Page 1 of 47

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

OFFICE OF PREVENTION, PESTICIDES,

AND TOXIC SUBSTANCES

MEMORANDUM

DATE: 05-JAN-2010

SUBJECT: Boscalid. Human Health Risk Assessment for Proposed Use on Alfalfa and 

Citrus (Crop Group 10), and for Proposed Increase in Tolerance on Stone Fruits 

(Crop Group 12).

PC Code: 128008 DP Barcode: 363305

Decision Number: 405556 Registration Number: NA

Petition Number: 9F7527, 9F9529 Regulatory Action: Section 3

Risk Assessment Type: Single Chemical/Aggregate Case Number: NA

TXR Number: NA CAS Number: 188425-85-6

Chemical Class: Carboxamide (Anilide) Fungicide 40CFR: §180.589

MRID Numbers: NA Trade Names: Boscalid Technical, 

Endura®Fungicide, Pristine®Fungicide

FROM: Nancy J. Tsaur, Risk Assessor

Amelia Acierto, Chemist

Barry O’Keefe, ORE Assessor

Risk Assessment Branch 3 (RAB3)

Health Effects Division (HED), 7509P

THROUGH: Paula Deschamp, Branch Chief

Registration Action Branch 3 (RAB3)

Health Effects Division (HED), 7509P

TO: Tony Kish and Bryant Crowe, RM Team 22

Fungicide Branch (FB)

Registration Division (RD), 7505P
Page 2 of 47

Introduction

This document addresses three different uses regarding the active ingredient (ai), boscalid,

submitted to the Agency under two petitions (PP#9F7527 and PP#9F9529): to set a tolerance 

in/on alfalfa, to set a tolerance in/on citrus crop group 10, and to increase the current established 

tolerance on stone fruit crop group 12. Concomitant with setting a tolerance on alfalfa, livestock 

tolerances must also be set to account for an updated livestock dietary burden. BASF 

Corporation (BASF) has submitted a petition to register new uses on alfalfa and citrus fruits for 

boscalid technical (EPA Reg. No. 7969-198), a new use on alfalfa for Endura®Fungicide (EPA 

Reg. No. 7969-197), and new uses on alfalfa and citrus fruits for Pristine®Fungicide (EPA Reg. 

No. 7969-199). Endura®is a water dispersible granular (WDG) formulation containing 70% 

boscalid and Pristine®is a WDG formulation containing 25.2% boscalid and 12.8% 

pyraclostrobin. Only boscalid is addressed in this document; pyraclostrobin is being evaluated 

separately. 

Currently, permanent tolerances are established in the U.S. and Canada for residues of

boscalid (3-pyridinecarboxamide, 2-chloro-N-(4’-chloro(1,1’-biphenyl)-2-yl)) in/on several 

crops. There are no tolerances for residues of boscalid in/on alfalfa and citrus crops. Boscalid 

tolerances are established in the U.S. for residues of boscalid in/on stone fruit crop group 12 at 

1.7 parts per million (ppm) (40 CFR §180.589).

HED has examined the database for boscalid and concludes that pending submission of a revised 

Section B for alfalfa, and a revised Section F for alfalfa, citrus fruit, stone fruit, and livestock as 

noted below, there are no deficiencies that would preclude establishing permanent tolerances for 

boscalid on alfalfa forage and hay and on the citrus crop group 10, for increasing the existing 

tolerance on the stone fruit crop group 12, and for increasing the existing tolerances on hog fat, 

poultry fat, and poultry meat byproducts. However, the deficiencies noted below must be 

resolved as a condition of registration. 

Note to PM: HED recommends that the following tolerance definition entries in 40 CFR 

§180.589 be revised and that tolerances for the listed commodities be established, as follows:

(a) General. 

(1) Tolerances are established for residues of the fungicide boscalid, including its 

metabolites and degradates, in or on the commodities listed below. Compliance 

with the tolerance levels specified below is to be determined by measuring only 

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

Alfalfa, forage ................................................................... 30.0 ppm

Alfalfa, hay ....................................................................... 65.0 ppm

Citrus, dried pulp ................................................................. 4.5 ppm

Citrus, oil............................................................................ 85.0 ppm

Fruit, citrus, group 10........................................................... 1.6 ppm

Fruit, stone, group 12........................................................... 3.5 ppm

(2) Tolerances are established for residues of the fungicide boscalid, including its 

metabolites and degradates, in or on the food commodities listed below. Compliance 

with the tolerance levels specified below is to be determined by measuring only the 
Page 3 of 47

sum of 3-pyridinecarboxamide, 2-chloro-N-(4'-chloro[1,1'-biphenyl]-2-yl) and 

metabolites 2-chloro-N-(4'-chloro-5-hydroxy-biphenyl-2-yl) nicotinamide and 

glucuronic acid conjugate of 2-chloro-N-(4'-chloro-5-hydroxy-biphenyl-2-yl)

nicotinamide, calculated as the stoichiometric equivalent of boscalid.

Hog, fat .............................................................................. 0.20 ppm

Poultry, fat.......................................................................... 0.20 ppm

Poultry, meat byproducts................................................... 0.20 ppm

The established tolerances of the following commodities remain unchanged. 

Cattle, fat............................................................................ 0.30 ppm

Cattle, meat ........................................................................ 0.10 ppm

Cattle, meat byproducts ..................................................... 0.35 ppm

Egg ..................................................................................... 0.02 ppm

Goat, fat.............................................................................. 0.30 ppm

Goat, meat.......................................................................... 0.10 ppm

Goat, meat byproducts....................................................... 0.35 ppm

Hog, meat........................................................................... 0.05 ppm

Hog, meat byproducts........................................................ 0.10 ppm

Horse, fat............................................................................ 0.30 ppm

Horse, meat ........................................................................ 0.10 ppm

Horse, meat byproducts ..................................................... 0.35 ppm

Milk.................................................................................... 0.10 ppm

Poultry, meat...................................................................... 0.05 ppm

Sheep, fat............................................................................ 0.30 ppm

Sheep, meat........................................................................ 0.10 ppm

Sheep, meat byproducts..................................................... 0.35 ppm

(d) Indirect or inadvertent residues. 

Tolerances are established for residues of the fungicide boscalid, including its 

metabolites and degradates, in or on the commodities listed below. Compliance 

with the tolerance levels specified below is to be determined by measuring only 3-

pyridinecarboxamide, 2-chloro-N-(4'-chloro[1,1'-biphenyl]-2-yl). 

Animal feed, nongrass, group 18, forage, excluding alfalfa 1.0 ppm

Animal feed, nongrass, group 18, hay, excluding alfalfa .... 2.0 ppm

Revision to Petitions for Tolerances

The recommended tolerances in/on alfalfa, citrus, and stone fruits are based on the crop field trial 

data. The appropriate tolerance levels were determined using the HED Standard Operating 

Proceedure (SOP) “Guidelines for Setting Pesticide Tolerances Based on Field Trial Data.” 

The adequacy of the existing livestock tolerances were assessed using the available cattle and 

poultry feeding studies that cover the potential levels of dietary exposure of livestock to boscalid 

residues. The data indicate that the existing tolerances for meat (0.05 ppm) and meat byproducts 

(0.10 ppm) of hogs are adequate; however, the tolerance for hog, fat should be increased to 0.20 

ppm. Additionally, the data indicate that the existing tolerances for eggs (0.02 ppm) and poultry

meat (0.05 ppm) are adequate; however, the tolerances for poultry, fat and poultry, meat 

byproducts should each be increased to 0.20 ppm.
Page 4 of 47

860.1200 Direction for Use

 A revised Section B for alfalfa is required to amend the label direction for the 70% WDG 

formulation since it could not be supported by the field trial data generated with a 

maximum seasonal use rate of 0.9 lb ai/A. The proposed label rate for the 70% WDG 

formulation is 1.7X higher; the label should be revised to match the field trial rate.

860.1550 Tolerances

 Boscalid residues concentrate in citrus dried pulp (3.1X) and citrus oil (59X). A revised 

Section F is required to propose separate tolerances for citrus, dried pulp at 4.5 ppm, 

citrus, oil at 85 ppm, and fruit, citrus, group 10 at 1.6 ppm.

 The available data for stone fruits will not support a tolerance level of 5.0 ppm. A 

revised Section F should be submitted with a tolerance for fruit, stone, group 12 at 3.5 

ppm.

 The available data will not support the proposed tolerances for meat, meat byproducts, 

and fat of cattle goat, horse, and sheep at 0.2 ppm, 1.5 ppm, and 1.5 ppm, respectively. 

The existing tolerances will be maintained for meat, meat byproducts, and fat of cattle, 

goat, horse, and sheep at 0.10 ppm, 0.35 ppm, and 0.30 ppm, respectively. The available 

data will not support the proposed tolerance of 0.2 ppm for milk and the proposed 

tolerance of 1.5 ppm for milk fat. The existing tolerance of 0.10 ppm will be maintained 

for milk, and it is adequate to cover milk fat. The proposed tolerances of 0.20 ppm for 

hog, fat; poultry, fat; and poultry, meat byproducts are adequate. For all remaining 

livestock commodities, the proposed tolerances must be revised to reflect the 

recommended tolerance levels as specified in Table 9.0.

870.7800 Immunotoxicity Study

 As part of the new 40CFR §158 Guidelines, an immunotoxicity study in rats and/or mice 

is required (see Appendix B). 

Note to PM: Revisions of the livestock commodities data collection methods have been included 

in the registrant’s submissions. However, BASF has not indicated whether any of the changes 

were made in their attempt to resolve any of the deficiencies noted by HED in the 2003 petition 

(M. Nelson, DP#278385, 08/15/2003). If the methods have been revised and finalized, this 

should be clarified and the entire final versions of the enforcement and the data collection 

methods should be submitted to the Office of Pesticide Programs (OPP). Otherwise, registration 

for the new or amended use patterns for the boscalid products should be made conditional until 

the deficiencies noted above are fully resolved. 

This document provides a summary of the findings from the data evaluation and subsequent 

assessment of human health risk resulting from these requests. The residue chemistry data 

review and dietary exposure assessment were conducted by Amelia Acierto (RAB3), the 

occupational exposure data review was conducted by Barry O’Keefe (RAB3), and the human 

health risk assessment was conducted by Nancy J. Tsaur (RAB3); additionally, the drinking 

water assessment was conducted by David Lieu of OPP’s Environmental Fate and Effects 

Division (EFED).
Page 5 of 47

TABLE OF CONTENTS

1.0 EXECUTIVE SUMMARY ...............................................................................................6

2.0 INGREDIENT PROFILE...............................................................................................10

2.1 Summary of Proposed New Uses............................................................................. 10

2.2 Structure and Nomenclature/Physical and Chemical Properties......................... 11

3.0 HAZARD CHARACTERIZATION/ASSESSMENT ..................................................12

3.1 FQPA Safety Factor.................................................................................................. 14

3.2 Summary of Toxicological Doses and Endpoints................................................... 15

3.3 Endocrine disruption................................................................................................ 16

4.0 DIETARY EXPOSURE/RISK CHARACTERIZATION ...........................................16

4.1 Nature of the Residue and Residue Analytical Methods....................................... 17

4.2 Pesticide Metabolites and Degradates of Concern................................................. 18

4.3 Drinking Water Residue Profile.............................................................................. 18

4.4 Food Residue Profile................................................................................................. 19

4.5 Dietary Exposure and Risk ...................................................................................... 25

4.5.1 Acute Dietary Exposure Results and Characterization ............................... 25

4.5.2 Chronic Dietary Exposure Results and Characterization ........................... 25

4.5.3 Cancer Dietary Exposure Results and Characterization............................. 26

4.5.4 Results of Chronic Dietary Exposure Analysis............................................. 26

4.6 Anticipated Residues and Percent Crop Treated .................................................. 26

5.0 RESIDENTIAL (NON-OCCUPATIONAL) EXPOSURE AND RISK 

CHARACTERIZATION .................................................................................26

5.1 Residential Handler Exposure................................................................................. 27

5.2. Residential Postapplication Exposure..................................................................... 27

6.0 AGGREGATE RISK ASSESSMENTS AND RISK CHARACTERIZATION ........29

6.1 Acute Aggregate Risk ............................................................................................... 29

6.2 Short-Term Aggregate Risk..................................................................................... 29

6.3 Intermediate-Term Aggregate Risk ........................................................................ 29

6.4 Long-Term Aggregate Risk ..................................................................................... 29

6.5 Cancer Aggregate Risk............................................................................................. 30

7.0 Cumulative Risk Characterization/Assessment............................................................30

8.0 OCCUPATIONAL EXPOSURE/RISK ASSESSMENT PATHWAY........................30

8.1 Occupational Pesticide Handler Exposure and Risk............................................. 30

8.2 Occupational Postapplication Worker Exposure and Risk .................................. 32

9.0 TOLERANCE HARMONIZATION AND RECOMMENDED TOLERANCE.......33

10.0 DATA NEEDS..................................................................................................................38

10.1 Toxicology Data Requirements................................................................................ 38

10.2 Residue Chemistry Data Requirements.................................................................. 38

10.3 Occupational/Residential Exposure Data Requirements...................................... 39

REFERENCES.............................................................................................................................39

APPENDIX A: TOXICITY PROFILES FOR BOSCALID TECHNICAL..........................41

APPENDIX B: RATIONALE FOR TOXICITY DATA REQUIREMENTS.......................45

APPENDIX C: INTERNATIONAL RESIDUE LIMIT STATUS..........................................46
Page 6 of 47

1.0 EXECUTIVE SUMMARY

The most recent human health risk assessment was prepared for the use of boscalid on imported 

coffee (W. Drew, DP#354689, 03/25/2009). References may be made to this previous risk 

assessment for details concerning the toxicological, residue chemistry, tolerance harmonization, 

environmental fate, drinking water, and residential aspects of the chemical. No new 

toxicological data have been submitted and no changes have been made to the endpoints selected 

for risk assessment. The submitted residue chemistry studies include crop field trials for alfalfa, 

citrus, and stone fruits; a processing study on citrus; and a cow feeding study. Apart from these 

submissions, no other changes have been made to the residue chemistry considerations, such as 

analytical enforcement methods, residues of concern (ROCs), environmental fate or drinking 

water information, etc. 

Background

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

(anilide) class fungicide that inhibits mitochondrial respiration, thereby inhibiting spore 

germination, germ tube elongation, mycelial growth, and sporulation in all major stages of fungal 

development and reproduction necessary for disease development in a variety of vegetable, fruit 

and row crops. There are currently two WDG boscalid end-use products (EPs) registered to 

BASF in the U.S. for use on food/feed crops, one containing only boscalid and one which is a 

mixture of two active ingredients. The single ai formulation is a 70% WDG (Endura®Fungicide; 

EPA Reg. No. 7969-197) and the mixture formulation is a WDG containing 25.2% boscalid and 

12.8% pyraclostrobin (Pristine®Fungicide; EPA Reg. No. 7969-199). Only boscalid is 

addressed in this document; pyraclostrobin is being evaluated separately. 

BASF has submitted several volumes of data in support of two petitions, PP#9F7527 and 

PP#9F9529, to establish permanent tolerances for the combined residues of the fungicide 

boscalid [3-pyridinecarboxamide, 2-chloro-N-(4’-chloro(1,1’-biphenyl)-2-yl)] in/on the 

following crops: 

Alfalfa Forage ................................................................................... 35 ppm

Alfalfa Hay........................................................................................ 85 ppm

Citrus Crop Group 10....................................................................... 2.0 ppm

Stonefruit Crop Group 12 ................................................................ 5.0 ppm

Use Profile

The fungicide boscalid has been proposed for use on alfalfa and citrus crop group 10. Broadcast 

foliar applications of boscalid may be applied to alfalfa (including alfalfa grown for seed) at a rate 

of 0.48 lb ai/A (Endura®) and 0.28 lb ai/A (Pristine®) and to citrus at a rate of 0.29 lb ai/A 

(Pristine®). For alfalfa, up to three applications can be made per season at retreatment intervals 

(RTI) of 14 to 21 days. The pre-harvest interval (PHI) is 14 days. For citrus, up to four 

applications can be made per season at RTIs of 10 to 21 days. The PHI is zero days. Handlers 

may apply boscalid to alfalfa using aerial, chemigation, or groundboom equipment. To citrus, 

handlers may apply boscalid using aerial, chemigation, airblast, or handgun equipment. 

 

Toxicity/Hazard
Page 7 of 47

The toxicity database for boscalid is complete and provides sufficient information to determine 

whether boscalid poses a human health hazard. Boscalid has a low acute toxicity and is not an 

eye or skin irritant. The target organs for boscalid are the liver and thyroid. An acute endpoint 

was not selected because no adverse effects attributable to a single exposure to boscalid were

seen in the database, including the developmental toxicity studies. The chronic dietary, 

incidental oral, dermal, and inhalation endpoints were all selected from combined results of the 

three studies: chronic rat, carcinogenicity rat, and chronic dog. The dose selected for regulation 

of oral, dermal and inhalation risk at all durations, for all populations is the NOAEL of 21.8 

mg/kg/day based on thyroid and hepatic toxicity seen in rats and dogs at higher dose levels. A 

dermal absorption factor of 15% was derived from an in vivo dermal penetration study in the rat. 

An inhalation absorption factor of 100% was assumed for the inhalation risk assessments. 

The standard UF of 100X to account for inter- and intra-species variability was applied to all risk 

assessments. The Food Quality Protection Act (FQPA) safety factor (SF) for boscalid was 

reduced to 1X. With the exception of an immunotoxicity study, the boscalid toxicity database is 

complete; there are no reproductive, developmental or developmental neurotoxic concerns. 

While the data did show increased quantitative and qualitative sensitivity, the effects noted were 

either transient or inconsistent, or occurred at the limit dose in the presence of maternal toxicity. 

There are clear NOAELs for these effects and EPA is regulating based on a point of departure

(PoD) below where these effects are seen. Additionally, the estimates of exposure are unlikely

to underestimate risk. Therefore, EPA has concluded that the application of an additional SF to 

protect infants and children is not needed. Boscalid is classified as "suggestive evidence of 

carcinogenicity" and the chronic PoD is protective of any tumor response seen in the boscalid 

cancer studies.

Recent changes to 40CFR §158 make immunotoxicity testing (OPPTS Guideline 870.7800) 

required for pesticide registration. The available data for boscalid do not show potential for 

immunotoxic effects. However, the 870.7800 immunotoxicity study is required, and should be 

considered confirmatory (see Appendix B). 

Dietary Exposure (food/drinking water)

Residues of Concern: For purposes of both the tolerance expression and dietary risk assessment, 

HED has concluded that the residues of concern in plant commodities include only boscalid, and 

the residues of concern in livestock commodities include boscalid, its 5-hydroxy metabolite, and 

the glucuronide conjugate of the 5-hydroxy metabolite.

Acute Dietary Exposure/Risk: 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.

Chronic Dietary Exposure/Risk: The chronic dietary analysis was performed using tolerance 

level residues and 100% crop treated assumptions. Dietary risk estimates were determined 

considering exposures from food plus drinking water. Boscalid exposure from the existing uses, 

the proposed new uses on citrus and alfalfa, the recommended tolerance increase for stone fruits, 

and the established and recommenced tolerances on livestock results in estimated risks that are 
Page 8 of 47

below the Agency’s LOC for food plus drinking water. The highest exposure and risk estimates 

for food plus drinking water are 11% of the chronic population adjusted dose (cPAD) for the 

U.S. population and 37% for children 1-2 years old, the most highly exposed population 

subgroup.

Cancer Dietary Risk: A cancer dietary assessment was not conducted since boscalid was 

classified by HED as “suggestive evidence of carcinogenicity” and quantification of human 

cancer risk is not recommended.

Residential Exposure

Residential Handler Exposure: There are no residential uses associated with this action and 

application of boscalid by homeowners is not anticipated. Therefore, residential handler 

exposure was not evaluated. 

Residential Postapplication Exposure: For existing uses on registered labels, there is potential 

for exposure to homeowners in residential settings from “pick-your own” (PYO) operations and 

from entering areas previously treated with boscalid, such as lawns where children might play, 

or golf courses that could lead to exposures for adults. Given the 1-day duration for PYO 

activities, a exposure/risk assessment was not conducted since there are no toxic effects

anticipated from a single exposure to boscalid. The margins of exposure (MOEs) for residential 

postapplication exposure to boscalid are all above 100, and therefore, do not exceed HED's LOC. 

There are no risks of concern from residential postapplication exposure during golfing.

Aggregate Risk

Acute Aggregate Risk: Acute exposures were not considered because an adverse effect 

attributable to a single dose was not identified. 

Short-Term and Intermediate-Term Aggregate Risk: There is potential short- and intermediateterm exposure to boscalid via the dietary (which is considered background exposure) and 

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

via the oral (background) and dermal (primary) routes. For children, these pathways lead to 

exposure via the oral (background), and incidental oral and dermal (primary) routes. All MOEs 

are greater than 100, which indicates that exposure and risk do not exceed HED’s LOC.

Long-Term Aggregate Risk: There is potential chronic exposure via dietary (food and drinking 

water) exposure. Refer to Chronic Dietary Exposure/Risk. 

Cancer Risk: Boscalid is classified as “suggestive evidence of carcinogenicity” and therefore, an 

aggregate cancer assessment was not conducted.

Occupational Exposure/Risk

Dermal: The results of the occupational handler exposure and risk assessment indicate that 

short- and intermediate-term dermal MOEs were greater than the LOC (MOEs ≥ 100) at the 

baseline clothing level, when baseline data are available. The short- and intermediate-term 

dermal risks do not exceed HED’s LOC for mixing/loading/applying with handgun equipment 
Page 9 of 47

when baseline attire plus chemical-resistant gloves are used. The short- and intermediate-term 

dermal risks do not exceed HED’s LOC for pilots using enclosed cockpits and wearing baseline 

attire.

Inhalation: The short- and intermediate-term inhalation risks to handlers do not exceed HED’s 

LOC at baseline (no respirator) for any of the handler scenarios. Only engineering control 

(enclosed cockpit) data are available to assess short- and intermediate-term inhalation risks to 

handlers operating aircraft. The short- and intermediate-term inhalation risks do not exceed 

HED’s LOC for pilots using enclosed cockpits and wearing no respirator.

Combined: Combined dermal plus inhalation risks do not exceed HED’s LOC, provided 

personal protective equipment (PPE) listed under the short- and intermediate-term dermal risks 

are worn. 

Postapplication: Short- and intermediate-term dermal postapplication exposures and risks to 

occupational workers were estimated using standard values established by HED since no 

chemical-specific data were submitted. Using HED default assumptions and surrogate

dislodgeable foliar residue (DFR) data, all scenarios resulted in MOEs greater than 100 on day 0 

(12 hours after application), and therefore risks do not exceed HED’s LOC. 

Restricted Entry Interval (REI): Since postapplication risks were not a concern on day 0 (12 

hours following application), the REI is based on the acute toxicity of boscalid technical 

material. Boscalid is classified as toxicity category III by the dermal route of exposure and 

category IV for eye irritation and skin irritation potential. Under the Worker Protection Standard 

(WPS) for Agricultural Pesticides, active ingredients classified as acute toxicity categories III or 

IV for these routes are assigned a 12-hour REI. Therefore, the 12-hour REI that appears on the 

proposed label is adequate.

International Harmonization

The Codex Alimentarius Commission, Canada, and Mexico have not established any maximum 

residue limits (MRLs) for residues of boscalid in/on alfalfa forage and hay or citrus fruits 

(Appendix I). However, there is an existing Codex MRL for stone fruits at 3 mg/kg, and Canada 

has established MRLs at 1.7 mg/kg for the various member of the stone fruits crop group. 

Canada also has also established MRLs for various livestock commodities. The Canadian MRLs 

for stone fruits and livestock commodities are currently harmonized with the respective U.S.

tolerances; however, once the recommended increases are made to U.S. tolerances, the U.S.

tolerances on stone fruits, poultry fat and meat byproducts, and hog fat will no longer be 

harmonized with the Canadian MRLs.

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.
Page 10 of 47

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 USDA under the Continuing Survey of Food Intake by Individuals (CSFII) 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, season of the year, ethnic group, and region of the 

country. 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 

postapplication 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.

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 studies, which comprise the 

Pesticide Handlers Exposure Database (PHED), have been determined to require a review of 

their ethical conduct and have received that review. 

2.0 INGREDIENT PROFILE

Reference: 

- Boscalid; Petition for Establishing Permanent Tolerances on Alfalfa and the Citrus Crop Group 10, and 

Amending the Established Tolerance on the Stone Fruit Crop Group 12. Summary of Analytical Chemistry and 

Residue Data. A. Acierto, DP#364447, 10/16/2009.

Boscalid is a carboxamide (an anilide) fungicide that inhibits mitochondrial respiration, thereby 

inhibiting spore germination, germ tube elongation, mycelial growth, and sporulation of 

pathogenic fungi on the leaf surface. Boscalid is currently registered to BASF as WDG 

formulations for use on a wide variety of food/feed crops. 

2.1 Summary of Proposed New Uses

BASF is proposing new uses for the 70% WDG (Endura®) formulation on alfalfa and for the 

25% WDG (Pristine®) on alfalfa and citrus fruits. Supplemental labels were provided. The use 

directions for alfalfa and citrus, including the directions for stone fruits, are summarized below in 

Table 2.1. 
Page 11 of 47

Table 2.1.` Summary of Directions for Use of Boscalid.

Application Timing, 

Type, and Equipment1

Trade Name

Formulation

[EPA Reg. No.]

Application

Rate 

(lb ai/A)

Max. No. 

Application

per Season

Max. Seasonal 

Application Rate

(lb ai/A)

PHI

(days)

Use Directions and 

Limitations 2

Alfalfa 3

Broadcast foliar 

applications when 

conditions are favorable 

to disease development; 

ground, aerial, or 

chemigation equipment. 

Endura®

70% WDG

[7969-197]

0.09-0.48

3 

(2 per cutting) 1.44 14

The minimum RTI is 14 days. 

For aerial applications, use a 

minimum of 10 gal/A

Do not make more than 2 

applications per cutting or 3 

applications per season.

Pristine®

25.2% WDG

[7969-199]

0.19-0.28 3 

(2 per cutting) 0.85 14

Citrus Fruits

Broadcast foliar 

applications prior to 

infection; ground, aerial, 

or chemigation

equipment.

Pristine®

25.2% WDG

[7969-199]

0.25-0.29 4 1.17 0

The minimum RTI is 10 days. 

For aerial applications, use a 

minimum of 10 gal/A.

Stone Fruits

Broadcast foliar 

applications from pink 

bud through fruit 

development; ground, 

aerial, or chemigation

equipment.

Pristine®

25.2% WDG

[7969-199]

0.17-0.23 5 1.14 0

The minimum RTI is 7 days.

For aerial applications, use a 

minimum of 10 gal/A.

1 Chemigation may be made through the following types of irrigation systems: center pivot, lateral move, end tow, side wheel roll, traveler, big 

gun, solid set, or hand move. 

2 Use directions allow for the use of spray adjuvants and specify a 14-day plant-back interval for rotational crops without registered uses for 

boscalid.

3

For stand establishment of fall seeded alfalfa, begin applications in fall through early winter prior to first snowfall or extended cool, wet 

conditions. For seed pod protection, begin applications at 10% to 30% bloom.

2.2 Structure and Nomenclature/Physical and Chemical Properties

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

physicochemical properties of the technical grade of boscalid are presented in Tables 2.2.1 and 

2.2.2.

Table 2.2.1. Nomenclature of Boscalid and its Hydroxy Metabolite.

Compound

N

N

O

Cl

Cl

Common name Boscalid; Nicobifen

Company experimental name BAS 510 F

IUPAC name 2-chloro-N-(4'-chlorobiphenyl-2-yl)-nicotinamide
Page 12 of 47

Table 2.2.1. Nomenclature of Boscalid and its Hydroxy Metabolite.

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

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)

70% WDG (Endura®Fungicide; EPA Reg. No. 7969-197)

Hydroxy-metabolite

N

N

O

Cl

Cl

OH

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

Table 2.2.2. 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 (ε[Lmol-1cm-1]): 3.15 

x104at 228 nm; 1.53 x103at 290 nm

3.0 HAZARD CHARACTERIZATION/ASSESSMENT

References:

- BAS 510 F - Report of the Hazard Identification Assessment Review Committee. A. Levy, TXR#0051613, 

03/07/2003.

- BAS 510 F: Report of the Cancer Assessment Review Committee. J. Kidwell, TXR#0051289, 11/14/2002.

- Boscalid. Human Health Risk Assessment for a Section 3 Tolerance on Endive, an Amendment to the Tolerances for 

Strawberries and Berries, Crop Group 13, and an Increase in Tolerances in/on Cucumber and Vegetable, Root, Subgroup 

1A, except Sugar Beet, Garden Beet, Radish, and Turnip. B. Hanson, DP#327906, 07/10/2007.

- PP# 1F06313 --Human Health Risk Assessment for New Fungicide BAS 510 F (Common Name: Boscalid) -- Proposal for 

Tolerances for Residues in/on Numerous Crops and Livestock Commodities. Y. Donovan, DP#290022, 09/08/2003.
Page 13 of 47

The toxicity database for boscalid is adequate for risk assessment purposes. However, as part of 

the new 40 CFR §158 Guidelines, an immunotoxicity study (OPPTS Guideline 870.7800) in rats 

and/or mice is required (see Appendix B). No indication of immunotoxicity was observed in the 

toxicity database; therefore, an additional 10X database UF is not warranted. 

Boscalid appeared to have effects on the liver and/or thyroid of several species. In a 90-day

mouse study, there were increased liver weights and increased incidences in marked fatty change 

in the liver. These liver changes were not noted in the 18-month mouse study. In 90-day as well 

as in 2-year rat studies, there were thyroid changes (increase in weights and incidence of 

follicular cell hyperplasia and hypertrophy). The thyroid changes were considered to have been 

the result of liver adaptive responses. The 90-day and one-year dog studies showed increases in 

the levels of alkaline phosphatase as well as hepatic weights. In three mechanistic rat studies, the 

following were observed: increase in liver microsomal activity, induction of total cytochrome 

P450 activity, disruption of thyroid homeostasis by decreasing circulating T3 and T4 and 

increasing TSH (likely the result of hepatic microsomal glucuronyltransferase), and reversal of 

liver and thyroid effects with the cessation of test article administration (it was concluded that 

the induction of liver microsomal enzyme system resulted 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). 

There were little or no effects on body weights or body weight gains.

In the developmental toxicity studies, no effects were noted in rats; whereas, in the rabbit study, 

abortions or early delivery were observed at the highest dose tested (1000 mg/kg/day). 

Regarding the 2-generation reproduction study in rats, decreased body weights and/or body 

weight gains and hepatocyte degeneration were noted in males only. No reproductive effects 

were observed. The only effects noted in pups of both generations were decreases in body

weights (both sexes of both generations) at the highest dose tested (>1000 mg/kg/day). 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 increased 

susceptibility in the developmental rat study (Limit Dose). Qualitative, but not quantitative, 

increased susceptibility was noted in the developmental rabbit study as characterized by an 

increased incidence of abortions or early delivery at the highest dose tested (1000 mg/kg/day). 

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

rat study where decreases in body weights and body weight gains in male offspring were seen in 

the F2 generation and in females from both generations at a dose that was lower than the dose that 

induced parental/systemic toxicity. Quantitative evidence of increased susceptibility was noted in 

the developmental neurotoxicity study in rats where decreases in pup body weights (PND 4) and 

body weight gains (PND 1-4) were seen in the absence of any maternal toxicity. The degree of 

concern is low for the qualitative evidence of susceptibility seen in the rabbit developmental 

study as the increased abortions or early delivery was seen only at the Limit Dose and the 

abortions may have been due to maternal stress. The degree of concern is low for the quantitative 

evidence of susceptibility seen in the two-generation reproduction study in rats because the 

decreases in body weight and body weight gains were seen only in the F2 generation in males and 

in females in both generations. The degree of concern is low for the quantitative evidence of 

susceptibility in the developmental neurotoxicity study because the decreases in pup body
Page 14 of 47

weights seen on post natal days 1 through 4 (at no other time periods) were most likely due to 

maternal toxicity.

Boscalid has low acute toxicity via the oral, dermal, and inhalation routes of exposure, and is not 

an eye or skin irritant (see Appendix A, Table A.1). Dermal sensitization could not be 

determined because the skin sensitization study was inadequate. The target organs for boscalid 

are the liver and thyroid. 

An acute dietary endpoint was not selected because no adverse effects attributable to a single 

exposure to boscalid were seen in the database, including the developmental toxicity studies. 

The chronic dietary, incidental oral, dermal, and inhalation endpoints were all selected from 

combined results of the three studies: chronic rat, carcinogenicity rat, and chronic dog. The dose 

selected for regulation of oral, dermal, and inhalation risk at all durations, for all populations, is 

the no observed adverse effect level (NOAEL) of 21.8 mg/kg/day, based on thyroid and hepatic 

toxicity seen in rats and dogs at higher dose levels. A dermal absorption factor of 15% was 

derived from an in vivo dermal penetration study in the rat. An inhalation absorption factor of 

100% was assumed for the inhalation risk assessments. 

Boscalid is classified as exhibiting “suggestive evidence of carcinogenicity, but not sufficient to 

assess human carcinogenic potential,” and, therefore, the quantification of human cancer risk is 

not recommended. 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. 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 of carcinogenic effects, the CARC indicated that a dose-response 

assessment for cancer (either linear low-dose extrapolation or MOE calculation) was not needed.

Thus, evidence of carcinogenicity was seen in males (significant trend and pair-wise at the high

dose) and in females (trend only); however, no malignancies were seen in either sex. Only

benign tumors were observed, and these occurred at dose levels above the dose level used to 

establish the cPAD. Additionally, there is no concern for mutagencity. The PoD for chronic risk 

assessment is protective of any tumor response seen in the boscalid cancer studies. 

The toxicological profiles for boscalid are outlined in Appendix A of this document.

3.1 FQPA Safety Factor

The standard UF of 100X to account for inter- and intra-species variability was applied to all risk 

assessments. The FQPA SF for boscalid was reduced to 1X for the reasons listed below.
Page 15 of 47

1. The toxicity database for boscalid is adequate for risk assessment, however an 

immunotoxicity study (OPPTS Guideline 870.7800) in rats and/or mice is required 

under the new 40 CFR part 158 data regulations. No indication of immunotoxicity

was observed in the toxicity database; therefore, an additional 10X database UF is not 

warranted.

2. There is no indication that boscalid is a neurotoxic chemical and there is no need for 

additional UFs to account for neurotoxicity. There is no evidence of neurotoxicity in 

the acute subchronic, or developmental neurotoxicity studies. The toxicity studies for 

boscalid demonstrate that, in general, the chemical has low mammalian toxicity, and 

the database reveals no reproductive, developmental, or developmental neurotoxicity

concerns.

3. Data involving the testing of young animals did show increased quantitative 

sensitivity in the young with regard to body weight effects, and qualitative sensitivity

was seen in one developmental study. However, clear NOAELs were identified for all 

of these effects. Moreover, the body weight effects at the LOAELs in these studies 

were either transient or inconsistent, and qualitative sensitivity occurred at the limit 

dose in the presence of maternal toxicity. Additionally, EPA is regulating based on a 

PoD below where these effects are seen. EPA concludes that there are no residual 

uncertainties for pre- and/or post-natal toxicity.

4. There are no residual uncertainties identified in the exposure databases. EPA has 

conservatively estimated human exposure to boscalid, relying on worst case 

exposures in food (assuming all registered crops contain residues at the tolerance 

level), and conservative models, as well as pesticide-specific data, in estimating 

exposure from residues in drinking water, and from residential uses. These 

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

Based on consideration of all of these data, HED has concluded that it has reliable evidence to 

show that infants and children would be adequately protected without application of an 

additional 10X SF. 

3.2 Summary of Toxicological Doses and Endpoints

The endpoints and doses selected for risk assessment purposes are summarized in Table 3.2. 

TABLE 3.2. Summary of Toxicological Doses and Endpoints for Boscalid. 

Exposure

[Scenario]

PoD Uncertainty and 

FQPA Safety 

Factors

RfD/PAD/

LOC

Study and Toxicological 

Effects

Acute Dietary

[All Populations]

No appropriate endpoint attributable to a single dose was available in the current database, 

including the developmental toxicity studies. Therefore, an acute RfD and acute PAD were

not established for any population.

Chronic Dietary

[All Populations]

NOAEL = 21.8 

mg/kg/day

UFA = 10X

UFH = 10X

FQPA SF = 1X

Chronic RfD = 

0.218 mg/kg/day

Chronic PAD = 

0.218 mg/kg/day

Combined results of chronic 

rat, carcinogenicity rat, and 1-

year dog studies. 

LOAEL = 57 mg/kg/day, based 

on liver and thyroid effects. 

Incidental Oral, 

Short- and 

NOAEL = 21.8 

mg/kg/day

UFA = 10X

UFH = 10X

Residential 

LOC = 

Combined results of chronic 

rat, carcinogenicity rat, and 1-
Page 16 of 47

TABLE 3.2. Summary of Toxicological Doses and Endpoints for Boscalid. 

Exposure

[Scenario]

PoD Uncertainty and 

FQPA Safety 

Factors

RfD/PAD/

LOC

Study and Toxicological 

Effects

IntermediateTermFQPA SF = 1X MOE < 100 year dog studies.

LOAEL = 57 mg/kg/day, based 

on liver and thyroid effects. 

Dermal

[All Durations]

Oral study NOAEL

= 21.8 mg/kg/day

Dermal absorption

= 15%

UFA = 10X

UFH = 10X

FQPA SF = 1X

Residential and 

Occupational

LOC = 

MOE < 100

Combined results of chronic 

rat, carcinogenicity rat, and 1-

year dog studies. 

LOAEL = 57 mg/kg/day, based 

on liver and thyroid effects. 

Inhalation

[All Durations]

Oral study NOAEL

= 21.8 mg/kg/day

Inhalation 

absorption = 100%

UFA = 10X

UFH = 10X

FQPA SF = 1X

Residential and 

Occupational

LOC = 

MOE < 100

Combined results of chronic 

rat, carcinogenicity rat, and 1-

year dog studies. 

LOAEL = 57 mg/kg/day, based 

on liver and thyroid effects. 

Cancer Classified as exhibiting “suggestive evidence of carcinogenicity.” Quantification of human 

cancer risk is not recommended.

PoD = Point of Departure, a data point (or estimated point) that is derived from observed dose-response data, and 

used to mark the beginning of extrapolation to determine risk associated with lower environmentally relevant human 

exposures. NOAEL = No Observed Adverse Effect Level. LOAEL = Lowest Observed Adverse Effect Level. UF 

= Uncertainty Factor. UFA = extrapolation from animal to human (interspecies). UFH = potential variation in 

sensitivity among members of the human population (intraspecies). FQPA SF = FQPA Safety Factor. PAD = 

Population Adjusted Dose. RfD = Reference Dose. LOC = Level Of Concern. MOE = Margin Of Exposure. 

3.3 Endocrine disruption

EPA is required under the FFDCA, as amended by FQPA, to develop a screening program to 

determine whether certain substances (including all pesticide active and other ingredients) “may

have an effect in humans that is similar to an effect produced by a naturally occurring estrogen, 

or other such endocrine effects as the Administrator may designate.” Following 

recommendations of its Endocrine Disruptor and Testing Advisory Committee (EDSTAC), EPA 

determined that there was a scientific basis for including, as part of the program, the androgen 

and thyroid hormone systems, in addition to the estrogen hormone system. EPA also adopted 

EDSTAC’s recommendation that the Program include evaluations of potential effects in wildlife. 

For pesticide chemicals, EPA will use FIFRA and, to the extent that effects in wildlife may help

determine whether a substance may have an effect in humans, FFDCA authority to require the 

wildlife evaluations. As the science develops and resources allow, screening of additional 

hormone systems may be added to the Endocrine Disruptor Screening Program (EDSP).

When additional appropriate screening and/or testing protocols being considered under the 

Agency’s EDSP have been developed, boscalid may be subjected to further screening and/or 

testing to better characterize effects related to endocrine disruption.

4.0 DIETARY EXPOSURE/RISK CHARACTERIZATION

A residue chemistry summary document has been prepared for the proposed uses on alfalfa, 

citrus fruits, and increased tolerance on stone fruits (A. Acierto, DP#364447, 10/16/2009). 
Page 17 of 47

Reference may be made to this document for details concerning residue chemistry considerations 

associated with the current use request, such as a summary of registered uses, boscalid 

nomenclature, physical and chemical properties, use directions, metabolism in plants and 

animals, analytical methods, storage stability, field trial results, etc. 

4.1 Nature of the Residue and Residue Analytical Methods

Boscalid residues in all samples associated with the current field trials and livestock studies were 

determined using the methods described below. For purposes of both the tolerance expression 

and dietary risk assessment, HED has concluded that the ROC in plant commodities include only

boscalid, and the ROC in livestock commodities include boscalid, its 5-hydroxy metabolite, and 

the glucuronide conjugate of the 5-hydroxy metabolite.

860.1300 Nature of the Residue and 860.1340 Residue Analytical Methods – Plants

The nature of boscalid residues in primary crops is adequately understood, based upon 

acceptable grape, lettuce, and bean metabolism studies; these studies were reviewed in the initial 

boscalid petition, PP#1F6313 (M. Nelson, DP#278385, 08/15/2003). An adequate gas 

chromatography with mass spectrometric detection (GC/MS) method (BASF Method D0008) is 

available for enforcing boscalid tolerances in plant commodities. The Analytical Chemistry

Branch (ACB) of the Biological and Economic Analysis Division (BEAD) concluded that the 

method is acceptable for enforcement purposes in plants, without the need for an EPA validation. 

An adequate high-performance liquid chromatography with ultraviolet detection (HPLC/UV)

method (BASF Method 441/0) is also available for collecting residue data on plant commodities. 

860.1300 Nature of the Residue and 860.1340 Residue Analytical Methods – Livestock

The nature of boscalid residues in livestock is adequately understood, based upon acceptable 14C 

metabolism studies conducted on lactating goats and laying hens. An enforcement method 

(BASF Method DFG S19) is available for determining the residues of concern in livestock and 

has been successfully validated by ACB/BEAD. For the current livestock feeding study, 

residues of boscalid and its hydroxyl metabolite M510F01 (including the glucoronide conjugate 

M510F02) were determined using a LC/MS/MS method (BASF Method 471/0, modified) which 

was previously reviewed in conjunction with earlier feeding studies.

For calculating combined residues, Metabolite M510F01 residues are converted into parent 

equivalents using a conversion factor of 0.96. The above method was adequately validated prior 

to and in conjunction with the analysis of feeding study samples, using control samples fortified 

with boscalid and M510F01 at 0.01 ppm – 2.5 ppm for milk, skim milk, and cream, and 0.025 

ppm – 2.5 ppm for liver, kidmey, muscle, and fat samples.

860.1360 Multiresidue Methods

Residues of boscalid and its metabolite M510F01 were not adequately recovered using the 

Multiresidue methods.

860.1380 Storage Stability
Page 18 of 47

Adequate storage stability studies are available indicating that boscalid is relatively stable at 

≤20°C in fortified samples of cabbage (leafy vegetables), canola seed (oil seed), peach 

(fruit/fruiting vegetable), sugar beet roots (root crop), peas (legume vegetable, wheat grain (nonoily grain), wheat forage (foliage), and wheat straw (dry feed) for up to 24 months. In addition 

to the above date, a concurrent storage stability study was conducted in conjunction with the 

orange processing study (MRID 47584402.der). The available storage stability data are adequate 

and support the storage conditions and durations for samples of alfalfa, citrus fruits, and stone 

fruits from the current field trials and the acceptable citrus processing study.

4.2 Pesticide Metabolites and Degradates of Concern

Boscalid is a persistent compound with low mobility in most soils. The primary degradation 

pathway is aerobic soil metabolism, which proceeds slowly and results in the formation of 

intermediates which are relatively rapidly transformed into CO2 or bound soil residues. Boscalid 

is stable to hydrolysis and to photolysis on soil and in water. The compound is also not 

transformed to any significant extent in either aerobic or anaerobic aquatic systems. The 

residues of concern to be included in the tolerance expression and for risk assessment purposes 

are summarized below in Table 4.2.

Table 4.2. 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 Parent only Parent only

Rotational Crop Parent only Parent only

Livestock Ruminant Parent and hydroxy and 

glucuronic acid metabolites

Parent and hydroxy and 

glucuronic acid metabolites

Poultry Parent and hydroxy and 

glucuronic acid metabolites

Parent and hydroxy and 

glucuronic acid metabolites

Drinking Water Parent only Not Applicable

4.3 Drinking Water Residue Profile

References: 

- Drinking Water Exposure Assessment for New Uses of Boscalid on Alfalfa Forage and Hay, Citrus group 10, 

and an Increase in Tolerance on Stone Fruit group 12. D. Lieu, DP#367184, 09/24/2009.

- Drinking Water Assessment for the IR-4 Petition for the Use of Boscalid on Tropical Fruits and Fresh Herbs, 

and a Proposed New Use on Cotton. C. Sutton, DP#336183, 08/08/2007.

EFED completed a drinking water assessment (DWA) for boscalid (D. Lieu, DP#367184, 

09/24/2009), indicating that the previous assessment conducted by C. Sutton (DP#336183, 

08/08/2007) yields higher EDWCs. The highest EDWCs were based on the turf use. The 

current requests for new uses on alfalfa and citrus and the increase of tolerances for stone fruit 

crop group 12 do not affect the EDWCs. As a result, the EDWCs used in the previous 

assessment were used in this assessment as well. The EDWCs were incorporated directly into 
Page 19 of 47

the dietary assessment via the food categories “water, direct, all sources” and “water, indirect, all 

sources.”

The EDWCs for boscalid in surface water and ground water were calculated using the screening 

model FIRST (FQPA Index Reservoir Screening Tool, Version 1.1.0, dated 12/12/2005), and the 

regression model SCI-GROW (Screening Concentration in Ground Water, Version 2.3, dated 

07/29/2003), respectively. An acute dietary risk assessment was not conducted. The maximum 

estimated chronic ground water EDWC was 0.63 ppb. The maximum estimated chronic surface 

water EDWC was 29.6 ppb. The surface water value is higher than the ground water value and

was, therefore, used in the dietary assessment. 

4.4 Food Residue Profile

References: 

- Boscalid; Petition for Establishing Permanent Tolerances on Alfalfa and the Citrus Crop Group 10, and 

Amending the Established Tolerance on the Stone Fruit Crop Group 12. Summary of Analytical Chemistry and 

Residue Data. A. Acierto, DP#364447, 10/16/2009.

BASF is proposing new uses for boscalid on alfalfa using the 25% WDG and 70% WDG 

formulations and on citrus fruits using the 25% WDG formulation. The proposed uses on alfalfa 

are for repeated broadcast foliar applications at up to 0.28 lb ai/A for the 25% WDG and 0.48 lb 

ai/A for the 70% WDG, with a minimum RTI of 14 days, for a maximum of 0.85 lb ai/A/season 

and 1.44 lb ai/A/season for the 25% WDG and 70% WDG, respectively. A maximum of 3 

applications to alfalfa are allowed per season with no more than 2 applications per cutting. The 

proposed use on citrus fruits is for up to four broadcast foliar applications during fruit 

development at rates up to 0.29 lb ai/A with a minimum RTI of 10 days, for a maximum of 1.17 

lb ai/A/season. All applications can be made using ground, aerial, or chemigation equipment, 

and the proposed PHIs are 14 days for alfalfa and 0 days for citrus fruits. 

860.1480 Meat, Milk, Poultry, and Eggs

Adequate cattle and poultry feeding studies are available. The maximum dietary burden for 

poultry was originally calculated to be 1.85 ppm (M. Nelson, DP#278385, 8/15/2003), and the 

maximum dietary burdens for other livestock were most recently calculated to be 16.4 ppm for 

beef cattle, 13.2 ppm for dairy cattle, and 1.79 ppm for swine (D. Dotson, DP#322235, 

11/03/2005). A summary of the combined residue data from the 2008 dairy cattle feeding study 

and the poultry feeding studies are summarized in DP#364447 (A. Acierto, 10/16/2009).

Cattle Feeding Studies. BASF submitted a new cattle feeding study conducted in 2008 in which 

two groups of lactating dairy cows were administered with encapsulated boscalid via balling gun 

for 29 consecutive days at the target doses of 35 ppm (Group 2; 3 cows) or 105 ppm (Group 3; 7 

cows). These dose levels are intended to represent 1X and 3X the anticipated European Union 

(EU) dietary burden of 35 ppm in the feed on a dry weight basis. 

Poultry Feeding Study. In the poultry feeding study, three groups of laying hens were dosed 

orally once a day for 29 consecutive days with boscalid at levels equivalent to 1.02 ppm, 5.31

ppm, and 19.6 ppm in the diet, which are respectively equivalent to 0.25X, 1.3X, and 4.8X of the 

maximum dietary burden of poultry to boscalid.
Page 20 of 47

Livestock Dietary Burdens. As alfalfa forage and hay are major livestock feedstuffs, the dietary

burdens for livestock were recalculated for this petition. Based on the recent changes in 

calculating residues in reasonably balanced livestock diets (Table 1, Feedstuffs, June 2008), the 

dietary burden for livestock from boscalid residues were recalculated to be 10.8 ppm for beef 

cattle, 22.5 ppm for dairy cattle, 4.0 ppm for poultry, and 5.3 ppm for swine (Table 4.4.3).

TABLE 4.4.3. Calculation of Dietary Burdens of Boscalid Residues to Livestock.

Feedstuff Type1 % Dry 

Matter2 % Diet2 Recommended 

Tolerance (ppm)

Dietary Contribution 

(ppm)3

Beef Cattle

Alfalfa, hay R 89 10 65 7.3

Cotton, gin byproducts R 90 5 55 3.06

Field corn, grain CC 88 80 0.2 0.18

Canola, meal PC 88 5 3.5 40.2

TOTAL BURDEN -- -- 100 -- 10.8

Dairy Cattle

Alfalfa, forage R 35 20 30 17.2

Grass, hay R 88 25 8.0 2.27

Apple, wet pomace CC 40 10 10 2.50

Field corn, grain CC 88 35 0.2 0.08

Canola, meal P 88 10 3.5 40.4

TOTAL BURDEN -- -- 100 -- 22.5

Poultry

Field corn, grain CC 88 75 0.2 0.15

Alfalfa, meal PC 90 5 65 43.25

Canola, meal PC 89 15 3.5 40.53

Peanut, meal PC 85 5 0.15 0.0075

TOTAL BURDEN -- -- 100 -- 4.0

Swine

Field corn, grain CC 88 85 0.2 1.70

Alfalfa, meal PC 90 5 65 43.25

Canola, meal PC 89 10 3.5 40.35

TOTAL BURDEN -- -- 100 -- 5.3

1 R: Roughage; CC: Carbohydrate concentrate; PC: Protein concentrate.

2 OPPTS 860.1000 Table 1 Feedstuffs (June 2008). 

3 Contribution = ([tolerance /% DM] X % diet) for beef and dairy cattle; contribution = ([tolerance] X % diet) for 

poultry and swine.

4 The tolerance for canola seed (3.5 ppm) was used for meal, and the tolerance for alfalfa hay (65 ppm) was used 

for alfalfa meal.

Conclusions. The available cattle and poultry feeding studies are adequate and cover the 

potential levels of dietary exposure of livestock to boscalid residues. The magnitude of the 

residues of boscalid and M510F01 was adequately determined in the new (2008) feeding study. 
Page 21 of 47

For hogs, the adequacy of the existing tolerances were assessed using residue data from the 5.9 

ppm dose group in the cattle feeding studies; this group represents 1.1X the calculated dietary

burden for swine. The data indicate that the existing tolerances for meat (0.05 ppm) and meat 

byproducts (0.10 ppm) of hogs are adequate; however, the tolerance for hog fat should be 

increased to 0.20 ppm.

For poultry, the adequacy of the existing tolerances were assessed using residue data from the 

5.31 ppm dose group in the poultry feeding studies; this group represents 1.3X the calculated 

dietary burden for poultry. These data indicate that the existing tolerances for eggs (0.02 ppm) 

and poultry meat (0.05 ppm) are adequate; however, the tolerances for poultry fat and meat 

byproducts should each be increased to 0.20 ppm.

860.1500 Crop Field Trials

References:

- Boscalid. Petition for a Tolerance for Belgian Endive; Petition for Increased Tolerances on Strawberry and the 

Berries Crop Group; Submission of Requested Field Trial Data on Cucumber, Mustard Greens, and Sunflower; 

and Supplemental Field Trial Data on Fruiting Vegetables, Radishes, Spearmint, Peppermint, Grapes, and 

Stone Fruits; and Submission of Field Trials and a Processing Study for Cotton. Summary of Analytical and 

Residue Data. D. Soderberg, DP#323288, 06/14/2007.

- Boscalid; Petition for Establishing Permanent Tolerances on Alfalfa and the Citrus Crop Group 10, and 

Amending the Established Tolerance on the Stone Fruit Crop Group 12. Summary of Analytical Chemistry and 

Residue Data. A. Acierto, DP#364447, 10/16/2009.

- PP#1F06313. BAS 510 F (Common Name: Boscalid), New Fungicide Active Ingredient. Residue Chemistry 

Summary Document. M. Nelson, DP#278385, 08/15/2003.

BASF submitted field trial data on alfalfa, oranges, lemons, and grapefruits in support of new 

uses for boscalid (WDG formulations) on alfalfa and the citrus fruits crop group. BASF also 

submitted new stone fruit field trial data supporting an amended tolerance for stone fruits. The 

results from the new field trials and the previously submitted stone fruit field trails are 

summarized in Table 4.4.4 and discussed below. Adequate storage stability studies and 

acceptable analytical methods are available.

TABLE 4.4.4. Summary of Residue Data from Crop Field Trials with Boscalid (WDG).

Crop Matrix

(DER)

Treatment 

Info.

Total Applic. 

Rate (lb ai/A)

PHI 

(days) 1

Residue Levels (ppm) 2

n Min. Max. HAFT 3 Median Mean Std. Dev.

Citrus Fruits (proposed use = 1.17 lb ai/A total application rate, 0-day PHI) 4

Orange

(45903601.de1)

Concentrated 1.19-1.22 0 12 0.179 1.425 1.393 0.388 0.610 0.467

Dilute 1.20-1.21 0 14 0.238 0.676 0.588 0.353 0.418 0.146

Grapefruit

(45903601.de1)

Concentrated 1.20 0 6 0.115 0.847 0.836 0.143 0.365 0.364

Dilute 1.20 0 6 0.064 0.272 0.261 0.125 0.155 0.086

Lemon

(45903601.de1)

Concentrated 1.18-1.23 0 6 0.522 1.51 1.239 0.671 0.822 0.370

Dilute 1.18-1.20 0 4 0.600 0.936 0.872 0.775 0.771 0.140

Stone Fruits (proposed use = 1.15 lb ai/A total application rate, 0-day PHI) 5

Cherry 

(47470201.de2)

NA

1.15

0 14 <0.05 2.98 1.63 1.47 1.57 0.89

1 14 <0.05 2.69 1.95 1.09 1.28 0.81

Peach

(47470201.de2) 1.15

0 12 0.56 3.79 1.94 0.76 1.15 1.03

1 12 0.46 3.87 2.74 0.75 1.19 1.15
Page 22 of 47

TABLE 4.4.4. Summary of Residue Data from Crop Field Trials with Boscalid (WDG).

Crop Matrix

(DER)

Treatment 

Info.

Total Applic. 

Rate (lb ai/A)

PHI 

(days) 1

Residue Levels (ppm) 2

n Min. Max. HAFT 3 Median Mean Std. Dev.

Plum

(47470201.de2) 1.15

0 10 <0.05 0.79 0.67 0.14 0.34 0.31

1 10 <0.05 0.57 0.71 0.11 0.26 0.24

Cherry

(45405121.der)

NA

1.35

0

2 1.28 1.70 1.49 1.49 1.49 NA

Peach

(45405121.der) 1.14-1.17 8 0.47 1.20 1.19 0.74 0.77 0.29

Plum

(45405121.der) 1.15-1.17 8 0.09 0.85 0.70 0.50 0.47 0.23

Cherry

(46665505.der)

Concentrated 1.15-1.16 0 6 0.641 1.635 1.635 0.999 1.056 0.370

Dilute 1.15 0 6 0.736 1.505 1.505 1.313 1.229 0.309

Peach

(46665505.der)

Concentrated 1.14-1.16 0 9 0.157 0.663 0.663 0.479 0.450 0.157

Dilute 1.14-1.17 0 9 0.193 0.746 0.746 0.422 0.434 0.203

Plum

(46665505.der)

Concentrated 1.14-1.15 0 6 0.081 0.566 0.566 0.154 0.214 0.182

Dilute 1.14-1.15 0 6 0.103 0.344 0.344 0.198 0.211 0.105

Alfalfa (proposed use = 0.85 lb ai/A total application rate, 14-day PHI) 6

Alfalfa Forage

(47584401.der) Trt #2 7

0.88-0.92

12-15 24 1.10 20.30 17.67 5.04 7.05 5.20

12-16 24 0.81 19.40 17.23 4.98 6.25 5.09

43-73 22 <0.05 0.53 0.37 0.12 0.17 0.14

Trt #3 0.86-0.93

19-23 24 0.11 6.16 6.10 1.94 2.05 1.66

20-23 24 0.32 5.59 5.06 2.12 2.29 1.62

49-76 22 <0.05 0.50 0.50 0.11 0.16 0.13

Trt #4 0.59-0.62

12-15 24 0.97 15.68 14.47 3.95 4.94 3.78

12-16 24 0.85 15.32 15.07 3.59 5.56 4.51

43-70 22 <0.05 0.38 0.32 0.08 0.12 0.09

Trt #5 0.57-0.62

19-23 24 0.05 5.44 5.38 1.21 1.75 1.58

20-23 24 0.29 3.64 3.46 2.12 2.03 1.07

49-76 22 <0.05 0.44 0.44 0.07 0.14 0.14

Alfalfa Hay

(47584401.der) Trt #2 7

0.88-0.92

12-15 24 3.36 43.02 42.62 14.00 17.37 11.19

12-16 24 5.22 51.12 48.91 16.10 20.93 13.64

43-73 22 0.07 3.63 2.38 0.37 0.62 0.78

(Trt #3 0.86-0.93

19-23 24 0.14 20.84 19.84 6.37 6.97 5.93

20-23 24 1.52 15.26 14.72 6.72 7.24 4.44

49-76 22 <0.05 1.36 1.17 0.24 0.49 0.45

Trt #4 0.59-0.62

12-15 24 3.11 33.78 31.34 10.80 15.30 9.21

12-16 24 4.48 40.06 39.33 16.89 18.23 11.40

43-70 22 <0.05 0.72 0.70 0.27 0.31 0.19

Trt #5 0.57-0.62

19-23 24 0.42 12.46 12.23 3.80 5.29 4.45

20-23 24 1.88 21.60 18.31 7.44 7.50 4.76

49-76 22 <0.05 1.12 1.10 0.25 0.45 0.40

1

For the alfalfa field trials, the three separate harvest intervals are the PHIs for the 1st, 2nd and 3rd cuttings.

2 The validated LOQ for boscalid is 0.05 ppm in plant commodities. For all calculations, the LOQ (0.05 ppm) was 

used for all values reported as <LOQ.
Page 23 of 47

3 HAFT = Highest average field trial result.

4 The citrus field trials were conducted using either concentrate or dilute spray volumes.

5

For stone fruits, the data are reported separately for the three MRIDs (47470201, 46665505, and 45405121). In 

MRID 45405121, applications to stone fruits were made using either concentrate or dilute spray volumes.

6

For the alfalfa field trials, Treatments #2 and #3 included three boscalid applications at ~0.3 lb ai/A/application 

with the first and second applications made prior to the 1st cutting and the final application made prior to the 2nd 

cutting. Treatments #4 and #5 included two applications at ~0.3 lb ai/A/application, with the first application 

made prior to the 1st cutting and the second application made prior to the 2nd cutting.

7 Treatment #2 represents the worse case use on alfalfa and reflects the proposed use pattern. As residues (bolded)

from the 1st and 2nd cutting were similar in magnitude and both reflected the proposed 14-day PHI, all values from 

these two cutting were used to access tolerances for forage and hay.

Citrus Fruits, Crop Group 10. BASF submitted field trial data for boscalid on citrus fruits. 

The submitted field trial data are adequate and support the use of boscalid (WDG) on citrus fruits 

as either dilute or concentrated broadcast foliar applications during fruit development and 

maturation at rates of up to 0.29 lb ai/A. The highest residues which were found were 1.43 ppm 

in oranges, 0.85 ppm in grapefruit, and 1.51 ppm in lemons. The data support a maximum of 4 

applications per season and a maximum seasonal use rate of 1.16 lb ai/A, a minimum RTI of 10 

days, and a minimum PHI of 0 days.

Some of the oranges were separated into wet peel and pulp. As compared to the whole fruit, 

boscalid residues were lower in orange pulp and higher in peel.

 

Stone Fruits, Crop Group 12. Adequate field trial data supporting the use of boscalid (WDG) 

on stone fruits were previously submitted (M. Nelson, DP#278385, 8/15/2003; and D. 

Soderberg, DP#323288, 6/14/2007). BASF has submitted additional field trial data for boscalid 

on stone fruits and the available stone fruit field trial data are adequate to support a tolerance 

increase from 1.7 ppm to 3.5 ppm for the stone fruit crop group 12. The recommended 

tolerance is based on the tolerance spreadsheet using the pooled data from field trials for 

representative crops of cherries, peaches, and plum treated at 1X rate with the PHI of 0 day. 

When residue data from all the adequate stone fruit field trials (1X rate with 0-day PHI) are 

pooled by crop, the data support the use of boscalid (WDG) on stone fruits for up to five 

broadcast foliar applications during fruit development at 0.23 lb ai/A/application, for a total 

application rate of 1.15 lb ai/A. The data support a minimum RTI of 7 days and a minimum PHI

of 0 days. 

Alfalfa. BASF submitted field trial data for boscalid and the submitted alfalfa field trial data are 

adequate and would support the use of two or three broadcast foliar applications of boscalid 

(25.2%, WDG formulation) to alfalfa at up to ~0.30 lb ai/A/application, with no more than two 

applications per cutting, for maximum seasonal use rates 0.6 or 0.9 lb ai/A. The data also 

support a minimum RTI of 14 days and minimum PHIs of either 14 or 21 days. However, the 

alfalfa field trial data will not support the proposed use rates of the 70% WDG as the proposed 

maximum single (0.48 lb ai/A) and seasonal (1.44 lb ai/A) application rates for the 70% WDG 

are approximately 1.6X higher than the rates used in the alfalfa field trials.

860.1520 Processed Food and Feed
Page 24 of 47

BASF submitted residue data from an orange processing study conducted in FL (Zone 3) during 

2008. A 70% WDG formulation of boscalid was applied to Valencia orange trees during fruit 

maturation as two broadcast foliar applications at rates of 0.30 lb ai/A/application at a RTI of 10 

days, for a total rate of 0.60 lb ai/A. 

The data collection LC/MS/MS method (BASF Method D9908, Version II) used to analyze 

boscalid residues in/on orange fruit and processed commodities was adequately validated prior to 

and in conjunction with the analysis of processing samples.

The average boscalid residues in the processed commodities were 0.694 ppm in dried pulp, 

<0.05 ppm in juice, and 13.1 ppm in oil. These data indicate that boscalid residues were reduced 

in juice by 0.23X, but concentrated 3.1X in dried pulp and 59X in oil. The theoretical processing 

factors for citrus are 2X for juice, 3.3X for dried pulp, and 1000X for oil (OPPTS 860.1520, 

Table 3).

For the storage stability study, whole orange fruits, dried pulp, and oil were stored at <-5°C for 

up to 3.6 months prior to analysis. After 3.6 months of frozen storage, the corrected recoveries of 

boscalid were 109-126% from all four citrus matrices. 

Table 4.4.5. Residue Data from Orange Processing Study with Boscalid (WDG).

RAC Processed

Commodity

Total Rate

(lb ai/A)

PHI

(days) Residues (ppm) 1 Processing Factor3

Orange Fruit (RAC) 0.602 1 0.2210, 0.2209 (0.2210) --

Dried Pulp 0.5884, 0.8002 (0.694)22.7X, 3.6X (3.1X)

Juice <0.05, <0.05 (<0.05) <0.23X, <0.23X (<0.23X)

Oil 13.6, 12.49 (13.05)261X, 57X (59X)

1 The LOQ is 0.05 ppm for all commodities. 

2 Residues are averages of 3 replicates each. Means of multiple processing study analyses are in parenthesis. 

3 The processing factor was calculated by dividing the residue in the processed commodity by the residue in the associated RAC 

sample. The LOQ was used to calculate the processing factor for the value below the LOQ. Mean processing factors are in 

parenthesis.

Conclusions. The orange processing study is adequate. As boscalid residues were reduced in 

juice (<0.2X), a separate tolerance is not required for citrus juice. However, separate tolerances 

are required for citrus dried pulp and oil. Based on the processing factors for dried pulp (3.1X) 

and oil (59X) and the HAFT residues (see Table 4.4.5) for citrus fruits (orange – 1.39 ppm), the 

maximum expected boscalid residues would be 4.31 ppm in dried pulp and 82 ppm in oil. These 

data support tolerances of 4.5 ppm for dried citrus pulp and 85 ppm for citrus oil.

860.1850 and 860.1900 Rotational Crops

The nature of the residue in rotational crops is adequately understood and was summarized in a 

previous residue chemistry summary document. HED has concluded that the residue of concern 

in rotated crops for purposes of risk assessment and the tolerance expression is parent compound.

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 plant 
Page 25 of 47

back interval of 14 days for crops without boscalid uses. No additional rotational crop data are 

required for purposes of this petition. 

4.5 Dietary Exposure and Risk

References: 

- Boscalid; Petition for Establishing Permanent Tolerances on Alfalfa and the Citrus Crop Group 10, and 

Amending the Established Tolerance on the Stone Fruit Crop Group 12. Summary of Analytical Chemistry and 

Residue Data. A. Acierto, DP#364447, 10/16/2009.

- Boscalid. Chronic Aggregate Dietary (Food and Drinking Water) Exposure and Risk Assessment for the Section 

3 Registration on the Citrus Crop Group 10 and Alfalfa, and an Increase in the Tolerance on the Stone Fruit 

Crop Group 12. A. Acierto, DP#365262, 11/19/2009.

- PP#1F06313. BAS 510 F (Common Name: Boscalid), New Fungicide Active Ingredient. Residue Chemistry 

Summary Document. M. Nelson, DP#278385, 08/15/2003.

- HED MARC Decision Memo, DP#286786, 01/09/2003.

A dietary exposure memorandum has been prepared for the proposed new uses on alfalfa and 

citrus and subsequent amendment of Section 3 registrations of BAS 510F (EPA Reg. No. 7969-

198), Endura®(EPA Reg. No. 7969-197), and Pristine®(EPA Reg. No. 7969-199), and the 

proposed increase of tolerances for the stone fruit crop group 12 (A. Acierto, DP#365262, 

11/19/2009). Reference may be made to this document for details concerning the dietary

exposure analysis that was performed in support of the new proposed tolerances in alfalfa and

citrus, and the increased tolerance in stone fruits. 

A chronic aggregate dietary (food and drinking water) exposure and risk assessment was 

conducted using the Dietary Exposure Evaluation Model DEEM-FCIDTM (Version 2.03) which 

uses food consumption data from the U.S. Department of Agriculture’s Continuing Surveys of 

Food Intakes by Individuals (CSFII) from 1994 to 1996, and 1998. The analysis was performed 

to support the establishment of tolerances for residues of boscalid in alfalfa and citrus, and the 

increased tolerance in stone fruits. 

4.5.1 Acute Dietary Exposure Results and Characterization

No toxic effects attributable to a single dose of boscalid have been identified. As a result, an

acute reference dose (RfD) was not established for this chemical; therefore, acute dietary risk is 

not of concern. Thus, an acute dietary exposure assessment was not conducted. 

4.5.2 Chronic Dietary Exposure Results and Characterization

A chronic dietary (food and drinking water) exposure and risk assessment was conducted for 

boscalid using tolerance level residues and 100% crop treated (%CT) assumptions. Boscalid 

exposure from the existing uses, the proposed new uses on citrus and alfalfa, the recommended 

tolerance increase for stone fruits, and the established and recommended tolerances on livestock 

results in estimated risks that are below HED’s LOC for food plus drinking water. The highest 

exposure and risk estimates for food plus drinking water are 11% of the cPAD for the general

U.S. population and 37% of the cPAD for children 1-2 years old, the most highly exposed 

population subgroup. 
Page 26 of 47

4.5.3 Cancer Dietary Exposure Results and Characterization

HED has classified boscalid as demonstrating “suggestive evidence of carcinogenicity” and has 

recommended against the quantification of human cancer risk (J. Kidwell, TXR#0051289, 

11/14/2002). No change has been made to the cancer classification. Quantification of human 

cancer risk is not required. As a result, dietary cancer risk is not of concern; thus, a dietary

cancer assessment was not conducted. 

4.5.4 Results of Chronic Dietary Exposure Analysis

The results of the dietary exposure analysis (food and drinking water) for the general U.S.

population, and all regulated population subgroups are listed below in Table 4.5.4.

TABLE 4.5.4. Summary of Dietary (Food and Drinking Water) Exposure and Risk for Boscalid.

Population Subgroup 1

Acute Dietary Chronic Dietary Cancer

Exposure 

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

General U.S. population

NA 2 NA

0.024694 11

NA NA

All infants (< 1 year old) 0.052987 24

Children 1-2 years old 0.081585 37

Children 3-5 years old 0.057899 27

Children 6-12 years old 0.030924 14

Youth 13-19 years old 0.017901 8

Adults 20-49 years old 0.018608 8

Adults 50+ years old 0.020774 10

Females 13-49 years old 0.019007 9

1 Values for the population subgroup with the highest estimated chronic exposure and risk are in bold type. 

2 NA = Not Applicable. 

4.6 Anticipated Residues and Percent Crop Treated

The chronic dietary exposure analysis was based on tolerance level residues and 100%CT 

assumptions for all commodities. As there were no risks of concern, the generation of 

anticipated residues was not needed, and %CT data were not incorporated into the assessment. 

5.0 RESIDENTIAL (NON-OCCUPATIONAL) EXPOSURE AND RISK 

CHARACTERIZATION

For a discussion of the residential exposures and risks associated with the use of boscalid, 

reference may be made to the previous risk assessment on coffee (W. Drew, DP#354689, 

03/25/2009), or to the occupational and residential exposure (ORE) memo prepared in support of 
Page 27 of 47

this risk assessment (B. O’Keefe, DP#364449, 10/23/2009). 

5.1 Residential Handler Exposure

There are no new residential (non-occupational) uses proposed for boscalid as a result of the 

requested uses on alfalfa forage, citrus fruits, and increased tolerance on stone fruits. Current 

labels specify that boscalid is to be applied to golf courses only, and is not for use on residential 

turfgrass or turfgrass being grown for sale or other commercial use such as sod production. 

Additionally, boscalid is neither packaged nor marketed for home orchard use. As the product is 

not intended for homeowner use, residential handler exposure and risk assessments are not 

required (B. O’Keefe, DP#364449, 10/23/2009). 

5.2. Residential Postapplication Exposure

Reference: 

- Boscalid: Human Health Risk Assessment to Support Proposed New Uses on Fresh Herbs (Herbs Subgroup 

19A), Avocado, Black Sapote, Canistel, Mamey Sapote, Mango, Papaya, Sapodilla, Star Apple and Cotton. D. 

Davis, DP#336182, 02/13/2008.

There are no new residential postapplication exposure scenarios resulting from the proposed uses 

on alfalfa forage, citrus fruits, or increased tolerance on stone fruits. Potential non-occupational 

postapplication exposure scenarios identified for boscalid, based on the established uses, include 

postapplication exposure to golfers and persons harvesting fruit at “pick-your-own” (PYO) farms 

and orchards. Exposure can occur during contact with treated golf course turf, or while picking 

strawberries, caneberries, and tree fruit at a PYO facility. 

Based on the low vapor pressure of boscalid (7 x 10-9hPa), the outdoor nature of the uses, and 

the weight of evidence from available residue studies, HED does not anticipate postapplication 

inhalation exposures from the currently approved uses of boscalid. 

PYO activities are considered to be one-time (<1 day) events. As no adverse effects were seen in 

the boscalid toxicity database resulting from a single exposure to the chemical, a postapplication 

exposure and risk assessment is not required for this scenario. 

HED conducted a postapplication exposure and risk assessment for golfers exposed to treated 

turf. Duration of exposure was anticipated to be short-term. The registrant, BASF, submitted a 

turf transferable residue (TTR) study (MRID #45405301) that HED previously reviewed and 

found acceptable to use in assessing postapplication exposure (S. Wang, DP#290072, 

06/23/2003). Subsequent to this review, HED Exposure Science Advisory Council (ExpoSAC) 

determined that the method used in the study for collecting residues (the modified California 

Roller method) can not be used with the standard turf transfer coefficients (TCs). Therefore, the 

TTR residue data from this study is no longer used to assess golfers exposure to turf treated with 

boscalid. HED considered it more appropriate to use the standard transfer coefficient (500 

cm2/hour) for golfers, along with the standard SOP TTR value of 5%. Additionally, the 

assessment assumed that boscalid would be present on all of the turf throughout the course, and 

that the duration of exposure was estimated to be 4 hours. Details of the assessment can be 

found in the ORE memoranda cited above.
Page 28 of 47

The postapplication dermal MOE for golfers exposed to boscalid is 18,000. This value exceeds 

100, and thus does not exceed HED’s LOC (i.e., the LOC is an MOE = 100). Table 5.2

summarizes the inputs for the assessment and the exposure and risk results to golfers. 

TABLE 5.2. Dermal Postapplication Exposure and Risk from Boscalid for Adults and Youth Golfers. 

Scenario TTR 1

(ug/cm2)

CF1 

(mg/ug)

TC

2

(cm2/hr)

ET 

(hr/day)

%DA BW 

(kg)

Daily Dose 3

(mg/kg/day)

Dermal 

MOE4

Golf course turf 0.28 0.001 500 4 15 70 0.0012 18,000

TTR = Turf Transferable Residue on day 0 (mg/day). CF1 = unit Conversion Factor to convert μg units in the TTR 

to mg for daily exposure (0.001 mg/ug). TC = Transfer Coefficient. ET = Exposure Time. DA = Dermal 

Absorption. BW = Body Weight. 

1 TTR = use rate (0.5 lb ai/A) x [4.54E+8 g/lb] x [24.7E-9 A/cm2

] x 0.05. 

2 Based on ExpoSAC SOP# 3.1. 

3 Daily dose (mg/kg/day) = [TTR x CF1 x TC x ET x %DA] ÷ BW. 

4 Dermal MOE = NOAEL (21.8 mg/kg/day) ÷ daily dose (mg/kg/day). 

Golfing is considered to be a lifetime sport. As a result, individuals of all ages, excluding very

small children, are assumed to play routinely. Children who are 12 years of age or older are 

likely to represent the vast majority of the youth who play golf on a routine basis. However, the 

popularity of golf as a recreational pastime has increased steadily over the last several years, 

which has resulted in more young children (less than 12 years old) becoming involved in the 

sport. Risk assessments for these children are more difficult to complete because of the 

increased uncertainties associated with extrapolation of adult dermal exposure data, and because 

of the increased likelihood of other behaviors that might contribute to exposure, such as 

mouthing contaminated hands or golf balls. Therefore, the risk associated with children in a 

golfing scenario is addressed qualitatively in the following discussion.

Five-year-old children were selected as the target group for this exercise because younger 

children are not believed to be a viable population for the purposes of assessing risk from a 

golfing scenario. The surface area to body weight ratio (SA/BW) for male children 5 years of 

age (i.e., the difference is larger for males compared to female making the value more protective) 

was calculated by using the 95th percentile body surface area and the 50th percentile for body

weight. The ratio was intentionally skewed to account for the uncertainties that would be 

expected with calculating dose levels for children if more definitive data were available, and for 

potential additional exposure that may occur from mouthing behaviors. This skewed SA/BW for 

children was compared to that of the average adult, and found to be approximately 70% greater. 

Based on this parameter alone, the child’s exposure could be almost twice that of the adult 

golfer, however, it should be noted that a child is not expected to use the golf course for the same 

length of time as an adult. While an adult is likely to play a full round of golf (i.e., 18 holes), 

which takes approximately 4 hours, a child would probably only spend about 2 hours (i.e., the 

75th percentile for time spent playing on grass by children aged 1-4 years and 5-11 years) on the 

course. Thus, the child’s shorter duration on the golf course offsets the higher SA/BW, and 

therefore, the child golfer’s exposure is likely to be similar to that of the adult golfer. [Note: The 

values used to calculate SW/BW and estimate time spent playing on grass were obtained from 

the EPA Exposure Factors Handbook (1997)].
Page 29 of 47

6.0 AGGREGATE RISK ASSESSMENTS AND RISK CHARACTERIZATION

Reference: 

- Boscalid. Chronic Aggregate Dietary (Food and Drinking Water) Exposure and Risk Assessment for the Section 

3 Registration on the Citrus Crop Group 10 and Alfalfa, and an Increase in the Tolerance on the Stone Fruit 

Crop Group 12. A. Acierto, DP#365262, 11/19/2009.

6.1 Acute Aggregate Risk

No toxic effects attributable to a single dose of boscalid have been identified. Therefore, an 

acute RfD has not been established for boscalid and acute aggregate risk is not of concern. 

6.2 Short-Term Aggregate Risk

The boscalid short-term aggregate exposure and risk assessments combine average dietary (food 

and drinking water) exposures with short-term postapplication exposures of adult and youth 

golfers. MOEs ranged from 840 to 1140. The LOC for this assessment is for MOEs that are 

below 100. Therefore, there are no short-term aggregate risks of concern. Short-term aggregate 

risks are summarized below in Table 6.2.

TABLE 6.2. Short-Term Aggregate Risk Calculations for Boscalid. 

Population

Short-Term Scenario

NOAEL

(mg/kg/day)

LOC 1 Maximum

Allowable

Exposure 2

(mg/kg/day)

Average

Dietary

Exposure

(mg/kg/day)

Residential 

Exposure 3

(mg/kg/day)

Aggregate 

(Dietary and

Rresidential)

MOE4

U.S. Population 21.8 100 0.218 0.024694 0.0012 840

Females (13-49 years) 21.8 100 0.218 0.019007 0.0012 1080

Adults (50+ years) 21.8 100 0.218 0.020774 0.0012 1000

Youth (13-19 years) 21.8 100 0.218 0.017901 0.0012 1140

1 The LOC includes the standard inter- and intraspecies UFs totaling 100; the FQPA SF = 1.

2 Maximum allowable exposure (mg/kg/day) = NOAEL ÷ LOC. 

3 Residential exposure = dermal exposure; the residential exposure value was taken from Table 5.2, above. 

4 Aggregate MOE = NOAEL ÷ [average dietary exposure + residential exposure]. 

6.3 Intermediate-Term Aggregate Risk

There are no intermediate-term residential scenarios; therefore, intermediate-term aggregate 

exposure and risk are not of concern. 

6.4 Long-Term Aggregate Risk

There are no long-term residential scenarios for boscalid; therefore the long-term aggregate risk 

assessment would incorporate only dietary (food and drinking water) residues. The long-term 
Page 30 of 47

aggregate risk assessment is identical to the chronic dietary risk assessment for which there are 

no concerns, as shown in Section 4.5.2 of this memorandum. 

6.5 Cancer Aggregate Risk

HED classified boscalid as demonstrating “suggestive evidence of carcinogenicity” and noted 

that quantification of human cancer risk was not recommended. As a result, aggregate cancer 

exposure and risk are not of concern.

7.0 Cumulative Risk Characterization/Assessment

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/.

8.0 OCCUPATIONAL EXPOSURE/RISK ASSESSMENT PATHWAY

Reference: 

- Boscalid: Occupational and Residential Exposure Assessment for proposed field uses of boscalid on alfalfa 

(including alfalfa grown for seed) and citrus fruits (crop group 10). B. O’Keefe, DP#364449, 10/23/2009.

8.1 Occupational Pesticide Handler Exposure and Risk

Broadcast foliar applications of boscalid may be applied to alfalfa (including alfalfa grown for 

seed) at a rate of 0.48 lb ai/A (Endura®) and 0.28 lb ai/A (Pristine®) and to citrus at a rate of 0.29 

lb ai/A (Pristine®). For alfalfa, up to three applications can be made per season at RTI of 14 to 

21 days. The PHI is 14 days. For citrus, up to four applications can be made per season at RTIs 

of 10 to 21 days. The PHI is zero days. Handlers may apply boscalid to alfalfa using aerial, 

chemigation, or groundboom equipment. To citrus, handlers may apply boscalid using aerial, 

chemigation, airblast, or handgun equipment. 

Agricultural Handlers

No chemical-specific handler exposure data were submitted in support of this registration. It is 

the policy of the HED to use data from the Pesticide Handlers Exposure Database (PHED) 

Version 1.1 as presented in PHED Surrogate Exposure Guide (8/98) to assess handler exposures 

for regulatory actions when chemical-specific monitoring data are not available (HED ExpoSAC 

SOP #7, dated 1/28/99). Additionally, data from Outdoor Residential Exposure Task Force 

(ORETF) were used to assess some scenarios. Handler exposure is expected to be short- or 

intermediate-term based on information provided on proposed labels.
Page 31 of 47

Dermal. The results of the occupational handler exposure and risk assessment indicate that 

short- and intermediate-term dermal MOEs were greater than the LOC (MOEs ≥ 100) at the 

baseline clothing level, when baseline data are available. There are no data to assess the 

mixing/loading/applying handgun scenario at baseline attire. The short- and intermediate-term 

dermal risks do not exceed HED’s LOC for mixing/loading/applying with handgun equipment 

when baseline attire plus chemical-resistant gloves are used. Additionally, only engineering 

control (enclosed cockpit) data are available to assess dermal risks to handlers operating aircraft. 

The short- and intermediate-term dermal risks do not exceed HED’s LOC for pilots using 

enclosed cockpits and wearing baseline attire.

Inhalation. The short- and intermediate-term inhalation risks to handlers do not exceed HED’s 

LOC at baseline (no respirator) for any of the handler scenarios. Only engineering control 

(enclosed cockpit) data are available to assess short- and intermediate-term inhalation risks to 

handlers operating aircraft. The short- and intermediate-term inhalation risks do not exceed 

HED’s LOC for pilots using enclosed cockpits and wearing no respirator.

Combined. Combined dermal plus inhalation risks do not exceed HED’s LOC, provided 

personal protective equipment (PPE) listed under the short- and intermediate-term dermal risks 

are worn. 

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

a 10X factor to account for interspecies extrapolation and a 10X factor to account for 

intraspecies sensitivity. The total UF that has been applied to the non-cancer risk assessment for 

boscalid is 100X for occupational exposure. Occupational exposure and risk resulting in MOEs 

greater than or equal to 100 will not exceed HED’s LOC. Summaries of the risks for 

occupational handlers are included in Table 8.1. The maximum application rate for each 

exposure scenario is presented as the worst-case scenario. All handler scenarios resulted in 

MOEs greater than the LOC (MOEs ≥ 100) at some level of risk mitigation. 

TABLE 8.1. Short- and Intermediate-Term Agricultural Handler Exposure and Risk for Boscalid.

Exposure 

Scenario

Crop 

or 

Target

App 

Ratea

(lb 

ai/A)

Acres 

Treated 

Dailyb

Mitigation 

Levelc

Unit Exposured Dose (mg/kg/day) MOE (Target MOE = 100)

Dermal

(mg/lb ai)

Inhalation

(μg/lb ai) Dermale

Inhalationf DermalgInhalationh

Combined 

Dermal + 

Inhalationi

Mixing/Loading 

Dry Flowables 

for Aerial 

Applications

Alfalfa 0.48 1200

Baseline

0.066 0.77 0.081 0.0063 270 3,400 250

0.28 1200 0.066 0.77 0.048 0.0037 460 5,900 430

Citrus 0.29 350 0.066 0.77 0.014 0.0011 1,500 20,000 1,400

Mixing/Loading 

Dry Flowables 

for Chemigation 

Applications

Alfalfa 0.48 350

Baseline

0.066 0.77 0.024 0.0018 920 12,000 850

0.28 350 0.066 0.77 0.014 0.0011 1,600 20,000 1,500

Citrus 0.29 350 0.066 0.77 0.014 0.0011 1,500 20,000 1,400

Mixing/Loading 

Dry Flowables 

for Groundboom 

Applications

Alfalfa

0.48 200

Baseline

0.066 0.77 0.014 0.0011 1,600 21,000 1,500

0.28 200 0.066 0.77 0.0079 0.00062 2,800 35,000 2,600

Mixing/Loading 

Dry Flowables 

for Airblast 

Applications

Citrus 0.29 40 Baseline 0.066 0.77 0.0016 0.00013 13,000 170,000 12,000
Page 32 of 47

TABLE 8.1. Short- and Intermediate-Term Agricultural Handler Exposure and Risk for Boscalid.

Exposure 

Scenario

Crop 

or 

Target

App 

Ratea

(lb 

ai/A)

Acres 

Treated 

Dailyb

Mitigation 

Levelc

Unit Exposured Dose (mg/kg/day) MOE (Target MOE = 100)

Dermal

(mg/lb ai)

Inhalation

(μg/lb ai) Dermale

Inhalationf DermalgInhalationh

Combined 

Dermal + 

Inhalationi

Applying Sprays 

via Aerial 

Equipment

Alfalfa 0.48 1200

Engineering 

Controls

0.005 0.068 0.0062 0.00056 3,500 39,000 3,200

0.29 1200 0.005 0.068 0.0037 0.00034 5,800 64,000 5,400

Citrus 0.29 350 0.005 0.068 0.0011 0.000099 20,000 220,000 18,000

Applying Sprays 

via Groundboom 

Equipment

Alfalfa

0.48 200

Baseline

0.014 0.74 0.0029 0.001 7,600 21,000 5,600

0.28 200 0.014 0.74 0.0017 0.00059 13,000 37,000 9,600

Applying Sprays 

via Airblast 

Equipment

Citrus 0.29 40 Baseline 0.36 4.5 0.0089 0.00075 2,400 29,000 2,200

Flagging for 

Aerial Sprays 

Applications

Alfalfa 0.48 350

Baseline

0.011 0.35 0.004 0.00084 5,500 26,000 4,500

0.28 350 0.011 0.35 0.0023 0.00049 9,400 44,000 7,800

Citrus 0.29 350 0.011 0.35 0.0024 0.00051 9,100 43,000 7,500

Mixing/Loading/

Applying Dry 

Flowables 

Concentrates 

with a Handgun 

Sprayer

Citrus 0.29 5

Dermal: 

Baseline 

Plus Gloves

Inhalation: 

Baseline

0.58 22 0.0018 0.00046 12,000 48,000 9,600

a Application Rates based on proposed uses on boscalid labels for Endura® (EPA Reg. No. 7969-197) and Pristine® (EPA Reg. No. 7969-198).

b

Science Advisory Council Policy # 9.1

c Baseline Dermal: Long-sleeve shirt, long pants, and no gloves.

Baseline Inhalation: no respirator.

Engineering control unit exposure for applying sprays via aerial equipment = enclosed cockpit. 

Baseline plus Gloves Dermal: Baseline plus chemical-resistant gloves.

d Unit Exposures based on PHED Version 1.1 or ORETF data. 

e Dermal Dose (mg/kg/day) = daily unit exposure (mg/lb ai) x application rate (lb ai/acre) x acres treated x dermal absorption factor (15%) /

body weight (70 kg adult).

f

Inhalation Dose (mg/kg/day) = daily unit exposure (μg/lb ai) x application rate (lb ai/acre) x acres treated x inhalation absorption (100%) / body 

weight (70 kg adult). 

g Dermal MOE = NOAEL (21.8 mg/kg/day) / dermal daily dose (mg/kg/day). Level of concern = 100.

h

Inhalation MOE = NOAEL (21.8 mg/kg/day) / inhalation daily dose (mg/kg/day). Level of concern = 100.

i Combined Baseline Dermal + Inhalation MOE = 1 / (1/Baseline Dermal MOE) + (1/Baseline Inhalation MOE).

8.2 Occupational Postapplication Worker Exposure and Risk

HED assumes that inhalation exposures are minimal following outdoor applications of an ai with 

low vapor pressure. Since the proposed uses of boscalid are applied only in outdoor settings and 

boscalid has a low vapor pressure, postapplication inhalation exposures and risks were not 

assessed. 

Short- and intermediate-term dermal postapplication exposures and risks to occupational workers 

were estimated using standard values established by HED since no chemical-specific data were 

submitted. The TCs used for all postapplication activities were established by ExpoSAC SOP

#3.1. The DFR levels were estimated using HED standard values where it is assumed that the 

initial residue on treated foliage is 20% of the application rate and the residues degrade at a rate 

of 10% per day. Using HED default assumptions and surrogate DFR data, all scenarios resulted 

in MOEs greater than 100 on day 0 (12 hours after application), and therefore risks do not exceed 
Page 33 of 47

HED’s LOC. Table 8.2.1 presents the default DFR values on day 0 (12 hours after application) 

that were used for this postapplication exposure and risk assessment. 

TABLE 8.2.1. Summary of DFRs by Crop Grouping Based on HED Default Assumptions.

1

Crop

Application 

rate

(lb ai/acre)

Fraction of 

ai retained 

on the 

foliage

Conversion 

Factor 1

(μg/lb)

Conversion 

Factor 2

(A/cm2)

Day after 

Application

Default DFR

(μg/cm2)

Alfalfa 0.48

20% 

(Default) 4.54E+8 2.47E-8

0

(12 hours)

1.077

0.28 0.628

Citrus 0.29 0.651

1 Default DFR (μg/cm2

) = application rate (lb ai/A) x (1- daily dissipation rate) tx 4.54E8 μg/lb x 24.7E-9 A/cm2 x 20% 

DFR after initial treatment.

The postapplication exposure associated with agricultural crops is summarized in Table 8.2.2. 

Using HED default assumptions and surrogate DFR data, all scenarios resulted in MOEs greater 

than 100 on day 0 (12 hours after application) and, therefore, risks do not exceed HED’s LOC. 

TABLE 8.2.2. Summary of Occupational Postapplication Risks (Short- and Intermediate-Term) with HED 

Default Assumptions.

Crop 

Grouping

Application 

rate

(lb ai/acre)

Default 

DFR 

(μg/cm2)

Maximum Transfer Coefficient 

(μg/cm2)

Day after 

Application

MOE

(LOC = 100)

Alfalfa 0.48 1.077 1,500 (Irrigating, Scouting) 0 (12 hours) 790

0.28 0.628 0 (12 hours) 1,300

Citrus 0.29 0.651 3,000 (Pruning) 0 (12 hours) 650

Notes: Crops were assessed using the highest transfer coefficient available.

Since postapplication risks were not a concern on day 0 (12 hours following application), the 

restricted entry interval (REI) is based on the acute toxicity of boscalid technical material. 

Boscalid is classified as toxicity category III by the dermal route of exposure and category IV for 

eye irritation and skin irritation potential. Under the Worker Protection Standard (WPS) for 

Agricultural Pesticides, active ingredients classified as acute toxicity categories III or IV for 

these routes are assigned a 12-hour REI. Therefore, the 12-hour REI that appears on the 

proposed label is adequate.

9.0 TOLERANCE HARMONIZATION AND RECOMMENDED TOLERANCE

For purposes of both the tolerance expression and dietary risk assessment, HED has concluded 

that the ROC in plant commodities include only boscalid, and the residues of concern in 

livestock commodities include boscalid, its 5-hydroxy metabolite, and the glucuronide conjugate 

of the 5-hydroxy metabolite.

According to the memo Interim Guidance on Tolerance Expressions by S. Knizner, the 

tolerances should be expressed as follows:
Page 34 of 47

(a) General. 

(1) Tolerances are established for residues of the fungicide boscalid, including its 

metabolites and degradates, in or on the commodities listed below. Compliance 

with the tolerance levels specified below is to be determined by measuring only 

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

Alfalfa, forage ................................................................... 30.0 ppm

Alfalfa, hay ....................................................................... 65.0 ppm

Citrus, dried pulp ................................................................. 4.5 ppm

Citrus, oil............................................................................ 85.0 ppm

Fruit, citrus, group 10........................................................... 1.6 ppm

Fruit, stone, group 12........................................................... 3.5 ppm

(2) Tolerances are established for residues of the fungicide boscalid, including its 

metabolites and degradates, in or on the food commodities listed below. Compliance 

with the tolerance levels specified below is to be determined by measuring only the 

sum of 3-pyridinecarboxamide, 2-chloro-N-(4'-chloro[1,1'-biphenyl]-2-yl) and 

metabolites 2-chloro-N-(4'-chloro-5-hydroxy-biphenyl-2-yl) nicotinamide and 

glucuronic acid conjugate of 2-chloro-N-(4'-chloro-5-hydroxy-biphenyl-2-yl)

nicotinamide, calculated as the stoichiometric equivalent of boscalid.

Hog, fat .............................................................................. 0.20 ppm

Poultry, fat.......................................................................... 0.20 ppm

Poultry, meat byproducts................................................... 0.20 ppm

The established tolerances of the following commodities remain unchanged. 

Cattle, fat............................................................................ 0.30 ppm

Cattle, meat ........................................................................ 0.10 ppm

Cattle, meat byproducts ..................................................... 0.35 ppm

Egg ..................................................................................... 0.02 ppm

Goat, fat.............................................................................. 0.30 ppm

Goat, meat.......................................................................... 0.10 ppm

Goat, meat byproducts....................................................... 0.35 ppm

Hog, meat........................................................................... 0.05 ppm

Hog, meat byproducts........................................................ 0.10 ppm

Horse, fat............................................................................ 0.30 ppm

Horse, meat ........................................................................ 0.10 ppm

Horse, meat byproducts ..................................................... 0.35 ppm

Milk.................................................................................... 0.10 ppm

Poultry, meat...................................................................... 0.05 ppm

Sheep, fat............................................................................ 0.30 ppm

Sheep, meat........................................................................ 0.10 ppm

Sheep, meat byproducts..................................................... 0.35 ppm

(d) Indirect or inadvertent residues. 

Tolerances are established for residues of the fungicide boscalid, including its 

metabolites and degradates, in or on the commodities listed below. Compliance 

with the tolerance levels specified below is to be determined by measuring only 3-

pyridinecarboxamide, 2-chloro-N-(4'-chloro[1,1'-biphenyl]-2-yl). 

Animal feed, nongrass, group 18, forage, excluding alfalfa 1.0 ppm
Page 35 of 47

Animal feed, nongrass, group 18, hay, excluding alfalfa .... 2.0 ppm

Permanent tolerances are established for residues of boscalid in/on various plant commodities at 

levels ranging from 0.05 to 60 ppm [40 CFR §180.589(a)(1)]. Separate tolerances are also 

established for indirect or inadvertent residues of boscalid in rotational crops at levels ranging 

from 0.05 to 8.0 ppm [40 CFR §180.589(d)]. Tolerances are also established for the combined 

residues of boscalid, its 5-hydroxy metabolite, and the glucuronic acid conjugate of the 5-

hydroxy metabolite, at levels ranging from 0.02 ppm to 0.35 ppm [40 CFR §180.589(a)(2)]. The 

proposed and recommended tolerances for boscalid are presented in Table 9.0.

An adequate number of field trials conducted at ~1X the existing or proposed use rates are 

available on alfalfa, citrus fruits (orange, lemon, grapefruit), and stone fruits (cherry, peach,

plum) to support permanent tolerances. The Agency’s SOP “Guidelines for Setting Pesticide 

Tolerances Based on Field Trial Data” was utilized for determining the appropriate tolerance 

level for each commodity. For alfalfa forage and hay, residue data from both the 1st and 2nd

cuttings of Treatment #2 (1X rate) were used to assess tolerances as both cuttings were collected 

around the proposed 14-day PHI, and residue levels were similar for the two cuttings. The 

recommended tolerances for alfalfa forage and hay are 30 and 65 ppm, respectively.

For the citrus fruits, the residue data were pooled by crop, and separate possible tolerances were 

calculated for oranges (1.6 ppm), lemons (1.6 ppm), and grapefruits (1.1 ppm) using the 

tolerance spreadsheet. As the minimum and maximum recommended tolerances differ by less 

than 5X, a crop group tolerance is appropriate for citrus, and the recommended tolerance is 1.6 

ppm.

For stone fruits, all the adequate residue data were pooled by crop (including previously 

reviewed studies), and separate possible tolerances were calculated for cherry (3.5 ppm), peach 

(3.0 ppm), and plum (1.6 ppm) using the tolerance spreadsheet. As the minimum and maximum 

recommended tolerances differ by less than 5X, a crop group tolerance is appropriate for stone 

fruits, and the recommended tolerance is 3.5 ppm.

As boscalid residues were reduced in orange juice (<0.2X), a separate tolerance is not required 

for citrus juice. However, boscalid residues were shown to concentrate in dried pulp (3.1X) and 

oil (59X). Based on these processing factors and the HAFT residues for citrus fruits (1.39 ppm), 

the maximum expected boscalid residues would be 4.31 ppm in dried pulp and 82 ppm in oil. 

These data support tolerances of 4.5 ppm for dried citrus pulp and 85 ppm for citrus oil.

For assessing the existing tolerances on livestock commodities, adequate cattle and poultry 

feeding studies are available that cover the potential levels of dietary exposure of livestock to 

boscalid residues. The 35.8 ppm dose group (1X dietary burden) from the cattle feeding study

was used to assess the current tolerances on milk (0.10 ppm) and on the fat (0.30 ppm), meat 

(0.10 ppm), and meat byproducts (0.35 ppm) of cattle, goats, horses, and sheep. For this dose 

group, the maximum combined residues of boscalid and M510F01 (free and conjugated) were 

<0.03 ppm in milk, <0.08 ppm in cream, ≤0.11 ppm in liver and kidneys, <0.05 ppm in muscle,

and <0.24 ppm in fat. These data indicate that the existing tolerances for milk and fat, meat, and 
Page 36 of 47

meat byproducts of cattle, goats, horses, and sheep are more than adequate. Separate tolerances 

for liver and kidney are not required.

For hogs, the adequacy of the existing tolerances were assessed using residue data from the 5.9 

ppm dose group (1.1X dietary burden for swine) in the cattle feeding studies. Maximum 

combined residues for this dose group were <0.064 ppm in liver, <0.090 ppm in kidney, <0.05 

ppm in muscle, and <0.12 ppm in fat. These data indicate that the existing tolerances for meat 

(0.05 ppm) and meat byproducts (0.10 ppm) of hogs are adequate; however, the tolerance for hog 

fat should be increased to 0.20 ppm. Separate tolerances of hog liver and kidney are not 

necessary.

For poultry, the adequacy of the existing tolerances were assessed using residue data from the 

5.31 ppm dose group in the poultry feeding studies; this group represents 1.3X the calculated 

dietary burden for poultry. Maximum combined residues for this dose group were <0.02 ppm in 

eggs, <0.175 ppm in liver, <0.05 ppm in muscle, and <0.124 ppm in fat. These data indicate that 

the existing tolerances for eggs (0.02 ppm) and poultry meat (0.05 ppm) are adequate; however, 

the tolerances for poultry fat and meat byproducts should each be increased to 0.20 ppm. A 

separate tolerance for liver is not necessary.

The Codex Alimentarius Commission, Canada, and Mexico have not established any maximum 

residue limits (MRLs) for residues of boscalid in/on alfalfa forage and hay or citrus fruits 

(Appendix C). However, there is an existing Codex MRL for stone fruits at 3 mg/kg, and 

Canada has established MRLs at 1.7 mg/kg for the various member of the stone fruits crop 

group. Canada also has also established MRLs for various livestock commodities. The 

Canadian MRLs for stone fruits and livestock commodities are currently harmonized with the 

respective U.S. tolerances; however, once the recommended increases are made to U.S.

tolerances, the U.S. tolerances on stone fruits, poultry fat and meat byproducts, and hog fat will 

no longer be harmonized with the Canadian MRLs.

While not officially part of the Codex Alimentarius Commission structure, the Joint FAO/WHO 

Meetings on Pesticide Residues (JMPR) provide independent scientific expert advice to the 

Commission and its specialist Committee on Pesticide Residues. To determine MRLs for the 

stone fruit crop group, both the U.S. and JMPR used the same database of field trial studies in 

2006. The resulting values are not in harmony because the U.S. uses the averages of duplicate 

samples for a given trial, whereas JMPR uses the highest value from each trial site. 

Additionally, the U.S. used the NAFTA statistical calculation method whereas the JMPR did not 

routinely use statistical calculation methods in 2006.
Page 37 of 47

TABLE 9.0. Tolerance Summary for Boscalid.

Commodity Proposed 

Tolerance 

(ppm)

Existing 

Tolerance 

(ppm)

Recommended 

Tolerance 

(ppm)

Comments; Correct Commodity 

Definition

40 CFR 180.589(a)(1)

Alfalfa, forage 35 -- 30 Adequate alfalfa forage and hay 

residue data are available. Alfalfa, hay 85 -- 65

Citrus, dried pulp None -- 4.5 An adequate orange processing study 

is available indicating that boscalid 

residues can concentrate in dried 

pulp (3.1X) and oil (59X).

Citrus, oil None -- 85

Fruit, citrus, group 10 2.0 -- 1.6 Adequate orange, grapefruit, and 

lemon residue data are available.

Fruit, stone, group 12 5.0 1.7 3.5

An increase in the established 

tolerance is required based on 

adequate cherry, peach, and plum 

residue data.

40 CFR 180.589(a)(2)

Cattle, fat 1.5 0.30 0.30 Based on the residue data from the 

35.8 ppm dose group in the cattle 

feeding studies and the calculated 

dietary burden for dairy cattle (35.2 

ppm), the existing tolerances are 

adequate. Separate tolerances for 

liver and kidney are not necessary.

Cattle, kidney 1.0 -- None

Cattle, liver 1.0 -- None

Cattle, meat 0.2 0.10 0.10

Cattle, meat byproducts 1.5 0.35 0.35

Egg 0.02 0.02 0.02 The existing tolerance on eggs is 

adequate.

Goat, fat 1.5 0.30 0.30 See Cattle above.

Goat, kidney 1.0 -- None

Goat, liver 1.0 -- None

Goat, meat 0.2 0.10 0.10

Goat, meat byproducts 1.5 0.35 0.35

Hog, fat 0.2 0.10 0.20 Based on the residue data from the 

5.9 ppm dose group in the cattle 

feeding studies and the calculated 

dietary burden for swine (5.30 ppm), 

the existing tolerances on hog meat 

and meat byproducts are adequate. 

However, the tolerance for hog fat 

should be increased to 0.20 ppm.

Hog, meat 0.05 0.05 0.05

Hog, meat byproducts 0.2 0.10 0.10

Hog, kidney 0.2 -- None

Hog, liver 0.2 -- None

Horse, fat 1.5 0.30 0.30 See Cattle above.

Horse, kidney 1.0 -- None

Horse, liver 1.0 -- None

Horse, meat 0.2 0.10 0.10

Horse, meat byproducts 1.5 0.35 0.35

Milk 0.2 0.10 0.10 The existing tolerance for milk will 
Page 38 of 47

TABLE 9.0. Tolerance Summary for Boscalid.

Commodity Proposed 

Tolerance 

(ppm)

Existing 

Tolerance 

(ppm)

Recommended 

Tolerance 

(ppm)

Comments; Correct Commodity 

Definition

Milk, fat (cream) 1.5 -- None adequately cover residues in both 

whole milk and milk fat

Poultry, liver 0.2 -- None Based on the residue data from the 

5.31 ppm dose group in the poultry 

feeding study and the calculated 

dietary burden for poultry (4.10 

ppm), the existing tolerance for meat 

is adequate and the tolerances of fat 

and meat byproducts should be 

increased to 0.20 ppm. A separate 

tolerance for liver is not necessary.

Poultry, fat 0.2 0.05 0.20

Poultry, meat 0.05 0.05 0.05

Poultry, meat byproducts 0.2 0.10 0.20

Sheep, fat 1.5 0.30 0.30 See Cattle above.

Sheep, kidney 1.0 -- None

Sheep, liver 1.0 -- None

Sheep, meat 0.2 0.10 0.10

Sheep, meat byproducts 1.5 0.35 0.35

10.0 DATA NEEDS

10.1 Toxicology Data Requirements

870.7800 Immunotoxicity Study

 As part of the new 40CFR §158 Guidelines, an immunotoxicity study in rats and/or mice 

is required (see Appendix B). 

10.2 Residue Chemistry Data Requirements

860.1200 Direction for Use

 A revised Section B for alfalfa is required to amend the label direction for the 70% WDG 

formulation since it could not be supported by the field trial data generated with a 

maximum seasonal use rate of 0.9 lb ai/A. The proposed label rate for the 70% WDG 

formulation is 1.7X higher; the label should be revised to match the field trial rate.

860.1550 Proposed Tolerances

 Boscalid residues concentrate in citrus dried pulp (3.1X) and citrus oil (59X). A revised 

Section F is required to propose separate tolerances for citrus, dried pulp at 4.5 ppm, 

citrus, oil at 85 ppm, and fruit, citrus, group 10 at 1.6 ppm.

 The available data for stone fruits will not support a tolerance level of 5.0 ppm. A 

revised Section F should be submitted with a tolerance for fruit, stone, group 12 at 3.5 

ppm.

 The available data will not support the proposed tolerances for meat, meat byproducts, 

and fat of cattle goat, horse, and sheep at 0.2 ppm, 1.5 ppm, and 1.5 ppm, respectively. 
Page 39 of 47

The existing tolerances will be maintained for meat, meat byproducts, and fat of cattle, 

goat, horse, and sheep at 0.10 ppm, 0.35 ppm, and 0.30 ppm, respectively. The available 

data will not support the proposed tolerance of 0.2 ppm for milk and the proposed 

tolerance of 1.5 ppm for milk fat. The existing tolerance of 0.10 ppm will be maintained 

for milk, and it is adequate to cover milk fat. The proposed tolerances of 0.20 ppm for 

hog, fat; poultry, fat; and poultry, meat byproducts are adequate. For all remaining 

livestock commodities, the proposed tolerances must be revised to reflect the 

recommended tolerance levels as specified in Table 9.0.

10.3 Occupational/Residential Exposure Data Requirements

None.

REFERENCES

BAS 510 F - Report of the Hazard Identification Assessment Review Committee. A. Levy, 

TXR#0051613, 03/07/2003.

BAS 510 F: Report of the Cancer Assessment Review Committee. J. Kidwell, TXR#0051289, 

11/14/2002.

Boscalid. Human Health Risk Assessment for a Section 3 Tolerance on Endive, an Amendment to 

the Tolerances for Strawberries and Berries, Crop Group 13, and an Increase in Tolerances 

in/on Cucumber and Vegetable, Root, Subgroup 1A, except Sugar Beet, Garden Beet, Radish, 

and Turnip. B. Hanson, DP#327906, 07/10/2007.

Boscalid: Human Health Risk Assessment to Support Proposed New Uses on Fresh Herbs 

(Herbs Subgroup 19A), Avocado, Black Sapote, Canistel, Mamey Sapote, Mango, Papaya, 

Sapodilla, Star Apple and Cotton. D. Davis, DP#336182, 02/13/2008.

Boscalid Occupational/Residential Exposure Memorandum. S. Wang, DP#290072, 06/23/2003.

Boscalid. Petition for a Tolerance for Belgian Endive; Petition for Increased Tolerances on 

Strawberry and the Berries Crop Group; Submission of Requested Field Trial Data on 

Cucumber, Mustard Greens, and Sunflower; and Supplemental Field Trial Data on Fruiting 

Vegetables, Radishes, Spearmint, Peppermint, Grapes, and Stone Fruits; and Submission of 

Field Trials and a Processing Study for Cotton. Summary of Analytical and Residue Data. D. 

Soderberg, DP#323288, 06/14/2007.

Boscalid; Petition for Establishing Permanent Tolerances on Alfalfa and the Citrus Crop Group 

10, and Amending the Established Tolerance on the Stone Fruit Crop Group 12. Summary of 

Analytical Chemistry and Residue Data. A. Acierto, DP#364447, 10/16/2009.

Drinking Water Assessment for the IR-4 Petition for the Use of Boscalid on Tropical Fruits and 

Fresh Herbs, and a Proposed New Use on Cotton. C. Sutton, DP#336183, 08/08/2007.
Page 40 of 47

Drinking Water Exposure Assessment for New Uses of Boscalid on Alfalfa Forage and Hay, 

Citrus group 10, and an Increase in Tolerance on Stone Fruit group 12. D. Lieu, DP#367184, 

09/24/2009.

PP# 1F06313 --Human Health Risk Assessment for New Fungicide BAS 510 F (Common Name: 

Boscalid) -- Proposal for Tolerances for Residues in/on Numerous Crops and Livestock 

Commodities. Y. Donovan, DP#290022, 09/08/2003.

PP#1F06313. BAS 510 F (Common Name: Boscalid), New Fungicide Active Ingredient. Residue

Chemistry Summary Document. M. Nelson, DP#278385, 08/15/2003.
Page 41 of 47

APPENDIX A: TOXICITY PROFILES FOR BOSCALID TECHNICAL

TABLE A.1. Acute Toxicity Profile for Boscalid. 

Guideline

Number

Study Type MRID Number Results Toxicity 

Category

870.1100 Acute Oral 45404814 LD50 =>5,000 mg/kg IV

870.1200 Acute Dermal 45404815 LD50 =>2000 mg/kg III

870.1300 Acute Inhalation 45404816 LC50 =>6.7 mg/L IV

870.2400 Primary Eye Irritation 45404817 Not irritating IV

870.2500 Primary Skin Irritation 45404818 Not irritating IV

870.2600 Dermal Sensitization 45404819 1 Could not be determined NA 2

1. Unacceptable because the 5% concentration used for the challenge was inadequate. 

2. NA = Not Applicable. 

TABLE A.2. Subchronic, Chronic and Other Toxicity Profile of Boscalid Technical

Guideline 

Number

Study Type Results

870.3100 90-Day oral toxicity rodents 

(rats)

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 

(mice)

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

870.3150 90-Day oral toxicity in 

nonrodents (dogs)

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

(rats)

NOAEL: 1000 mg/kg/day (HDT)

LOAEL: >1000 mg/kg/day

870.3700 Prenatal developmental in 

rodents (rats)

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)

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.
Page 42 of 47

TABLE A.2. Subchronic, Chronic and Other Toxicity Profile of Boscalid Technical

Guideline 

Number

Study Type Results

870.3800 Reproduction and fertility 

effects (rat)

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 and body weight gain (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) 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.

870.4100 Chronic toxicity dogs 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 rats 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 body weight gain and 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 mice NOAEL:65/443 mg/kg/day (M/F)

LOAEL: 331/1804 mg/kg/day (M/F):

M = decreases in body weight and body weight gains F = 

decreases in body weight and body weight gains No evidence of 

carcinogenicity.

870.4300 Chronic 

feeding/Carcinogenicity rat

See 870.4100a and 870.4200.

870.5100 Gene Mutation bacterial 

reverse mutation assay

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)

Negative without and with S-9 activation up to the limit of 

solubility of 25 μg/mL.

870.5375 In vitro mammalian 

cytogenetics assay in Chinese 

hamster V79 cells

Negative without and with S-9 activation up to 3500 μg/mL with 

precipitation showing at concentrations of 100 μg/mL and higher.
Page 43 of 47

TABLE A.2. Subchronic, Chronic and Other Toxicity Profile of Boscalid Technical

Guideline 

Number

Study Type Results

870.5395 Cytogenetics - mammalian 

erythrocyte micronucleus test 

in the mouse

Negative at doses up to 2000 mg/kg.

870.5500 In vitro unscheduled DNA 

synthesis (primary rat 

hepatocytes)

Negative response up to 50 μg/mL. Cytotoxicity at 100-500 

μg/mL.

870.6200 Acute neurotoxicity 

screening battery (rat)

NOAEL:1050.0/1272.5 mg/kg/day (M/F)

LOAEL: >1050.0/1272.5 mg/kg/day (M/F)

870.6200 Subchronic neurotoxicity 

screening battery (rat)

NOAEL:1050.0/1272.5 mg/kg/day (M/F)

LOAEL: >1050.0/1272.5 mg/kg/day (M/F)

870.6300 Developmental neurotoxicity 

(rat)

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)

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) 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)

None SPECIAL STUDY: Hepatic 

enzyme induction (rat)

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 44 of 47

TABLE A.2. Subchronic, Chronic and Other Toxicity Profile of Boscalid Technical

Guideline 

Number

Study Type Results

None SPECIAL STUDY: Hormone 

and enzyme induction (rat)

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

None SPECIAL STUDY: 

Reversibility study (dietary): 

4-week administration 

followed by 4 weeks 

recovery or 13 weeks 

recovery (rat)

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 45 of 47

APPENDIX B: RATIONALE FOR TOXICITY DATA REQUIREMENTS

OPPTS Guideline Number: 870.7800

Study Title: Immunotoxicity

Rationale for Requiring the Data

The immunotoxicity study is a new data requirement under 40CFR §158 as a part of the 

data requirements for registration of a pesticide (food and non-food uses). 

The Immunotoxicity Test Guideline (OPPTS 870.7800) prescribes functional 

immunotoxicity testing, and is designed to evaluate the potential of a repeated chemical 

exposure to produce adverse effects (such as suppression) on the immune system. 

Immunosuppression is a deficit in the ability of the immune system to respond to a challenge of 

bacterial or viral infections, such as tuberculosis (TB), Severe Acquired Respiratory Syndrome 

(SARS), or neoplasia. Because the immune system is highly complex, studies not specifically 

conducted to assess immunotoxic endpoints are inadequate to characterize a pesticide’s 

potential immunotoxicity. While data from hematology, lymphoid organ weights, and 

histopathology in routine chronic or subchronic toxicity studies may offer useful information 

on potential immunotoxic effects, these endpoints alone are insufficient to predict 

immunotoxicity. 

Practical Utility of the Data

How will the data be used?

Immunotoxicity studies provide critical scientific information needed to characterize 

potential hazard to the human population on the immune system from pesticide exposure.

Since epidemiologic data on the effects of chemical exposures on immune parameters are 

limited, and are inadequate to characterize a pesticide’s potential immunotoxicity in humans, 

animal studies are used as the most sensitive endpoint for risk assessment. These animal 

studies can be used to select endpoints and doses for use in risk assessment of all exposure 

scenarios, and are considered a primary data source for reliable reference dose calculation. For 

example, animal studies have demonstrated that immunotoxicity in rodents is one of the more 

sensitive manifestations of TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) among developmental, 

reproductive and endocrinologic toxicities. Additionally, the EPA has established an oral 

reference dose (RfD) for tributyltin oxide (TBTO), based on observed immunotoxicity in 

animal studies (IRIS, 1997). 

How could the data impact the Agency's future decision-making? 

If the immunotoxicity study shows that the test material poses either a greater or a 

diminished risk than that given in the interim decision’s conclusion, the risk assessments for the 

test material may need to be revised to reflect the magnitude of potential risk derived from the 

new data. 

If the Agency does not have these data, a 10X database UF may be applied for 

conducting a risk assessment from the available studies. 
Page 46 of 47

APPENDIX C: INTERNATIONAL RESIDUE LIMIT STATUS

INTERNATIONAL RESIDUE LIMIT STATUS

Chemical Name: 

3-pyridinecarboxamide, 2-chloro-N-(4'-

chloro[1,1'-biphenyl]-2-yl

Common 

Name:

Boscalid

X Proposed tolerances

X Reevaluated tolerance

□ Other

Date: 8/05/09

Codex Status (Maximum Residue Limits) U. S. Tolerances

□ No Codex proposal step 6 or above

□ No Codex proposal step 6 or above for the crops 

requested

Petition Numbers: PP#9F7527 and PP#9F9529

DP#: 364447 

Other Identifier: 

Residue definition (step 8/CXL): Boscalid Reviewer/Branch: P. Deschamp/RAB3

Residue definition: boscalid for plant commodities; and 

combined residues of boscalid and M510F01 (free and 

conjugates) for animal commodities

Crops/Commodities MRL (mg/kg) Crops/Commodities Recommended 

Tolerance (ppm)

Alfalfa, forage 30

Alfalfa, hay 65

Fruit, citrus, group 10 1.6

Stone fruits 3.0 Fruit, stone, group 12 3.5

Egg 0.02 Egg 0.02

Fat of cattle, goat, horse and sheep 0.30

Meat (mammalian other than marine) 0.7 Meat of cattle, goat, horse and sheep 0.10

Edible offal, mammalian 0.2 Meat byproducts (cattle, goat, horse 

and sheep) 0.35

Milks 0.1 Milk 0.10

Hog, Fat 0.20

Hog, kidney None

Hog, meat byproducts 0.35

Hog, liver None

Poultry fat/meat 0.02 Poultry, fat 0.20

Poultry, liver None

Poultry, edible offal 0.02 Poultry, meat byproducts 0.20
Page 47 of 47

INTERNATIONAL RESIDUE LIMIT STATUS

Chemical Name: 

3-pyridinecarboxamide, 2-chloro-N-(4'-

chloro[1,1'-biphenyl]-2-yl

Common 

Name:

Boscalid

X Proposed tolerances

X Reevaluated tolerance

□ Other

Date: 8/05/09

Limits for Canada Limits for Mexico

□ No Limits

□ No Limits for the crops requested

X No Limits

□ No Limits for the crops requested

Residue definition: boscalid for plant commodities; and 

combined residues of boscalid and M510F01 (free and 

conjugates) for animal commodities

Residue definition: NA. Mexico defers to U.S.

tolerances or Codex MRLs for its export purposes.

Crops/Commodities MRL (mg/kg) Crops/Commodities MRL (ppm)

apricot, plumcot, plum, peach, sweet 

cherry, and tart cherry 1.7

Eggs 0.02

Fat of cattle, goats, hogs, horses, and 

sheep 0.3

Fat of poultry 0.05

Meat of cattle, goats, hogs, horses, and 

sheep 0.1

Meat of poultry 0.05

Meat byproducts of cattle, goats, hogs, 

horses, and sheep 0.35

Meat byproducts of poultry 0.1

Milk 0.1

Notes/Special Instructions: S.Funk, 10/14/2009.