20-25 

toluene 2-5 n-heptane <0.01

1-octanol <0.01 olive oil 2.9

N,N-DMF >25

Vapor pressure 7 x 10-9 hPa 

Dissociation constant, pKa None (does not dissociate in water)

Octanol/water partition coefficient, 

Log(KOW)

2.96 

UV/visible absorption spectrum UV molecular extinction (e[lmol-1cm-1]): 3.15 

x104at 228 nm; 1.53 x103at 290 nm

Appendix C. Review of Human Research

The PHED Task Force, 1995. The Pesticide Handlers Exposure Database, Version 1.1. 

Electronic Database. Task Force Members: Health Canada, U.S. EPA, and the National 

Agricultural Chemicals Associations, released February 1995. 

The Agricultural Handler Exposure Task Force (AHETF), 2011. The Occupational Handler Unit 

Exposure Surrogate Reference Table. U.S. EPA. Released June 21, 2011. 

Data from the Outdoor Residential Exposure Task Force (ORETF). 

HED Residential Standard Operating Procedures (2012). 
Page 41 of 45

Appendix D. Residential Handler and Post-application Exposure and Risk Estimates

Table D.1. Residential Handler Non-cancer Exposure and Risk Estimates for Boscalid.

Exposure Scenario 

Dermal 

Unit 

Exposure 

(mg/lb ai)

Inhalation 

Unit 

Exposure 

(mg/lb ai)

Maximum 

Application Rate1

Area 

Treated or 

Amount 

Handled 

Daily2

Dermal Inhalation

Total ARI7 Dose 

(mg/kg/day)3 MOE4 Dose 

(mg/kg/day)5 MOE6

Mixer/Loader/Applicator

Liquid Garden/Trees : 

manually pressurized handwand

63 0.018 0.0076 lb ai/gal 5 gal 0.0045 4,900 0.0000086 2,500,000 48

Liquid Garden/Trees : 

manually pressurized handwand

63 0.018 0.0000051 lb ai/ft2 1200 ft2 0.00072 30,000 0.0000014 16,000,000 300

Liquid Garden/Trees : 

hose-end sprayer

58 0.0014 0.0000051 lb ai/ft2 1200 ft2 0.00067 33,000 0.00000011 200,000,000 330

Liquid Garden/Trees : 

hose-end sprayer

58 0.0014 0.0076 lb ai/gal 11 gal 0.0091 2,400 0.0000015 15,000,000 24

Liquid Garden/Trees : 

backpack sprayer

130 0.14 0.0000051 lb ai/ft2 1200 ft2 0.0015 15,000 0.000011 2,000,000 140

Liquid Garden/Trees : 

backpack sprayer

130 0.14 0.0076 lb ai/gal 5 gal 0.0093 2,400 0.000067 330,000 22

Liquid Garden/Trees : 

sprinkler can

58 0.0014 0.0000051 lb ai/ft2 1200 ft2 0.00067 33,000 0.00000011 200,000,000 330

Liquid Garden/Trees : 

sprinkler can

58 0.0014 0.0076 lb ai/gal 5 gal 0.0041 5,300 0.00000067 33,000,000 53

1 Based on the proposed garden/tree use on Bonide FT09 label (EPA Reg. No. 4-UII) 

2 Based on HED’s 2012 Residential SOPs (http://www.epa.gov/pesticides/science/residential-exposure-sop.html).

3 Dermal Dose = Dermal Unit Exposure (mg/lb ai) × Application Rate (lb ai/acre or gal) × Area Treated or Amount Handled (A/day or gallons/day) × Dermal Absorption Factor 

(15%) ÷ Body Weight (80 kg).

4 Dermal MOE = Dermal NOAEL (21.8 mg/kg/day) ÷ Dermal Dose (mg/kg/day).

5 Inhalation Dose = Inhalation Unit Exposure (21.8 mg/lb ai) × Application Rate (lb ai/acre or gal) × Area Treated or Amount Handled (A/day or gallons/day) ÷ BW (80 kg).

6 Inhalation MOE = Inhalation NOAEL (mg/kg/day) ÷ Inhalation Dose (mg/kg/day).

7 Aggregate Risk Index (ARI) = 1÷ (1 ÷ RIdermal) + (1 ÷ RIinhalation) 

 Risk Index (RI) = MOE ÷ LOC; Inhalation LOC = 1,000 and Dermal LOC = 100
Page 42 of 45

Table D.2. Residential Post-application Non-cancer Exposure and Risk Estimates for Boscalid.

Lifestage

Post-application Exposure Scenario

Application 

Rate1

Dose 

(mg/kg/day) MOEs2

Use Site Route of Exposure

Adult

Gardens Dermal 0.33 lb ai/A

0.032 680

Child (6-11 yrs) 0.022 990

Adult Fruit and Nut Trees Dermal 0.22 lb ai/A 0.0019 11,000

Child (6-11 yrs) 0.0013 16,000

Adult

Lawn/Turf

Dermal Golfing

0.35 lb ai/A

0.0015 14,000

Youth (11-16 yrs) Dermal Golfing 0.0018 12,000

Child (6-11 yrs) Dermal Golfing 0.0021 10,000

1 Based on the proposed tree use on Bonide FT09 label (EPA Reg. No. 4-UII); the proposed garden use on Homeowner Garden Spray SC (EPA 

Reg. No. 7969-GLG); the proposed tomato transplant use on Pagent® Fungicide (EPA Reg. No.7969-251); and the registered golf turf use on 

Emerald® Fungicide label (EPA Reg. No. 7969-196).

2 Dermal MOE = Dermal NOAEL (21.8 mg/kg/day) ÷ Dermal Dose (mg/kg/day).
Page 43 of 45

Appendix E. Occupational Handler and Post-application Exposure and Risk Estimates

Table E.1. Baseline Occupational Handler Non-Cancer Exposure and Risk Estimates for Boscalid.

Exposure Scenario Crop

Dermal Unit 

Exposure 

(μg/lb ai)1

Inhalation 

Unit Exposure 

(μg/lb ai)1

Max

Applic Rate2

(lb ai/A)

Area Treated 

or Amount 

Handled 

Daily3

Dermal Inhalation

ARI8

Baseline Baseline Dose 

(mg/kg/day)4

MOE5

(LOC=100)

Dose 

(mg/kg/day)6

MOE7

(LOC=1,000)

Mixer/Loader of WDG

Aerial applications

and

Chemigation application

Herbs 

Dill

227 8.96 0.29 350 0.043 510 0.011 1,900 1.4

Groundboom application Herbs 227 8.96 0.29 80 0.010 2,200 0.0026 8,400 6.1

Groundboom application Dill 227 8.96 0.29 200 0.025 880 0.0065 3,400 2.5

Applicator of Liquids

Aerial application

Herbs

Dill 2.08 0.0049 0.29 350 0.00040 55,000 0.0000062 3,500,000 480

Groundboom application Herbs 78.6 0.34 0.29 80 0.0034 6,400 0.000010 220,000 50

Groundboom application Dill 78.6 0.34 0.29 200 0.0086 2,500 0.00025 89,000 20

Flagger

Flagger Herbs

Dill 11 0.35 0.29 350 0.0021 10,000 0.00044 49,000 33

Mixer/Loader/Applicator of WDG

Mechanically pressurized 

handgun

Herbs

Dill 1300 3.9

0.0058

lb ai/gal

1000

gal 0.14 150 0.0033 7,700 1.3

1 Based on the “Occupational Pesticide Handler Unit Exposure Surrogate Reference Table” (March 2013); 

2 Based on proposed label (See Table 4).

3 Exposure Science Advisory Council Policy #9.1.

4 Dermal Dose = Dermal Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre or gal) × Area Treated or Amount Handled Daily (A or gal/day) × DAF (%) ÷ BW 

(kg).

5 Dermal MOE = Dermal NOAEL (mg/kg/day) ÷ Dermal Dose (mg/kg/day).

6 Inhalation Dose = Dermal Unit Exposure (μg/lb ai) × Conversion Factor (0.001 mg/μg) × Application Rate (lb ai/acre or gal) × Area Treated or Amount Handled Daily (A or gal/day) ÷ BW (kg).

7 Inhalation MOE = Inhalation NOAEL (mg/kg/day) ÷ Inhalation Dose (mg/kg/day).

8 Aggregate Risk Index (ARI) = 1÷ (1 ÷ RIdermal) + (1 ÷ RIinhalation) 

 Risk Index (RI) = MOE ÷ LOC; Inhalation LOC = 1,000 and Dermal LOC = 100
Page 44 of 45

Table E.2. Occupational Post-application Non-Cancer Exposure and Risk Estimates for Boscalid.

Crop/Site Activities Transfer Coefficient 

(cm2/hr)

DFR1

(μg/cm2)

Dermal Dose 

(mg/kg/day)2 MOE3

Dill and Herbs

Irrigation

(Hand Set) 1,900

0.81

0.023 940

Scouting 1,100 0.013 1,600

Hand weeding 70 0.00085 26,000

1 DFR = Application Rate × F × (1-D)t × 4.54E8 μg/lb × 2.47E-8 acre/cm2; where F = 0.25 and D = 0.10 per day 

2 Daily Dermal Dose = [DFR (μg/cm2) × Transfer Coefficient × 0.001 mg/μg × 8 hrs/day × dermal absorption (15%)]  BW (69 kg).

3 MOE = POD (mg/kg/day) / Daily Dermal Dose. Daily Dermal Dose = [DFR (μg/cm2) × TC × 0.001 mg/μg × 8 hrs/day × dermal 

absorption factor (15%)]  BW (80 kg).

Appendix F. Summaries of Field Residue Data

Table F.1. Summary of Residue Data from Field Trials with Boscalid

Crop Matrix

Total Applic. 

Rate

(lb ai/A)

PHI 

(days)

Residue Levels of Boscalid (ppm)1

n Min. Max. HAFT Median

(STMdR)

Mean

(STMR) Std. Dev.

BASIL Proposed use pattern: Two foliar sprays at 0.29 lb ai/A/application for a seasonal rate of 0.58 lb ai/A with a 0-day PHI. 

Fresh Basil 0.60-0.63

0 8 11.3 30.6 24.1 15.5 17.7 7.2

3-4 8 2.0 16.0 13.5 9.3 8.7 4.9

Dried Basil 0 4 60.6 142.0 142.0 117.7 109.5 36

CHIVES. Proposed use pattern: Two foliar sprays at 0.29lb ai/A/application for a seasonal rate of 0.58 lb ai/A with a 0-day PHI.

Chives 0.60-0.62 0 8 1.6 13.2 12.8 11.6 9.5 4.8

DILL. Proposed use pattern: Two foliar sprays at 0.29 lb ai/A/application for a seasonal rate of 0.58 lb ai/A with a 0-day PHI.

Fresh Dill 

(dillweed) 0.60-0.61 0 8 5.88 29.2 28.6 15.6 16.3 8.5

Dill Seed 0.59-0.62 0 6 5.70 42.2 41.2 10.6 22.5 16

Dill Seed 0.91 0 2 117 129 123 N/A N/A N/A

1 n = number of samples, typically 2X number of trials. Min = lowest replicate sample value. Max = highest replicate sample 

value. HAFT = highest average field trial. STMdR = median of average field trials. Mean = mean of average field trials.
Page 45 of 45

Appendix G. International Residue Limits Status Sheet

Boscalid (128008; 06/30/2014)

Summary of US and International Tolerances and Maximum Residue Limits 

Residue Definition:

US Canada Mexico2 Codex3

40 CFR §180.589. Plant commodities:

boscalid, 3-pyridinecarboxamide, 2-chloro- N

-(4′-chloro[1,1'-biphenyl]-2-yl),

Plant commodities:

2-chloro-N-(4'-

chloro[1,1'-biphenyl]-2-

yl)-3-pyridinecarboxamide

- Plant commodities: boscalid. 

Commodity1 Tolerance (ppm) /Maximum Residue Limit (ppm)

US Canada Mexico2 Codex3

Herbs subgroup 19A

(fresh and dried)

150 None None

Dill, seed 100 None None

Nut, tree, group 14-12 0.70 0.7 0.05 (*)

Fruit, stone, group 12-12 3.5 1.7 3

1

Includes only commodities of interest for this action. Tolerance values should be the HED recommendations and 

not those proposed by the applicant.

2 Mexico adopts US tolerances and/or Codex MRLs for its export purposes.

3 * = absent at the limit of quantitation; Po = postharvest treatment, such as treatment of stored grains. PoP = 

processed postharvest treated commodity, such as processing of treated stored wheat. (fat) = to be measured on the 

fat portion of the sample. MRLs indicated as proposed have not been finalized by the CCPR and the CAC.