2 

better able to characterize potential risks by eliminating uncertainties for both non-listed and 

listed species that cannot be accounted for using alternate methods or weight of evidence. 

Data from the following studies are considered to have high potential to add value to the 

ecological risk assessment for captan: 

 

Environmental fate studies: 

Guideline 835.4100 – Aerobic Soil Metabolism: Two aerobic soil metabolism studies are 

acceptable for risk assessment. Additional data are required under 40 CFR Part 158 for 

terrestrial outdoor uses. OCSPP guidance recommends that these tests be performed with four 

soils. Because OCSPP uses an upper 90th percentile estimate of soil metabolism half-lives based 

on available study data for modeling purposes, any additional data can reduce uncertainty related 

to the exposure assessment as well as the half-life value used in modeling. Additional data are 

considered to have a high potential to add value to the ecological risk and drinking water 

assessments. 

Guideline 835.4200 – Anaerobic Soil Metabolism: Two anaerobic soil metabolism studies are 

acceptable for risk assessment. Additional data are required under 40 CFR Part 158 for 

terrestrial outdoor uses. OCSPP guidance recommends that these tests be performed with four 

soils. Because OCSPP uses an upper 90th percentile estimate of soil metabolism half-lives based 

on available study data for modeling purposes, any additional data can reduce uncertainty related 

to the exposure assessment as well as the half-life value used in modeling. In the absence of 

anaerobic aquatic metabolism data, additional data are considered to have a high potential to add 

value to the ecological risk and drinking water assessments. 

Guideline 835.4400 – Anaerobic Aquatic Metabolism: Data are required under 40 CFR Part 

158. OCSPP guidance recommends that these tests be performed with two sediments. 

Additional data are considered to have a high potential to add value to the ecological risk and 

drinking water assessments. 

Ecological effects studies: 

Guideline 850.2100 – Avian Acute Oral Toxicity Test, upland game or waterfowl species: 

The avian endpoints for acute oral toxicity are non-definitive (i.e., LD50 > highest dose tested). 

The highest concentrations tested, 2150 and 2000 mg/kg-bw for bobwhite quail and mallard 

duck, respectively (MRIDs 00151236 and 00160000), are less than the highest avian EECs 

calculated in the most recent assessments (i.e., 4968 mg/kg-bw in the 2007 CRLF litigation 

assessment; 6107 mg/kg-bw in the 2012 Section 24(c) SLN assessment, DP 400401), and 

sublethal effects including weight loss, ataxia, and tremors were noted in the studies. Based on 

guidance for using non-definitive endpoints1, requesting additional data is recommended and 

considered to have a high potential to add value to the Registration Review ecological risk 

assessment. 

 

1

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_reregistration_work

group/esa_non_definitive_endpoints.htm
3 

Guideline 850.2100 – Avian Acute Oral Toxicity Test, passerine species: Acute oral toxicity 

data for a passerine species are required under the new 40 CFR Part 158. No studies have been 

submitted for this data requirement. Given the concerns identified for existing toxicity data for 

upland game and waterfowl species and the need to be protective of passerine species, fulfilling 

this data requirement has a high potential to add value to the Registration Review ecological risk 

assessment. 

Guideline 850.2200 – Avian Dietary Toxicity Test, upland game: The avian endpoints for 

sub-acute dietary toxicity are non-definitive (i.e., LC50 > highest concentration tested). The 

highest concentration tested, 4680 mg/kg-diet (if corrected for % a.i.) for both bobwhite quail 

and mallard duck (MRIDs 43869802 and 43869803) is greater than the highest avian EEC of 

4362 mg/kg-diet calculated in the 2007 California Red-legged Frog (CRLF) litigation 

assessment, but less than the highest avian EEC of 5112 mg/kg-diet calculated in the 2012 

Section 24(c) SLN assessment (DP 400401). Furthermore, there was 30% (3 out of 10) mortality 

in the 5200 mg/kg-diet treatment group in the bobwhite quail study, and frank sublethal effects 

including reduced body weight gain were noted at ≥ 2600 mg/kg-diet for both species. Based on 

guidance for using non-definitive endpoints2, requesting additional data is recommended and 

considered to have a high potential to add value to the Registration Review ecological risk 

assessment. 

Guideline 850.4100 – Seedling Emergence and Seedling Growth & Guideline 850.4150 – 

Vegetative Vigor: Data for terrestrial plant species are required under 40 CFR Part 158. Open 

literature studies indicate that applications of captan as low as 2.5 lb a.i./A could affect dicots 

(2007 CRLF litigation assessment; DP 400401). In addition, incidents associated with the use of 

captan and involving plants have been reported (see Section 5.3). Therefore, effects to terrestrial 

plants from use of captan cannot be discounted, and data from terrestrial plant studies are 

considered to have a high potential to add value to the Registration Review ecological risk 

assessment. 

Guideline 850.4500 – Algal Toxicity, freshwater diatom: Data for aquatic non-vascular plant 

species including a freshwater diatom are required under 40 CFR Part 158. No data has been 

submitted for this data requirement. Results of aquatic non-vascular plant toxicity studies with 

folpet, a phthalimide fungicide that is a structural analogue of captan, show a freshwater diatom 

to be the most sensitive species tested. Therefore, freshwater diatoms are likely to be the most 

sensitive aquatic non-vascular plant species for captan. The freshwater diatom endpoints for 

folpet (EC50/NOEC = 50/30 μg a.i./L) are close to the highest peak EEC of 21.6 μg/L calculated 

in the 2007 CRLF litigation assessment and less than the highest peak EEC of 91.3 calculated for 

the 2012 Section 24(c) SLN assessment (DP 400401). Data for a freshwater diatom exposed to 

captan could impact risk conclusions and are considered to have a high potential to add value to 

the Registration Review ecological risk assessment. 

 

2

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_reregistration_work

group/esa_non_definitive_endpoints.htm
4 

Non-Guideline Studies – Adult and Larval Honey Bee Acute Oral Toxicity Tests: A honey 

bee incident involving brood losses and the use of captan has been reported. In addition, the 

“White Paper in Support of the Proposed Risk Assessment Process for Bees” as submitted to the 

FIFRA Scientific Advisory Panel3 proposes a screening-level risk assessment process that 

includes acute contact and oral toxicity tests with adult bees and an acute oral toxicity test with 

larval bees. Adult honey bee acute contact toxicity data are available for captan. However, adult 

and larval honey bee acute oral toxicity data are not. Therefore, data from the following nonguideline honey bee toxicity studies are recommended for request and considered to have a high 

potential to add value to the Registration Review ecological risk assessment: 

• (adult) honey bee acute oral toxicity test and 

• larval honey bee acute oral toxicity test. 

 

 

3

http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2012-0543-0004
REGISTRATION REVIEW

PROBLEM FORMULATION

US EPA PC CODE 

Prepared by: 

Robin Sternberg, Ph.D., Wildlife Biologist 

Faruque Khan, Ph.D., Senior Fate Scientist

Environmental Risk Branch 1 

Reviewed by: 

Anita Ullagaddi, M.S., Biologist 

Stephen P. Wente, Ph.D., Biologist 

Environmental Risk Branch 1 

Environmental Fate and Effects Division

5 

REGISTRATION REVIEW

PROBLEM FORMULATION

Captan 

CAS Number 133-06-2 

US EPA PC CODE 081301 

Robin Sternberg, Ph.D., Wildlife Biologist 

Faruque Khan, Ph.D., Senior Fate Scientist

Environmental Fate and Effects Division

U.S. Environmental Protection Agency

Office of Pesticide Programs

Environmental Fate and Effects Division

Environmental Risk Branch I

1200 Pennsylvania Ave., NW

Washington, DC 20460

S. Environmental Protection Agency

Office of Pesticide Programs

e and Effects Division

Environmental Risk Branch I

1200 Pennsylvania Ave., NW

Mail Code 7507P 

Washington, DC 20460
6 

Contents 

1 Introduction ............................................................................................................................. 7

2 Previous Assessments ............................................................................................................. 7

3 Overview of Captan Use ......................................................................................................... 9

4 Environmental Fate Summary .............................................................................................. 13

5 Ecological Effects Summary................................................................................................. 16

5.1 Parent: Captan ................................................................................................................ 16

5.1.1 Changes to Toxicity Endpoints and Study Classifications ..................................... 20

5.2 Captan Degradates.......................................................................................................... 21

5.3 Review of Incident Databases ........................................................................................ 22

6 Risk Hypothesis .................................................................................................................... 24

7 Exposure Pathways of Concern ............................................................................................ 24

8 Analysis Plan ........................................................................................................................ 24

8.1 Stressors of Concern....................................................................................................... 25

8.2 Measures of Exposure .................................................................................................... 25

8.3 Measures of Effect ......................................................................................................... 25

8.4 Integration of Exposure and Effects ............................................................................... 26

8.5 Drinking Water Assessment ........................................................................................... 26

8.6 Endangered Species Assessments .................................................................................. 26

8.7 Endocrine Disruptor Screening Program ....................................................................... 27

9 Data Gaps .............................................................................................................................. 27

9.1 Environmental Fate Data ................................................................................................ 28

9.1.1 Environmental Fate Data for Degradate, THPI ...................................................... 30

9.2 Ecological Effects Data .................................................................................................. 30

10 References ............................................................................................................................. 36

11 Bibliography of Cited MRIDs .............................................................................................. 37

Appendix A: Chemical Structures of Captan and Its Degradates ................................................. 42

Appendix B: SIP (v 1.0) Inputs and Results ................................................................................. 43

Appendix C: STIR (v 1.0) Inputs and Results .............................................................................. 45

 
7 

1 Introduction 

The purpose of this problem formulation is to provide an understanding of the environmental 

fate and ecological effects of the registered uses of captan in support of Registration Review. 

Captan is a non-systemic, broad-spectrum fungicide that inhibits normal cell division of 

microorganisms and fungi. Captan is registered for agricultural use on orchard and vineyard 

crops, beets, corn, cotton, cucurbits, forage grasses, ginseng, grain crops, legumes, melons, 

peanuts, potatoes, rapeseed, soybeans, strawberries, and vegetables. In addition, captan is 

registered for non-agricultural use on turf, grasses grown for seed, and ornamental woody 

shrubs, vines, trees, and herbaceous plants. 

2 Previous Assessments 

Captan was first registered as a pesticide under the Federal Insecticide, Fungicide and 

Rodenticide Act in 1951 to control fungal diseases of fruit crops. Prior to 1980, there were many 

use patterns registered and tolerances established for this broad-spectrum fungicide. 

The captan Reregistration Eligibility Decision (RED) document was completed in September 

19994

. The RED ecological risk assessment (DP 207651+) identified risk to: 

• birds from chronic exposure5; 

• mammals from chronic exposure; 

• listed and non-listed freshwater fish from acute exposure; and 

• listed freshwater invertebrates from acute exposure. 

The Agency assessment determined that the data were sufficient to support reregistration of 

products containing captan, except for those with uses on turf and aerially-applied wettable 

powder formulations. Products applied to turf at sod farms or golf courses were eligible for 

reregistration; uses at all other turf sites were voluntarily cancelled. Wettable powder 

formulations that are applied aerially were eligible for reregistration, provided either: 1) the 

products are packaged in water soluble packaging; or 2) the application rates are reduced to a 

level that is no higher than 1.2 lb a.i./A.

An amendment to the RED was issued on November 1, 20044

. The amendment included the 

following ecological risk mitigations: 

• The dichondra, ornamental grass, golf course turf, and turf sod farm use rates have been 

reduced from a single application rate of 43 lb a.i./A to 4.3 lb a.i./A. Two applications per 

year are allowed for a seasonal maximum application rate of 8.6 lb a.i./A. 

• Spray drift language has been modified to include an additional requirement for a 

maximum nozzle height of 4 feet above the crop canopy with ground boom application. 

 

4

http://www.epa.gov/oppsrrd1/reregistration/captan/

5 The potential for chronic risk to avian species is uncertain because test animals were not dosed at levels sufficient 

to cause an effect. However, multiple applications of captan at the minimum application interval would potentially 

result in maximum residues greater than the NOEL of 1000 mg/kg-diet for most avian food items.
8 

• Application restrictions for products used on turf have been expanded to specify a 

prohibition on applications to turf in residential sites, apartment buildings, daycare 

centers, playgrounds, sports fields, or other residential areas. 

An endangered species assessment for listed Pacific Anadromous salmon and steelhead was 

conducted in 20036. This regional assessment concluded that use of captan in the Pacific 

Northwest may have the following effects on salmonid evolutionarily significant units (ESUs): 

• may affect the Upper Columbia ESU of chinook salmon and the Snake River ESU of 

sockeye salmon; 

• may affect, but not likely to adversely affect, the Snake River fall-run, Upper Willamette, 

Lower Columbia, and Puget sound ESUs of chinook salmon and the Snake River Basin, 

Upper Columbia River, Middle Columbia River, Upper Willamette River, South-Central 

California Coast, and Southern California Coast ESUs of steelhead; and 

• no effect on California Coastal, Central Valley spring-run, and Sacramento River winter 

run ESUs of chinook salmon, the ESUs of coho and chum salmon considered, the Ozette 

Lake ESU of sockeye salmon, and the Lower Columbia River, Norther California, 

Central California Coast, and Central Valley, California ESUs of steelhead. 

In 2006, an ecological risk assessment was conducted in response to the IR-4 petition for use of 

captan on ginseng (DP 318448+). The assessment was for a maximum single application rate of 

2.0 lb a.i./A applied up to 8 times with a minimum application interval of 7 days. The 

assessment concluded that there is potential for risk to mammals from chronic exposure and 

freshwater fish from acute exposure due to the use of captan on ginseng. 

A litigation assessment for the federally-threatened California Red-legged Frog (CRLF; Rana 

aurora draytonii) was conducted in 20077

. Overall, a likely to adversely affect (LAA) 

determination was concluded for the aquatic-phase CRLF, based on direct acute effects and 

indirect effects related to fish and frogs as food items to adult frogs. For the terrestrial-phase 

CRLF, an LAA determination was concluded based on direct effects and indirect effects related 

to a reduction in mammals and frogs as food items. Given these direct and indirect effects to the 

CRLF, the assessment concluded that modification of critical habitat is also expected for both 

aquatic and terrestrial primary constituent elements (PCEs) of the CRLF. 

Most recently, a 2012 ecological risk assessment evaluated a Section 24(c) Special Local Need 

(SLN) for the use of captan on strawberries in Florida to control botrytis and leaf spot (DP 

400401). The assessment was for a maximum application rate of 72 lb a.i./A/year, 

corresponding to 3 crop cycles. The assessed label specified a maximum single application rate 

of 3 lb a.i./A, a maximum seasonal rate per berry crop cycle of 24 lb a.i./A (i.e., 8 individual 

applications at 3 lb a.i./A), and an application interval of 7 to 14 days. The assessment 

concluded that there is potential for risk to freshwater fish from acute exposure; birds and 

mammals from acute and chronic exposure; and terrestrial plants due to the proposed use of 

captan. 

 

6

http://epa.gov/espp/litstatus/effects/#captan

7

http://epa.gov/espp/litstatus/effects/redleg-frog/index.html#captan
9 

A drinking water assessment was performed as a part of EFED's RED Chapter for captan (DP 

207651+). 

3 Overview of Captan Use 

Registered uses of captan are provided in Table 3-1. Captan is formulated as dust, flowable 

concentrate, liquid, water dispersible granule (dry flowable), and wettable powder and can be 

applied by aerial equipment or ground equipment. Methods of application include: band 

treatment, broadcast, dip treatment, foliar treatment, spray (including high volume), soak, soil 

treatment (including drench), soil in-furrow treatment, wash, and seed treatment. Application 

information for each use is provided in Table 3-2. It should be noted that some labels do not 

specify one or more of the following parameters: maximum number of applications per crop 

cycle or year; maximum application rate per crop cycle or year; and/or minimum application 

interval. The registrant(s) should provide this information to reduce the use of conservative 

assumptions. 

Table 3-1. Registered Uses of Captan 

Spray-Based Application Methodsa, Food Use 

 Almond Apple Apricot Blackberry 

Blueberry Caneberries Cheery Dewberry 

Ginseng (medicinal) Grapes Nectarine Peach 

Plum Prune Raspberry (black, red) Strawberry 

Seed Treatment, Non-Food Use 

Alfalfa Barley Beans, dried-type Bean, succulent (snap) 

Beets (unspecified) Broccoli Brussels sprouts Cabbage 

Canola/rape Cauliflower Chard, Swiss Clover 

Corn, field Corn, sweet Cotton (unspecified) Cowpea/blackeyed pea 

Cucumber Flax Grasses grown for seed kale 

Lespedeza Melons, cantaloupe Melons, musk Melons, water 

Mustard Oats Onion Peanuts (unspecified) 

Peas, dried-type Peas, succulent Peas (unspecified) Pepper 

Potato, white/Irish Pumpkin Radish Rye 

Sorghum (unspecified) Soybeans (unspecified) Spinach Squash (all or unspecified) 

Sugar beet Sunflower Tomato Trefoil 

Turnip (greens) Turnip (root) Wheat 

Spray-Based Application Methodsa, Non-Food Use 

Ginseng (medicinal) Golf course turf Ornamental and/or shade 

trees 

Ornamental herbaceous 

plants 

Ornamental lawns and turf Ornamental sod farm 

(turf) 

Ornamental woody shrubs 

and vines 

Rose 

a

 for each use, may include one or more of the following methods of application: band treatment, broadcast, dip 

treatment, foliar treatment, spray (including high volume), soak, soil treatment (including drench), soil in-furrow 

treatment, wash 

Table 3-2. Application Information for Registered Uses of Captan 

Use a.i. Max. Single 

App. Rate 

Max. No. of 

App. per 

Crop Cycle 

Max. App. 

Rate per Crop 

Cycle 

(lb a.i./A) 

Max. No. 

of App. 

per Year 

Min. 

App. 

Interval 

(Days) 

Strawberry 3.3 lb/A NS 26.4 NS 7 

0.0001 lb/linear ft 4 NS NS 7 
10 

Use a.i. Max. Single 

App. Rate 

Max. No. of 

App. per 

Crop Cycle 

Max. App. 

Rate per Crop 

Cycle 

(lb a.i./A) 

Max. No. 

of App. 

per Year 

Min. 

App. 

Interval 

(Days) 

Ginseng (medicinal) 2.0 lb/A 8 16.0 NS 7 

Orchard Crops 

Almond 4.9 lb/A NS 22.0 NS NSa

Apple 

4.4 lb/A NS 35.2 NS 5 

0.009 lb/gal NS NS 2 7 

0.013 lb/gal NS 32.5 or NS NS NS 

0.014 lb/gal NS 35.2 NS NS 

Apricot 2.7 lb/A NS 13.7 NS NSb

Cherry 

2.2/3.2 lb/A NS 15.4/13.8 NS 3 

0.009 lb/gal NS NS 4 7 

0.013 lb/gal NS 14.2 or NS NS NS 

0.014 lb/gal NS 15.4 NS NS 

Nectarine 4.4 lb/A NS 26.4 NS 3 

Peach 

4.4 lb/A NS 35.2 NS 3 

0.009 lb/gal NS NS 3 11 

0.02 lb/A NS 32.6 NS NS 

Pear 0.014 lb/gal NS NS NS NS 

Plum/Prune 3.3 lb/A NS 29.7 NS 7 

Vineyard Crops 

Blackberry 2.2 lb/A NS 11.0 NS 10 

Blueberry 2.7 lb/A NS 38.5 NS 7 

Caneberries 2.0 lb/A NS 10 NS 10 

Dewberry 2.2 lb/A NS 11.0 NS 10 

Grapes 2.2 lb/A NS 13.2 NS 10 

Raspberry (black, red) 2-2.2 lb/A NS 10-11.0 NS 7 or 10 

Turf 

Golf course turf 4.4 lb/A NS 8.8 NS 7 

Ornamental lawns and turf 47.8 lb/A NS NS NS 7 

6.5-6.6 lb/A NS 8.6 or NS NS NS 

Ornamental sod farm (turf) 4.3-4.4 lb/A NS 8.5-8.8 or NS NS 7 or NS 

Ornamentals 

Ornamental and/or shade 

trees 

6.5 lb/A NS NS NS NS 

0.0054 lb/gal NS NS 4 7 

Ornamental herbaceous 

plants 

184.3-184.7 lb/A 2 or NS 8.6 NS 7 

44.2 lb/A NS NS NS 7 

0.0054 lb/gal NS NS 6 7 

0.0825 lb/gal NS NS NS NS 

Ornamental woody shrubs 

and vines 

6.6 lb/A NS NS NS NS 

0.021 lb/gal NS NS NS 7 or NS 

Rose 0.0054 lb/gal NS NS 6 7 

0.012 lb/gal NS NS NS 7 

Seed Treatments 

Alfalfa 0.2545 lb/lb seed NS NS NS NS 

Barley 0.0954 lb/lb seed NS NS NS NS 

Beans, dried type 0.0938 lb/lb seed NS NS NS NS 

Beans, succulent (snap) 0.0938 lb/lb seed NS NS NS NS 

Beets (unspecified) 0.3817 lb/lb seed NS NS NS NS 

Broccoli 0.07 lb/lb seed NS NS NS NS 

Brussels sprouts 0.07 lb/lb seed NS NS NS NS 

Cabbage 0.07 lb/lb seed NS NS NS NS 
11 

Use a.i. Max. Single 

App. Rate 

Max. No. of 

App. per 

Crop Cycle 

Max. App. 

Rate per Crop 

Cycle 

(lb a.i./A) 

Max. No. 

of App. 

per Year 

Min. 

App. 

Interval 

(Days) 

Canola/rape 0.0625 lb/lb seed NS NS NS NS 

Cauliflower 0.07 lb/lb seed NS NS NS NS 

Chard, Swiss 0.3817 lb/lb seed NS NS NS NS 

Clover 0.2545 lb/lb seed NS NS NS NS 

Collards 0.0283 lb/lb seed NS NS NS NS 

Corn, field 0.0743 lb/lb seed NS NS NS NS 

Corn, sweet 0.1272 lb/lb seed NS NS NS NS 

Cotton (unspecified) 0.2227 lb/lb seed NS NS NS NS 

Cowpea/blackeyed pea 0.0938 lb/lb seed NS NS NS NS 

Cucumber 0.1018 lb/lb seed NS NS NS NS 

Flax 0.1272 lb/lb seed NS NS NS NS 

Grasses grown for seed 0.2608 lb/lb seed NS NS NS NS 

Kale 0.0283 lb/lb seed NS NS NS NS 

Lentils 0.0788 lb/lb seed NS NS NS NS 

Lespedeza 0.2545 lb/lb seed NS NS NS NS 

Melons - cantaloupe 0.1018 lb/lb seed NS NS NS NS 

Melons - musk 0.0636 lb/lb seed NS NS NS NS 

Melons - water 0.0636 lb/lb seed NS NS NS NS 

Mustard 0.0625 lb/lb seed NS NS NS NS 

Oats 0.1272 lb/lb seed NS NS NS NS 

Onion 0.8143 lb/lb seed NS NS NS NS 

Peanuts (unspecified) 0.1909 lb/lb seed NS NS NS NS

Peas (unspecified) 0.0827 lb/lb seed NS NS NS NS 

Peas, dried-type 0.0611 lb/lb seed NS NS NS NS 

Peas, succulent 0.0611 lb/lb seed NS NS NS NS 

Pepper 0.0945 lb/lb seed NS NS NS NS 

Potato, white/Irish 0.0733 lb/lb seed NS NS NS NS 

Pumpkin 0.0636 lb/lb seed NS NS NS NS 

Radish 0.07 lb/lb seed NS NS NS NS 

Rye 0.0954 lb/lb seed NS NS NS NS 

Sorghum (unspecified) 0.1909 lb/lb seed NS NS NS NS

Soybeans (unspecified) 1.2 lb/lb seed NS NS NS NS 

0.0246 lb/cu ft NS NS NS NS 

Spinach 0.2099 lb/lb seed NS NS NS NS 

Squash (all or unspecified) 0.0636 lb/lb seed NS NS NS NS 

Sugar beet 0.3817 lb/lb seed NS NS NS NS 

Sunflower 0.1272 lb/lb seed NS NS NS NS 

Tomato 0.0528 lb/lb seed NS NS NS NS 

Trefoil 0.2545 lb/lb seed NS NS NS NS 

Turnip (greens) 0.0625 lb/lb seed NS NS NS NS 

Turnip (root) 0.0954 lb/lb seed NS NS NS NS 

Wheat 0.1251 lb/lb seed NS NS NS NS 

App. = application; Min. = minimum; Max. = maximum; NS = not specified 

a A 7-day application interval was assumed in the 7007 CRLF litigation assessment. 

b

 A 5-day application interval was assumed in the 2007 CRLF litigation assessment. 
12 

The results of a Screening Level Usage Analysis (SLUA) for captan8 as performed by the 

Biological Economic Analysis Division (BEAD) of OPP are listed in Table 3-3. This analysis 

provides estimated agricultural uses of captan (i.e., turf uses are not included) in terms of total 

pounds of active ingredient. SLUA data sources include: 

• USDA-NASS (United States Department of Agriculture's National Agricultural Statistics 

Service) 

• Private Pesticide Market Research 

• California DPR (Department of Pesticide Regulation)

The top 5 agricultural uses of captan from 2003 to 2010 in terms of pounds of a.i. applied are 

apples, strawberries, peaches, almonds, and blueberries. 

Table 3-3. Screening Level Estimates of Agricultural Uses of Captan Sorted Alphabetically

(Reporting Timeframe: 2003-2010)

Crop Average Annual 

Lbs. A.I. 

Annual Percent Crop Treated 

Average Maximum 

1 Almonds 200,000 5 10 

2 Apples 1,400,000 40 45 

3 Apricots 10,000 30 60 

4 Beans, Green 1,000 <1 <2.5 

5 Blueberries 100,000 50 60 

6 Caneberries 40,000 45 70 

7 Cantaloupes <500 <1 <2.5 

8 Cherries 60,000 15 25 

9 Cucumbers 2,000 <1 <2.5 

10 Grapes 40,000 <2.5 <2.5 

11 Nectarines* 3,000 N/C N/C 

12 Onions <500 <2.5 <2.5 

13 Peaches 300,000 25 40 

14 Peanuts 

Peanuts (seed treatment) 

20,000 

5,000 

<1 

5 

<2.5 

5 

15 Pears 1,000 <1 <2.5 

16 Peppers 3,000 <1 <2.5 

17 Plums/Prunes 90,000 25 40 

18 Pumpkins 2,000 <1 <2.5 

19 Soybeans (seed treatment) 1,000 <1 <2.5 

20 Squash <500 <1 <2.5 

21 Strawberries 400,000 75 90 

22 Tomatoes 3,000 <1 <2.5 

23 Watermelons <500 <1 <2.5 

24 Wheat (seed treatment) 3,000 <1 <2.5 

N/C= not calculated since only pounds a.i. available 

All numbers rounded. 

<500 Less than 500 pounds of a.i. 

 <2.5 Less than 2.5% of crop treated 

 <1 Less than 1% crop treated 

* Based on CA DPR data only (80% or more of U.S. acres grown are in California) 

 

8

 Date: June 12, 2012 
13 

4 Environmental Fate Summary 

Selected physical, chemical, and environmental fate properties of captan are listed in Table 4-1. 

Captan has a low solubility (3.3 mg/L at 25°C) in water. The vapor pressure (<9.75 × 10-6 mm 

Hg) and Henry's Law Constant (4.6 x 10-9atm-m3/mol) indicate that captan is a low-volatile 

chemical. Over a 9-day period, approximately 0.003% of ring-labeled captan volatilized from a 

sand soil treated at a rate of 1 lb a.i./A in a laboratory volatility study. Laboratory studies also 

suggest that captan has a relatively short degradation half-life (t1/2 <1 to 15days) in soil and 

aquatic environments. Abiotic hydrolysis and aerobic metabolism appear to be the major routes 

of captan dissipation in the environment. In both soil and water, the sulfur-nitrogen bond 

cleaves, thus separating the trichloromethylthio (TCMT) and tetrahydrophthalamide (THPI) 

moieties of the molecule. The TCMT moiety degrades by aerobic soil metabolism to form CO2, 

thiophosgene, and inorganic sulfur and chlorine. Dissipation of thiophosgene is expected to be 

controlled by volatilization (est. vapor pressure=29.7 mm Hg and estimated Henry’s Law 

Constant of 0.00586 atm•M-3 mole-1). It should be noted that thiophosgene was not detected as a 

volatile component in any of the submitted laboratory studies for captan. In aerobic aquatic 

metabolism study, the maximum reported THPI concentration (81.2% of applied) detected at day 

0 and tetrahydrophthalimic acid (THPAm) (27.0% of applied) and tetrahydrophthalic acid 

(THPAL) (10.8% of applied) reached their maximum at day 14. THPI and THPAm were also 

major degradates identified in aerobic soil metabolism study. Captan photodegradation on soil 

also occurs, but is secondary to hydrolysis and aerobic soil metabolism. 

THPI is degraded (t1/2 = 5.8 to 20 days) by aerobic soil metabolism to a series of ring-containing 

products (including THPAm) and ultimately CO2 (MRID 438689-02). Evidence indicates that 

THPI is more persistent (t1/2 of 5.8 to 20 days) than parent compound which may be present in 

soil for several weeks following captan application (Table 4.2). An additional cyano-acid major 

metabolite, cis-6-cyano-3-cyclohexenecarboxylic acid (THCY) of captan was also identified in 

anaerobic soil metabolism and soil photolysis studies. A maximum 20% of applied was detected 

in anaerobic soil metabolism study. THCY is unlikely to be present in soil in significant 

amounts under aerobic soil condition. Two minor degradates were also detected in laboratory 

studies. These degradates are tetrahydrophthalamide epoxide (THPI-Epoxide) and 5,6 

dihydroxyhexaryohophthalamide (Diol). Various degradate structures of captan can be found in 

Appendix A. 

Since captan is unstable due to rapid hydrolysis, batch equilibrium adsorption/desorption is not a 

reliable method to determine adsorption/desorption coefficient of captan. Soil Kd values were 

estimated using soil thin layer chromatography (TLC) method. Soil Koc of 103 to 575 ml/g 

indicate that captan is generally expected to be mobile to moderate mobile in soil according to 

FAO pesticide mobility classification (FAO 2000). Koc values of 33 to 600 have also been 

reported in the open literature9

 for captan. In terrestrial field studies, however, captan was shown 

to be relatively immobile to slightly mobile at 6 different field sites. Soil Adsorption coefficient 

(Koc) values for THPI ranged from 8.3 to 13 L/kg in six soils (MRID 438689-11) and is 

expected to be mobile with surface water runoff or leaching into the soil (Table 4-2). 

 

 

9

http://toxnet.nlm.nih.gov/cgi-bin/sis/search/f?./temp/~ixIqg7:1
Table 4-1. Selected Physical and Chemical Properties of Captan

Parameter 

Chemical Structure 

Chemical Name 

Chemical Name (CAS) 

Chemical Name (IUPAC) 

Smiles notation 

CAS Number 

PC Code 

Molecular Formula 

Molecular Weight 

Physical State 

Color 

Odor 

Density 

Vapor pressure 

Water Solubility (pH 7, 25oC) 

Henry’s law constant 

Octanol/Water Partition Coefficient 

(logKow) 

Laboratory Volatility 

Hydrolysis 

pH 5 

pH 7 

pH 9 

Photodegradation in water (pH 5) 

Photodegradation in soil 

Aerobic soil metabolism half-life 

14 

1. Selected Physical and Chemical Properties of Captan

Value and Unit Sources 

MRID 48112502

Captan MRID 48112502

3a,4,7,7a-tetrahydro-2-[(trichloro 

methyl)thio]-1H-isoindole-1,3(2H)-

dione 

MRID 48112502

N-(trichloromethylthio)cyclohex-4-

ene-1,2-dicarboximide 

MRID 48112502

O=C(N(SC(Cl)(Cl)Cl)C(=O)C1CC=C

C2)C12 

EPISUITE 4.1

133-06-2 MRID 48112502

081301 MRID 48112502

C9H8CI3NO2S MRID 48112502

300.57 gram/mol MRID 48112502

Amorphous powder MRID 48112504

White to beige MRID 48112504

Odorless MRID 48112504

1.62g/cm3 @ 22°C MRID 48112504

<1.3 mPa at 25°C 

<9.75x 106 mm Hg at 25°C 

Pesticide Manual, 15

cited in MRID

3.3 mg/L at 25°C Pesticide Manual, 15

cited in MRID 481125

4.6 E-09 atm.M3 Mol-1 EPISUITE 4.1

2.8 Pesticide Manual, 15

cited in MRID 481125

0.003% Volatilized over 9 day period MRID 40231001

0.8 days 

0.20 days 

0.006 days 

MRIDs 41176301

00096974 

Stable MRID 40208102

15 days 

Degradates

THPI (21.3%) 

THCY (9.4%) 

MRIDs 40658009

1.1 daysa

<1.0 days 

Major Degradates

THPI (66.0%) 

THPAm (16.5%) 

Minor Degradates (≤ 3.2) 

THPAI 

MRIDs 00070414

02

02

02

02

02

02

02

02

04

04

04

04

Pesticide Manual, 15th ed, p-155 

48112504 

Pesticide Manual, 15th ed, p-155 

MRID 48112504 

Pesticide Manual, 15th ed, p-155 

MRID 48112504 

MRID 40231001

41176301, 40208101, 

40208102

658009, 40658010 

s 00070414 and 40658007 
15 

Parameter Value and Unit Sources 

Diol 

THPI-Epoxide

Anaerobic soil metabolism half-life <1.0 days 

Metabolitesb

THPI (≈46%) 

THPAm (≈35%) 

THPAI (≈22%) 

THCY (≈20%) 

MRIDs 00098881, 40658008 

Aerobic aquatic metabolism half-life <1.0 days 

Degradates 

THPI (81.2%) 

THPAm (27%) 

THPAL (10.8%) 

THPI Epoxide (9.4%) 

MRIDs 00096974, 40114502, 

43868905 

Soil Kd (Koc) Mackburg Silt clay loam- 4 (164) ml/g

 Crowley clay loam – 3 (185) ml/g 

Stockton Adobe clay 8 (585) ml/g 

Oakley sandy loam 7 (549) ml/g 

Nicollet clay loam 4 (103) ml/g 

MRIDs 00096972, 4065801 

Terrestrial Field Dissipation (t 1⁄2 ) Study Sites 

 Florida 3 days 

 California 24 days 

 Florida 3 days 

 California 6 days 

 New York 14 days 

 Texas 4 days 

MRIDs 40823901, 40893601, 

40893602, 40893603, 40932201, 

40932202 

Bioconcentration (BCFs) 102X for edible 

126X non-edible 

113X whole fish 

MRIDs 40756601, 40756602 

a

= No reported half-life. Estimated based on first-order degradation equation using 99% applied captan degraded in 

7 day 

b

 = Visual estimates. Degradates estimate were presented in a graphic form in the Data Evaluation Report. 

Table 4-2. Environmental Fate Properties for the Degradate, THPI 

Parameters Values and Unit Sources 

Chemical Structure EPISUIE 4.1 

Chemical Name 1,2,3,6-Tetrahydrophthalimide MRID 43868902 

Soil Partition Coefficient Kd(Koc) Gayton loamy sand - 0.16 (9.1) ml/g 

East Anglia sandy loam – 0.16 (8.6) 

Kenny Hill sandy loam 0.23 (7.6) ml/g 

Lily field sand 0.04 (8.3) ml/g 

Nebo silty clay loam 0.19 (13) ml/g 

Salmonds Bridge sandy loam 0.13 

(8.4) ml/g 

MRID 438689-11 

Molecular Weight 151.6 EPISUITE 4.1 

Solubility (25° C) 42778 mg/L EPISUITE 4.1 

Aerobic soil Metabolism t1/2 5.8 - 20.0 days MRID 43868902 

Aerobic Aquatic Metabolism Half-Life 21 days MRID 00098881 
16 

Captan has a low potential for bioaccumulation in fish due to rapid hydrolysis in aquatic 

environments and low log Kow (2.79) (Table 4-1). Captan residues had fish bioconcentration 

factors (BCF) of 102X, 126X, and 113X for edible, non-edible, and whole fish tissue, 

respectively. After a 14-day depuration period, captan residues in edible tissue, non-edible 

tissue, and whole fish declined by 94%, 96%, and 95%, respectively. 

In terrestrial field dissipation study, parent captan degraded with half-lives of 3 to 24 days and 

was relatively immobile to slightly mobile at six sites. The maximum depth at which captan was 

detected was 6-12 inches. The degradate THPI was detected at all sites and declined to less than 

detectable (0.01 ppm) levels between 14 and 184 days after the final captan treatment. THPI was 

not detected below 12 inches of soil profiles. 

5 Ecological Effects Summary 

5.1 Parent: Captan 

Studies characterizing the toxicity of captan are summarized in Table 5-1. No studies have been 

submitted since the 2007 CRLF litigation assessment. 

Captan is practically non-toxic to birds on an acute oral and sub-acute dietary basis; practically 

non-toxic to terrestrial invertebrates on an acute contact basis; and moderately toxic to very 

highly toxic to fish and aquatic invertebrates on an acute basis. 

Data are not available for the following:

• acute toxicity to a passerine species; 

• acute oral toxicity to adult honey bees (Apis mellifera); 

• acute oral toxicity to larval honey bees (Apis mellifera); 

• toxicity to terrestrial plants (seedling emergence and vegetative vigor); 

• chronic toxicity to an estuarine/marine fish; 

• chronic toxicity to estuarine/marine invertebrate; 

• toxicity to a freshwater diatom (aquatic non-vascular plant); and 

• a definitive NOEC for the cyanobacterium Anabaena flos-aquae. 

It should be noted that the avian endpoints for acute oral and sub-acute dietary toxicity are nondefinitive (i.e., LD50 or LC50 > highest dose or concentration tested). For avian acute oral 

toxicity, the highest concentrations tested, 2150 and 2000 mg/kg-bw for bobwhite quail and 

mallard duck, respectively (MRIDs 00151236 and 00160000), are less than the highest avian 

EECs calculated in the most recent assessments (i.e., 4968 mg/kg-bw in the 2007 CRLF 

litigation assessment; 6107 mg/kg-bw in the 2012 Section 24(c) SLN assessment, DP 400401), 

and sublethal effects including weight loss, ataxia, and tremors were noted in the studies. 

For avian sub-acute dietary toxicity, the highest concentration tested, 4680 mg/kg-diet (if 

corrected for % a.i.) for both bobwhite quail and mallard duck (MRIDs 43869802 and 

43869803), is greater than the highest avian EEC of 4362 mg/kg-diet calculated in the 2007 
17 

CRLF litigation assessment, but less than the highest avian EEC of 5112 mg/kg-diet calculated 

in the 2012 Section 24(c) SLN assessment (DP 400401). Furthermore, there was 30% (3 out of 

10) mortality in the 5200 mg/kg-diet treatment group in the bobwhite quail study, and reduced 

body weight gain was noted at ≥ 2600 mg/kg-diet for both species. 

Table 5-1. Summary of the Endpoints from Toxicity Studies with Captan 

Study Type

TGAI/TEP 

(% a.i.) 

Species Toxicity Endpoints, Effects, and 

Acute Toxicity Classification (If Applicable)

Source & Study 

Classification 

Acute oral 

(NS) 

Bobwhite quail 

(Colinus 

virginianus)

14-day LD50 > 2150 mg/kg-bw (nom) 

(no mortality; sublethal effects: reduced body 

weight gain/weight loss at 2150 mg/kg-bw) 

Practically non-toxic 

MRID 00151236 

Acceptable 

Acute oral limit 

test 

TGAI (91)

Mallard duck 

(Anas 

platyrhynchos)

14-day LD50 > 2000 mg/kg-bw (nom) 

(no mortality; sublethal effects: ataxia, tremors 

with remission taking up to 1 week) 

Practically non-toxic 

MRID 00160000 

Supplemental 

(due to sample size 

of n = 3) 

Acute oral Passerine species No data 

Sub-acute 

dietary 

TGAI (95)

Bobwhite quail 

(Colinus 

virginianus)

8-day LC50 > 2400 mg/kg-diet (nom) 

(no mortality; sublethal effects: not documented) 

No more than slightly toxic 

MRID 00022923 

Supplemental 

(due to sample size 

of n = 8 per 

treatment level and 

lack of 

documentation of 

sublethal effects) 

Sub-acute 

dietary 

TGAI (95)

Mallard duck 

(Anas 

platyrhynchos) 

8-day LC50 > 5000 mg/kg-diet (nom) 

(no mortality; sublethal effects: not documented) 

Practically non-toxic 

MRID 00022923 

Supplemental 

(due to only 3 

treatment levels 

being tested and 

lack of 

documentation of 

sublethal effects) 

Sub-acute 

dietary 

TGAI (90) 

Bobwhite quail 

(Colinus 

virginianus)

8-day LC50 > 5200 mg/kg-dieta (nom) 

8-day NOEC = 1300 mg/kg-dieta (nom) 

(mortality: 3.3% [1 out of 30] in the control group; 

30% [3 out of 10] at 5200 mg/kg-diet sublethal 

effects: NOEC based on reduced food 

consumption and body weight gain at ≥ 2600 

mg/kg-diet) 

Practically non-toxic 

MRID 43869802 

Acceptable 

Sub-acute 

dietary 

TGAI (90) 

Mallard duck 

(Anas 

platyrhynchos) 

8-day LC50 > 5200 mg/kg-dieta (nom) 

8-day NOEC = 1300 mg/kg-dieta (nom) 

(mortality: 3.3% [1 out of 30] in the control group; 

none in the treatment groups; 

sublethal effects: NOEC based on reduced food 

consumption and body weight gain at ≥ 2600 

mg/kg-diet) 

Practically non-toxic 

MRID 43869803 

Acceptable 
18 

Study Type

TGAI/TEP 

(% a.i.) 

Species Toxicity Endpoints, Effects, and 

Acute Toxicity Classification (If Applicable)

Source & Study 

Classification 

Chronic 

TGAI (NS) 

Bobwhite quail 

(Colinus 

virginianus)

8-week LC50 > 4640 mg/kg-diet 

8-week NOEC = 2150 mg/kg-diet 

(no mortality; sublethal effects: NOEC based on 

reduced weigth gain and food consumption at 4650 

gm/kg-diet) 

MRID 000104686 

Supplemental 

(due to deviations 

from guideline; 

range-finding 

study) 

Reproduction 

(chronic) 

(NS) 

Bobwhite quail 

(Colinus 

virginianus)

NOEC = 1000 mg/kg-diet (nom) 

(no effects) 

MRID 00098295 

Acceptable 

Reproduction 

(chronic) 

(NS)

Mallard duck 

(Anas 

platyrhynchos)

NOEC = 1000 mg/kg-diet (nom) 

(no effects) 

MRID 00098296 

Acceptable 

Acute contact 

TEP: Captan 

50WP (48.9) 

Blue orchard bee 

(Osmia ligaria) 

72-hr LD50 (95% C.I.) = 270 (151-2842) μg a.i./bee

Practically non-toxic 

E087252d

Quantitative 

Acute oral 

TEP: Captan 

50WP (48.9) 

Blue orchard bee 

(Osmia ligaria) 

72-hr LC50 (95% C.I.) = 46 (33-77) μg a.i./bee 

Practically non-toxic 

Acute contact 

limit 

TGAI (NS) 

Honey bee 

(Apis mellifera) 

48-hr LD50 > 215 μg/bee 

Practically non-toxic 

MRID 00080871 

Acceptable 

Terrestrial plant 

seedling 

emergence 

No data 

Terrestrial plant 

vegetative vigor No data 

Acute 

TGAI (90) 

Freshwater fishb, 

most sensitive: 

Brown trout

(Salmo trutta) 

96-hr LC50 (95% C.I.) = 26.2 (21.8-31.3) μg/L 

(nom) 

Very Highly Toxic 

MRID 40098001 

Supplemental 

(due to only 1 

replicate per 

treatment 

concentration) 

Acute 

TGAI (90) 

Bluegill sunfish 

(Lepomis 

macrochirus) 

96-hr LC50 (95% C.I.) = 310 (280-340) μg/La

(nom) 

Highly toxic 

MRID 00162740 

Acceptable 

Chronic 

TGAI (88.4) 

Fathead minnow 

(Pimephales 

promelas) 

NOEC = 16.5 μg a.i./L (mm) 

LOEC = 39.5 μg a.i./L (mm) 

(based on reductions in parental and F1 survival 

and growth) 

E000945d 

(MRID 00057846) 

Qualitative 

Acute 

TGAI (99.8) 

Sheepshead minnow

(Cyprinodon 

variegatus) 

96-hr LC50 (95% C.I.) = 1926 (1816-2046) μg 

a.i./L (im) 

Probit slope (95% C.I.) = 8.4 (6.8-10.0) 

96-hr NOEC = 1000 μg a.i./L (im) 

NOEC based on 35% (7 out of 20) mortality at 

1700 μg a.i./L 

Moderately toxic 

MRID 44806504 

Acceptable 

Acute 

TGAI (90) 

Water flea 

(Daphnia magna)

48-hr EC50 (95% C.I.) = 8400 (7060-9960) μg 

a.i./La

 (nom) 

Moderately Toxic 

MRID 00162739 

Acceptable 
19 

Study Type

TGAI/TEP 

(% a.i.) 

Species Toxicity Endpoints, Effects, and 

Acute Toxicity Classification (If Applicable)

Source & Study 

Classification 

Acute 

TGAI (NS) 

Water flea 

(Daphnia magna)

48-hr EC50 > 7100 μg a.i./L (m) 

No more than moderately toxic 

MRID 00070751 

Supplemental 

(due to solubility 

issues & guideline 

deviations) 

Acute 

TGAI (93.5) 

Water flea 

(Daphnia magna)

48-hr EC50 and NOEC: Could not be determined 

due to unknown exposure concentrations 

13.3% (4 out of 30) immobility at 1930 μg a.i./L 

(im) 

23.3% (7 out of 30) immobility at 3250 μg a.i./L 

(im) 

MRID 43869807 

Supplemental 

(due to uncertainty 

associated with 

measured 

concentrations 

which were below 

the limit of 

detection at test 

termination) 

Life cycle 

(chronic) 

TGAI (90) 

Water flea 

(Daphnia magna) 

21-day NOEC = 560 μg/L (nom) 

21-day LOEC = 1000 μg/L (nom) 

(based on reductions in length and number of 

young) 

MRID 44148801 

Supplemental 

(due to lack of 

measured 

concentrations 

because of 

instability of test 

material in water; 

only the stock 

concentration was 

measured) 

Acute 

TGAI (91.3) 

Eastern oyster 

(Crassostrea 

virginica) 

96-hr EC50 (95% C.I.) = 3.3 (2.2-4.9) μg a.i./L 

(mm) 

Probit slope = 9.12 

96-hr NOEC = 1.1 μg a.i./L (mm) 

Very highly toxic 

MRID 46061701 

Acceptable 

Acute 

TGAI (99.8) 

Mysid shrimp 

(Mysidopsis bahia) 

96-hr LC50 (95% C.I.) = 8435 (7160-1012) μg 

a.i./L (im) 

Probit slope (95% C.I.) = 7.6 (3.8-11.3) 

96-hr NOEC = 2800 μg a.i./L (im) 

NOEC based on 5% (1 out of 20) mortality at 5.1 

mg a.i./L 

Moderately toxic 

MRID 44806505 

Acceptable 

Aquatic vascular 

plant 

TGAI (99.8) 

Duckweed 

(Lemna gibba) 

7 day EC50 > 12700 μg a.i./L (im) 

7-day NOEC = 443 μg a.i./L (im) 

(based on frond numbers) 

MRID 44806503 

Acceptable 

Aquatic nonvascular plant 

TGAI (92.7) 

Green alga 

(Scenedesmus 

subspicatus) 

96-hr EC50 = 320 μg/L (nom) 

NOEC: Could not be determined 

(based on cell density) 

MRID 00137688 

Supplemental 

(due to lack of a 

NOEC and data 

for individual 

replicates) 

Aquatic nonvascular plant 

Tier II 

TGAI (90) 

Green alga 

(Selenastrum 

capricornutum) 

96-hr EC50 (95% C.I.) = 1970 (1800-2160) μg 

a.i./L (im) 

96-hr NOEC = 200 μg a.i./L (im) 

(based on cell density) 

MRID 43869809 

Acceptable 
20 

Study Type

TGAI/TEP 

(% a.i.) 

Species Toxicity Endpoints, Effects, and 

Acute Toxicity Classification (If Applicable)

Source & Study 

Classification 

Aquatic nonvascular plant Freshwater diatom No data 

Aquatic nonvascular plant 

Tier II (99.8) 

Cyanobacterium 

(Anabaena flosaqua) 

96-hr EC50 (95% C.I.) = 994 (814-1120) μg a.i./L 

(im) 

96-hr EC05 (95% C.I.) = 148 (NA-296) μg a.i./L 

(im) 

96-hr NOEC < 234 μg a.i./L (im) 

(based on cell density) 

MRID 44806501 

Acceptable 

Aquatic nonvascular plant 

Tier II (99.8) 

Marine diatom 

(Skeletonema 

costatum) 

96-hr EC50 (95% C.I.) = 169 (149-191) μg a.i./L 

(im) 

96-hr NOEC = 32.3 μg a.i./L (im) 

(based on cell density) 

MRID 44806502 

Acceptable 

Aquatic nonvascular plant 

Tier II (99.8) 

Marine algaec, 

most sensitive: 

Skeletonema 

costatum

48-hr EC50 = 160 μg/L (nom) MRID 40228401 

Supplemental 

(due to 48-hr 

exposure period) 

NA = not applicable; NS = not specified; C.I. = confidence interval; nom = nominal concentration; im = initialmeasured concentration; mm = mean-measured concentration 

a

 Not corrected for % a.i. 

b

 Other species tested include: Channel catfish (Ictalurus punctatus); Chinook salmon (Oncorhynchus tshawytscha); 

Coho salmon (Oncorhynchus kisutch); Cutthroat trout (Salmo clarki); Fathead minnow (Pimephales promelas); 

Lake trout (Salvelinus fontinalis); Rainbow trout (Salmo gairdneri); Yellow perch (Perca flavescens); Bluegill 

sunfish (Lepomis macrochirus) 

c

 Other species tested include: Isochrysis galbana, Pavlova lutheri, Pavlova gyrans, and Dunaliella tertiolecta 

d identified via a query of the ECOTOXicology10 database which is maintained by the U.S. EPA Office of Research 

and Development (ORD) 

5.1.1 Changes to Toxicity Endpoints and Study Classifications 

Raw data for several of the aquatic plant studies (MRIDs 44806501, 44806502, 44806503) were 

re-analyzed because previous statistical comparisons were made using the solvent control instead 

of the negative control. 

• Re-analysis of raw data for a study with Anabaena flos-aquae (MRID 44806501) yielded 

a new EC50 (994 μg a.i./L), confirmed the lack of a NOEC (< 234 μg a.i./L), and 

generated an EC05 (148 μg a.i./L) in lieu of a NOEC; the study remained classified as 

Acceptable. 

• Re-analysis of raw data for a study with Skeletonema costatum (MRID 44806502)

yielded new endpoints (EC50 = 169 μg a.i./L; NOEC = 32.3 μg a.i./L); the study remained 

classified as Acceptable. 

• Re-analysis of the raw data for a study with Lemna gibba (MRID 44806503) yielded the 

same endpoints as previously determined; the study remained classified as Acceptable. 

A NOEC could not be determined for a study with green alga Scenedesmus subspicatus (MRID 

000137688) because data for treatment replicates was not provided. Therefore, the study 

classification was downgraded to Supplemental (from Acceptable). 

 

10 http://cfpub.epa.gov/ecotox/ 
21 

The raw data for a study with green alga Selenastrum capricornutum (MRID 43869809) was reanalyzed because the previous EC50 was determined using probit analysis rather than non-linear 

Bruce and Versteeg analysis. This re-analysis yielded a new EC50 endpoint (1970 μg a.i./L); the 

study remained classified as Acceptable. 

In previous ecological risk assessments (e.g., 2004 RED; DP 318448+; 2007 CRLF litigation 

assessment; DP 400401), ECOTOX11 open literature study E000945 (MRID 00057846) was 

referenced for characterizing the toxicity of captan to freshwater fish from chronic exposure. A 

formal review of this study conducted in accordance with current guidelines for evaluating 

ecological toxicity data in the open literature12 resulted in a study classification of qualitative for 

use in the Registration Review ecological risk assessment due to significant uncertainty 

associated with exposure concentrations which varied greatly over the study. 

5.2 Captan Degradates 

Four major degradates of captan have been identified based on environmental fate studies: THPI, 

THPAm, THPAI and THCY. Studies characterizing the toxicity of THPI and THPAm to aquatic 

organisms are summarized in Table 5-2. No toxicity data are available for degradates THPAI 

and THCY. THPI and THPAm are several orders of magnitude less toxic than parent captan to 

aquatic organisms. As a result, TPHI and THPAm will not be considered stressors of concern in 

the Registration Review ecological risk assessment. Since THPAI and THCY are major 

metabolites under anaerobic conditions, substantial amounts of these degradates are unlikely to 

form in the aerobic environment due to terrestrial uses of captan. There are no aquatic uses of 

captan. Therefore, THPAI and THCY will not be considered stressors of concern in the 

Registration Review ecological risk assessment 

The classification for the study with THPI and rainbow trout (MRID 43869806) was 

downgraded to Supplemental (from Acceptable) due a guideline deviation, i.e., only 10 fish, 

rather than 30, were exposed at the limit concentration. 

Table 5-2. Summary of the Endpoints from Toxicity Studies with Captan Degradates 

THPI and THPAm 

Study Type 

TGAI/TEP 

(% a.i.) 

Species Toxicity Value, Effects, and Acute 

Toxicity Classification (If 

Applicable) 

Source and Status 

THPI 

Acute limit test 

(96) 

Rainbow trout 

(Oncorhynchus 

mykiss) 

96-hr LC50 > 120 mg a.i./L (mm) 

96-hr NOEC = 120 mg a.i./L (mm) 

(no effects) 

Practically non-toxic 

MRID 43869806 

Supplemental 

(due to only 10 fish not 30 being 

exposed at limit concentration) 

THPAm 

Acute limit test 

(95) 

Rainbow trout 

(Oncorhynchus 

mykiss) 

96-hr LC50 > 126 mg a.i./L (mm) 

96-hr NOEC = 126 mg a.i./L (mm) 

(no effects) 

Practically non-toxic 

MRID 44738801 

Supplemental 

(due to only 10 fish not 30 being 

exposed at limit concentration) 

 

11 identified via a query of the ECOTOXicology11 database (http://cfpub.epa.gov/ecotox/) which is maintained by 

the U.S. EPA Office of Research and Development (ORD) 

12

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_reregistration_work

group/esa_evaluation_open_literature.htm
22 

Study Type 

TGAI/TEP 

(% a.i.) 

Species Toxicity Value, Effects, and Acute 

Toxicity Classification (If 

Applicable) 

Source and Status 

THPI 

Acute limit test 

(96) 

Water flea 

(Daphnia magna) 

48-hr EC50 > 113 mg a.i./L (mm) 

48-hr NOEC = 113 mg a.i./L (mm) 

(no effects) 

Practically non-toxic 

MRID 43869808 

Acceptable 

THPI 

Aquatic nonvascular plant 

Tier II (96) 

Green alga 

(Selenastrum 

capricornutum) 

72-hr EC50 > 181 mg a.i./L (mm) 

72-hr NOEC = 181 mg a.i./L (mm) 

(no effects) 

MRID 43869810 

Supplemental 

(due to test being terminated 

early when algal growth was still 

in the middle of the exponential 

phase of the growth curves) 

mm = mean-measured concentration 

5.3 Review of Incident Databases 

Reviews on January 11, 2013 of the Ecological Incident Information System (EIIS, version 

2.1.1), which is maintained by the Agency’s Office of Pesticide Programs, and the Avian 

Monitoring Information System (AIMS), which is maintained by the American Bird 

Conservatory, indicate a total of five reported ecological incidents (in EIIS) associated with the 

use of captan. This total for captan excludes incidents classified as ‘unlikely’ or ‘unrelated’ and 

only includes incidents with the certainty categories of ‘possible’, ‘probable’, and ‘highly 

probable’ for EIIS. 

One of the reported captan incidents involved aquatic organisms and was a result of accidental 

misuse of the pesticide. Specifically, according to the "Summary of Reported DDT, Endrin, and 

Methyl Parathion Episodes Involving Fish from 1967 to February, 1975", there was a large fish 

kill in the state of New York on May 24, 1972 (Incident B000-245-01). A spray rig being filled 

with thiodan and captan overflowed into a stream, resulting in the death of 10,000 fish. The 

certainty index for this incident is ‘highly probable’ because although no analytical data were 

included in the report, it is certain that spillage of captan concentrate into a stream would be 

lethal to fish. 

Two of the reported captan incidents involved terrestrial organisms; the legality of the use for 

both incidents is undetermined. In the first incident, an extension apiculturist from UC Davis 

wrote in a short paper titled "Honey Bees and Fungicides" that California beekeepers 

documented a possible connection between brood problems of honey bees and crop diseasepreventing fungicides in 1967 (Incident I0020302-001). The beekeepers noticed substantial 

brood losses following application of captan in some almond orchards in northern California. 

Similar reports in 1971 led to an investigation of dying larvae, pupae and emerging bees. This 

investigation found that many emerging adults were light in color and often had deformed wings 

and that up to 50% of the brood could be negatively affected by captan used at field doses. The 

certainty index for this incident is ‘probable.’ 

In the second terrestrial incident, an estimated 30 to 35 snow geese were found dead or dying in 

a field on the eastern shore of Virginia in Accomack County on January 30, 1985. Necropsy of 

two of the birds showed aquatic vegetation in the digestive tract, but there were no gross lesions 

or evidence of infectious diseases. Empty bags of Vitavax flowable fungicide were found in the 
23 

nearby field. The certainty index for this incident is ‘probable’ because in the absence of 

analyses of tissue residues, it can only be surmised that the birds died from ingestion of captan 

that once filled the bags found nearby. 

Two of the reported captan incidents involved plants; both were the result of accidental misuse 

of the pesticide. In the first incident, Gustafson LLC reported that a formulator erroneously 

added the antimicrobial tebuconazole to a 790 gallon lot of the fungicide Rival 

(pentachloronitrobenzene [PCNB], thiabendazol, captan) to create a formulation of an 

unregistered end-use product for soybean seed treatment. About 403 gallons of this lot was sold 

to and used by 10 commercial seed treating companies for soybeans. The material was used in 

IL, IN, OH, MI and LA. Gustafson was notified on May 21, 2004 of stunted soybean growth 

from treated seeds and instructed growers, via the associated seed treating companies, to destroy 

their crops (Incident I015152-001). The certainty index for this incident is ‘possible’ for all four 

listed pesticides. Whether or not an individual pesticide or some combination of the pesticides 

caused the stunted growth could not be determined. 

In the second plant incident, Zeneca reported a complaint from a grower in North East, PA, that 

Abound (AI: azoxystrobin) had damaged his apples. In his deposition, the grower admitted to 

spraying grapes with parathion, captan, and Stop-It (a calcium supplement) prior to spraying the 

apples and may not have completely washed out the tank before adding Abound. The worst 

damage occurred with the first tank full of pesticide suggesting that the pesticides used on the 

grapes were responsible for the damage. However, Abound is not registered for use on apples, 

and the current label for Abound states: “Abound is extremely phytotoxic to certain apple 

varieties. AVOID SPRAY DRIFT. Extreme care must be used to prevent injury to apple trees 

(and apple fruit). DO NOT spray Abound where spray drift may reach apple trees.” This label 

language suggests that Abound was responsible for the damage. The certainty index for this 

incident is ‘possible’ for all of the involved pesticides. Whether or not an individual pesticide or 

some combination of the pesticides caused the damage could not be determined. 

In addition to the incidents recorded in EIIS and AIMS, additional incidents are reported to the 

Agency in aggregated form. Pesticide registrants report certain types of incidents to the Agency 

as aggregate counts of incidents occurring per product per quarter. Ecological incidents reported 

in aggregate reports include those categorized as ‘minor fish and wildlife’ (W-B), ‘minor plant’ 

(P-B), and ‘other non-target’ (ONT) incidents. ‘Other non-target’ incidents include reports of 

adverse effects to insects and other terrestrial invertebrates. For captan, registrants have reported

no minor fish and wildlife incidents, 38 minor plant incidents, and no other non-target incidents 

as of January 11, 2013. All of the minor incidents are associated with Ortho Home Orchard 

Spray (Reg No. 239-568). 

The total number of actual incidents associated with the use of captan may be higher than what is 

reported to the Agency. Incidents may go unreported since effects may not be immediately 

apparent and/or readily attributed to the use of a chemical. 
24 

6 Risk Hypothesis 

The Registration Review ecological risk assessment will test the following risk hypothesis: 

Based on the application methods, the assumed fate and transport, and the assumed 

sensitivity of non-target aquatic and terrestrial species, captan has the potential to reduce 

survival, growth, and/or reproduction of non-target terrestrial and aquatic organisms. These 

non-target organisms include Federally-listed threatened and endangered species as well as 

non-listed species. 

7 Exposure Pathways of Concern 

For terrestrial vertebrates, the major route of exposure to captan is considered to be via dietary 

ingestion of food items such as seeds, plants, and/or animals that have captan residues as a result 

of direct application, spray drift, and runoff. Exposure to captan through the consumption of 

drinking water alone is not considered a potential concern for birds and mammals based on the 

results of EFED’s Screening Imbibition Program (SIP v. 1.0) indicates (Appendix B). Exposure 

to terrestrial vertebrates through inhalation is considered not likely significant given captan’s low 

vapor pressure and the results of EFED’s Screening Tool for Inhalation Risk (STIR v. 1.0) 

(Appendix C).

For terrestrial invertebrates, the major routes of exposure to captan are considered to be direct 

contact as a result of direct application and spray drift and dietary ingestion of plants, animals, 

and/or soil that have captan residues as a result of direct application, spray drift, and runoff. 

For aquatic animal species, the major route of exposure to captan is considered to be uptake via 

the respiratory surface (gills) or the integument from surface water/sediment that has captan 

residues as a result of spray drift, runoff, and leaching to groundwater from soil. 

For terrestrial (upland and semi-aquatic) non-target plants, the major routes of exposure to captan 

are considered to be direct contact as a result of direct application and spray drift and root uptake 

via soil contaminated via spray drift and runoff. 

For aquatic plants, the major routes of exposure to captan are considered to be uptake from 

surface water/sediment containing captan residues as a result of spray drift, runoff, and leaching 

to groundwater from soil. 

8 Analysis Plan 

To address the risk hypothesis, the potential for adverse effects on the environment will be 

estimated. Usage, environmental fate, and ecological effects of captan will be characterized and 

integrated to assess the risks. As outlined in the Overview Document (USEPA, 2004), the 

likelihood of effects to individual organisms from particular uses of a chemical is estimated 
25 

using the probit dose-response slope and either the level of concern (LOC) or the actual 

calculated risk quotient value. 

This analysis plan will be revisited and may be revised depending upon a full review of the data 

available in the open literature and the information submitted by the public in response to the 

opening of the Registration Review docket. 

8.1 Stressors of Concern 

Toxicity data indicates that degradates TPHI and TPHAm are much less toxic to aquatic 

organisms than parent captan. Furthermore, environmental fate data indicates that substantial 

amounts of degradates THPAI and THCY are unlikely to form in environments where captan is 

used, i.e., terrestrial aerobic environments. Therefore, only parent captan will be considered a 

stressor of concern in the Registration Review ecological risk assessment. 

8.2 Measures of Exposure 

To estimate risks to aquatic and terrestrial organisms from exposure to captan, all exposure 

modeling and resulting risk conclusions will be made based on maximum application rates, 

application methods, and any mitigation measures specifically indicated on the label. Models 

that will be used to predict estimated environmental concentrations (EECs) of captan are 

discussed on OPP’s model website13. These models include: PRZM (Pesticide Root Zone 

Model) and EXAMS (EXposure Analysis Modeling System), PRZM-groundwater (PRZM-GW), 

T-REX, and TerrPlant. 

8.3 Measures of Effect 

Ecological effects data are used as measures of direct and indirect effects to non-target 

organisms. Data are obtained from registrant-submitted studies or from literature studies 

identified via a query of the ECOTOXicology database

14 which is maintained by the U.S. EPA 

Office of Research and Development (ORD). Information on the potential effects of captan to 

non-target organisms is also collected from reviews of incidents associated with the use of captan 

(see Section 5.3). 

Where available, sub-lethal effects observed in both registrant-submitted and open literature 

studies will be evaluated qualitatively. Such effects may include behavioral changes (e.g., 

lethargy and changes in coloration). Quantitative assessments of risks, though, are limited to 

those endpoints that can be directly linked to the Agency’s assessment endpoints of impaired 

survival, growth, and reproduction. 

The assessment of risk for direct effects to non-target organisms makes the assumption that 

toxicity of captan to birds is similar to terrestrial-phase amphibians and reptiles. The same 

assumption is made for fish and aquatic-phase amphibians. 

 

13 http://www.epa.gov/pesticides/science/models_db.htm

14 http://cfpub.epa.gov/ecotox/
26 

8.4 Integration of Exposure and Effects 

Risk characterization is the integration of exposure and ecological effect characterizations to 

determine the potential ecological risk from the use of captan and the likelihood of direct and 

indirect effects to non-target organisms in aquatic and terrestrial habitats. The exposure and 

effects data are integrated to evaluate potential adverse ecological effects on non-target species. 

For the captan ecological risk assessment, the risk quotient (RQ) method will be used to compare 

estimated exposure and measured toxicity values. Acute and chronic EECs will be divided by 

acute and chronic toxicity values. The resulting RQs will then be compared to the Agency’s 

Levels of Concern (LOC) (USEPA, 2004). These criteria are used to indicate when captan’s use, 

as directed on the labels, has the potential to cause adverse direct or indirect effects to non-target

organisms. In addition, incident data from EIIS, aggregate incident reports, and AIMS will be 

considered as part of the risk characterization. 

8.5 Drinking Water Assessment 

A new drinking water assessment may be conducted if warranted to support future human health 

dietary risk assessments of captan and will consider all currently registered uses. The new 

drinking water assessment will incorporate model estimates as well as available monitoring data 

of captan and any transformation products of toxicological concern in surface water and 

groundwater that might be identified by the Health Effects Division (HED). The potential 

toxicity of captan and its transformation product THPI will be considered in the drinking water 

assessment conducted during the Registration Review process. Any additional determination of 

the residues of concern in the drinking water assessment will be made through consultation with 

HED and through any proceedings of the ROCKS (Residues of Concern Knowledge 

Subcommittee). 

8.6 Endangered Species Assessments 

Consistent with the Agency’s responsibility under the Endangered Species Act (ESA), the 

Agency will evaluate risks to Federally-listed threatened and/or endangered (listed) species from 

registered uses of captan. This assessment will be conducted in accordance with the Overview 

Document (USEPA, 2004), provisions of the ESA, and the Services’ Endangered Species 

Consultation Handbook (USFWS/NMFS, 1998). 

The assessment of effects associated with the registration of captan is based on an action area. 

The action area is considered to be the area directly or indirectly affected by the federal action, as

indicated by the exceedance of Agency Levels of Concern (LOCs) used to evaluate direct or 

indirect effects. The Agency’s approach to defining the action area under the provisions of the 

Overview Document (USEPA, 2004) considers the results of the risk assessment process to 

establish boundaries for that action area with the understanding that exposures below the 

Agency’s defined LOCs constitute a no-effect threshold. For the purposes of this assessment, 

attention will be focused on the footprint of the action (i.e., the area where captan application 

occurs), plus all areas where offsite transport (i.e., spray drift, runoff, etc.) may result in potential 

exposure that exceeds the Agency’s LOCs. Specific measures of ecological effect that define the 

action area for listed species include any direct and indirect effects and/or potential modification 

of its critical habitat, including reduction in survival, growth, and reproduction as well as the full
27 

suite of sub-lethal effects available in the effects literature. Therefore, the action area extends to 

a point where environmental exposures are below any measured lethal or sub-lethal effect 

threshold for any biological entity at the whole organism, organ, tissue, and cellular level of 

organization. In situations where it is not possible to determine the threshold for an observed 

effect, the action area will be assumed to encompass the entire United States. 

8.7 Endocrine Disruptor Screening Program 

As required by FIFRA and FFDCA, EPA reviews numerous studies to assess potential adverse 

outcomes from exposure to chemicals. Collectively, these studies include acute, subchronic and 

chronic toxicity, including assessments of carcinogenicity, neurotoxicity, developmental, 

reproductive, and general or systemic toxicity. These studies include endpoints which may be 

susceptible to endocrine influence, including effects on endocrine target organ histopathology, 

organ weights, estrus cyclicity, sexual maturation, fertility, pregnancy rates, reproductive loss, 

and sex ratios in offspring. For ecological hazard assessments, EPA evaluates acute tests and 

chronic studies that assess growth, developmental and reproductive effects in different 

taxonomic groups. As part of the most recent registration decision, EPA reviewed these data and 

selected the most sensitive endpoints for relevant risk assessment scenarios from the existing 

hazard database. However, as required by FFDCA section 408(p), captan is subject to the 

endocrine screening part of the Endocrine Disruptor Screening Program (EDSP). 

EPA has developed the EDSP to determine whether certain substances (including pesticide 

active and other ingredients) may have an effect in humans or wildlife similar to an effect 

produced by a “naturally occurring estrogen, or other such endocrine effects as the Administrator 

may designate.” The EDSP employs a two-tiered approach to making the statutorily required 

determinations. Tier 1 consists of a battery of 11 screening assays to identify the potential of a 

chemical substance to interact with the estrogen, androgen, or thyroid (E, A, or T) hormonal 

systems. Chemicals that go through Tier 1 screening and are found to have the potential to 

interact with E, A, or T hormonal systems will proceed to the next stage of the EDSP where EPA 

will determine which, if any, of the Tier 2 tests are necessary based on the available data. Tier 2 

testing is designed to identify any adverse endocrine-related effects caused by the substance, and 

establish a dose-response relationship between the dose and the E, A, or T effect. 

Under FFDCA section 408(p), the Agency must screen all pesticide chemicals. Between 

October 2009 and February 2010, EPA issued test orders/data call-ins for the first group of 67 

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. Captan is 

among the group of 58 pesticide active ingredients on the initial list to be screened under the 

EDSP. For additional information on the EDSP program, visit http://www.epa.gov/endo/. 

9 Data Gaps 

The following two sections identify environmental fate and effects data that are needed to 

complete an environmental fate and ecological risk assessment in support of the Registration 

Review of the registered uses of captan. 
28 

Submission of data to eliminate data gaps would reduce uncertainties in the ecological risk 

assessment. Data gaps have been assigned either a low or high potential to add value to the 

Registration Review ecological risk assessment. While still considered data gaps according to 40 

CFR Part 158, data from low potential studies are unlikely to change risk conclusions, and 

alternate methods and weight of evidence can be used in the absence of data. In contrast, data 

from high potential studies are likely to impact risk conclusions and allow the Agency to be 

better able to characterize potential risks by eliminating uncertainties for both non-listed and 

listed species that cannot be accounted for using alternate methods or weight of evidence. 

9.1 Environmental Fate Data 

Table 9-1 provides environmental fate studies by MRID that offer data for each guideline 

requirement as well as study classifications and whether or not further data are needed to support 

the Registration Review ecological risk assessment (i.e., whether there is a data gap). The fate 

database for captan is adequate for exposure assessment. Additional data as noted in Table 9-1

will reduce uncertainty related to the exposure assessment.

 

Table 9-1. Registrant-Submitted Fate Data for Captan and Remaining Data Gaps

Guideline Description MRID/ 

Source Classification Data Gap? 

835.2120 

161-1 Hydrolysis 

41176301 

40208101 

00096974 

Acceptable No 

835.2240 

161-2 Photodegradation in water 40208102 Acceptable No 

835.2410 

161-3 Photodegradation in soil 40658009 Acceptable No 

835.4100 

162-1 

Aerobic 

soil metabolism 

00070414 

40658007 Acceptable 

Yes. Partially fulfilled 

Two aerobic soil metabolism studies 

are acceptable for risk assessment. 

Additional data are required under 40 

CFR Part 158 for terrestrial outdoor 

uses. OCSPP guidance recommends 

that these tests be performed with 

four soils. Because OCSPP uses an 

upper 90th percentile estimate of soil 

metabolism half-lives based on 

available study data for modeling 

purposes, any additional data can 

reduce uncertainty related to the 

exposure assessment as well as the 

half-life value used in modeling. 

Additional data are considered to 

have a high potential to add value to 

the ecological risk and drinking water 

assessments. 
29 

Guideline Description MRID/ 

Source Classification Data Gap? 

835.4200 

162-2 

Anaerobic 

soil metabolism 

00098881 

40658008 Supplemental 

Yes. Partially fulfilled 

Two anaerobic soil metabolism 

studies are acceptable for risk 

assessment. Additional data are 

required under 40 CFR Part 158 for 

terrestrial outdoor uses. OCSPP 

guidance recommends that these tests 

be performed with four soils. 

Because OCSPP uses an upper 90th

percentile estimate of soil metabolism 

half-lives based on available study 

data for modeling purposes, any 

additional data can reduce uncertainty 

related to the exposure assessment as 

well as the half-life value used in 

modeling Additional data are 

considered to have a high potential

to add value to the ecological risk and 

drinking water assessments. 

835.4300 

162-4 

Aerobic aquatic 

metabolism 

00096974 

40114502 

43868905 

Acceptable No 

835.4400 

162-3 

Anaerobic aquatic 

metabolism No data --- 

Yes. Data are required under 40 CFR 

Part 158. OCSPP guidance 

recommends that these tests be 

performed with two sediments. In 

absence of anaerobic aquatic 

metabolism data, anaerobic soil 

metabolism data will be used in 

exposure modeling purposes. 

Additional data are considered to 

have a high potential to add value to 

the ecological risk and drinking water 

assessments. 

835.1230 

835.1240 

163-1 

Leaching-adsorption/ 

desorption 

00096972 

40658001 Acceptable No 

835.6100 

164-1 

Terrestrial 

field dissipation 

40823901 

40893601 

40893602 

40893603 

40932201 

40932202 

Supplemental No 

850.6100 Analytical method - Soil 40823901 Acceptable No 
30 

Guideline Description MRID/ 

Source Classification Data Gap? 

850.6100 

Analytical method - Water No data --- 

Yes. Environmental chemistry 

method (ECM) and independent 

laboratory validation method (ILV) 

for water are required to support 

monitoring for captan residues and to 

evaluate submitted environmental fate 

and ecological effects data. 

850.1730 

165-4 Accumulation in fish 

40756601 

40756602 Acceptable No 

9.1.1 Environmental Fate Data for Degradate, THPI 

There are limited registrant-submitted environmental fate data available for THPI (Table 4-2). 

Several key environmental fate data (i.e., hydrolysis [OCSPP 835-2120], aquatic photolysis 

[OCSPP 835-2240], and anaerobic aquatic metabolism [OCSPP 835-4400]) are not available for 

the aquatic exposure assessment. The registrant and/or public are welcome to submit additional 

information that would provide THPI's environmental fate properties. In the absence of these 

data, conservative assumptions will be made about the fate properties for THPI, including the use 

of predictive models to generate appropriate data. The Agency would be interested in any public 

perspective regarding the availability of environmental fate data. 

9.2 Ecological Effects Data 

Table 9-2 provides ecological effects studies by MRID that offer data for each guideline 

requirement as well as study classifications and whether or not further data are needed to support 

the Registration Review ecological risk assessment (i.e., whether there is a data gap). 

Table 9-2. Ecological Effects Data for Captan and Remaining Data Gaps

Guideline Description MRID/ 

Source Classification Data Gap? 

850.1010 

Acute toxicity 

freshwater 

invertebrates 

00070751 

00162739 

43869807 

Supplemental 

Acceptable 

Supplemental 

No 

850.1025 

850.1055 

Acute toxicity 

estuarine/marine 

mollusk 

46061701 Acceptable No 

850.1035 

850.1045 

Acute toxicity 

estuarine/marine 

invertebrate 

44806505 Acceptable No 

850.1075 

Acute toxicity 

freshwater fish 

(cold water species) 

40098001 Supplemental 

Yes. Acceptable acute toxicity data are not 

available for a cold water species. However, 

data from repeating this study are considered 

to have a low potential to add value to the 

ecological risk assessment. 
31 

Guideline Description MRID/ 

Source Classification Data Gap? 

Acute toxicity 

freshwater fish 

(warm water species) 

00162740 

40098001 

Acceptable 

Supplemental No 

Acute toxicity 

estuarine/marine fish 44806504 Acceptable No 

850.1300 

Aquatic invertebrate 

 life cycle 

(freshwater) 

44148801 Supplemental 

Yes. Acceptable chronic toxicity data are not 

available for a freshwater aquatic 

invertebrate. However, data from repeating 

this study are considered to have a low 

potential to add value to the ecological risk 

assessment. 

850.1350 

Aquatic invertebrate 

 life cycle 

(saltwater) 

No data -- 

Yes. Aquatic invertebrate life cycle toxicity 

data for an estuarine/marine invertebrate are 

required under 40 CFR Part 158 if the 

product is expected to enter the environment 

in significant concentrations because of its 

expected use or mobility patterns. However, 

data for this guideline requirement are 

considered to have a low potential to add 

value to the ecological risk assessment. 

850.1400 

Fish early life stage 

(freshwater) 

00057846 

(E000945a) Qualitative 

Yes. Acceptable early life stage toxicity data 

are not available for a freshwater fish. 

However, data from repeating this study are 

considered to have a low potential to add 

value to the ecological risk assessment. 

Fish early life-stage 

(saltwater) No data -- 

Yes. Early-life stage toxicity data for an 

estuarine/marine fish are required under 40 

CFR Part 158 if the product is expected to 

enter the environment in significant 

concentrations because of its expected use or 

mobility patterns. However, data for this 

guideline requirement are considered to have 

a low potential to add value to the ecological 

risk assessment. 

850.2100 

Avian oral toxicity 

(upland game or 

waterfowl species) 

00151236 

00160000 

Acceptable 

Supplemental 

No. However, based on guidance for using 

non-definitive endpoints15, requesting 

additional toxicity data is recommended (see 

discussion below) and considered to have a 

high potential to add value to the ecological 

risk assessment. 

Avian oral toxicity 

(passerine species) No data -- 

Yes. Avian acute oral toxicity data for a 

passerine species are required under the new 

40 CFR Part 158. Data for this guideline 

requirement are considered to have a high 

potential to add value to the ecological risk 

assessment. 

 

15

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_reregistration_work

group/esa_non_definitive_endpoints.htm
32 

Guideline Description MRID/ 

Source Classification Data Gap? 

850.2200 

Avian dietary toxicity 

(upland game species)

00022923 

43869802 

Supplemental 

Acceptable 

No. However, based on guidance for using 

non-definitive endpoints9

, requesting 

additional toxicity data is recommended (see 

discussion below) and considered to have a 

high potential to add value to the ecological 

risk assessment. 

Avian dietary toxicity 

(waterfowl species) 

00022923 

43869803 

Supplemental 

Acceptable 

850.2300 

Avian reproduction 

(upland game species) 00098295 Acceptable No 

Avian reproduction 

(waterfowl species) 00098296 Acceptable No 

850.3020 Honeybee acute 

contact toxicity 

E087252a 

00080871 

Quantitative 

Acceptable 

No. However, based on a documented honey 

bee incident involving the use of captan and 

the “White Paper in Support of the Proposed 

Risk Assessment Process for Bees” as 

submitted to the FIFRA Scientific Advisory 

Panel, data from the following non-guideline 

honey bee toxicity studies are recommended 

for request and considered to have a high 

potential to add value to the ecological risk 

assessment: 

• (adult) honey bee acute oral toxicity 

test and 

• larval honey bee acute oral toxicity 

test. 

850.4100 Seedling emergence 

(terrestrial plants) No data -- Yes. Data for terrestrial plant species are required under 40 CFR Part 158. Data for 

this guideline requirement are considered to 

have a high potential to add value to the 

ecological risk assessment. 

850.4150 Vegetative vigor 

(terrestrial plants) No data -- 

850.4400 

Aquatic plant growth 

(aquatic vascular plant 

toxicity) 

44806503 Acceptable No 

850.4500 

Aquatic plant growth 

(aquatic non-vascular 

plant: algal toxicity) 

Green alga: 

00137688 

43869809 

Supplemental 

Acceptable 

No 

Freshwater 

diatom: 

No data 

-- 

Yes. Data for aquatic non-vascular plant 

species including a freshwater diatom are 

required under 40 CFR Part 158. Data for 

this guideline requirement are considered to 

have a high potential to add value to the 

ecological risk assessment. 

Marine 

diatom: 

40228401 

44806502 

Supplemental 

Acceptable 

No 

850.4550 

Aquatic plant growth 

(aquatic non-vascular 

plant: cyanobacteria 

toxicity) 

44806501 Acceptable No 
33 

FW = freshwater; SW = saltwater 

a

identified via a query of the ECOTOXicology16 database which is maintained by the U.S. EPA Office of Research 

and Development (ORD) 

Data from the following studies are considered to have high potential to add value to the 

ecological risk assessment for captan: 

 

Guideline 850.2100 – Avian Acute Oral Toxicity Test, upland game: The avian endpoints for 

acute oral toxicity are non-definitive (i.e., LD50 > highest dose tested). The highest 

concentrations tested, 2150 and 2000 mg/kg-bw for bobwhite quail and mallard duck, 

respectively (MRIDs 00151236 and 00160000), are less than the highest avian EECs calculated 

in the most recent assessments (i.e., 4968 mg/kg-bw in the 2007 CRLF litigation assessment; 

6107 mg/kg-bw in the 2012 Section 24(c) SLN assessment, DP 400401), and sublethal effects 

including weight loss, ataxia, and tremors were noted in the studies. Based on guidance for 

using non-definitive endpoints17, requesting additional data is recommended and considered to 

have a high potential to add value to the Registration Review ecological risk assessment. 

Guideline 850.2100 – Avian Acute Oral Toxicity Test, passerine species: Acute oral toxicity 

data for a passerine species are required under the new 40 CFR Part 158. No studies have been 

submitted for this data requirement. Given the concerns identified for existing toxicity data for 

upland game and waterfowl species and the need to be protective of passerine species, fulfilling 

this data requirement has a high potential to add value to the Registration Review ecological risk 

assessment. In the absence of these data, passerine toxicity data for surrogate pesticides – 

starting with data for surrogate chemicals (e.g., folpet) and proceeding to data for less related 

chemicals – may be used to characterize the toxicity of captan to passerine species.

Guideline 850.2200 – Avian Dietary Toxicity Test, upland game and waterfowl species: The 

avian endpoints for sub-acute dietary toxicity are non-definitive (i.e., LC50 > highest 

concentration tested). The highest concentration tested, 4680 mg/kg-diet (if corrected for % a.i.) 

for both bobwhite quail and mallard duck (MRIDs 43869802 and 43869803) is greater than the 

highest avian EEC of 4362 mg/kg-diet calculated in the 2007 CRLF litigation assessment, but 

less than the highest avian EEC of 5112 mg/kg-diet calculated in the 2012 Section 24(c) SLN 

assessment (DP 400401). Furthermore, there was 30% (3 out of 10) mortality in the 5200 

mg/kg-diet treatment group in the bobwhite quail study, and frank sublethal effects including 

reduced body weight gain were noted at ≥ 2600 mg/kg-diet for both species. Based on guidance 

for using non-definitive endpoints18, requesting additional data is recommended and considered 

to have a high potential to add value to the Registration Review ecological risk assessment. 

Guideline 850.4100 – Seedling Emergence and Seedling Growth & Guideline 850.4150 – 

Vegetative Vigor: Data for terrestrial plant species are required under 40 CFR Part 158. Open 

 

16 http://cfpub.epa.gov/ecotox/ 

17

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_reregistration_work

group/esa_non_definitive_endpoints.htm

18

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_reregistration_work

group/esa_non_definitive_endpoints.htm
34 

literature studies indicate that applications of captan as low as 2.5 lb a.i./A could affect dicots 

(2007 CRLF litigation assessment; DP 400401). In addition, incidents associated with the use of 

captan and involving plants have been reported (see Section 5.3). Therefore, effects to terrestrial 

plants from use of captan cannot be discounted, and data from terrestrial plant studies are 

considered to have a high potential to add value to the Registration Review ecological risk 

assessment. In the absence of these data, terrestrial plant toxicity data for surrogate pesticides – 

starting with data for surrogate chemicals (e.g., folpet) and proceeding to data for less related 

chemicals – may be used to characterize the toxicity of captan to terrestrial plants.

Guideline 850.4500 – Algal Toxicity, freshwater diatom: Data for aquatic non-vascular plant 

species including a freshwater diatom are required under 40 CFR Part 158. No data has been 

submitted for this data requirement. Results of aquatic non-vascular plant toxicity studies with 

folpet, a phthalimide fungicide that is a structural analogue of captan, show a freshwater diatom 

to be the most sensitive species tested. For folpet, a comparison of EC50’s for the tested species 

yields the following order of sensitivities (most to least sensitive): freshwater diatom 

(EC50/NOEC = 50/30 μg a.i./L; MRID 45784605) > marine diatom (EC50/NOEC = 220/41 μg 

a.i./L; MRID 45784607) > cyanobacterium (EC50/NOEC = 1100/350 μg a.i./L; MRID 

45784606) > green alga (EC50/NOEC = 1800/480 μg a.i./L; MRID 45784604). This order of 

sensitivities for folpet matches that for captan with respect to available data: marine diatom 

(EC50/NOEC = 169/32.3 μg a.i./L; MRID 44806502) > cyanobacterium (EC50/NOEC = 

995/<234 μg a.i./L; MRID 44806501) > green alga (EC50/NOEC = 1972/200 μg a.i./L; MRID 

43869809). Therefore, freshwater diatoms are likely to be the most sensitive aquatic nonvascular plant species for captan. The freshwater diatom endpoints for folpet are (EC50/NOEC = 

50/30 μg a.i./L) are close to the highest peak EEC of 21.6 μg/L calculated in the 2007 CRLF 

litigation assessment and less than the highest peak EEC of 91.3 calculated for the 2012 Section 

24(c) SLN assessment (DP 400401). Data for a freshwater diatom exposed to captan could 

impact risk conclusions and are considered to have a high potential to add value to the 

Registration Review ecological risk assessment. In the absence of these data, data for a 

freshwater diatom exposed to folpet may be used to characterize toxicity of captan to freshwater 

diatoms. 

Non-Guideline Studies – Adult and Larval Honey Bee Acute Oral Toxicity Tests: A honey 

bee incident involving brood losses and the use of captan has been reported. In addition, the 

“White Paper in Support of the Proposed Risk Assessment Process for Bees” as submitted to the 

FIFRA Scientific Advisory Panel19 proposes a screening-level risk assessment process that 

includes acute contact and oral toxicity tests with adult bees and an acute oral toxicity test with 

larval bees. Adult honey bee acute contact toxicity data are available for captan. However, adult 

and larval honey bee acute oral toxicity data are not. Therefore, data from the following nonguideline honey bee toxicity studies are recommended for request and considered to have a high 

potential to add value to the Registration Review ecological risk assessment: 

• (adult) honey bee acute oral toxicity test and 

• larval honey bee acute oral toxicity test. 

Data from the following studies are considered to have low potential to add value to the 

ecological risk assessment for captan: 

 

19 http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPP-2012-0543-0004
35 

Guideline 850.1075 – Fish Acute Toxicity Test, cold water species: Acceptable acute toxicity 

data is not available for a cold water species. A study with brown trout (Salmo trutta) is 

classified as Supplemental due to a guideline deviation, i.e., there was only one replicate per 

treatment concentration (MRID 40098001). Repeating this study has a low potential to add 

value to the Registration Review ecological risk assessment. In the absence of these data, the 

existing endpoint for brown trout may be used to characterize the toxicity of captan to freshwater 

fish from acute exposure. 

Guideline 850.1300 – Daphnid Chronic Toxicity Test: Acceptable chronic toxicity data is not 

available for a freshwater aquatic invertebrate. A study with Daphnia magna is classified as 

Supplemental due to the lack of measured concentrations; only the stock concentration was 

measured (MRID 44148801). Repeating this study has a low potential to add value to the 

Registration Review ecological risk assessment. In the absence of these data, the existing 

endpoint for Daphnia may be used to characterize the toxicity of captan to freshwater aquatic 

invertebrates from acute exposure. 

 

Guideline 850.1350 – Mysid Chronic Toxicity Test: Aquatic invertebrate life cycle toxicity 

data for an estuarine/marine invertebrate are required under 40 CFR Part 158 if the product is 

expected to enter the environment in significant concentrations because of its expected use or 

mobility patterns. No studies have been submitted for this data requirement. Given that there is 

no evidence to indicate that estuarine/marine animals are substantially more sensitive to captan 

than freshwater animals, fulfilling this data requirement has a low potential to add value to the 

Registration Review ecological risk assessment. In the absence of these data, toxicity to 

estuarine/marine invertebrates from chronic exposure to captan may be characterized by 

applying an acute to chronic ratio (ACR) generated from toxicity data for Daphnia to the acute 

toxicity endpoint for mysid shrimp. 

Guideline 850.1400 – Fish Early Life Stage Toxicity Test, freshwater: Acceptable early life 

stage toxicity data are not available for a freshwater fish. In previous ecological risk assessments 

(e.g., 2004 RED; DP 318448+; 2007 CRLF litigation assessment; DP 400401), ECOTOX open 

literature study E000945 (MRID 00057846) was referenced for characterizing the toxicity of 

captan to freshwater fish from chronic exposure. A formal review of this study conducted in 

accordance with current guidelines for evaluating ecological toxicity data in the open literature20

resulted in a study classification of qualitative for use in the Registration Review ecological risk 

assessment due to significant uncertainty associated with exposure concentrations which varied 

greatly over the study. Since repeating this study is likely to yield the same uncertainty with 

respect to exposure concentrations, fulfilling this data requirement has a low potential to add 

value to the Registration Review ecological risk assessment. 

An acceptable early life stage toxicity test with folpet, a phthalimide fungicide that is a structural

analogue of captan, yielded a NOEC and LOEC of 8.8 μg a.i./L and 17.7 μg a.i./L, respectively, 

based on reductions in growth of fathead minnow (MRID 43786301). So in the absence of these 

 

20

http://www.epa.gov/pesticides/science/efed/policy_guidance/team_authors/endangered_species_reregistration_work

group/esa_evaluation_open_literature.htm
36 

data, toxicity to freshwater fish from chronic exposure to captan may be characterized by 

applying an acute to chronic ratio (ACR) generated from toxicity data for freshwater fish 

exposed to folpet to the most sensitive acute toxicity endpoint for freshwater fish exposed to 

captan. 

Guideline 850.1400 – Fish Early Life Stage Toxicity Test, estuarine/marine: Early life stage 

toxicity data for an estuarine/marine fish are required under 40 CFR Part 158 if the product is 

expected to enter the environment in significant concentrations because of its expected use or 

mobility patterns. No studies have been submitted for this data requirement. Given that there is 

no evidence to indicate that estuarine/marine animals are substantially more sensitive to captan 

than freshwater animals, fulfilling this data requirement has a low potential to add value to the 

Registration Review ecological risk assessment. In the absence of these data, toxicity to 

estuarine/marine fish from chronic exposure to captan may be characterized using toxicity data 

for freshwater fish. 

10 References 

DP 207651, 222887. EFED's Reregistration Eligibility Decision Chapter for Captan (Chemical 

#081301, DP Barcodes D207651, D222887) including Data Evaluation report. U.S. 

Environmental Protection Agency, Office of Prevention, Pesticides and Toxic Substances, 

Office of Pesticide Programs, Washington D.C. July 10, 1997. 

DP 318448, 318449, 318450, 318451, and 318452. IR-4-Local Registration for Captan Use on 

Ginseng (PC Code 081301; CAS Number 133-06-2). March 2, 2006. 

DP 400401. Ecological Risk Assessment in Response to the Section 24(c) Special Local Need 

for the Use of Captan on Strawberries in Florida. May 16, 2012. 

E000945 (MRID 00057846). Hermanutz, R.O., Mueller, L.H., Kemper, K.D. 1973. Effects 

Captan toxicity to fathead minnows (Pimephales promelas), bluegills (Lepomis 

macrochirus), and brook trout (Salvelinus fontinalis). J. Fish. Res. Board. Can. 30: 1811-

1817. 

E087252. Ladurner, E., Bosch, J., Kemp, W. P., and Maini, S. 2005. Assessing delayed and 

acute toxicity of five formulated fungicides to Osmia lignaria Say and Apis mellifera. 

Apidologie 36: 449-460. 

Food and Agricultural Organization of the United Nations (FAO). 2000. FAO Pesticide 

Disposal Series 8. Assessing soil contamination: A Reference Manual. Appendix 2. FAO 

Information Division: Rome. http://www.fao.org/docrep/003/X2570E/X2570E00.HTM

USEPA. 2004. Overview of the Ecological Risk Assessment Process in the Office of Pesticide 

Programs. U.S. Environmental Protection Agency, Office of Prevention, Pesticides and 

Toxic Substances, Office of Pesticide Programs, Washington D.C. January 23, 2004. 
37 

U.S. Fish and Wildlife Service (USFWS) and National Marine Fisheries Service (NMFS). 1998. 

Endangered Species Consultation Handbook: Procedures for Conducting Consultation and 

Conference Activities Under Section 7 of the Endangered Species Act. Final Draft. March 

1998.

11 Bibliography of Cited MRIDs 

Environmental Fate Studies 

48112502 Byrd, C. (2010) Captan Technical- Product Identity and Composition, Description 

of Beginning Materials, Manufacturing Process, and Discussion of Formation of 

Impurities. Unpublished study prepared by RedEagle International, LLC. 63 p.

48112504 Sun, G. (2010) Captan Technical Grade Active Ingredient Physical and Chemical 

Characteristics: Final Report. Project Number: 01/15419/01/002, GLP/SP/082. 

Unpublished study prepared by Southwest Research Institute. 25 p.

00070414 Pack, D.E. (1974) The soil metabolism of carnoyl-14-c-captan. File No 773.2. 

Unpublished study prepared by Chevron Chemical Co. 49 p. 

00096972 Pack, D.E. (1977) Soil Mobility of Captan, Folpet and Captafol As Determined by 

Soil Thin-layer Chromatography: File No. 722.0. (Unpublished study received 

May 30, 1978 under 239-2211; sub- mitted by Chevron Chemical Co., Richmond, 

Calif.; CDL:234046-N) 

00096974 Wolfe, N.L.; Zepp, R.G.; Doster, J.C.; et al. (1976) Captan hydrolysis. Journal of 

Agricultural and Food Chemistry 24(5):1041- 1045. (Also~In~unpublished 

submission received May 30, 1978 under 239-2211; submitted by Chevron 

Chemical Co., Richmond, Calif.; CDL:234046-R)

00098881 Pack, D.E. (1979) The Anaerobic Soil Metabolism of Carbonyl-^14IC|captan: 

File No. 721.14. (Unpublished study received Aug 27, 1979 under 239-2457; 

submitted by Chevron Chemical Co., Richmond, Calif.; CDL:240891-B) 

40208101 Pack, D. (1987) [Trichloromethyl-[Carbon-14]] Captan Hydrolysis Products: 

Laboratory Project ID: MEF-0002, 8702383. Unpublished study prepared by 

Chevron Chemical Co. 28 p 

40231001 Pack, D. (1987) Captan Volatility from Soil--Laboratory Study: Laboratory 

Project ID: MEF-0027; 8704537. Unpublished study prepared by Chevron 

Chemical Co. 13 p. 

40208102 Pack, D. (1986) Photolysis of Captan in Sterile Aqueous Solution: Laboratory 

Project ID: MEF-0001. Unpublished study prepared by Chevron Chemical Co. 13 

p. 
38 

40658007 Pack, D.; Verrips, I. (1988) Aerobic Soil Metabolism of Trichloro-methyl-Carbon 

14||Captan: Laboratory Project ID: MEF-0060/ 8809887. Unpublished study 

prepared by Chevron Chemical Co. 49 p. 

40658008 Pack, D.; Verrips, I. (1988) Anaerobic Soil Metabolism of Tri- chloromethylCarbon 14||Captan: Laboratory Project ID: MEF- 0061/8809887. Unpublished 

study prepared by Chevron Chemical Co. 39 p. 

40658009 Ruzo, L. (1988) Soil Surface Photolysis of Carbon 14-Trichloro- methyl| Captan 

in Natural Sunlight: Laboratory Project ID: 231. Unpublished study prepared by 

Pharmacology and Toxicology Re- search Laboratory. 117 p. 

40658010 Ruzo, L. (1988) Soil Surface Photolysis of Carbon 14| Captan in Natural Sunlight: 

Laboratory Project ID: 232. Unpublished study prepared by Pharmacology and 

Toxicology Research Laboratory. 109 p. 

40658011 Pack, D. (1987) Estimation of Soil Adsorption Coefficient of Captan from TLC 

Data: Laboratory Project ID: MEF-0073/8726836. Unpublished study prepared by 

Chevron Chemical Co. 39 p. 

40756601 Surprenant, D. (1988) Bioconcentration and Elimination of Carbon 14|-residues 

by Bluegill (Lepomis macrochirus) exposed to Cyclohexane Carbon 14|-Captan: 

T-13068: Final Report: SLS Report #87-11-2558: Study 

#723.0387.6109.140/240. Unpublished study prepared by Springborn Life 

Sciences, Inc. 67 p. 

40756602 Surprenant, D. (1988) Bioconcentration and Elimination of Carbon 14|-residues 

by Bluegill (Lepomis macrochirus) exposed to Trichloromethyl Carbon 14|-

Captan: T-13069: Final Report: SLS Report #87-12-2574: Study 

#723.0387.6108.140/240. Unpublished study prepared by Springborn Life 

Sciences, Inc. 70 p. 

40823901 Jones, P. (1988) Captan 50-WP Field Dissipation Study on California 

Strawberries: Project ID PAL-EF-87-17F. Unpublished study prepared by Morse 

Laboratories, Inc. in association with Pan-Agricultural Laboratories, Inc. 199 p. 

40893601 Jones, P. (1988) Captan 50-WP Field Dissipation Study on Oregon Grapes: 

Project ID: PAL-EF-87-17D. Unpublished study prepared by Morse Laboratories, 

Inc. 216 p. 

40893602 Jones, P. (1988) Captan 50-WP Field Dissipation Study on Florida Tomatoes: 

Project ID: PAL-EF-87-17C. Unpublished study prepared by Morse Laboratories, 

Inc. 184 p 
39 

40893603 Jones, P. (1988) Captan 50-WP Field Dissipation Study on California Tomatoes: 

Project ID: PAL-EF-87-17E. Unpublished study prepared by Morse Laboratories, 

Inc. 170 p. 

40932201 Jones, P. (1988) Captan 50-WP Field Dissipation Study on New York Apples: 

Proj. I.D. PAL-EF-87-17A. Unpublished study prepared by Morse Laboratories, 

Inc. 209 p 

40932202 Jones, P. (1988) Captan 50-WP Field Dissipation Study on Texas Cantaloupes: 

Proj. I.D. PAL-EF-87-17B. Unpublished study pre- pared by Morse Laboratories, 

Inc. 185 p. 

41176301 Lee, K. (1989) Trichloromethyl-carbon 14|Captan--Hydrolysis at 25(degree)C: 

Project ID: Report No. WRC 89-44; Study No. ENV-011. Unpublished study 

prepared by ICI Americas Inc. 37 p. 

43868905 Travis, J.S. and N.D. Simmons (1993). Captan: Degradation in sediment-water 

systems under laboratory conditions. Laboratory Project ID 92JH101. 

Unpublished study prepared by ICI Agrochemicals, Jealott's Hill Research 

Station. 53p. Not listed in fate bibliography. 

43869811 Rowe, D.; Lane, M. (1993) Captan: Adsorption and Desorption Properties of Soil 

Metabolites THPI and THPAM: Lab Project Number: RJ1448B: 92JH086. 

Unpublished study prepared by ICI Agrochemicals, Jealott's Hill Research 

Station. 100 p. 

Ecological Effects Studies 

00022923 Hill, E.F., R.G. Heath, J.W. Spann, et al. (1975) Lethal Dietary Toxicities of 

Environmental Pollutants to Birds: Special Scientific Report – Wildlife No. 191. 

(U.S. Dept. of the Interior, Fish and Wildlife Service, Patuxent Wildlife Research 

Center; Unpublished Report.) 

00070751 Boudreau, P.; Forbis, A.D.; Cranor, W.; et al. (1980) Static Acute Toxicity of 

Captan Technical (SX-1086) to Daphnia magna: ABC Report # 26633. 

(Unpublished study received Jan 12, 1981 under 239-1246; prepared by 

Analytical Bio Chemistry Laboratories, Inc., submitted by Chevron Chemical Co., 

Richmond, Calif.; CDL: 244428-A) 

00080871 Atkins, E.L., E.A. Greywood, R.L. Macdonald (1972) Effect of Pesticides on 

Apiculture: Project No. 1499. 1972 Annual Report. (Unpublished Study Received 

Jan. 24, 1974 under 4F1459; Prepared by Univ. of California – Riverdale, Dept. of 

Entomology, Div. of Economic Entomology, Submitted by Nor-Am Agricultural 

Products, Inc., Naperville, Ill.; CDL: 093885-A) 

00098295 Chevron Chemical Company (1980) One Generation Reproduction Studies with 

Captan (SX-1086)|. (Compilation; unpublished study received Apr 5, 1982 under 
40 

239-1246; CDL:247147-C) 

00098296 Chevron Chemical Company (1980) Captan (SX-1086)/One Generation 

Reproduction Studies, Including Diet Analyses|. Includes method dated Jun 15, 

1979. (Compilation; unpublished study received Apr 5, 1982 under 239-1246; 

CDL:247147-D) 

00137688 Dickhaus, S.; Heisler, E. (1983) Algal Growth Inhibition Test with Captan: 

E.H./P. 1-8-150-83. (Unpublished study received Feb 22, 1984 under 11678-1; 

prepared by Pharmatox Forschung und Beratung GmbH, W. Ger., submitted by 

Makhteshim Beer Sheva Chemical Works Ltd., New York, NY; CDL:252586-A) 

00151236 Beavers, J. (1978) Acute Oral LD50 - Bobwhite Quail: Orthocide Technical: Final 

Report: Project No. 162-102. Unpublished study prepared by Wildlife 

International, Inc. 15 p. 

00160000 Hudson, R.H., R.K. Tucker, M.A. Haegele (1984) Handbook of Toxicity of 

Pesticides to Wildlife. USDI. Pb. 153, Washington, DC. 

00162739 Palmateer, S. (1979) Biological Report of Analysis: [Toxicity Test of Captan on 

Daphnia magna]. Unpublished study prepared by U.S. Environmental Protection 

Agency, Terrestrial & Aquatic Biology Laboratory. 1 p. with technical 

00162740 Palmateer, S. (1979) Biological Report of Analysis: [Toxicity Test of Captan on 

Bluegills]. Unpublished study prepared by U.S. Environmental Protection 

Agency, Terrestrial & Aquatic Biology Laboratory. 1 p. 

40098001 Mayer, F.; Ellersieck, M. (1986) Manual of Acute Toxicity: Interpretation and 

Data Base for 410 Chemicals and 66 Species of Freshwater Animals. US Fish & 

Wildlife Service, Resource Publication 160. 579 p. 

40228401 Mayer, F.L. 1986. USEPA Gulfbreeze Laboratory Test Results 

With 5 species of Marine algae 

43869802 Hakin, B.; Johnson, A.; Anderson, A.; et al. (1990) Captan: Dietary Toxicity 

(LC50) Study with the Bobwhite Quail: Lab Project Number: ISN 230/901123: 

ISN/230. Unpublished study prepared by Huntingdon Research Centre Ltd. 28 p. 

43869803 Hakin, B.; Johnson, A.; Anderson, A.; et al. (1990) Captan: Dietary Toxicity 

(LC50) Study to the Mallard Duck: Lab Project Number: ISN 229/901208: 

ISN/229. Unpublished study prepared by Huntingdon Research Centre Ltd. 28 p. 

43869806 Kent, S.; Sankey, S.; Caunter, J.; et al. (1994) THPI: Acute Toxicity to Rainbow 

Trout (Oncorhynchus mykiss): Lab Project Number: BL5237/B: AA0427/B. 

Unpublished study prepared by Zeneca Ltd., Brixham Environmental Lab. 19 p. 

43869807 Rapley, J.; Hamer, M. (1993) Captan: Acute Toxicity of the Technical Material to 

First Instar Daphnia magna: Lab Project Number: 91JH187: RJ1116B. 

Unpublished study prepared by ICI Agrochemicals, Jealott’s Hill Research 

Station. 16 p. 

43869808 Kent, S.; Sankey, S.; Banner, A.; et al. (1994) THPI: Acute Toxicity to Daphnia 
41 

magna: Lab Project Number: BL5239/B: AA0427/D. Unpublished study prepared 

by Zeneca Ltd., Brixham Environmental Lab. 18 p. 

43869809

 

Smyth, D.; Sankey, S.; Tapp, J.; et al. (1990) Captan: Toxicity to the Green Alga 

Selenastrum capricornutum: Lab Project Number: BL3954/B: T505/C: FT78/90. 

Unpublished study prepared by Imperial Chemical Industries PLC. 22 p. 

43869810 Kent, S.; Sankey, S.; Morgan, D.; et al. (1994) THPI: Toxicity to the Green Alga 

Selenastrum capricornutum: Lab Project Number: BL5238/B: AA0427/C. 

Unpublished study prepared by Zeneca Ltd., Brixham Environmental Lab. 22 p. 

44148801 Stewart, K.; Tapp, J.; Sankey, S. et al. (1991) Captan: Chronic Toxicity to 

Daphnia magna: (Final Report): Lab Project Number: T505/F: FT11/91: 

BL4102/B. Unpublished study prepared by Imperial Chemical Industries PLC. 26 

p. 

44738801 Kelso, H.; Kent, S.; Morris, D. et al. (1995) THP Am: Acute Toxicity to Rainbow 

Trout (Oncorhynchus mykiss): Lab Project Number: AB0085/C: BL5445/B. 

Unpublished study prepared by Zeneca Limited. 19 p. 

44806501 Drottar, K.; Krueger, H. (1999) Captan: A 96-Hour Toxicity Test with the 

Freshwater Alga (Anabaena flos-aquae): Final Report: Lab Project Number: 

493A-101A. Unpublished study prepared by Wildlife International Ltd. 45 p. 

{OPPTS 850.5400} 

44806502 Drottar, K.; Krueger, H. (1999) Captan: A 96-Hour Toxicity Test with the Marine 

Diatom (Skeletonema costatum): Final Report: Lab Project Number: 493A-102. 

Unpublished study prepared by Wildlife International Ltd. 45 p. {OPPTS 

850.5400} 

44806503 Drottar, K.; Krueger, H. (1999) Captan: A 7-Day Toxicity Test with Duckweed 

(Lemna gibba G3): Final Report: Lab Project Number: 493A-103. Unpublished 

study prepared by Wildlife International Ltd. 44 p. {OPPTS 850.4400} 

44806504 Drottar, K.; Krueger, H. (1999) Captan: A 96-Hour Static Acute Toxicity Test 

with the Sheepshead Minnow (Cyprinodon variegatus): Final Report: Lab Project 

Number: 493A-104. Unpublished study prepared by Wildlife International Ltd. 39 

p. {OPPTS 850.1075} 

44806505 Drottar, K.; Krueger, H. (1999) Captan: A 96-Hour Static Acute Toxicity Test 

with the Saltwater Mysid (Mysidopsis bahia): Final Report: Lab Project Number: 

493A-105. Unpublished study prepared by Wildlife International Ltd. 39 p. 

{OPPTS 850.1035} 

46061701 Boeri, R.; Wyskiel, D.; Ward, T. (2003) Captan Technical: Oyster Shell 

Deposition Test. Project Number: 2428/MA. Unpublished study prepared by T.R. 

Wilbury Laboratories, Inc. 35 p. 
Appendix A: Chemical Structures of Captan and 

Table C-1. Chemical Names and Structures of 

Chemical Name 

Captan 

3a,4,7,7a-tetrahydro-2-[(trichloro 

methyl)thio]-1H-isoindole-1,3(2H)-

dione 

THPI 

Tetrahydrophthalamide 

THPAm 

Tetrahydrophthalimic acid 

THCY 

Cis-6-cyano-3-cyclohexenecarboxylic 

acid 

THAPI (THAPL) 

Tetrahydrophthalic acid 

THPA-Epoxide 

Tetrahydrophthalamide epoxide

5,6 dihydroxyhexaryohophthalamide 

(Diol)

42 

Chemical Structures of Captan and Its Degradates

1. Chemical Names and Structures of Diflubenzuron and its Degradates

Structure 

cyclohexenecarboxylic 

Structure not found 

and its Degradates
43 

Appendix B: SIP (v 1.0) Inputs and Results 

The purpose of this model is to provide an upper bound estimate of exposure of birds and mammals to 

pesticides through drinking water alone. This model is intended for use in problem formulation to 

determine whether or not drinking water exposure alone is a potential pathway of concern. This does not 

aggregate drinking water exposure with other exposure routes (i.e., diet, inhalation, dermal). 

 

Assumptions:

 

SIP employs the following conservative assumptions to derive upper bound exposure estimates: 

1) The chemical concentration in drinking water is at the solubility limit in water (at 25oC). 

2) The assessed animals obtain 100% of their daily water needs through drinking water. 

3) The daily water need is equivalent to the daily water flux rate as calculated by Nagy and Peterson 

(1988). 

4) The body weight of the assessed bird is equivalent to the smallest generic bird modeled in T-REX (i.e., 

20 g). This assumption results in the highest ratio of exposure to toxicity for the 3 assessed avian body 

weights of T-REX (i.e., 20, 100, 1000 g). 

5) The body weight of the assessed mammal is equivalent to the largest generic mammal modeled in TREX (i.e., 1000 g). This results in the highest ratio of exposure to toxicity for the 3 assessed mammalian 

body weights of T-REX (i.e., 15, 35, 1000 g). 

 

Table 1. Inputs 

Parameter Value 

Chemical name captan 

Solubility (in water at 25oC; mg/L) 3.3 

 

Mammalian LD50 (mg/kg-bw) 5000 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian 

species 

 

Mammalian NOAEL (mg/kg-bw) 250 

Mammalian test species laboratory rat 

Body weight (g) of "other" mammalian 

species 

 

Avian LD50 (mg/kg-bw) 1255 

Avian test species northern bobwhite quail 

Body weight (g) of "other" avian species 

Mineau scaling factor 1.15 

 

Mallard NOAEC (mg/kg-diet) 1000 

Bobwhite quail NOAEC (mg/kg-diet) 1000 

NOAEC (mg/kg-diet) for other bird species 

Body weight (g) of other avian species 

NOAEC (mg/kg-diet) for 2nd other bird 

species 

Body weight (g) of 2nd other avian species 

 
44 

Table 2. Mammalian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 0.5676 0.5676 

Adjusted toxicity value (mg/kg-bw) 3845.8028 192.2901 

Ratio of exposure to toxicity 0.0001 0.0030 

Conclusion* 

Drinking water 

exposure alone is NOT 

a potential concern for 

mammals 

Drinking water exposure 

alone is NOT a potential 

concern for mammals 

 

Table 3. Avian Results 

Parameter Acute Chronic 

Upper bound exposure (mg/kg-bw) 2.6730 2.6730 

Adjusted toxicity value (mg/kg-bw) 904.1390 49.6126 

Ratio of exposure to acute toxicity 0.0030 0.0539 

Conclusion* 

Drinking water 

exposure alone is NOT 

a potential concern for 

birds 

Drinking water exposure 

alone is NOT a potential 

concern for birds 

 

*Conclusion is for drinking water exposure alone. This does not combine all routes of 

exposure. Therefore, when aggregated with other routes (i.e., diet, inhalation, dermal), 

pesticide exposure through drinking water may contribute to a total exposure that has potential 

for effects to non-target animals. 

 
45 

Appendix C: STIR (v 1.0) Inputs and Results 

Welcome to the EFED 

Screening Tool for Inhalation Risk 

This tool is designed to provide the risk assessor with a rapid method for determining 

the potential significance of the inhalation exposure route to birds and mammals in a 

risk assessment. 

 

Input 

Application and Chemical Information 

Enter Chemical Name captan 

Enter Chemical Use 

Is the Application a Spray? (enter y or n) y 

If Spray What Type (enter ground or air) air 

Enter Chemical Molecular Weight (g/mole) 300.57 

Enter Chemical Vapor Pressure (mmHg) 8.00E-08 

Enter Application Rate (lb a.i./acre) 

 

Toxicity Properties 

Bird 

Enter Lowest Bird Oral LD50 (mg/kg bw) 1255 

Enter Mineau Scaling Factor 1.15 

Enter Tested Bird Weight (kg) 0.178 

Mammal 

Enter Lowest Rat Oral LD50 (mg/kg bw) 5000 

Enter Lowest Rat Inhalation LC50 (mg/L) 0.72 

Duration of Rat Inhalation Study (hrs) 4 

Enter Rat Weight (kg) 0.35 

 

Output 

Results Avian (0.020 kg ) 

Maximum Vapor Concentration in Air at Saturation 

(mg/m3) 1.29E-03 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 1.63E-04 

Adjusted Inhalation LD50 1.01E+00 

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.61E-04 Exposure not Likely Significant 

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 0.00E+00 

Ratio of Droplet Inhalation Dose to Adjusted 

Inhalation LD50 0.00E+00 Exposure not Likely Significant 

 

Results Mammalian (0.015 kg ) 

Maximum Vapor Concentration in Air at Saturation 1.29E-03 
46 

(mg/m3) 

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 2.04E-04 

Adjusted Inhalation LD50 4.29E+01 

Ratio of Vapor Dose to Adjusted Inhalation LD50 4.77E-06 Exposure not Likely Significant 

Maximum Post-treatment Spray Inhalation Dose 

(mg/kg) 0.00E+00 

Ratio of Droplet Inhalation Dose to Adjusted 

Inhalation LD50 0.00E+00 Exposure not Likely Significant