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OFFICE OF

CHEMICAL SAFETY AND 

POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON D.C., 20460

 

PC Code: 128008

DP Barcode: D416697, D416698, D417193

Date: September 2, 2014

MEMORANDUM

SUBJECT: Drinking Water and Ecological Risk Assessment in Support of the Boscalid Section 3 

New Use on Stone Fruit Group 12-12, Tree Nut Group 14-12, Herb Subgroup 19A, and 

Dill Seed

TO: Heather Garvie, Risk Manager

Shaja Joyner, Product Manager

Cynthia Giles-Parker, Branch Chief

Fungicide Branch

Registration Division, 7505P

Andrew Ertman, Risk Manager Reviewer

Barbara Madden, Minor Use Team Leader

Risk Integration, Minor Use, and Emergency Response Branch

Registration Division (7505P)

Stephen Funk, Dietary Assessor

Barry O'Keefe, Risk Assessor

Christine Olinger, Branch Chief

Risk Assessment Branch 3

Health Effects Division (7509P)

FROM: Katrina White, Ph.D., Environmental Toxicologist

Catherine Aubee, Biologist

Environmental Risk Branch IV

Environmental Fate and Effects Division (7507P)

REVIEWED 

BY: James N. Carleton, Ph.D., Senior Scientist

Thomas Steeger, PhD., Senior Science Advisor

Environmental Risk Branch IV

Environmental Fate and Effects Division (7507P)

THROUGH: Sarah Winfield, Acting Branch Chief

Environmental Risk Branch IV (ERB4)

Environmental Fate and Effects Division (7507P)
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The Environmental Fate and Effects Division (EFED) has completed its evaluation in support of

the proposed Section 3 new use registration submitted by BASF Corporation and the 

Interregional Research Project Number 4 (IR-4) for the use of the fungicide boscalid (PC Code 

128008; 2-chloro-N-(4'-chlorobiphenyl-2-yl)nicotinamide). The proposed actions include 

broadening certain registered uses beyond individual crops to include entire crop groups, 

specifically for the stone fruit crop group1 12-12 and the tree nuts crop group 14-12. 

Additionally, there is a proposed new use on herbs subgroup 19A2and dill seed. These updates 

are being proposed on supplements to the Pristine Fungicide label (EPA registration number 

7969-199), which is a dual active ingredient (a.i.) fungicide (25.2% boscalid; 12.8% 

pyraclostrobin, by mass) formulated as a water-dispersible granule. This assessment pertains 

only to the active ingredient boscalid. The request proposes two applications per season of 0.292

lbs boscalid a.i./A at a 7-day interval, for a seasonal maximum of 0.584 lbs boscalid a.i./A.

There is ambiguity in the proposed label language, and EFED recommends the label be 

clarified to include a maximum yearly application rate or the maximum number of seasons 

that are allowed per year. Beyond this issue, EFED has concluded that the potential for 

drinking water exposure from the proposed new uses is no greater than that from previously 

assessed uses (USEPA, 2013, D409880), and a new drinking water assessment is not needed. 

Similarly, ecological risk from the proposed new uses is within the scope of risk from registered 

uses that were previously assessed (USEPA, 2003, D278387; USEPA, 2010, D363523; USEPA, 

2013, D405817+). The risks are characterized in detail in the cited assessments and are

summarized here for quick reference.

Use Characterization

The proposed new uses of boscalid include crop group conversions for stone fruit and tree nuts 

and new uses on Subgroup 19A (herb subgroup) and dill seed. Table 1 provides details on the 

proposed new uses and summarizes similar uses that have been reviewed. Unless otherwise 

specified, application rates in this document are presented in terms of lbs boscalid a.i./A.

Boscalid is already registered for use on stone fruit and tree nuts and the proposal is to broaden 

these uses for individual crops on the label to include their respective crop groups. The proposed 

use patterns for herb crop group 19A and dill seed are similar to those already approved on 

labels; however, because the labels provide the maximum number of applications and a 

maximum seasonal application rate, without a maximum annual application rate, it is possible 

that boscalid could be applied to the same field for multiple crop cycles (i.e., “seasons”). In 

 

1

Information on crop groups is available at: http://ir4.rutgers.edu/other/CropGroup.htm (accessed 6/23/2014).

2 Herb subgroup 19A contains: Angelica; balm; basil; borage; burnet; camomile; catnip; chervil (dried); chive; 

chive, Chinese; clary; coriander (leaf); costmary; cilantro (leaf); curry (leaf); dillweed; horehound; hyssop; lavender; 

lemongrass; lovage (leaf); marigold; marjoram; nasturtium; parsley (dried); pennyroyal; rosemary; rue; sage; savory, 

summer and winter; sweet bay; tansy; tarragon; thyme; wintergreen; woodruff; and wormwood.
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south Florida, four crop cycles per year have the potential to occur (assuming 70-80 days to crop 

maturity and planting dates throughout the year) (Huchmuth et al., 1999; Mossler, 2005). 

Assuming up to four crop cycles per year for herbs would allow for eight possible applications 

per year and a maximum rate similar to the maximum annual rate assumed for turf (0.29 lbs 

a.i./A × 8 = 2.2 lb a.i./A/year; turf maximum annual rate = 2.1 lbs a.i./A/season, where turf is 

assumed to have one season per year). 

Table 1. Summary of proposed new uses for boscalid along with similar uses that have been reviewed 

previouslyUse Site/ Source

Single App. 

Rate

(lbs. ai/A)

# of App.

Seasonal App. 

Rate

(lbs. ai/A)

Retreatment 

Interval (days)

PHI

App. Type

6

Comment

Uses on Proposed Labels

Stone Fruit 

(12-12

0.229 5* 1.15 7-14 0 A**, C 

G, AB

This use pattern was assessed in 2003 

with an airblast application (USEPA, 

2002, D278418, 2003, D278387+). 

This use pattern is on the currently 

approved Pristine® label. It is not 

registered in California.

Almond 0.229 4* 0.916 7-14 25 A**, C 

G, AB

Tree nuts assessed in 2003 (USEPA, 

2003, D278387+) for an airblast 

application. This use pattern is on the 

currently approved Pristine® label. 

The use on pistachio is nationwide; 

other uses in this group are not 

registered in California.

Filbert 7-14 14 A**, C 

G, AB

Pecan 7-21 14 A**, C 

G, AB

Pistachio 10-30 14 A**, C 

G, AB

Other tree 

nut

7-28 14 A**, C 

G, AB

Subgroup 

19A (herb 

subgroup) 

and dill 

seed

0.292 2 0.584 7 NS A**, C 

G, AB

See risk in 2013 assessment for globe 

artichoke and turnip greens to 

understand risk to aquatic organisms 

(USEPA, 2013, D405817+). See also 

2013 drinking water assessment,

which applies to this use pattern 

(USEPA, 2013, D409880). This use is 

not registered in California.

Use Historically Resulting in the Highest EDWCs

Golf 

Course 

Turf

0.350 6 2.1 14 0 G

Other Use Patterns that Inform the Proposed New Uses

Globe 

artichoke

0.360 3 1.08 7-14 0 Not 

specified

(USEPA, 2012a, D405064, 2013, 

D405817+)

Turnip 

greens

0.395 2 0.790 7-14 14 Not 

specified

(USEPA, 2012a, D405064, 2013, 

D405817+)
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Abbreviations: A=aerial; G=ground boom; C=chemigation; AB=airblast; EDWC=estimated drinking water 

concentration; EEC=estimated environmental concentration

*Do not make more than two (2) sequential applications of Pristine before alternating to a labeled fungicide with a 

different mode of action.

**For aerial application to stone fruit trees, use no less than 10 gallons spray solution per acre.

Drinking Water Exposure

For drinking water, Estimated Drinking Water Concentrations (EDWC) were previously based 

on the use of boscalid on turf (USEPA, 2013, D409880). As shown in Appendix A, EDWCs for 

the proposed use on herbs are lower than those previously calculated for turf. This is true even 

when up to four crop cycles per year are assumed for herbs, given the label ambiguity with 

respect to maximum annual application rate. Therefore, EFED recommends that the EDWCs for 

turf in the 2013 drinking water assessment (D409880) continue to be used in the Health Effects 

Division’s (HED) dietary assessment. The recommended EDWCs are summarized in Table 2.

Table 2. Tier I EDWCs for residues of boscalid and unextracted residues based on use on turf1

Source of Drinking 

Water (Model)

Boscalid and unextracted residue concentration in drinking water (μg/L)

Acute Annual Average or Post Breakthrough 

Average

Surface water (FIRST) 97.3 26.4

Groundwater (PRZMGW) 773 697

1 These are the highest EDWCs for the proposed and relevant previously evaluated use scenarios; see USEPA, 2013, 

D409880 for additional information.

Ecological Exposure

The proposed crop group conversions for stone fruit and tree nuts do not include any changes to 

the labeled application rates; therefore, new EECs were not calculated for either aquatic or 

terrestrial exposure. Surface water and terrestrial EECs for stone fruit and tree nuts are taken 

from the Section 3 new chemical assessment for boscalid (synonym: nicobifen) (USEPA, 2003, 

D278387). Peak surface water EECs for stone fruit and tree nuts ranged from 29.4 to 36.5 μg 

a.i./L, respectively; 21-day and 60-day EECs were only slightly lower. In the new chemical 

assessment, terrestrial EECs for dietary exposure based on uses for stone fruit and tree nuts were 

determined conservatively using an application rate of 0.350 lbs a.i./A applied five times with a 

retreatment interval of seven days, which was the maximum of all single application rates 

assessed at that time. The dietary EECs ranged from 20.3 mg a.i./kg diet for animals feeding 

exclusively on fruits, pods, and large insects, to 324 mg a.i./kg diet for animals feeding 

exclusively on items like short grass.

For the new use on herbs, peak surface water EECs ranged from 32.7 to 152 μg a.i./L, depending

on the number of crop cycles (i.e., one to four) assumed per year (Appendix A); the 21-day and 

60-day EECs were only slightly lower. Overall, the aquatic EECs for herbs were similar to those

most recently calculated for globe artichoke (peak EEC = 101 μg a.i./L) and turnip greens (peak 

EEC = 261 μg a.i./L) (USEPA, 2013, D405817+). Terrestrial EECs for globe artichoke and 
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turnip greens ranged from 70 to 227 mg a.i./kg diet; dose-adjusted values ranged from <1 to 259 

mg a.i./kg bw. As with stone fruit and tree nuts, the proposed application scenario for herbs (two 

applications at 0.292 lbs a.i./A with a minimum seven day retreatment interval) is within the 

range of application scenarios assessed in the original new chemical assessment (USEPA, 2003, 

D278387); therefore, the terrestrial EECs from that assessment may also be used as a 

conservative reference.

Exposure to terrestrial non-target plants may occur via spray drift and runoff from the proposed 

new uses of boscalid. Based on the previously described assessments (USEPA, 2013, 

D405817+), the screening-level EECs for nontarget terrestrial and semi-aquatic plants would 

range from <0.01 lbs a.i./A to no more than 0.05 lbs a.i./A.

Ecological Risk

The risks from the proposed new uses on stone fruits, tree nuts, and herbs are expected to be 

within the scope of risks from previously assessed uses (USEPA, 2013, D405817+). These risks 

are summarized in Table 3. Most notably,

 When four crop cycles per year are considered, the proposed new use on herbs results in 

risk to freshwater fish (and by proxy to aquatic-phase amphibians). Specifically, risk 

quotient (RQ) values exceed the level of concern (LOC) for acute risk to federally listed 

threatened and endangered (“listed”) species and for chronic risk to both listed and nonlisted species. RQ values from three or fewer crop cycles per year is below all LOCs. 

 Chronic toxicity data are not available for estuarine/marine fish and invertebrates; 

therefore, chronic risks to these taxa are uncertain. 

 Risk from all proposed uses exceeds the acute risk LOC for estuarine/marine molluscs, 

and this risk is presumed to extend to freshwater molluscs.

 Acute risk to freshwater crustaceans is uncertain because a definitive toxicity endpoint is 

not available; available data suggest that the LD50 may be near the water solubility limit 

of the compound. Chronic risk is not expected.

 All proposed uses have risk that exceeds the chronic risk LOC for mammals. Effects 

seen in laboratory toxicity studies at these dietary concentrations included reductions in 

body weight (absolute and weight gain) in second generation (F2), male rat pups.

 All proposed uses may result in risk to listed species of terrestrial plants in adjacent areas, 

based on EECs and reductions in plant growth parameters (i.e., shoot length, dry weight) 

in a greenhouse phytotoxicity study (Tier II vegetative vigor). Risk to dicotyledonous 

(dicot) plants may extend to certain non-listed species; dicots generally appear to be more

sensitive to boscalid exposure than monocotyledonous (monocot) species.

 This assessment evaluates hazard to honey bees (Apis mellifera) as a surrogate for 

terrestrial invertebrates. Reports of adverse effects on honey bees associated with nearby 

uses of boscalid co-formulated with pyraclostrobin (Pristine®) have not been 

substantiated by a growing body of higher-tiered experimental data with Pristine® and 
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with laboratory-based studies of individual adult and larval bees with each constituent of 

Pristine®. 

Table 3. Screening level risk conclusions for proposed uses of boscalid on stone fruit, tree nuts, and herbs

Taxonomic groups Type of Risk

Uses with Risk Quotients that Exceed the 

Level of Concern are shaded

Acute Chronic

Freshwater fish and aquaticphase amphibians

Listed species Herbs1 Herbs2

Nonlisted species None Herbs2

Estuarine/marine fish Listed species None3 Not determined

Nonlisted species None3 Not determined

Freshwater invertebrates Listed species Not determined None

Nonlisted species Not determined None

Molluscs Listed species

Stone fruit

Tree nuts

Herbs

Not determined

Nonlisted species None Not determined

Benthic invertebrates Listed species Not determined None

Nonlisted species Not determined None

Aquatic vascular plants Listed species None

Nonlisted species None

Aquatic nonvascular plants Listed species None

Nonlisted species None

Mammals

Listed species None

Stone fruit

Tree nuts

Herbs4

Nonlisted species None

Stone fruit

Tree nuts

Herbs4

Birds, reptiles, and terrestrialphase amphibiansListed species Unlikely5 None

Nonlisted species None None

Terrestrial plants

Listed species

Monocots6 and dicots7:

Stone fruit

Tree nuts

Herbs

Nonlisted species

Dicots7 only:

Stone fruit

Tree nuts

Herbs

1 RQ = EEC 152 ug a.i./L (four crop cycles)  LC50 2,700 ug a.i./L = 0.06; acute risk to listed species LOC = 0.05.

2 RQ = EEC 150 ug a.i./L (four crop cycles)  NOAEC 116 ug a.i./L = 1.29; chronic risk LOC = 1.

3

 A comparison of the highest peak EEC for the proposed new uses (152 ug a.i./L for herbs with four crop cycles) to 

the nondefinitive endpoint for acute toxicity to estuarine/marine fish (LC50 > 3,860 ug a.i./L) indicates that acute risk 

is unlikely to exceed the LOCs for this taxon.

4 The chronic risk LOC is exceeded for all size classes of mammals foraging on vegetation, e.g., broadleaf plants 

and grasses.

5

 Acute risk of mortality in birds is considered unlikely based on the absence of mortality at the highest dose tested, 

although sublethal effects were observed in one study.

6

 Risk to listed species of monocots exceeds the LOC based on EECs up to 0.05 lbs a.i./A and reductions in shoot 

length in the Tier II vegetative vigor test (NOAEC = 0.035 lbs a.i./A, corn).
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7

 Risk to listed and non-listed species of dicots is concluded because EECs (up to 0.05 lbs a.i./A) exceed the lowest 

treatment rate (0.035 lbs a.i./A) in the vegetative vigor test, where significant reductions (p<0.05, >25%) in cabbage 

dry weight were observed.

Recent Incident Data

Reported incidents associated with boscalid exposure consist primarily of beekeeper reports of 

honey bee mortality and adverse effects on honey bee brood (larval) development. These 

incidents are described in detail in prior assessments (USEPA, 2010, D363523; USEPA, 2013, 

D405817+) and generally identify the end-use product, Pristine, or tank mixes of boscalidcontaining products with other pesticides. 

In 2014, an anonymous beekeeper reported a new incident of adverse effects on honey bee 

colonies, potentially associated with exposure to Pristine in almond orchards (Incident No. 

I026240‐001). The exposure was reported as a tank mix of Pristine with the insect growth 

regulator, Intrepid® (a.i.: methoxyfenozide). The pesticide application was reported to have 

occurred both during the day and at night in February 2014 when almond orchards were in full 

bloom. Physical injury from airblast exposure was cited as a potential contributing factor to the 

injury and mortality observed. The beekeeper reported that 80% of the colonies had noticeable 

brood and adult loss; up to 7,800 colonies were reportedly on contract in area almond orchards at 

the time.

Considerations for Listed Species

In November 2013, the EPA, along with the U.S. Fish & Wildlife Service (USFWS), the 

National Marine Fisheries Service (NMFS) (collectively, the Services), and the U.S. Department 

of Agriculture (USDA) released a summary of their joint Interim Approaches for assessing risks 

to listed species from pesticides. The Interim Approaches were developed jointly by the 

agencies in response to the National Academy of Sciences’ (NAS) recommendations and reflect 

a common approach to risk assessment shared by the agencies as a way of addressing scientific 

differences between the EPA and the Services. The NAS report (National Research Council, 

2013) outlines recommendations on specific scientific and technical issues related to the 

development of pesticide risk assessments that EPA and the Services must conduct in connection 

with their obligations under the Endangered Species Act (ESA) and the Federal Insecticide, 

Fungicide, and Rotenticide Act (FIFRA). 

The joint Interim Approaches were released prior to a stakeholder workshop held on November 

15, 2013. In addition, the EPA presented the joint Interim Approaches at the December 2013 

Pesticide Program Dialogue Committee (PPDC) and State-FIFRA Issues Research and 

Evaluation Group (SFIREG) meetings, and held a stakeholder workshop in April 2014, allowing 

additional opportunities for stakeholders to comment on the Interim Approaches. As part of a 

phased, iterative process for developing the Interim Approaches, the agencies will also consider 

public comments on the Interim Approaches in connection with the development of upcoming 

Registration Review decisions. The details of the joint Interim Approaches are contained in the 
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white paper “Interim Approaches for National-Level Pesticide Endangered Species Act 

Assessments Based on the Recommendations of the National Academy of Sciences April 2013 

Report,” dated November 1, 2013 (NRC, 2013). 

Given that the agencies are continuing to develop and work toward implementation of the 

Interim Approaches to assess the potential risks of pesticides to listed species and their 

designated critical habitat, the risk assessment for boscalid does not contain a complete ESA 

analysis that includes individual species effects determinations for particular listed species or 

designated critical habitat. Although EPA has not yet completed effects determinations for 

particular species or habitats, EPA conducted a screening-level assessment for all taxa of nontarget wildlife and plants that assumes (for the purpose of the assessment) that listed species and 

designated critical habitats may be present in the vicinity of the application of boscalid. This 

screening-level assessment will allow EPA to focus its future evaluations on the types of species 

where the potential for effects exists once the scientific methods being developed by the agencies 

have been fully vetted. This screening-level risk assessment for boscalid indicates potential risks 

of direct effects to listed fish, molluscs, mammals, and terrestrial plants in all of boscalid’s

proposed use sites. Listed species in other taxonomic groups may also be affected through 

indirect effects because of the potential for direct effects on listed and non-listed species upon 

which such species may rely. Further, potential direct effects on listed fish, molluscs, mammals, 

and terrestrial plants from the use of boscalid may be associated with modification of Primary

Constituent Elements (PCEs) of designated critical habitats, where such designations have been 

made. Once the agencies have fully developed and implemented the scientific methods 

necessary to complete risk assessments for listed species and their designated critical habitats, 

these methods will be applied to subsequent analyses for boscalid. 

Uncertainties

The following uncertainties have been identified regarding the environmental fate and 

ecotoxicity of boscalid. These are continuing uncertainties which have been discussed in detail 

in previous assessments (e.g., USEPA, 2010, D363523). Submission of appropriate data would 

reduce these uncertainties, and such data may be required as part of the upcoming Registration 

Review process.

With respect to the environmental fate of boscalid, EFED continues to recommend submission of 

the following:

 Anaerobic aquatic metabolism data: data on anaerobic aquatic metabolism (OCSPP 

guideline 835.4400) in two sediments are recommended in the guideline; however, data 

are currently only available for one sediment. This data gap could result in 

underestimation or overestimation of typical half-lives in such media. To account for this 

uncertainty, standard EFED procedure is to multiply a single anaerobic aquatic 

metabolism half-life by three to derive a representative benthic half-life for use as a 

model input. 
Page 9 of 19

 Identification of unextracted residues in aerobic soil and anaerobic aquatic metabolism 

studies: the identity of unextracted residues is unknown in a number of submitted fate 

studies in which unextracted residues made up greater than 10% of applied radioactivity 

(<1 to 63%). This creates significant uncertainty in the risk assessment. Due to the 

uncertainty in the identity of the unextracted residues, past assessments of boscalid have 

conservatively assumed that the unidentified residues are of toxicological concern when 

estimating half-lives for use in aquatic modeling. Additionally, past assessments of 

boscalid have conservatively assumed that they (the unextracted residues) exhibit the 

same toxicity to aquatic organisms as the parent compound.

If aquatic EECs and the associated RQ values were to be less conservatively based only on 

extracted boscalid residues in environmental fate studies (i.e., nondefinitive RQ values, or 

NRQs), and not on the combination of extracted and unextracted residues, RQ values would be 

reduced by approximately one-half. In this case, the RQ values for the proposed new use on 

herbs (four crop cycles per year) would no longer exceed the LOCs for risk to freshwater fish 

and amphibians. However, RQ values would generally still approach or exceed the acute risk to 

listed species LOC for molluscs.

With respect to ecotoxicity, uncertainties discussed in previous assessments also carry forward 

into this risk assessment and include the following:

 Acute toxicity to the waterflea (Daphnia magna);

 Acute toxicity to estuarine/marine invertebrates (crustaceans);

 Chronic toxicity to estuarine/marine fish and invertebrates;

 Sediment toxicity data for aquatic invertebrates; and,

 Tier II terrestrial plant vegetative vigor data given the nondefinitive endpoint for 

cabbage.

Summary

Boscalid has the potential to reach surface water and groundwater, and to be transported in air 

either in vapor phase or on particles3. Boscalid has been measured in all of these matrices, and in 

other matrices such as sediment and bees’ wax, through ambient monitoring. Boscalid is also 

persistent to very persistent and residues are expected to remain in the environment for months to 

years. 

The proposed new uses of boscalid include crop group conversions for stone fruit and tree nuts 

and new uses on herbs (subgroup 19a) and dill seed. These use patterns are expected to result in 

acute RQ values that exceed the LOC acute risk to listed species of freshwater fish and aquatic-

 

3 Although boscalid is classified as non-volatile under field conditions (according to the classification system in 

Guideline 835.6100) (USEPA, 2008), based on monitoring data it still has the potential to be transported in air or on 

particles in air. Boscalid was measured in air monitoring studies in air and associated with particles in air (Schumer

et al., 2010). Based on results of the Screening Tool for Inhalation Risk model, exposure through inhalation is not a 

potential pathway of concern for either avian or mammalian species on an acute basis.
Page 10 of 19

phase amphibians (herb use only) and listed species of molluscs. Chronic risk is anticipated for 

freshwater fish and aquatic-phase amphibians (herb use only) and for mammals. RQ values from 

exposure through offsite transport exceeds LOCs for risk to listed terrestrial and semi-aquatic 

plants and for certain nonlisted species of plants (dicots). Adverse effects seen in chronic 

exposure studies with animals and with terrestrial plants generally reflect reductions in growth 

parameters following exposure to boscalid.

The potential for human exposure through drinking water and the ecological risks identified for 

the proposed new uses of boscalid are consistent with conclusions of previous assessments for 

uses that were subsequently registered. Similarly, uncertainties about the environmental fate and 

ecotoxicity of boscalid have been discussed in prior assessments. While these uncertainties are 

not specific to the proposed new uses, EFED continues to recommend the submission of 

appropriate data to support a more accurate and comprehensive risk assessment.

Specific to this assessment, EFED notes that there is ambiguity in the proposed label language 

and recommends that the label be clarified to include a maximum yearly application rate or the 

maximum number of seasons that are allowable for boscalid use per year. Clarification of the 

label language would support a more accurate risk assessment and may result in certain risks 

(e.g., risk to freshwater fish and aquatic-phase amphibians from use on herbs) being identified as 

below LOCs.

REFERENCES

Huchmuth, G. J., Maynard, D. N., Vavrina, C. S., Stall, W. M., Kucharek, T. A., Stansley, P. A., 

et al. 1999. Parsley Production in Florida. HS731. February 1999. University of Florida. 

Cooperative Extension Service. Institute of Food and Agricultural Sciences. Available at 

http://university.uog.edu/cals/people/PUBS/Parsley/CV12900.pdf (Accessed June 23, 

2014).

Mathur, S. 2002.D285692. Secondary Product Chemistry Review of MP. D. B. 3285692. October 

31, 2002. Registration Division. Office of Pesticide Programs. United States 

Environmental Protection Agency. 

Mossler, M. 2005. Crop Profile for Herbs in Florida (Basil, Cilantro, Dill, Mint, Parsley, 

Rosemary, Sage, Thyme). July 2005. Pesticide Information Office. University of Florida. 

Institute of Food and Agricultural Sciences. Available at 

http://www.ipmcenters.org/cropprofiles/docs/FLherbs.pdf (Accessed June 23, 2014).

Schumer, C., Mothiron, E., Appenzeller, B. M. R., Rizet, A., Wennig, R., & Millet, M. 2010. 

Temporal variations of concentrations of currently used pesticides in the atmosphere of 

Strasbourg, France. Environmental Pollution, 158, 576-584. 

USEPA. 2002.D278418. BAS 510 F: Tier 1 Drinking Water EECs for Use in the Human Health 

Risk Assessment. D278418. September 16, 2002. Environmental Fate and Effects Division. 

Office of Prevention, Pesticides, and Toxic Substances. U.S. Environmental Protection 

Agency. 
Page 11 of 19

USEPA. 2003.D278387+. EFED Risk Assessment for Section 3 Registration of BAS 510 F 

(Nicobifen). D. D278387, D278389, D278390, D278418. May 28, 2003. Environmental 

Fate and Effects Division. Office of Prevention, Pesticides, and Toxic Substances. U.S. 

Environmental Protection Agency. 

USEPA. 2008. Fate, Transport, and Transformation Guidelines. OPPTS 835.6100 Terrestrial 

Field Dissipation. EPA 712-C-08-020. October 2008. Office of Prevention, Pesticides, 

and Toxic Substances. U.S. Environmental Protection Agency. Available at 

http://www.epa.gov/opptsfrs/publications/835_6100.pdf (Accessed July 30, 2009).

USEPA. 2012a.D405064. Tier I Drinking Water Exposure Assessment for the Section 3 New Use 

of Boscalid on Various Agricultural Crops Including Cranberries. D405064. 

Memorandum From K. White to S. Funk, B. O'Keefe, A. Ertman & B. Madden. November 

27, 2012. Environmental Fate and Effects Division. Office of Pesticide Programs. Office 

of Chemical Safety and Pollution Prevention. U.S. Environmental Protection Agency. 

USEPA. 2012b.D405064. Tier I Drinking Water Exposure Assessment for the Section 3 New Use 

of Boscalid on Various Agricultural Crops Including Cranberries. D405064. November 

27, 2012. Environmental Fate and Effects Division. Office of Pesticide Programs. U.S. 

Environmental Protection Agency. 

USEPA. 2013.D405817+. Environmental Fate and Ecological Risk Assessment for the Proposed 

New Uses of Boscalid for Various Agricultural Crops, Ornamentals, and Residential 

Gardens. D405817+. August 13, 2013. Environmental Fate and Effects Division. Office 

of Pesticide Programs. U.S. Environmental Protection Agency. 

USEPA. 2013.D409880. Tier I Drinking Water Exposure Assessment for the Section 3 New Use 

of Boscalid on Various Agricultural Crops and Homeowner Uses. D409880. April 30, 

2013. Environmental Fate and Effects Division. Office of Pesticide Programs. U.S. 

Environmental Protection Agency. 
Page 12 of 19

Appendix A. Aquatic Modeling for Herb Use Assuming Four Seasons Per Year

Table A1. Estimated Concentrations of Boscalid and Unextracted Residues in Surface Water (Version 1.106) and Groundwater Source Drinking Water

(PRZM-GW Version 1.07). 

Use Site

Single 

App. 

Rate

lbs. ai/Aa

(kg 

a.i./ha)

# of 

Ap

p

Ret. Int.

days

App. 

Type6

EDWC for parent and unextracted residues in μg/L

EDWC for parent alone in μg/L*

Surface Water

Ground Water

SCIGROW PRZM-GW

Acute Annual 

Average Peak Scenario Highest Daily Peak

Post

Breakthrough 

Average

Average Simulation 

Breakthrough Time for 

PRZM-GW (Days)

Proposed Use on Herb Crop Group 19A and Dill Seed

Herb 4 

crop 

cycles

0.292

(0.327) 8 7 Air 34.7 26.4 1.98 WISand 736 672 12704

Previous Results From 2013 Drinking Water Assessment1

Turf 0.35

(0.39) 6 14 G

97.33

93.56*

26.45∞

26.35

25.36*

0.27∞

1.8

NJ/DE 328 269 6602

FL Citrus 347 335 6528

FL Potato 123 118 16467α

NC 407 370 7292

WI 773

423*

697

389*

13295α

13295*

GA 201 187 13529α

1 USEPA. 2013.D409880. Tier I Drinking Water Exposure Assessment for the Section 3 New Use of Boscalid on Various Agricultural Crops and Homeowner Uses. D409880. 

April 30, 2013. Environmental Fate and Effects Division. Office of Pesticide Programs. U.S. Environmental Protection Agency.
Page 13 of 19

Table A2. Summary of EECs for Residues of Boscalid and Unextracted Residues for Proposed Use on Herb 

Crop Group 19A and Dill Seed (0.327 kg a.i.kg/ha) and Comparison to EECs evaluated in 2013 

Ecological Risk Assessment

Scenario 1-in-10 year EECs for EPA Pond (μg/L) 1-in-10 Year EDWC (μg/L)

Peak 21-day 60-day Acute Annual 

Average

EECs in 2013 Ecological Risk Assessment2, 3

Globe 

Artichoke 101 99.8 99.8 -- --

Turnip Greens 261 260 260 -- --

Turf 93.4 93.2 93.0 97.3 26.4

EECs Estimated for Proposed Use on Herb Crop Group 19A1

Herb 4 crop 

cycles, Aerial 

app

152 151 150 34.7 26.4

Herb 3 crop 

cycles 113 112 111 27.0 20.1

Herb 2 crop 

cycles 77.4 76.7 75.9 21.8 14.0

Herb 1 crop 

cycles 32.7 32.1 31.5 6.37 4.02

1 Eight applications every 3 months were assumed for four crop cycles, 6 applications were assumed for 3 crop 

cycles, 4 applications were assumed for 2 crop cycles, and 2 applications (on April 15 and April 22) were assumed 

for 1 crop cycle. The OR mint scenario was developed with the crop on the field from April 15 to August 1. 

Applications occurring outside of that date were assumed to be surface applied instead of applied to the crop. 

2 USEPA. 2013.D409880. Tier I Drinking Water Exposure Assessment for the Section 3 New Use of Boscalid on 

Various Agricultural Crops and Homeowner Uses. D409880. April 30, 2013. Environmental Fate and Effects 

Division. Office of Pesticide Programs. U.S. Environmental Protection Agency.

3 USEPA. 2013. Environmental Fate and Ecological Risk Assessment for the Proposed New Uses of Boscalid for 

Various Agricultural Crops, Ornamentals, and Residential Gardens. D405817+. August 13, 2013. Environmental 

Fate and Effects Division. Office of Pesticide Programs. U.S. Environmental Protection Agency.
Page 14 of 19

TableA3. Input Values Used for Boscalid Tier II Surface Water Modeling with SWCC

Inputs were the same as those used in the most recently completed ecological risk assessment (USEPA, 2013, 

D405817+)

Parameter (units) Value (s) Source Comments

Chemical Tab

Organic-carbon 

Normalized Soil-water 

Distribution Coefficient 

(KOC (L/kg-OC))

772 MRID 45405216, 

45405217 Mean of six KFOC values. 

Water Half-life or Aerobic 

Aquatic Metabolism Halflife (days) and Reference 

Temperature

Stable (0) at 21oC MRID 45405214

84% remained at end of study 

with 12-13% unextracted 

residues in two pond systems. 

Studies were conducted at 19-

21oC.

Benthic Half-life or 

Anaerobic Aquatic 

Metabolism Half-life 

(days) and Reference 

Temperature

Parent Only: 1155

Parent+Unextracted 

Residues: Stable (0)

At 20oC

MRID 45405213

Parent: single value (385)×3

Parent+Unextracted Residues: 

No significant degradation

Aqueous Photolysis Halflife @ pH 7 (days) and 

Reference Latitude

Stable (0) at 40o

Latitude MRID 45405206 --

Hydrolysis Half-life @ pH 

4, 7, 9 (days) Stable (0) MRID 45405205 --

Soil Half-life or Aerobic 

Soil Metabolism Half-life 

(days) and Reference 

Temperature

Parent Only: 503

Parent+Unextracted 

Residues: 2136

At 27oC

MRID 45643802

The 90th percent upper 

confidence bound on the mean of 

four half-life values. Half-life 

values were not adjusted for 

temperature of 27oC.

Foliar Degradation Rate 0 d-1 Default --

Molecular weight (g/mol) 343.21 -- --

Vapor Pressure (Torr) at 

25oC

2×10-8

(Mathur, 2002, 

D285692)

Solubility in Water @ 20 

OC, pH not reported (mg/L) 4.64 (Mathur, 2002, 

D285692)

−

Applications Tab

Day Month Amount 

(kg/ha)

App 

Method Depth

Efficiency 

(Reservoir, 

Pond)

Drift 

(Reservoir, 

Pond)

1 1 0.327 Foliar 0 0.95 0.135, 0.125

8 1 0.327 Foliar 0 0.95 0.135, 0.125

1 4 0.327 Foliar 0 0.95 0.135, 0.125

8 4 0.327 Foliar 0 0.95

1 7 0.327 Foliar 0 0.95 0.135, 0.125

8 7 0.327 Foliar 0 0.95 0.135, 0.125

1 10 0.327 Foliar 0 0.95 0.135, 0.125

8 10 0.327 Foliar 0 0.95 0.135, 0.125

Crop/Land Tab

Scenario ID ORmintSTD

Post-Harvest Foliage Surface Applied
Page 15 of 19

1 Source data are in Appendix A of the 2012 drinking water assessment (USEPA, 2012b, D405064).

Table A4. SCI-GROW (v2.3) Input Parameter Values for Boscalid1

Parameter Value Source Comments

Application Rate (lbs 

a.i./acre) 0.292 Proposed label See Section titled “Proposed Use” for 

Number of full explanation.

applications 8 Proposed label

Koc (mL/g) 716 MRID 45405216

Median of six KFOC values. There is not 

a three-fold difference in observed 

values.

Aerobic soil 

metabolism t 1⁄2 (days)

Parent Only: 349

Parent+Unextracted 

Residues: 1305

MRIDs 45643802 Median of four values. There was not a 

five-fold difference in values.

1 Source data are in Appendix A of the 2012 drinking water assessment (USEPA, 2012b, D405064).

Table A5. Tier I PRZM-GW (Version 1.07) Input Parameters for Boscalid

Parameter (units) Input Value Data 

Source Comments

Application Rate

See Table A2

Labels

--

Number of Applications --

--

Annual Application Retreatment --

Application Method Above canopy (2)

Soil (1) for in furrow --

Date of first Application 

10 days after crop 

emergence

14 days before crop 

emergence for furrow 

application

-- --

Hydrolysis (half-life (days) Stable (0) MRID 

45405205 --

Soil Metabolism half-life at 25oC 

(days)

Parent Only: 578

Parent+Unextracted 

Residues: 2454

MRID 

45643802

The 90th percent upper confidence 

bound on the mean of four half-life 

values. Half-life values adjusted from 

27oC to 25oC according to input 

parameter guidance.

Koc (L/kg-OC) 772 MRID 

45405216 Mean of six KFOC values. See text.

1 Source data are in Appendix A of the 2012 drinking water assessment (USEPA, 2012b, D405064).
Page 16 of 19

Summary of Water Modeling of BoscalidUN and the USEPA 

Standard Pond

Estimated Environmental Concentrations for BoscalidUN are presented in Table 1 for the 

USEPA standard pond with the ORmintSTD field scenario. A graphical presentation of the yearto-year peaks is presented in Figure 1. These values were generated with the Surface Water 

Concentration Calculator (SWCC Version 1.106). Critical input values for the model are 

summarized in Tables 2 and 3.

This model estimates that about 1.6% of BoscalidUN applied to the field eventually reaches the 

water body. The main mechanism of transport from the field to the water body is by spray drift 

(75.8% of the total transport), followed by runoff (24.1%) and erosion (0.09%).

In the water body, pesticide dissipates with an effective water column half-life of 145707.8 days. 

(This value does not include dissipation by transport to the benthic region; it includes only 

processes that result in removal of pesticide from the complete system.) The main source of 

dissipation in the water column is volatilization (effective average half-life = 145707.8 days).

In the benthic region, pesticide dissipation is negligible (1990.2 days). The main source of 

dissipation in the benthic region is metabolism (effective average half-life = 1990.2 days). The 

vast majority of the pesticide in the benthic region (98.81%) is sorbed to sediment rather than in 

the pore water.

Table 1. Estimated Environmental Concentrations (ppb) for BoscalidUN.

Peak (1-in-10 yr) 139.

4-day Avg (1-in-10 yr) 139.

21-day Avg (1-in-10 yr) 138.

60-day Avg (1-in-10 yr) 137.

365-day Avg (1-in-10 yr) 135.

Entire Simulation Mean 91.5

Table 2. Summary of Model Inputs for BoscalidUN.

Scenario ORmintSTD

Cropped Area Fraction 1

Koc (ml/g) 772

Water Half-Life (days) @ 21 °C 0

Benthic Half-Life (days) @ 20 °C 1155

Photolysis Half-Life (days) @ 40 

°Lat

0
Page 17 of 19

Hydrolysis Half-Life (days) 0

Soil Half-Life (days) @ 27 °C 2136

Foliar Half-Life (days) 0

Molecular Wt 343.21

Vapor Pressure (torr) 2E-8

Solubility (mg/l) 4.64

Table 3. Application Schedule for BoscalidUN.

Date (Mon/Day) Type Amount (kg/ha) Eff. Drift

4/15 Foliar 0.327 0.95 0.125

4/22 Foliar 0.327 0.95 0.125

4/1 Foliar 0.327 0.95 0.125

4/8 Foliar 0.327 0.95 0.125

7/1 Foliar 0.327 0.95 0.125

7/8 Foliar 0.327 0.95 0.125

10/1 Foliar 0.327 0.95 0.125

10/8 Foliar 0.327 0.95 0.125

Figure 1. Yearly Peak Concentrations
Page 18 of 19

Summary of Water Modeling of BoscalidUN and the USEPA 

Standard Reservoir

Estimated Environmental Concentrations for BoscalidUN are presented in Table 1 for the 

USEPA standard reservoir with the ORmintSTD field scenario. A graphical presentation of the 

year-to-year peaks is presented in Figure 1. These values were generated with the Surface Water 

Concentration Calculator (SWCC Version 1.106). Critical input values for the model are 

summarized in Tables 2 and 3.

This model estimates that about 0.98% of BoscalidUN applied to the field eventually reaches the 

water body. The main mechanism of transport from the field to the water body is by runoff 

(57.9% of the total transport), followed by spray drift (41.9%) and erosion (0.23%).

In the water body, pesticide dissipates with an effective water column half-life of 204.3 days. 

(This value does not include dissipation by transport to the benthic region; it includes only 

processes that result in removal of pesticide from the complete system.) The main source of 

dissipation in the water column is washout (effective average half-life = 204.5 days) followed by 

volatilization (199619.6 days).

In the benthic region, pesticide dissipation is negligible (1990.2 days). The main source of 

dissipation in the benthic region is metabolism (effective average half-life = 1990.2 days). The 

vast majority of the pesticide in the benthic region (98.81%) is sorbed to sediment rather than in 

the pore water.

Table 1. Estimated Environmental Concentrations (ppb) for BoscalidUN.

Peak (1-in-10 yr) 34.7

4-day Avg (1-in-10 yr) 34.4

21-day Avg (1-in-10 yr) 33.8

60-day Avg (1-in-10 yr) 31.9

365-day Avg (1-in-10 yr) 26.4

Entire Simulation Mean 22.0

Table 2. Summary of Model Inputs for BoscalidUN.

Scenario ORmintSTD

Cropped Area Fraction 1.0

Koc (ml/g) 772

Water Half-Life (days) @ 21 °C 0

Benthic Half-Life (days) @ 20 °C 1155
Page 19 of 19

Photolysis Half-Life (days) @ 40 

°Lat

0

Hydrolysis Half-Life (days) 0

Soil Half-Life (days) @ 27 °C 2136

Foliar Half-Life (days) 0

Molecular Wt 343.21

Vapor Pressure (torr) 2E-8

Solubility (mg/l) 4.64

Table 3. Application Schedule for BoscalidUN.

Date (Mon/Day) Type Amount (kg/ha) Eff. Drift

1/1 Foliar 0.327 0.95 0.135

1/8 Foliar 0.327 0.95 0.135

4/1 Foliar 0.327 0.95 0.135

4/8 Foliar 0.327 0.95 0.135

7/1 Foliar 0.327 0.95 0.135

7/8 Foliar 0.327 0.95 0.135

10/1 Foliar 0.327 0.95 0.135

10/8 Foliar 0.327 0.95 0.135

Figure 1. Yearly Peak Concentrations