1 

OFFICE OF CHEMICAL SAFETY 

AND POLLUTION PREVENTION 

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460 

August 5, 2015 

PC Code: 038901, 038904, 038905 

DP Barcode: 426244

MEMORANDUM 

SUBJECT: EFED Registration Review Problem Formulation for Endothall 

FROM: Christina Wendel, Biologist 

James Lin, Environmental Engineer 

Environmental Risk Branch 2 

Environmental Fate and Effects Division (7507P) 

And 

Laura Parsons, Associate Branch Chief 

Risk Assessment & Science Support Branch (RASSB) 

Antimicrobials Division (7510P) 

REVIEWED 

BY: R. David Jones, Ph.D., Senior Agronomist 

Elyssa Arnold, Risk Assessment Process Leader (RAPL) 

Brian Anderson, Branch Chief 

Environmental Risk Branch 2 

Environmental Fate and Effects Division (7507P) 

TO: Garland Waleko, Chemical Review Manager 

Tom Myers, Team Leader 

Kevin Costello, Branch Chief 

Risk Management and Implementation Branch 2 

Pesticide Re-evaluation Division (7508P)

2015.08.06 08:15:59 -04'00'

2015.08.06 08:25:25 

-04'00'

2015.08.06 

09:55:34 -04'00'

2015.08.06 

15:08:48 -04'00'

ROBERT JONES Digitally signed by ROBERT JONES 

DN: c=US, o=U.S. Government, ou=USEPA, ou=Staff, 

cn=ROBERT JONES, dnQualifier=0000006506 

Date: 2015.08.10 11:00:40 -04'00'

'PS

STEVEN WEISS Digitally signed by STEVEN WEISS 

DN: c=US, o=U.S. Government, ou=USEPA, ou=Staff, 

cn=STEVEN WEISS, dnQualifier=0000013584 For Date: 2015.08.11 12:52:49 -04'00'
2 



 

1. Executive summary ................................................................................................................. 3

2. Introduction ............................................................................................................................. 5

a. Mode of Action .................................................................................................................... 5

3. Use Characterization ............................................................................................................... 6

4. Conclusions from Previous Risk Assessments ....................................................................... 7

a. Ecological Risk Assessment ................................................................................................ 7

b. Drinking Water Exposure Assessments ............................................................................... 9

c. Clean Water Act Programs .................................................................................................. 9

5. Environmental Fate and Transport.......................................................................................... 9

6. Receptors............................................................................................................................... 13

a. Effects to Aquatic Organisms ............................................................................................ 15

b. Effects to Terrestrial Organisms ........................................................................................ 17

c. Ecological Incidents ........................................................................................................... 19

7. Exposure Pathways of Concern ............................................................................................ 21

8. Analysis Plan ........................................................................................................................ 23

a. Stressors of Concern .......................................................................................................... 23

b. Measures of Exposure ........................................................................................................ 23

c. Measures of Effect ............................................................................................................. 24

d. Endangered Species Assessments ...................................................................................... 24

e. Endocrine Disruptor Screening Program ........................................................................... 25

9. Preliminary Identification of Data Gaps ............................................................................... 25

a. Environmental Fate ............................................................................................................ 25

b. Effects ................................................................................................................................ 26

10. References .......................................................................................................................... 47

a. Submitted Environmental Fate Studies .............................................................................. 48

b. Submitted Ecological Toxicity Studies .............................................................................. 52

APPENDIX A. SLUA Summary Table for Endothall.................................................................. 84

APPENDIX B. Endothall Incidents .............................................................................................. 85

APPENDIX C. SIP & STIR Inputs and Outputs for Endothall Acid, and the dipotassium and 

mono (N,N-dimethylalkylamine) salts of endothall ..................................................................... 89
3 

1. Executive summary

The Environmental Fate and Effects Division (EFED) has completed the problem formulation for 

the ecological risk, environmental fate, endangered species, and drinking water assessments to be 

conducted as part of the registration review of endothall (PC code 038901). Endothall acid is the 

herbicidal active ingredient in all of the endothall-containing herbicide formulations but only salts 

of endothall are sold as pesticide products. For consistency, concentrations and endpoints are all 

presented in terms of endothall acid equivalents. The endothall formulations for this risk 

assessment consist of either a dipotassium salt (PC code 038904) or a mono N,Ndimethylalkylamine salt (PC code 038905). The problem formulation describes the methods 

planned to be used during the completion of drinking water and ecological risk assessments in 

support of registration review and provides an overview of the environmental fate, ecological 

effects, potential risks associated with the use, and uncertainties unique to the risk assessment of 

endothall. This document also identifies additional studies that would be beneficial to the conduct 

of an ecological risk assessment. 

Endothall is applied directly to water to control aquatic vegetation and to terrestrial, agricultural 

sites for weed control. The mono N,N-dimethylalkylamine salt can also be applied directly to water 

in cooling towers to control freshwater and saltwater molluscs. Risk assessments conducted to date 

have identified potential risks to aquatic and terrestrial plants and animals, although risks vary 

somewhat across the different salts and use patterns. The mono N,N-dimethylalkylamine salt has 

been shown to be substantially more toxic than the dipotassium salt for all aquatic species tested, 

likely due to toxicity of the cation in addition to that of the endothall acid following dissociation of 

the salt. Therefore, toxicity data on both salts and the free acid are recommended for the aquatic 

risk assessment. However, a full suite of dimethylalkylamine salt, and a full suite of either the acid 

or the dipotassium salt is sufficient (including chronic toxicity), as the toxicity of the acid and the 

dipotassium salt is similar, and the endpoints can be bridged on an acid equivalent basis. 

Additional data are needed primarily for either the acid and/or dipotassium salt to have a complete 

data set for aquatic toxicity. In addition, there are two previously submitted freshwater and 

estuarine/marine invertebrate chronic toxicity studies, for the free acid and the dimethylalkylamine 

salt, respectively, that do not provide reliable endpoints for use in risk assessment, and, therefore, 

new toxicity data are needed. 

For terrestrial species, like the aquatic species, a full suite of dimethylalkylamine salt, and a full 

suite of either the acid or the dipotassium salt are recommended for risk assessment. Therefore, 

toxicity data needed include acute oral passerine toxicity, avian reproduction, and honey bee data 

(due to the new data requirements). 

For both the aquatic and terrestrial assessments, the most sensitive endpoint from the 

dimethylalkylamine salt or the free acid will be used to assess dimethylalkylamine salt uses. The 

most sensitive endpoint from the dipotassium salt or the free acid will be used to assess dipotassium 

salt uses. All endpoints will be expressed in terms of endothall acid equivalents for risk estimation. 
4 

The following are the needed data for endothall: 

Data Needs 

x Ecotoxicity Data 

Aquatic

o OCSPP 850.1300: Freshwater invertebrate life cycle (acid and/or dipotassium salt)

o OCSPP 850.1350: Saltwater invertebrate life cycle (acid and/or dipotassium salt and

dimethylalkylamine salt)

o OCSPP 850.1400: Saltwater fish early-life stage (acid and/or dipotassium salt)

o or OCSPP 850.1075 Freshwater fish acute toxicity with fathead minnow (acid only) for 

calculation of an ACR

Terrestrial

o OCSPP 850.2100: Avian acute oral toxicity with passerine species (dimethylalkylamine 

salt and acid or dipotassium salt) 

o OCSPP 850.2300: Avian reproduction; bobwhite quail (acid and/or dipotassium salt) 

and mallard duck (dimethylalkylamine salt) 

o OCSPP 850.3020: Honeybee acute contact toxicity study (both salts) 

o OECD TG 213 and Non-guideline special studies: Honey bee adult acute and chronic 

oral toxicity studies (both salts) 

o OECD TG 237 and Non-guideline special studies: Honeybee larval acute and chronic 

oral toxicity studies (both salts) 

o Non-guideline special studies: Field trial measuring residues of endothall in pollen and 

nectar (both salts) 

o Special study OECD TG 75 and OSCPP 850.3040: Semi-field testing for pollinators and 

Field testing for pollinators (both studies are conditionally required pending the results 

of the Tier I – laboratory based studies listed above; if needed protocols for each study 

must be submitted for review prior to study initiation; both salts would be tested). 

x Environmental Fate Data 

For coco-alkylamine cation, a part of mono (N,N-dimethylalkylamine) salt of endothall, 

including: 

o OCSPP 835.2100: Hydrolysis

o OCSPP 835.2240: Aqueous Photolysis

o OCSPP 835.4100: Aerobic Soil Metabolism

o OCSPP 835.4400: Anaerobic Aquatic Metabolism

o OCSPP 835:4300: Aerobic Aquatic Metabolism

o OCSPP 835.1230: Batch Equilibrium 

 

 
5 

For the mono N,N-dimethylalkylamine salt to support the Down the Drain assessment1

: 

o OCSPP 850.3300: Activated Sludge Respiration Inhibition

o OCSPP 835.3110: Ready Biodegradation

o OCSPP 835.3220: Porous Pot Study

o OCSPP 835.3240: Simulation Test – Aerobic Sewage Treatment

o OCSPP 835.3280: Simulation Test – Assess Biodegradability in Wastewater

2. Introduction

Endothall, known by the trade names Aquathol K®, Aquathol Super K®, Hydrothol 191®, 

Desicate II, and Accelerate®, is a liquid or granular herbicide that has two salt forms, a dipotassium 

salt, and a mono-(N,N-dimethylalkylamine) salt (referred to as N,N-amine in this assessment). The 

dipotassium formulations (Aquathol® product line) are used to control submerged aquatic weeds, 

such as hydrilla and curlyleaf pondweed and for irrigation to non-food crops. The endothall N,Ndimethylalkylamine salt formulations are used in both aquatic (Hydrothol 191) and terrestrial 

(Accelerate and Desicate product line) applications. Hydrothol 191 is used to control algae and 

submerged aquatic vegetation in small areas, such as drainage and irrigation canals and small pond 

or lake areas and for irrigation to non-food crops. Accelerate and Desicate II are used terrestrially 

as defoliants on cotton, seed production alfalfa and clover. 

One N,N amine product, TD 2335 Industrial Biocide-Molluscicide, is used to control freshwater 

and saltwater mussels in once-through and recirculating cooling tower waters. The product is to 

control established populations and to prevent settlement/attachment of immature forms of 

molluscs. 

a. Mode of Action 

Endothall acid is the herbicidal active ingredient in all of the endothall-containing herbicide 

formulations. Endothall is formulated as a dipotassium salt or a mono (N,N-dimethylalkylamine) 

salt. The dissociation constants of both of the endothall salts indicate that at most environmental 

pH levels, the endothall salt, endothall acid, and the corresponding cation (potassium or N,Ndimethylalkylamine) will all be present. In addition, there are significant differences in toxicity to 

certain organisms between the endothall dipotassium salt and the endothall mono (N,Ndimethylalkylamine) salt. Therefore, this risk assessment examines all of the potential chemical 

exposures from endothall application separately. For consistency, concentrations are presented in 

terms of endothall acid equivalents. Terrestrial toxicity data are not available for the potassium 

cation or coco-alkylamine cation. 

 

1

 Only one of the biodegradation studies is required. The results of the ASRI test will determine which of four 

biodegradation tests is/are required. If the ASRI test EC50 is less than or equal to 20 mg/L, then either the 

(i)Biodegradation in Activated Sludge Study or (ii) Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge 

Units or (iii) the Porous Pot Test is expected to be required. If the ASRI test EC50 is greater than 20 mg/L, then the 

registrant would likely be required to conduct either: (i) Ready Biodegradability or (ii) a) Biodegradation in Activated 

Sludge or b) Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge Units or c) the Porous Pot Test. If the 

Ready Biodegradability study is conducted and passes, then no further testing would be expected to be required. If, 

however, the antimicrobial fails the Ready Biodegradability study, then the a) Biodegradation in Activated Sludge or b) 

Simulation Test – Aerobic Sewage Treatment: A. Activated Sludge Units, or c) the Porous Pot study would likely be 

required.
6 

Endothall acts mainly as a contact herbicide, although it is somewhat mobile in plant tissues when 

applied at rates lower than those used for contact kill and can cause plant death through foliage 

absorption. Endothall interferes with plant respiration by affecting protein and lipid biosynthesis 

and disrupting plant cell membranes. 

3. Use Characterization

Endothall is used for (1) direct application to water to control aquatic plants, (2) as a desiccant on 

cotton, potatoes, seed production alfalfa and clover, and (3) as a blossom thinner on apples. 

According to the Screening Level Usage Analysis (SLUA) provided by the Biological and Economic 

Analysis Division (BEAD), for endothall case (002245) between 2004 and 2012 an average of 3,000 

lbs a.i./yr was used on alfalfa, 2,000 lbs a.i./yr was used on cotton, and 4,000 lbs a.i./yr was used on 

potatoes in the United States (USEPA, 2014). The SLUA reports do not include non-crop uses. 

Application rates are similar for all three use patterns. The highest maximum application rates are < 

2.5 lb a.i./A. 

Table 1 lists the maximum use patterns for the labeled use sites for endothall, mono (N,N,-

dimethylalkylamine) salt (038905). Table 2 lists the maximum use patterns for the labeled use sites 

for endothall dipotassium salt (038904). All these uses are based on the Label Use Report Package 

created by BEAD in support of Registration Review (USEPA, 2014b). 

Table 1. Endothall, mono (N,N,-dimethylalkylamine) salt (PC 038905) Label Use Information 

Use 

Single Max 

Application 

Rate 

(lbs a.i./A) 

Max 

Application 

Rate per 

Crop Cycle 

(lbs a.i./A) 

Max 

Application 

Rate per 

Year 

(lbs a.i./A) 

Min 

Application 

Retreatment 

Interval 

(days) 

Max # of 

Applications 

Per Year 

Formulation, 

Application 

Methods 

Alfalfa 1.7 NS NS NS NS 

SC, 

Broadcast - 

Aerial, Ground 

Clover 1.7 NS NS NS NS 

Potato, White/ Irish 

(or Unspecified) 2.3 NS NS NS NS

Aquatic Areas/ Water* 30.9 

(lb/a-ft) NS NS 7 NS SC, (* also for 

Granular), 

Ground, 

Water Treatment, 

Water Treatment 

(Surface) 

Irrigation Systems 30.7 

(lb/a-ft) NS NS NS NS

Lakes/ Ponds/ 

Reservoirs (w/o Human 

or Wildlife Use) 

30.7 

(lb/a-ft) NS NS NS NS

Cotton 

(Unspecified) 0.2859 NS NS NS NS

SC, 

Ground, 

Aerial,

Desiccation 

NS=not specified; NDC=no dosage conversion; SC= Soluble Concentration/Liquid 
7 

Table 2. Endothall, dipotassium salt (PC 038904) Label Use Information 

Use 

Single Max 

Application 

Rate

(lbs a.i./A) 

Max 

Application 

Rate per Crop 

Cycle

(lbs a.i./A) 

Max 

Application 

Rate per 

Year 

(lbs a.i./A) 

Min 

Application 

Retreatment 

Interval (days) 

Max # of 

Applications 

Per Year 

Formulation, 

Application 

Methods 

Aquatic Areas/ 

Water 

13.9 

(lb/a-ft) NS NS

NS 

NS

SC, 

Ground, 

Aerial, 

Water Treatment, 

Water Treatment 

(Surface), 

Dripline 

Application 

5 ppm 7 

Lakes/ Ponds/ 

Reservoirs 

(w/o Human or 

Wildlife Use) 

30.7 

(lb/a-ft) NS NS

NS 

NS

5 ppm 5 

Apples 0.28

(0.3 lbs ae) NS 0.846 (0.6 lb ae) 

>24 hrs 

(cannot be 

applied more 

than once in 24 

hour period) 

2 

SC, 

Ground,

Airblast spray 

NS=not specified; SC= Soluble Concentration/Liquid 

For the antimicrobial use of N,N-amine to control molluscs in industrial cooling towers, the product 

can be applied at up to 3 ppm endothall (24 gallons product per 1 million gallons of water) and the 

concentration should be maintained for up to 140 hours. Applications should be made to an area of 

uniform mixing within the system. No holding period or deactivation time is required by the label. 

4. Conclusions from Previous Risk Assessments

a. Ecological Risk Assessment 

A number of ecological risk assessments have been conducted on endothall. The conclusions from 

the past assessments are summarized in Figure 1 and Table 3 below. 

Figure 1. Graphic Summary of Potential Risks of Current Endothall Uses 
8 

Table 3. Evidence of Risk to Taxonomic Groups from Assessed Endothall Uses 

Conclusion: No Risks of Concern 

Certainty: High 

Conclusion: Risks of Concern Identified 

Certainty: High 

Fish: Acute listed and non-listed fish (freshwater and 

estuarine/marine) and chronic LOC exceedances for 

freshwater fish. No estuarine/marine fish chronic toxicity data 

was previously available. A study was submitted for the mono 

(N,N,-dimethylalkylamine) salt and the endpoint was 

converted to a.e.; therefore it can be used to represent the 

endothall estuarine/marine fish chronic toxicity endpoint for 

both salts. The estuarine/marine toxicity fish data are an order 

of magnitude more sensitive than the freshwater data, 

indicating there would also be chronic risk to 

estuarine/marine fish as well.

Aquatic Invertebrates: Acute listed and non-listed fish 

(freshwater and estuarine/marine) LOCs were exceeded. No 

estuarine/marine aquatic invertebrate (mysid) chronic toxicity 

data was previously available. A study was submitted for the 

mono (N,N,-dimethylalkylamine) salt and the endpoint was 

converted to a.e.; therefore it can be used to represent the 

endothall estuarine/marine aquatic invertebrate (mysid) 

chronic toxicity endpoint for both salts. The estuarine/marine 

toxicity fish data are within an order of magnitude of the 

freshwater invertebrate data, indicating there would also be 

chronic risk to estuarine/marine invertebrates as well. 

Terrestrial & Aquatic Plants: Endothall is an herbicide used 

to control aquatic and terrestrial vegetation; risk to non-target 

listed and non-listed terrestrial monocot and dicot plants 

based on exposure via runoff and/or spray drift have been 

identified. Incidents have been reported on terrestrial plants. 

Birds (surrogates for reptiles and terrestrial-phase 

amphibians): Acute dose- and dietary-based LOC 

exceedances for multiple size classes and feeding guilds of 

birds; both acute and chronic LOCs have been exceeded.

Consuming a variety of dietary items (RQ values ranged 0.1-

42.13). Chronic LOC exceedances for birds consuming a 

variety of dietary items (RQ values ranged 1.03-23.66). . 

Mammals: Acute dose- and dietary-based LOC exceedances 

for multiple size classes and feeding guilds of mammals; both 

acute and chronic LOCs have been exceeded. 

Conclusion: No Risks of Concern 

Certainty: Low 

Conclusion: Risks of Concern Identified 

Certainty: Low 

Terrestrial Invertebrates: No toxicity was observed in the 

only available study (adult acute contact) for honey bees. 

Toxicity to larval life-stages is unknown; therefore, risk is 

presumed in the absence of acute and chronic oral toxicity 

data for larvae. In addition, toxicity data evaluating the oral 

route of exposure on an acute and chronic basis is also needed 

for the adult honey bees as well. Data are also needed to 

examine residues of endothall in pollen and nectar. 
9 

b. Drinking Water Exposure Assessments 

The most recent drinking water exposure assessment conducted for endothall was completed for the 

new use on apple trees (DP 404321, September 2012). The report has indicated that the irrigation 

water uses will provide the most conservative drinking water values and designate the Maximum 

Concentration Level (MCL) of 0.1 mg/L as the maximum value. The estimated drinking water 

concentrations (EDWC) were 100 g/L for the acute (peak) and 31 g/L for the chronic (annual 

average). 

c. Clean Water Act Programs 

The Clean Water Act requires the Agency to publish water quality criteria that accurately reflect the 

latest scientific knowledge on the kind and extent of all identifiable effects on health and welfare 

that might be expected from the presence of pollutants in any body of water, including ground 

water. While these recommended criteria do not, in themselves, impose any requirements, states 

and authorized tribes can use them to develop water quality standards. An Aquatic Life Ambient 

Water Quality Criteria document has not been published for endothall (see url: 

http://www.epa.gov/waterscience/criteria/). 

The Office of Pesticide Programs (OPP) publishes aquatic life benchmarks for freshwater species 

based on toxicity values for the most sensitive species from the most recent risk assessments. The 

aquatic life benchmarks have been published for endothall (acid, dipotassium salt and N,Ndimethylalkylamine salt; Table 4). 

Table 4. Aquatic Life Benchmarks Published for Endothall 

Endothall Form Fish (g/L) Invertebrates (g/L) 

Acute Chronic Acute Chronic 

Acid 24500 1300 46000 <2200 

Dipotassium salt 4576 1790 31900 

N,N-dimethylalkylamine 7.5 56 6 2.3 

 (See url: http://www.epa.gov/oppefed1/ecorisk_ders/aquatic_life_benchmark.htm#benchmarks). 

Endothall is not identified as a cause of impairment for any water bodies listed as impaired under 

section 303(d) of the Clean Water Act, based on information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885. 

No Total Maximum Daily Load (TMDL) criteria have been developed for endothall, based on 

information provided at 

http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=88

5&p_pollutant_group_name=PESTICIDES. 

5. Environmental Fate and Transport

The endothall salts dissociate at environmentally relevant pH levels and all three endothall forms 

will be found in the environment. Endothall has two carboxylic acid groups and hence can 

dissociate one or two protons. Due to the high water solubility and low Henry’s Law constant, the 

volatilization will not be a concern. 
10 

The mobility of the endothall compound is highly sensitive to pH. In batch equilibrium studies 

(MRID 41616404) on endothall acid, Freundlich Kads values were 0.15, 0.80, 0.56, and 7.94 on 

loamy sand, sandy loam, clay loam, and silt loam respectively. These mobility values are inversely 

related to soil pH, as evidenced by soils with a pH of >6.1-6.2 demonstrating low sorption (0.15-

0.80). A soil with a pH of 6.1-6.2 or less will be more tightly sorbed to the soil. 

Endothall degrades only via biotic processes such as aerobic metabolism, and not as the result of 

abiotic processes such as hydrolysis and photolysis. The submitted laboratory studies indicate that 

the amine salt (MRID 44578401) and di-potassium salt (MRID 42289106) forms of endothall are 

stable to hydrolysis at pH 5, 7 and 9. The acid form of endothall was also found to be stable to 

aqueous photolysis in a laboratory study (MRID 42289205, 42641201). In aquatic environment, 

the endothall acid is negatively charged. It will be repelled from the soil and sediment and be found 

primarily in the water column. The potassium and amine cations are positively charged and will 

bind to most sediments and soils. In an aerobic soil metabolism study, the dipotassium salt of 

endothall degraded with a half-life of 14.5 days in Huntington sandy loam soil (MRID 44949401). 

In aerobic lake water over flooded silt loam sediment, endothall dipotassium salt degraded with a 

half-life of 10 days (MRID 42618901). There were no major degradates. Endothall acid is not 

expected to be present for adequate time to result in long-term exposure. 

In terrestrial field dissipation studies residues of endothall were not persistent. Dipotassium 

endothall applied to sugar beet fields in California and Pennsylvania (loam and silty clay loam soils, 

respectively) dissipated from the upper 4 inches of soil with half-lives of <7 days and 9 days. 

Similarly, endothall (N,N-dimethyl alkyl amine salt) applied to potato fields in California and 

Pennsylvania (loam and silty clay loam soils, respectively) dissipated from the upper 4 inches of 

soil with half-lives of 12.6 and 19.2 days, respectively. 

Numerous aquatic dissipation studies ranging from laboratory, greenhouse, ponds (partial and 

whole treatment), lakes, and reservoirs demonstrate dissipation half-lives of 0.5 to 30 days. The 

persistence of endothall in the aquatic environment is consistent regardless of the type of study. For 

laboratory studies, the median half-life of endothall was 8.5 days (4.1-30 days). For ponds and 

lakes, the median half-lives were 4.1 days (0.5-20 days) and 1.2 days (0.24-8.5 days), respectively. 

The chemical properties and environmental fate parameters are tabulated in Table 5. 

Table 5. Chemical Properties and Environmental Fate Parameters of Three Endothall Products 

Acid Dipotassium N,N-dimethylalkylamine 

CAS Registry Number #145-73-3 #2164-07-0 #66330-88-9 

Physical state solid liquid or solid (granular)* liquid or solid (granular)* 

Water solubility 

(g/ml @25qC) >11 >65 >50

Octanol:Water 

partition coefficient 

(Kow@25qC) 

<1 <1 <1

Dissociation Constant 

(pKa1, pKa2) 4.32, 6.22 4.16, 6.14 4.24, 6.04

pH 2.7 6.5 - 7.5* 4.4 - 4.6* 
11 

Acid Dipotassium N,N-dimethylalkylamine 

Vapor pressure 

(torr@24.3qC) 3.92 x 10-5 3.92 x 10-5 2.09 x 10-5

Henry’s Law Constant

(atm-m3/mole) < 6.64 x 10-10

< 1.58 x 10-10 < 9.53 x 10-11

Hydrolysis No Data acid stable at pH 5, 7, & 9 

(MRID 42289106)

acid stable at pH 5, 7, & 9 

(MRID 44578401)

Direct Aqueous 

Photolysis

does not absorb 

light >290nm

(MRID 42289205) 

does not absorb light 

>290nm (MRID 42289205) 

does not absorb light 

>290nm (MRID 42289205) 

Soil Photolysis 

(half-life, days) 

48.7 (irradiated) 

100.4 (dark)1

(MRID 42641202)4

No Data No Data

Aerobic Soil 

Metabolism

(half-life, days) 

No Data 14.5 (sandy loam)2

(MRID 44949401) No Data 

Anaerobic Aquatic 

Metabolism

(half-life, days) 

No Data 9.0 (silt loam)3

(MRID 42903901)4 No Data

Aerobic Aquatic 

Metabolism

(half-life, days) 

No Data 10.0 (flooded silt loam)2

(MRID 42618901) No Data

Kd-ads / Kd-des (ml/g) 

0.15/0.0 

 (loamy sand) 

0.80/4.3 

 (sandy loam) 

0.56/2.57 

 (clay loam) 

7.94/37.25 

 (silt loam) 

(MRID 4161604) 

No Data No Data

Soil Dissipation No Data

CA: <7.0 (loam) 

PA: <9.0 (silty clay loam) 

(MRID 42670101) 

CA: 13 (loam) 

PA: 19 (silty clay loam)

(MRID 42670201) 

Sediment Dissipation 

(half-life, days) No Data 8.9 (MRID 44093403)42.5-3.4 (MRID 44093402) 4 No Data

Aquatic Dissipation 

(half-life, days) No Data

0.8 (lake water) 

(MRID 44093403)4

0.4 (uncontained)

5.4-8.5 (contained 

(MRID 44093402)4

<24h in sediment5

Max. residues of 7.7, 5.4, 

4.6, 4.0, and 3.4 ug/L; 0, 

3.6, 10, 13, and 15 miles 

from treatment canal in CO. 

(MRID 44820103) 

Fish Accumulation 

(BCF) No Data

0.08x (edible) 

0.35x (whole)

(MRID 4264001) 

No Data

*dependent on commercial formulation 

1

Non-volatile unidentifiable degradates (18% of applied) 

2

Unextractable degradates and CO2

3

mono-and di- methyl ester degradates 
12 

o

o

o

o

[NH(CH3)2(CH2)n(CH3)]+ O [NH

-

n=7-17 

 4 Study unacceptable

5

 endothall acid and monohydrate degradates 

The structures of all three endothall products and environmental degradates are listed in Table 6. 

Table 6. Chemical Structure of All Three Endothall Products and Environmental Degradates 

Product Name Chemical Structure 

Parent Endothall Products

 Endothall Acid

 7-Oxabicyclo (2,2,1)heptane-2,3-dicarboxylic acid 

 MW: 186.2 g/mole

 Molecular Formula: C8H10O5

 Endothall, Dipotassium salt

7-Oxabicyclo (2,2,1)heptane-2,3-dicarboxylic 

 acid dipotassium salt 

 MW: 262.3 g/mole

 Molecular Formula: C8H8K2O5

Endothall, mono (N,N,-dimethyl alkyl amine) salt 

MW: 228.1 g/mole 

Minor Environmental Degradates

Endothall Monomethyl Ester 

Max. detection 0.03% 

 (aerobic soil metabolism study, MRDI 4494901) 

Max. detection 4.75% 

 (anaerobic aquatic metabolism study, MRDI 

42903901)

Endothall Dimethyl Ester 

Max. detection 4.75% 

(anaerobic aquatic metabolism study, MRDI 

42903901)

There is no fate and transport information about the coco-alkylamine cation, which is a part of 

mono (N,N-dimethylalkylamine) salt of endothall. For this reason, several fate guideline studies 

are required, in order to better assess the ecological impacts due to coco-alkylamine cation. 
13 

6. Receptors

The toxicity endpoints that will be used in risk assessment for aquatic and terrestrial organisms 

exposed to endothall are presented in Table 7 through Table 10 below. 

Endothall acid is the herbicidal active ingredient in all of the endothall-containing herbicide 

formulations. The mono N,N-dimethylalkylamine salt has been shown to be substantially more 

toxic than the acid and dipotassium salt for all aquatic species tested. For example, LC50s for 

rainbow trout are 49 mg ae/L, 9 mg ae/L, and 0.1 mg ae/L, respectively, for the three endothall 

forms. The dimethylalkylamine salt is consistently and substantially (2 orders of magnitude or 

more) more toxic than the acid and dipotassium salt to aquatic organisms. For both the aquatic and 

terrestrial assessments, the most sensitive endpoint from the dimethylalkylamine salt or the free 

acid will be used to assess dimethylalkylamine salt uses. The most sensitive endpoint from the 

dipotassium salt or the free acid will be used to assess dipotassium salt uses. All endpoints will be 

expressed in terms of endothall acid equivalents for risk estimation. 

In general, endothall acid and the dipotassium salt have similar toxicity values and are slightly to 

practically non-toxic to aquatic animals on an acute exposure basis. Only a few chronic studies are 

available for the endothall acid and dipotassium salt; however, chronic effects were seen at 

substantially lower test concentrations than the LC50’s. The available dipotassium freshwater fish 

chronic study was not a guideline study, as fertilized rainbow trout eggs and sac fry, were exposed to 

the chemical for 4hrs followed by clean water for the remainder of the test duration. This study 

cannot be used to estimate risk to fish on a chronic basis for dipotassium; however, an acceptable 

freshwater early life-stage study (ELS) is available for the acid, and so a new study for the 

dipotassium salt is not needed for freshwater fish. No chronic estuarine/marine fish data is available 

for either the acid or the dipotassium salt. The available chronic daphnid study for endothall acid 

could not establish a no effect level as significant reductions were noted in length and number of 

offspring in the lowest test concentration that was tested, 2.2 mg ae/L, when compared to the 

controls. However, as previously mentioned, the dimethylalkylamine salt is consistently more toxic 

on an acute and chronic basis to aquatic animals. It is typically highly to very highly toxic on an 

acute exposure basis, and chronic effects were often seen in the low ug ae/L range for the 

dimethylalkylamine salt. The available chronic estuarine/marine invertebrate toxicity study for the 

dimethylalkylamine salt was classified as supplemental, and not upgradable because the offspring 

were not held until test termination for evaluation of mortality, sex ratios, and growth, offspring were 

apparently observed for abnormalities at the time of counting, and then they were discarded. It 

should be noted that there may be some small differences in endpoints from previous risk 

assessments, it was determined after review that the conversion to acid equivalent was incorrect, and 

therefore the endpoints were updated accordingly. Endpoints affected were the fathead and 

sheepshead minnow early life-stage toxicity tests, the daphnid, and mysid life-cycle chronic toxicity 

tests; as well as the two sediment toxicity tests, (a summary of the data is in Table 7). 

Aquatic plant studies are available for only the dipotassium and mono (N,N-dimethylalkylamine) 

salt of endothall; no aquatic plant toxicity data are available for the endothall acid. Again the 

dimethylalkylamine salt is substantially (2 orders of magnitude or more) more toxic than the 

dipotassium salt to aquatic non-vascular plants; however it is similarly toxic to aquatic vascular 

plants. There are no aquatic plant toxicity data available for endothall acid; aquatic plant toxicity 
14 

data are only available for the dipotassium salt and the mono (N,N-dimethylalkylamine) salt, (a 

summary of the data is in Table 8). 

Endothall acid is moderately toxic to avian species on an acute oral basis, practically non-toxic to 

avian species on a sub-acute dietary basis, highly toxic to mammals on an acute oral basis; and 

practically non-toxic to honeybees (LD50 >11 g/bee). The dipotassium salt is moderately toxic to 

avian species on an acute oral basis, slightly toxic to avian species on a sub-acute dietary basis, 

highly toxic to mammals on an acute oral basis, and practically non-toxic to honeybees (LD50 >11 

g/bee; although the test product was given (Aquathol K, 28.6% ae) and it is not clear if any 

additional adjustments are needed to present the data as ae). The mono (N,N-dimethylalkylamine) 

salt is moderately toxic for avian species on an acute oral basis, slightly on a sub-acute dietary 

basis, highly toxic to mammals on an acute oral basis, and practically non-toxic to honeybees (LD50 

>11 g/bee; although the test product was given (Hydrothol 191 23.4% ae) it is not clear if any 

additional adjustments are needed to present the data as ae). Due to the uncertainty surrounding the 

honeybee data, and in accordance with the new pollinator guidance, a full suite of honeybee data 

are being requested for the dipotassium salt and the mono (N,N-dimethylalkylamine) salt) (a 

summary of the available data is in Table 9 and the requested data are in Section 9b). 

Birds exposed to endothall acid on a chronic basis showed effects on early embryonic mortality in 

the offspring of mallard ducks. There was a high incidence of midterm eggs, a high number of eggs 

cracked, and a loss of an entire hatch due to incubator malfunction that can be indicative of an 

atypical population and masked effects during the study, this study was considered scientifically 

sound, but as a result of these issues, was classified as supplemental, and does not fulfill guideline 

requirements for an avian reproduction toxicity study. Birds exposed to the mono (N,Ndimethylalkylamine) salt on a chronic basis showed effects on adult female body weight gain in all 

treatment levels for mallard ducks; and a no effect level could be established. There were no effects 

to bobwhite quails exposed to mono (N,N-dimethylalkylamine) salt on a chronic basis. No data was 

submitted for dipotassium salt for chronic toxicity to birds, and there was no chronic toxicity to 

mammals for endothall acid, the dipotassium salt or the mono (N,N-dimethylalkylamine) salt, (a 

summary of the data is in Table 9). 

The only available mammalian 2-generation reproduction study for endothall utilized a formerly 

registered salt of endothall (disodium salt), and it was determined by HED that this data was 

acceptable to fulfill mammalian data needs, and no additional data would be requested for other 

forms of endothall. The study showed effects to mammals based on effects to the offspring, 

including decreased pup weight observed at day 0 of F1 and F2a generations. Parental systemic 

toxicity endpoints affected were the proliferative lesions of the gastric epithelium for both sexes, (a 

summary of the data is in Table 9). 

There are no terrestrial plant toxicity data available for endothall acid; terrestrial plant toxicity data 

are only available for the dipotassium salt and the mono (N,N-dimethylalkylamine) salt, (a 

summary of the data is in Table 10). 

Terrestrial plant toxicity data, both seedling emergence and vegetative vigor, are available for the 

dipotassium salt of endothall and the mono (N,N-dimethylalkylamine) salt of endothall. For the 

dipotassium salt, the vegetative vigor study was the more sensitive endpoint. The EC25 and 

NOAEC for lettuce (Lactuca sativa) was 0.011 and 0.005 lb ae/acre, respectively, based on 

vegetative vigor shoot weight. For the mono (N,N-dimethylalkylamine) salt of endothall, the 
15 

vegetative vigor study was also the most sensitive endpoint. The EC25 and NOAEC for perennial 

ryegrass (Lolium perenne) was 0.004 and 0.00006 lb ae/acre, respectively, based on vegetative 

vigor shoot length, (a summary of the data is in Table 10). 

a. Effects to Aquatic Organisms 

Table 7. Summary of the Most Sensitive Acute and Chronic Toxicity Data for Aquatic Animals 

Exposed to Endothall Acid, or the Dipotassium or Mono (N,N-dimethylalkylamine) Salts of Endothall 

Species Test 

Substance

(% ae) 

Acute Toxicity Chronic Toxicity 

LC50/EC50

(mg ae/L) 

(Toxicity 

Classification) 

 MRID

(Study 

Classification) 

NOAEC/LOAEC 

(mg ae/L) 

(Endpoints) 

MRID

(Study 

Classification) 

Rainbow trout 

(Oncorhynchus 

mykiss) 

Acid 

(77.9% ae) 

49.0 

(slightly toxic) 

42327702 

(Acceptable) ND ND 

Dipotassium

(28.6% ae)

9.152 

(moderately 

toxic) 

40098001 

(Supplemental) 

1.79/3.58 

(percent eggs hatch)1 

00095812 

(Supplemental) 

Mono 

(23.4% ae) 

0.131 

(highly toxic) 

40098001 

(Supplemental) ND ND 

Fathead 

minnow 

(Pimephales 

promelas) 

Acid 

(91.2% ae) ND ND 1.3/2.6 (wet weight & length) 

43295401 

(Acceptable) 

Mono 

(Acute: 23.4% ae; 

Chronic: 23.5% ae) 

0.175

(highly toxic) 

40098001 

(Supplemental) 

0.046/0.098 

(survival at test termination) 

0.098/0.019 

(percent hatch, length, & 

wet weight)

43276501 

(Acceptable) 

Waterflea

(Daphnia 

magna)

Acid 

(Acute: 77.9% ae; 

Chronic: 91.2% ae) 

92.0

(slightly toxic) 

42359702 

(Acceptable) 

<2.2/2.2 

 (total body length & number 

offspring/female)2 

43007801 

(Supplemental) 

Dipotassium 

(28.6% ae) 

70.7 

(slightly toxic) 

42695403 

(Acceptable) ND ND 

Mono 

(23.4% ae)

0.084

(very highly 

toxic)

00035242 

(Acceptable) 

0.055/0.11 

(reproduction) 

0.11/0.23 

(young survival, length & 

weight) 

43437901 

(Acceptable) 

Waterflea 

(Ceriodaphnia 

Dubia) 

Mono 

(23.4% ae)

48-hr LC50 = 

0.11

(highly toxic) 

Keller et al., 

1988

(Quantitative) 

0.0023/0.0058 

(Survival & number of 

broods) 

Keller et al., 

1988 

(Quantitative) 

Sheepshead 

minnow

(Cyprinodon 

variegatus) 

Acid 

(77.9% ae)

110 

(practically 

non-toxic) 

42914102 

(Acceptable) ND ND 

Dipotassium

(28.6% ae)

103 

(practically 

non-toxic) 

42695405 

(Acceptable) ND ND 

Mono 

(23.5% ae) 

0.823 

(highly toxic) 

43196903 

(Acceptable) 

0.006/0.0014 

(dry weight) 

47563701 

(Acceptable) 
16 

Species Test 

Substance

(% ae) 

Acute Toxicity Chronic Toxicity 

LC50/EC50

(mg ae/L) 

(Toxicity 

Classification) 

 MRID

(Study 

Classification) 

NOAEC/LOAEC 

(mg ae/L) 

(Endpoints) 

MRID

(Study 

Classification) 

Eastern oyster 

(Crassostrea 

virginica) 

Acid 

(91.2% ae) 

43 

(slightly toxic) 

42895201 

(Acceptable) -- -- 

Dipotassium 

(28.6% ae) 

99.1 

(slightly toxic) 

42695404 

(Acceptable) -- -- 

Mono 

(23.5% ae) 

0.161 

(highly toxic) 

43550201 

(Acceptable) -- -- 

Mysid

(Americamysis 

bahia) 

Acid 

(91.2% ae) 

39 

(slightly toxic) 

42914101 

(Acceptable) ND ND 

Dipotassium 

(28.6% ae) 

78 

(slightly toxic) 

42695406 

(Acceptable) ND ND 

Mono 

(23.5% ae)

0.517

(highly toxic) 

43210001 

(Acceptable) 

0.014/0.028 

(number of offspring per 

female & number of offspring 

per female per reproductive 

day)

47563701 

(Supplemental) 

Midges 

(Chironomus 

tentans) 

Mono 

(23.4% ae) -- -- 

NOAEC = 48.2 mg ae/kg 

sediment 

(21.2 mg ae/kg pore water) 

(None, not biologically 

relevant) 

47742801 

(Acceptable) 

Amphipods 

(Leptocheirus 

plumulosus) 

Mono 

(23.4% ae) -- -- 

NOAEC = 9.8 mg ae/kg 

sediment 

(6.4 mg ae/kg pore water) 

(None) 

47742802 

(Acceptable) 

ND = No Data; -- = Not applicable 

1

 A non-guideline study, conducted on fertilized rainbow trout eggs and sac fry; the fish were exposed for 4-hours to AquatholK.

At the highest concentration (12.5 mg/L), the percent hatch was 72.2% vs. 84.4% in controls. No protocol was provided. 

2

 The NOAEC could not be established, as significant reductions were noted in length and the number of offspring in the lowest 

test concentration that was tested, 2.2 ppm a.e., when compared to the controls. 

Table 8. Summary of the Most Sensitive Toxicity Data for Aquatic Plants Exposed to Endothall 

Acid, or the Dipotassium or Mono (N,N-dimethylalkylamine) Salts of Endothall1

Species 

Test 

substance 

(% ae) 

Endpoint 

(mg ae/L) 

Effect 

(MRID; Study Classification) 

Vascular Plants 

Duckweed 

(Lemna gibba) 

Dipotassium 

(28.6% ae) 

14-d EC50 = 0.61 

14-d NOAEC = 0.0046 

Frond counts 

(42396406; Acceptable)

Duckweed

(L. gibba) 

Mono

(23.6% ae) 

7-d EC50 = 0.74 

7-d NOAEC (EC05) = 0.15 

Inhibition in growth rate based on 

frond count after 7-days. 

(44949402; Acceptable) 

Non-Vascular Plants 

Green algae 

(Kirchneria subcapitata, 

formerly Selenastrum 

capricornutum) 

Mono

(23.6% ae) 

96 hr EC50 = 0.0023 

96 hr NOAEC (EC05) = 0.00054 

Inhibition in growth rate based on cell 

counts after 96 hours. 

(44949203; Acceptable) 
17 

Species 

Test 

substance 

(% ae) 

Endpoint 

(mg ae/L) 

Effect 

(MRID; Study Classification) 

Freshwater Diatom 

(Navicula pelliculosa) 

Mono

(23.6% ae) 

96 hr EC50 = 0.0072 

96 hr NOAEC = 0.0023

Inhibition in growth rate based on 

cell counts after 96 hours.

 (44949201; Acceptable) 

Marine Diatom 

(Skeletonema costatum) 

Mono

(23.6% ae) 

96 hr EC50 = 0.022 

96 hr NOAEC (EC05) = 0.0037 

Inhibition in growth rate based on 

cell counts after 96 hours.

 (44976701; Acceptable) 

Blue-green algae 

(Anabaena flos-aquae) 

Mono

(23.6% ae) 

96 hr EC50 = 0.040 

96 hr NOAEC = 0.024 

Inhibition in growth rate based on 

cell counts after 96 hours.

(44949202; Acceptable) 

Blue-green algae 

(A. flos-aquae) 

Dipotassium 

(28.6% ae) 

120 hr EC50 = 1.56 

120 hr NOAEC (EC05) = 0.071 

Inhibition in growth rate based on 

cell counts after 120 hours.

(44408801; Acceptable) 

Green algae 

(K.subcapitata) 

Dipotassium 

(28.6% ae) 

120 hr Tier I study, 

EC50 >7.0 mg ae/L; 

2% reduction in growth 

Effects were less than 50%

(44392801; Acceptable) 

Freshwater Diatom 

(N. pelliculosa) 

Dipotassium 

(28.6% ae) 

120 hr Tier I study, 

EC50 > 7.8 mg ae/L; 

42% reduction in growth 

42% reduction in growth, effects 

were less than 50% 

(44392802; Acceptable) 

Marine Diatom 

(S. costatum) 

Dipotassium 

(28.6% ae) 

120 hr Tier I study, 

EC50 > 6.4 mg ae/L; 

23% reduction in growth 

23% reduction in growth; Effects 

were less than 50% 

(42396404; Acceptable) 1

No aquatic plant toxicity data are available for endothall acid. 

b. Effects to Terrestrial Organisms 

Table 9. Summary of the Most Sensitive Acute and Chronic Toxicity Data for Terrestrial Animals 

Exposed to Endothall Acid, or the Dipotassium or Mono (N,N-dimethylalkylamine) Salts of Endothall 

Species Test 

substance 

(% ae) 

Acute Toxicity Chronic Toxicity 

LD50

(mg ae/kg bw) 

(Toxicity 

Classification) 

LC50

(mg ae/kg diet 

(ppm ae)) 

(Toxicity 

Classification) 

 MRID

(Study 

Classification) 

NOAEC/ 

LOAEC

(mg ae/kg diet 

(ppm ae)) 

(Endpoints) 

 MRID

(Study 

Classification) 

Bobwhite 

Quail

(Colinus 

virginianus) 

Acid

(75% ae & 

84% ae) 

500 

(moderately 

toxic)

>10,000 

(practically nontoxic) 

00074220 

(Supplemental) 

& 

00116270 

(Acceptable) 

ND ND 

Dipotassium 

(28.6% ae) -- >2860 (slightly toxic) 

00035239 

(Acceptable) ND ND 

Mono 

(23.4% ae) 

173 

(moderately 

toxic)

>1170 

(slightly toxic) 

00035237 

(Acceptable) 

& 

43167901 

(Acceptable) 

613/>613

(No effects) 

47861102 

(Acceptable) 
18 

Species Test 

substance 

(% ae) 

Acute Toxicity Chronic Toxicity 

LD50

(mg ae/kg bw) 

(Toxicity 

Classification) 

LC50

(mg ae/kg diet 

(ppm ae)) 

(Toxicity 

Classification) 

 MRID

(Study 

Classification) 

NOAEC/ 

LOAEC

(mg ae/kg diet 

(ppm ae)) 

(Endpoints) 

 MRID

(Study 

Classification) 

Mallard Duck 

(Anas

platyrhynchos) 

Acid

(83.6% ae & 

84% ae) 

229 

(moderately 

toxic)

>10,000 

(practically nontoxic) 

00160000 

(Acceptable) 

& 

00116271 

(Acceptable) 

50 

(early 

embryonic 

mortality)

42507301 

(Supplemental) 

Dipotassium 

(29.5% ae) 

61.6 

(moderately 

toxic)

>2860 

(slightly toxic) 

42359501 

(Acceptable) 

& 

00035238 

(Acceptable) 

ND ND 

Mono 

(23.4% ae) 

91

(moderately 

toxic)

>1170 

(slightly toxic) 

42359601 

(Supplemental) 

& 

43167902 

(Acceptable) 

<82.4/82.4 

(adult female 

body weight gain) 

47861101 

(Supplemental) 

Laboratory rat 

(Rattus 

norvegicus) 

Acid 

(81.1% ae) 

44.4 (F) 

(highly toxic) -- 42289201 (Acceptable) ND ND Acid 

(89.5% ae) 

Acute rat inhalation LC50 = 1.27 

mg/L (M); 2.2 mg/L (F) (4 hrs)

42169501 

(Acceptable) 

Disodium 

(19.9% ae) ND ND ND 

150/30 ppm ae 

(9.4/2 mg

ae/kg/day)

(decreased pup 

body weight)

43152101; 

43629301 

(Acceptable) 

Dipotassium 

(28.6% ae) 

24.3 (M) 

(highly toxic) -- 42338901 (Acceptable) 

Acute rat inhalation LC50 = 0.53 ND ND 

mg ae/L (M); 0.62 mg ae/L (F) 

(4 hrs) 

42407101 

(Acceptable) 

Mono 

(23.4% ae) 

49.1 (F)

(highly toxic) -- 42774001 (Acceptable) 

Acute rat inhalation LC50 = 0.50 ND ND 

mg ae/L (M); 0.57 mg ae/L (F) 

(4 hrs) 

42560901 

(Acceptable) 

Honey Bee 

(Apis mellifera) 

Acid

>11 g/bee 

(practically 

non-toxic) 

-- 

44038201 

(Acceptable) 

-- -- 

Dipotassium 

(Aquathol K, 

28.6% ae) 

>11 g/bee 

(practically 

non-toxic) 

-- -- -- 

Mono 

(Hydrothol 

191, 23.4% ae) 

>11 g/bee 

(practically 

non-toxic) 

-- -- -- 

ND = No Data; NA = Not Available; -- = Not applicable 
19 

Table 10. Summary of the Most Sensitive Toxicity Data for Terrestrial Plants (Tier II) Exposed to 

the Dipotassium or Mono (N,N-dimethylalkylamine) Salts of Endothall1

ND = No Data; NA = Not Available; -- = Not applicable 

1

No terrestrial plant toxicity data are available for endothall acid. 

2

 EC05 values were calculated since the NOAEC could not be determined. 

c. Ecological Incidents 

The ecological incident information system (EIIS) is an OPP database that houses ecological 

incidents that have been reported to the Agency. When available, EIIS includes date and location of 

an incident, type and magnitude of effects observed in various species, use(s) of pesticides known 

or suspected of contributing to the incident, and results of any chemical residue analysis or other 

analyses conducted during incident investigation. EIIS incidents are categorized according to the 

Plant Type Species/ 

Test Substance (% ae)

EC25

(lb ae/acre) 

NOAEC2

(lb ae/acre)

Most 

Sensitive 

Endpoint 

MRID/ 

Study Classification

Seedling Emergence 

Monocots 

Ryegrass (Lolium perenne)/ 

Dipotassium (28.6% ae) 0.035 0.005(EC05) Length

42396405 & 

44392803 

(Acceptable) 

Ryegrass 

Mono (23.4% ae) 0.033 0.014 Length 43870401 (Acceptable) 

Dicots

Lettuce (Lactuca sativa)/ 

Dipotassium (28.6% ae) 0.018 0.013 Length

42396405 & 

44392803 

(Acceptable) 

Soybean (Glycine max)/ 

Dipotassium (28.6% ae) 0.033 0.0099 (EC05) Length

42396405 & 

44392803 

(Acceptable) 

Lettuce/Mono (23.4% ae) 0.016 0.003 Shoot length 43870401 

(Acceptable) 

Vegetative Vigor 

Monocots 

Ryegrass/Dipotassium 

(28.6% ae) 0.004 0.00006 (EC05) Shoot Length 42396405 & 

44392803 

Oat (Avena sativa (Acceptable) )/ 

Dipotassium (28.6% ae) 0.065 0.114(EC05) Shoot weight 

Oat/Mono (23.4% ae) 0.056 0.028 

(EC05) Root weight 43870401 (Acceptable) 

Plant Type Species/ 

Test Substance (% ae)

EC25

(lb ae/acre)

NOAEC2

(lb ae/acre)

Most Sensitive 

Endpoint

MRID/ 

Study 

Classification

Dicots

Lettuce /Dipotassium 

(28.6% ae) 0.011 0.005(EC05) Shoot weight 

42396405 & 

44392803 

(Acceptable) 

Lettuce/Mono (23.4% ae) 0.055 0.017 

(EC05) Shoot weight 43870401 

Turnip (Brassica rapa)/ (Acceptable)

Mono (23.4% ae) 0.045 0.028 Shoot weight 
20 

certainty that the incident resulted from pesticide exposure. The Avian Monitoring System (AIMS) 

is a database administered by the American Bird Conservancy that contains publicly available data 

on reported avian incidents involving pesticides. Many of the incidents listed in this database are 

also in the EIIS. The Aggregate Incident Reports database is an Agency database that may contain 

minor wildlife and plant incidents for chemicals. 

Reviews of the Ecological Incident Information System (EIIS, version 2.1.1), the Avian Incident 

Monitoring System (AIMS)2

, and the EPA Incident Data System (IDS, Aggregate Incident Reports 

database) were conducted on April 7, 2015; looking under all PC codes related to endothall; 

endothall acid, disodium dipotassium and mono (N,N-dimethylalkylamine) salts of endothall; 

038901, 038903, 038904 and 038905, respectively). There were three ecological incidents reported 

in EIIS listed under endothall acid (I015726-001, B0000-231-03 and I013884-031), and two 

incidents listed under the mono (N,N-dimethylalkylamine) salt of endothall (I010688-001 and 

I014385-001); summarized in Appendix B. One incident (I015726-001) involved aquatic 

invertebrates (mussels); two incidents (B0000-231-03 and I010688-001) involved fish, and two 

incidents (I013884-031 and I010688-001) involved terrestrial plants. The one incident involving 

aquatic invertebrates was of an unknown legality and occurred in the presence of another chemical 

as well, diuron; endothall was listed as a possible cause of the incident. The two incidents that 

involved fish were from accidental misuses of endothall, resulting from a spill (near a drain; B0000-

231-03) and increased application in the presence of higher temperatures (I010688-001). One 

incident was identified to be the highly probable cause of the incident (B0000-231-03); and the 

second incident was identified to be the probable cause of the incident. The two incidents on 

terrestrial plants involved registered uses (I013884-031 and I014385-001) of endothall. The 

identified registered use incident on terrestrial plants (I013884-031) occurred in the presence of 

additional pesticides, and endothall is listed as a possible cause of the incident. The second 

identified registered use incident in the terrestrial environment was the result of a registered use on 

ponds (I014385-001) where two birds were found dead, one egret 3 days after application and one 

pelican 7 days after application; however, chemical analysis on the birds or the pond were not 

reported. There were no reported incidents in the AIMS database for endothall. 

There were a total of 4 minor incidents in the Aggregate Incident Reports database for endothall 

(looking under all PC codes related to endothall; endothall acid, disodium (because of the 

mammalian data), dipotassium and mono (N,N-dimethylalkylamine) salts of endothall. One minor 

wildlife incident was reported in 2003 (014385-00001) for the Hydrothol 191 soluble concentrate 

formulation of endothall (mono (N,N-dimethylalkylamine) salt); one minor plant incident was 

reported in 2003 (014705-00001) for the Hydrothol 191 granular formulation of endothall (mono 

(N,N-dimethylalkylamine) salt); one minor wildlife incident was reported in 2004 (015437-00001) 

for the Aquathol K soluble concentrate formulation of endothall (dipotassium salt); and one minor 

wildlife incident was reported in 2010 (022510-00007) for the EVAC soluble concentrate 

formulation of endothall. The lack of reported incidences should not be construed as an absence of 

incidents. Incident reports for non-target organisms typically provide information only on mortality 

events and plant damage. Sublethal effects in organisms such as abnormal behavior, reduced 

growth and/or impaired reproduction are rarely reported, except for phytotoxic effects in terrestrial 

plants. 

 

2

 http://www.abcbirds.org/abcprograms/policy/pesticides/aims/aims/index.cfm 
21 

7. Exposure Pathways of Concern

The environmental fate properties and use patterns of endothall indicate that direct spray, spray 

drift, and runoff represent potential transport mechanisms to aquatic and terrestrial organisms. The 

conceptual model will consider endothall acid, dipotassium salt and mono (N,Ndimethylalkylamine) salt as the residues of concern. 

Drinking water and inhalation exposure pathways were screened using the SIP (Screening 

Imbibition Program, version 1.0) and STIR (Screening Tool for Inhalation Risk, version 1.0) 

screening methods. Drinking water exposure alone was determined to be a potential pathway of 

concern for avian and mammalian species on an acute and chronic basis for endothall acid and for 

the dipotassium and mono (N,N-dimethylalkylamine) salts of endothall (Tables 11 - 16). However, 

due to the very high solubility of all three compounds (endothall acid, dipotassium salt and 

dimethylalkylamine salt; >11,000,000->65,000,000 mg/L) the model is likely over estimating 

exposure. As a result, EFED will explore other methods to look at this exposure route at the time of 

the risk assessment. The inhalation pathway was determined not to be a potential exposure pathway 

of concern (no LOC exceedances were found for STIR). Outputs for each model are located in 

Appendix C. SIP and STIR are described in detail at: 

http://www.epa.gov/oppefed1/models/terrestrial/index.htm. 

Table 11. SIP Mammalian Results – Endothall Acid 

Parameter Acute Chronic 

Upper bound exposure (mg ae/kg-bw) 1892000 1892000 

Adjusted toxicity value (mg ae/kg-bw) 34 7.23 

Ratio of exposure to toxicity 55401 261683

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for mammals 

Exposure through drinking 

water alone is a potential 

concern for mammals 

 

Table 12. SIP Avian Results – Endothall Acid

Parameter Acute Chronic 

Upper bound exposure (mg ae/kg-bw) 8910000 8910000 

Adjusted toxicity value (mg ae/kg-bw) 119 2.48 

Ratio of exposure to acute toxicity 74935 3591832

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for birds 

Exposure through drinking 

water alone is 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. 

**Due to the very high solubility of this compound, the model may be over estimating exposure. As a result, EFED will 

explore other methods to look at this exposure route at the time of the risk assessment. 
22 

Table 13. SIP Mammalian Results – Dipotassium Salt of Endothall 

Parameter Acute Chronic 

Upper bound exposure (mg ae/kg-bw) 11180000 11180000 

Adjusted toxicity value (mg ae/kg-bw) 18.7 7.23 

Ratio of exposure to toxicity 598162 1546311

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for mammals 

Exposure through drinking 

water alone is a potential 

concern for mammals 

Table 14. SIP Avian Results – Dipotassium Salt of Endothall

Parameter Acute Chronic 

Upper bound exposure (mg ae/kg-bw) 52650000 52650000 

Adjusted toxicity value (mg ae/kg-bw) 32 0.0000 

Ratio of exposure to acute toxicity 1646121 0.0000

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for birds 

Due to insufficient data, 

risk cannot be precluded 

 *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. 

**Due to the very high solubility of this compound, the model may be over estimating exposure. As a result, EFED 

will explore other methods to look at this exposure route at the time of the risk assessment. 

Table 15. SIP Mammalian Results – Mono (N,N-dimethylalkylamine) Salt of Endothall

Parameter Acute Chronic 

Upper bound exposure (mg ae/kg-bw) 8600000 8600000 

Adjusted toxicity value (mg ae/kg-bw) 38 7.23 

Ratio of exposure to toxicity 227719 1189470

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for mammals 

Exposure through drinking 

water alone is a potential 

concern for mammals 

Table 16. SIP Avian Results – Mono (N,N-dimethylalkylamine) Salt of Endothall

Parameter Acute Chronic 

Upper bound exposure (mg ae/kg-bw) 40500000 40500000 

Adjusted toxicity value (mg ae/kg-bw) 47 4.09 

Ratio of exposure to acute toxicity 857152 9906863

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for birds 

Exposure through drinking 

water alone is 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. 

**Due to the very high solubility of this compound, the model may be over estimating exposure. As a result, EFED 

will explore other methods to look at this exposure route at the time of the risk assessment. 

Exposure from release of cooling tower water is estimated using a Down the Drain (DtD) module 

from E-FAST. A screening-level DtD analysis has not been performed since such an analysis is 

appropriate only for uses of antimicrobial pesticides that would be released to domestic waste water 

treatment plants. Since N,N-amine treated water can be released through industrial treatment 
23 

facilities, the screen is not appropriate. Chemicals coming into a WWTP can take roughly a day to 

go through the facility and be released to surface waters if they are not degraded or sorbed within 

the facility. A DtD analysis will be conducted for the registration review risk assessment. Output is 

reported as the number of days per year the concentration of concern is exceeded for each type of 

organism which may be exposed. 

8. Analysis Plan

In addition to the need for honeybee data, there is the need for data to evaluate chronic toxicity to 

aquatic animals (freshwater and saltwater), acute toxicity to passerine species, chronic toxicity to 

birds, and phytotoxicity to aquatic plants. 

a. Stressors of Concern 

i. Ecological Risk Assessment 

For the endothall ecological risk assessment, the stressors of concern in this assessment is primarily 

the dimethylalkylamine salt for the aquatic assessment. The dimethylalkylamine salt is consistently 

and substantially (2 orders of magnitude or more) more toxic than the acid and dipotassium salt to 

aquatic organisms. Therefore, the dimethylalkylamine salt data will be used to assess risks to 

aquatic organisms. However, data on the acid and dipotassium salt will also be used when the 

dimethylalkylamine salt shows risks that are above concern levels. If the dimethylalkylamine salt 

does not present risks of concern, then risks from the endothall acid or dipotassium salt will not 

need to be quantified. For the terrestrial assessment, the stressors of concern are the endothall acid, 

dipotassium salt, and dimethylalkylamine salt; examining the most sensitive endpoints of all 

ecological studies as converted to endothall acid equivalents. 

ii. Drinking Water 

EPA office of water has identified endothall may cause health problems in the water supply and set 

a maximum contaminant level (MCL) of 0.1 mg/L, see the following link; 

http://water.epa.gov/drink/contaminants/basicinformation/endothall.cfm. This standard is reflected 

in the most recent drinking water exposure assessment (DP 404321, September 2012). 

b. Measures of Exposure 

Past assessments of endothall EFED have used standard available models to evaluate potential 

exposures to aquatic and terrestrial organisms as described at 

http://www.epa.gov/oppefed1/models/water/index.htm and 

http://www.epa.gov/pesticides/science/models_db.htm. The Surface Water Concentration 

Calculator (SWCC, version 1.106) is currently the model that is typically used to estimate aquatic 

exposure. T-REX (version 1.5.2), and TerrPlant (version 1.2.2) are currently the models that are 

typically used to estimate terrestrial exposure. 
24 

i. Available Monitoring Data 

Endothall is not an analyte in any of the following water monitoring programs: the California 

Department of Pesticide Regulation (CDPR) surface water database -

http://www.cdpr.ca.gov/docs/emon/surfwtr/surfcont.htm, the USGS NAWQA surface and ground 

water database - http://cida.usgs.gov/nawqa_queries_public/, and the USEPA STORET Data 

Warehouse - http://www.epa.gov/storet/. Monitoring will be considered in the assessment to the 

extent that any future data on endothall are available. 

c. Measures of Effect 

Toxicity data presented in Section 0 of this problem formulation would be used to calculate risk 

quotients (RQs). Any additional information submitted by the registrant or found in the open 

literature prior to conduct of the risk assessment would also be considered. The open literature 

studies are identified using EPA’s ECOTOXicology database (ECOTOX) (USEPA, 2007a), which 

employs a literature search engine for locating chemical toxicity data for aquatic life, terrestrial 

plants, and wildlife. The evaluation of both sources of data can also provide insight into the direct 

and indirect effects of pesticides on biotic communities from loss of species that are sensitive to the 

chemicals and from changes in structure and functional characteristics of the affected communities. 

d. Endangered Species Assessments 

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

evaluate risks to federally listed threatened and endangered (listed) species from registered uses of 

pesticides in accordance with the Joint Interim Approaches developed to implement the 

recommendations of the April 2013 National Academy of Sciences (NAS) report, Assessing Risks 

to Endangered and Threatened Species from Pesticides. The NAS report outlines recommendations 

on specific scientific and technical issues related to the development of pesticide risk assessments 

that EPA and the Services must conduct in connection with their obligations under the ESA and 

FIFRA. EPA will address concerns specific to endothall in connection with the development of its 

final registration review decision for endothall.

In November 2013, EPA, the U.S. Fish and Wildlife Service, National Marine Fisheries (the 

Services), and USDA released a white paper containing a summary of their joint Interim 

Approaches for assessing risks to listed species from pesticides. These Interim Approaches were 

developed jointly by the agencies in response to the NAS recommendations, and reflect a common 

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

between the EPA and the Services. Details of the joint Interim Approaches are contained in the 

November 1, 2013 white paper, Interim Approaches for National-Level Pesticide Endangered 

Species Act Assessments Based on the Recommendations of the National Academy of Sciences April 

2013 Report.

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

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

habitat, this ecological problem formulation supporting the Preliminary Work Plan for endothall 

does not describe the specific ESA analysis, including effects determinations for specific listed 
25 

species or designated critical habitat, to be conducted during registration review. While the 

agencies continue to develop a common method for ESA analysis, the planned risk assessment for 

the registration review of endothall will describe the level of ESA analysis completed for this 

particular registration review case. This assessment will allow EPA to focus its future evaluations 

on the types of species where the potential for effects exists, once the scientific methods being 

developed by the agencies have been fully vetted. Once the agencies have fully developed and 

implemented the scientific methods necessary to complete risk assessments for listed species and 

their designated critical habitats, these methods will be applied to subsequent analyses of endothall 

as part of completing this registration review.

e. Endocrine Disruptor Screening Program 

Endothall was not included in the first group of 67 chemicals issued an order to conduct Tier 1 

EDSP testing, but it was included on the second list of chemicals for Tier 1 screening. For 

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

9. Preliminary Identification of Data Gaps 

a. Environmental Fate 

Table 17 identifies 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 in order to 

support risk assessment. 

Table 17. Submitted Environmental Fate Data for Endothall 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data 

Need 

835.2120 Hydrolysis 42289106 

44578401 Acceptable Yes None

835.2240 Aqueous 

photolysis 42289205 Acceptable Yes None 

835.2410 Soil photolysis 42641202 Acceptable Yes None

835.4100 Aerobic soil 

metabolism 44949401 Acceptable Yes None

835.4300 Aerobic aquatic 

metabolism 42618901 Acceptable Yes None

835.4400 

Anaerobic 

aquatic 

metabolism 

42903901 Acceptable Yes None

835.1230 

835.1240 

Adsorption/ 

desorption and 

leaching 

41616404 Acceptable Yes None

835.6100 

Terrestrial field 

dissipation

(including ECM 

and ILV) 

42670101 

42670201 Supplemental Yes 

None

One of the test sites is without 

stability confirmation. 
26 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data 

Need 

835.6200 Aquatic field 

dissipation

44828801 

44828802 

44820101 

44820102 

44820103 

44093403 

44093402 

Acceptable Yes None

850.1730 Fish 

bioconcentration 42644001 Acceptable Yes None

Data Gaps 

Fate Studies are needed to address coco-alkylamine cation (part of mono (N,Ndimethylalkylamine) salt of endothall), including: 

o OCSPP 835.2100: Hydrolysis 

o OCSPP 835.2240: Aqueous Photolysis 

o OCSPP 835.4100: Aerobic Soil Metabolism 

o OCSPP 835.4400: Anaerobic Aquatic Metabolism 

o OCSPP 835:4300: Aerobic Aquatic Metabolism 

o OCSPP 835.1230: Batch Equilibrium 

 For the DtD analysis 

o OCSPP 850.3300: Activated Sludge Respiration Inhibition

o OCSPP 835.3110: Ready Biodegradation

o OCSPP 835.3220: Porous Pot Study

o OCSPP 835.3240: Simulation Test – Aerobic Sewage Treatment

o OCSPP 835.3280: Simulation Test – Assess Biodegradability in Wastewater

b. Effects 

Table 18 through Table 24 identify ecological effects studies by MRID for endothall acid, 

dipotassium, and mono (N,N-dimethylalkylamine) salts of endothall that offer data for each 

guideline requirement, as well as study classifications and whether further data are needed in order 

to support risk assessment. 

The rationale for additional aquatic data needs are as follows: since the dimethylalkylamine salt is 

consistently and substantially (2 orders of magnitude or more) more toxic than the acid and 

dipotassium salt to aquatic organisms, additional data are needed for the acid and/or dipotassium 

salt to have a complete data set for aquatic toxicity. In addition, there are two previously submitted 

invertebrate chronic toxicity studies, one for endothall acid and one for the dimethylalkylamine salt, 

that do not fulfill that data requirement and therefore new data are needed for freshwater and 

estuarine/marine invertebrates, respectively. If a full suite of aquatic toxicity data was to be 

completed for the acid, aquatic plant toxicity data would be needed. 

For terrestrial species, like the aquatic species, a full suite of dimethylalkylamine salt, and a full 

suite of either the acid or the dipotassium salt is needed for risk assessment. To have a complete 

data set, additional information is needed for birds due to the results from previously submitted 
27 

studies; a no effect level was not established in the avian reproduction study for mono (N,Ndimethylalkylamine) salt, and an acute passerine study is needed for dimethylalkylamine salt, and 

either the acid or the dipotassium salt. Again, there are some available mammalian data that utilizes 

data from other salts (i.e., disodium) that are no longer registered; this data was deemed acceptable 

by HED, and it is EFED’s understanding that no additional data for the two-generation mammalian 

reproduction test has been requested (Table 23). 

Although all test materials were practically non-toxic to adult honeybees on a contact exposure 

basis, it is not clear if any additional adjustments were made to the available data for conversion to 

endothall acid equivalence. Given this uncertainty and due to the new data requirements for 

pollinators, a full set of honey bee data is needed for both salts (dipotassium and 

dimethylalkylamine), as pollinators can potentially be exposed to both test materials in the field. 

The rationale for additional non-guideline data requested is presented below the tables. 

Table 18. Submitted Aquatic Ecological Effects Data for Endothall Acid 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data 

Need 

850.1010 

Freshwater 

invertebrate 

acute toxicity 

42359702 Acceptable 

Yes None

00071137 Supplemental 

850.1025 

850.1035 

Saltwater 

invertebrate 

acute toxicity 

42895201 Acceptable 

Yes None

42914101 Acceptable 

00074227 Supplemental 

00084151 Acceptable 

850.1075 Freshwater fish 

acute toxicity 

42327701 Acceptable Yes None

42327702 Acceptable 

850.1075 Saltwater fish 

acute toxicity 

42914102 Acceptable Yes None

00074225 Acceptable 

850.1300 

Freshwater 

invertebrate 

life cycle 

43007801 Supplemental No 

Significant effects were 

observed in the lowest test 

concentration. Data are 

needed for either the free 

acid or dipotassium salt; and 

data are already available for 

the dimethylalkylamine salt. 
28 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data 

Need 

850.1350 

Saltwater 

invertebrates 

life cycle 

(None) (Not applicable) No

No chronic estuarine/marine 

toxicity data are available 

for endothall acid. More 

sensitive endpoints are 

available using ae 

conversion for mono salt; or 

a NOAEC value could be 

estimated for endothall acid 

with an ACR and available 

toxicity data for endothall 

acid. Data are needed for 

either the free acid or

dipotassium salt; and data 

are already available for the 

dimethylalkylamine salt. 

850.1400 Freshwater fish 

early-life stage 43295401 Acceptable Yes

Chronic toxicity test species 

for endothall acid was the 

fathead minnow; however, 

no acute toxicity test was 

available for this species for 

endothall acid. 

850.1400 Saltwater fish 

early-life stage (None) (Not applicable) No

No chronic estuarine/marine 

toxicity data are available for 

endothall acid. Data are 

needed for either the free acid 

or dipotassium salt; data are 

already available for the 

dimethylalkylamine salt. OR 

an acceptable acute fathead 

minnow study for the acid is 

submitted, and this can be 

used to calculate an ACR 

derived E/M NOAEC. 

850.1500 Fish life cycle (None) (Not applicable) Yes None 

850.4400 

Aquatic plant 

Toxicity Test 

using Lemna spp. 

(None) (Not applicable) No 

No aquatic plant toxicity 

data are available for 

endothall acid; it is only 

available for the dipotassium 

and mono (N,Ndimethylalkylamine) salts of 

endothall. Data are 

presented as the ae. No 

aquatic plant toxicity data 

are needed for the endothall 

acid. 

850.4500 Algal toxicity (None) (Not applicable) 

No 

850.4550 

Cyanobacteria 

(A. flos-aquae) 

toxicity

(None) (Not applicable) 
29 

Table 19. Submitted Aquatic Ecological Effects Data for the Dipotassium Salt of Endothall 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data 

Need 

850.1010 

Freshwater 

invertebrate 

acute toxicity 

42695403 Acceptable 

Yes None

00084150 Supplemental 

40098001 Supplemental 

05009242 Acceptable 

850.1025 

850.1035 

Saltwater 

invertebrate 

acute toxicity 

42695404 Acceptable 

42695406 Acceptable Yes None

00035243 Supplemental 

850.1075 Freshwater fish 

acute toxicity 

40098001 Supplemental Yes None

42695401 Acceptable 

850.1075 Saltwater fish 

acute toxicity 

42695405 Acceptable Yes None

40098001 Supplemental 

850.1300 

Freshwater 

invertebrate 

life cycle 

(None) (Not applicable) No

No chronic aquatic 

invertebrate toxicity data are 

available for the dipotassium 

salt of endothall. Data are 

needed for either the 

dipotassium salt or the free 

acid; and data are already

available for the 

dimethylalkylamine salt. 

850.1350 

Saltwater 

invertebrates 

life cycle 

(None) (Not applicable) No

850.1400 Freshwater fish 

early-life stage 00095812 Supplemental No

Available study was 

conducted on fertilized 

rainbow trout eggs and sac 

fry, the fish were exposed for 

4hrs to AquatholK, and 

returned to flow-through 

conditions for the duration of 

the experiment. This is not a 

guideline study. Data are 

needed for either the 

dipotassium salt or the free 

acid; data are already 

available for the 

dimethylalkylamine salt.

However, since acceptable 

FW data are available for the 

acid, it is not being requested 

at this time for the 

dipotassium salt. 
30 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data 

Need 

850.1400 Saltwater fish 

early-life stage (None) (Not applicable) No

No chronic estuarine/marine 

fish toxicity data are available 

for the dipotassium salt or the 

free acid. The FW dish data 

cannot be used to estimate 

E/M toxicity in the absence of 

data. Data are needed for 

either the dipotassium salt or

free acid; data are already 

available for the 

dimethylalkylamine salt. OR 

an acceptable acute fathead 

minnow study for the acid is 

submitted, and this can be 

used to calculate an ACR 

derived E/M NOAEC for the 

acid. The endpoint can be 

used for the dipotassium salt. 

850.1500 Fish life cycle (None) (Not applicable) Yes None 

850.4400 

Aquatic plant 

Toxicity Test 

using Lemna spp. 

42396406 Acceptable Yes None

850.4500 Algal toxicity 

42396404 Acceptable Yes None 

44392801 Acceptable Yes None 

44392802 Acceptable Yes None 

850.4550 

Cyanobacteria 

(A. flos-aquae) 

toxicity 

44408801 Acceptable Yes None

Table 20. Submitted Aquatic Ecological Effects Data for the Mono (N,N-dimethylalkylamine) 

Salt of Endothall 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data 

Need 

850.1010 

Freshwater 

invertebrate 

acute toxicity 

00035242 Acceptable 

05009242 Supplemental Yes None

40098001 Supplemental 

850.1025 

850.1035 

Saltwater 

invertebrate 

acute toxicity 

43550201 Acceptable 

Yes None

43210001 Acceptable 

00035244 Supplemental 

00074223 Supplemental 
31 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data 

Need 

850.1075 Freshwater fish 

acute toxicity 

40098001 Supplemental 

Yes None

43196901 Acceptable 

43472801 Acceptable 

00084148 Acceptable 

00046269 Supplemental 

850.1075 Saltwater fish 

acute toxicity 

43196903 Acceptable 

44700401 Supplemental Yes None

00074226 Acceptable 

850.1300 

Freshwater 

invertebrate 

life cycle 

43437901 Acceptable Yes None

850.1350 

Saltwater 

invertebrate 

life cycle 

47563701 Supplemental No 

The study was classified as 

supplemental because the 

offspring were not held 

until study termination for 

evaluation of mortality, sex 

ratios, and growth; 

therefore, the study is not 

upgradable. A new study is 

needed to fulfill the data 

requirement for the 

dimethylalkylamine salt. 

850.1400 Freshwater fish 

early-life stage 43276501 Acceptable Yes None

850.1400 Saltwater fish 

early-life stage 47563701 Acceptable Yes None

850.1500 Fish life cycle (None) (Not applicable) Yes None 

NG

Sediment 

Invertebrate 

Toxicity 

47742801 Acceptable 

Yes None

47742802 Acceptable 

850.4400 

Aquatic plant 

Toxicity Test 

using Lemna spp. 

44949402 Acceptable Yes None

850.4500 Algal toxicity 

44976701 Acceptable Yes None 

44949203 Acceptable Yes None 

44949201 Acceptable Yes None 

850.4550 

Cyanobacteria 

(A. flos-aquae) 

toxicity 

44949202 Acceptable Yes None
32 

Table 21. Submitted Terrestrial Ecological Effects Data for Endothall Acid 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data Need 

850.2100 Avian oral 

toxicity

00074220 Supplemental 

No 

Data are needed on a passerine 

species for either the free acid or

the dipotassium salt; and data are 

also needed for the 

dimethylalkylamine salt.

00160000 Acceptable 

850.2200 Avian dietary 

toxicity 

00116270 Acceptable Yes None

00116271 Acceptable 

850.2300 Avian 

reproduction 42507301 Supplemental No 

MRID 42507301 (mallard): the 

study was scientifically sound, 

classified as supplemental, but did 

not fulfill the guideline 

requirements for an avian 

reproduction study. MRID 

42507302 (northern bobwhite 

quail): the study was recently 

downgraded to invalid due to high 

control mortality (22%), crowding 

of the pens, and at the higher doses 

birds became more lethargic, as a 

result there is concern with the 

reliability of the data presented in 

the study. A study for bobwhite 

quail is needed for either the free 

acid or the dipotassium salt; data 

are available for the 

dimethylalkylamine salt, but 

additional data are also needed for 

the salt. 

870.1100 Mammalian 

acute oral 42289201 Acceptable Yes None

870.1300 

Mammalian 

acute 

inhalation 

42169501 Acceptable Yes None

870.3800 

Mammalian 2- 

generation 

Reproduction 

(None) (Not applicable) Yes

None with endothall acid; test 

substance is only the disodium 

salt of endothall; MRID #’s 

43152101 and

43629301 (see below). 

850.3020 

Honey bee 

adult acute 

contact toxicity 

44038201 Acceptable Yes

Based on classification in paper 

by Atkins, E.L. Division of 

Agricultural Sciences, University 

of California. MRID 44038201. 

A LD50 of >11 ȝg/bee was 

classified as practically non-toxic. 
33 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data Need 

850.4100 Seedling 

Emergence 

(None) (Not applicable) Yes

No terrestrial plant toxicity data 

are available for endothall acid; it 

is only available for the 

dipotassium and mono (N,Ndimethylalkylamine) salts of 

endothall. Data are presented as 

the ae. No terrestrial plant 

toxicity data are needed for the 

endothall acid. 

850.4150 Vegetative 

Vigor

Table 22. Submitted Terrestrial Ecological Effects Data for the Dipotassium Salt of Endothall 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data Need 

850.2100 Avian oral 

toxicity 42359501 Acceptable No 

Yes – a passerine species is needed 

to fulfill guideline requirements. 

Tier 1 EECs from past assessments 

ranged from approx. 161-1347.45 

ppm ae, and the acute LD50 was 

61.6 mg ae/kg-bw and the subacute LC50 was >2860 mg ae/kgdiet. The passerine LD50 would 

have to be at least 30-220 times 

greater than the other avian species 

to no longer result in an acute listed 

species LOC exceedance of 0.1. 

Data are needed for either the 

dipotassium salt or the free acid; 

and data are also needed for the 

dimethylalkylamine salt. 

850.2200 Avian dietary 

toxicity 

00035239 Acceptable 

Yes None

00035238 Acceptable 
34 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data Need 

850.2300 Avian 

reproduction (None) (Not applicable) No 

No avian reproduction toxicity data 

for the dipotassium salt of 

endothall are available. Two 

acceptable avian reproduction 

studies are needed for either the 

free acid or the dipotassium salt. 

Data are available for the mallard 

duck for the free acid; however, a 

new bobwhite quail study is needed 

for the free acid; and data are 

already available for the 

dimethylalkylamine salt. 

Information is needed to fulfill the 

guideline requirement for the free 

acid or the dipotassium salt. 

Therefore, based on the available 

toxicity data for the acid, a study 

for bobwhite quail is needed for 

either the free acid or the 

dipotassium salt. 

870.1100 Mammalian 

acute oral 

42338901 Acceptable Yes None

44319605 Acceptable 

870.1300 

Mammalian 

acute 

inhalation 

42407101 Acceptable 

Yes None

44319607 Acceptable 

870.3800 

Mammalian 2- 

generation 

Reproduction 

(None) (Not applicable) Yes

None with the dipotassium salt of 

endothall; test substance is only 

the disodium salt of endothall; 

MRID #’s 43152101 and 

43629301 (see below). 

850.3020 

Honey bee 

adult acute 

contact toxicity 

44038201 Acceptable No

Based on classification in paper 

by Atkins, E.L. Division of 

Agricultural Sciences, University 

of California. MRID 44038201. A 

LD50 of >11 ȝg/bee was classified 

as practically non-toxic. Although 

the test product was given 

(Aquathol K, 28.6% ae); it is not 

clear if any additional adjustments 

are needed to present the data as 

ae. A new acute contact toxicity 

study is needed based on the new 

guideline methods. 
35 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data Need 

Special 

study 

OECD 

213

Honey bee 

adult acute oral 

toxicity 

(None) (Not applicable) No 

An acute oral toxicity study with 

the adult honey bee is needed; 

testing should be completed using 

the salts, as that is what the bees 

will be exposed to. 

Special 

Study 

(NG) 

Honey bee 

adult chronic 

toxicity

(None) (Not applicable) No 

A chronic oral toxicity study with 

the adult honey bee is needed; 

testing should be completed using 

the salts, as that is what the bees 

will be exposed to. 

Special 

study 

OECD 

237

Honey bee 

larvae acute 

oral toxicity 

(None) (Not applicable) No 

An acute oral toxicity study with 

the honey bee larvae is needed; 

testing should be completed using 

the salts, as that is what the bees 

will be exposed to. 

Special 

Study 

(NG) 

Honey bee 

larvae chronic 

toxicity 

(None) (Not applicable) No 

A repeat dose toxicity study with 

honey bee larvae is needed; testing 

should be completed using the 

salts, as that is what the bees will 

be exposed to. 

Special 

Study 

(NG) 

Field trial of 

residues in 

pollen and 

nectar

(None) (Not 

applicable) No 

A field trial measuring the 

residues of Endothall in pollen 

and nectar is needed; testing 

should be completed using the 

salts, as that is what the bees will 

be exposed to. 

Special 

Study 

OECD 75 

Semi-field 

testing for 

pollinators 

(None) (Not 

applicable) 

Tiered 

Approach 

Results of the Tier I studies could 

trigger the higher Tier studies 

(Tier II and III), see below; testing 

should be completed using the 

salts, as that is what the bees will 

be exposed to. 

850.3040 Field testing 

for pollinators (None) (Not 

applicable) 

Tiered 

approach 

Results of the Tier I studies could 

trigger the higher Tier studies 

(Tier II and III), see below; testing 

should be completed using the 

salts, as that is what the bees will 

be exposed to. 

850.4100 Seedling 

Emergence 

42396405 Acceptable 

Yes None

44392803 Acceptable 

850.4150 Vegetative 

Vigor

42396405 Acceptable 

Yes None

44392803 Acceptable 
36 

Table 23. Submitted Terrestrial Ecological Effects Data for the Disodium Salt of Endothall 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data 

Need 

870.3800 

Mammalian 

2- generation 

Reproduction 

43152101 Acceptable 

Yes None

43629301 Acceptable 

Table 24. Submitted Terrestrial Ecological Effects Data for the Mono (N,N-dimethylalkylamine) 

Salt of Endothall 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data Need 

850.2100 Avian oral 

toxicity

00035237 Acceptable 

No 

Yes – a passerine species is 

needed to fulfill guideline 

requirements. Tier 1 EECs from 

past assessments ranged from 

approx. 23.52-1347.45 ppm ae, 

and the acute LD50 was = 91 mg 

ae/kg-bw and the sub-acute LC50

was >1170 mg ae/kg-diet. The 

passerine LD50 would have to be at 

least 4-150 times greater than the 

other avian species to no longer 

result in an acute listed species 

LOC exceedance of 0.1. Data are 

needed for passerine species using 

the mono (N,Ndimethylalkylamine) salt, 

especially given the uncertainty 

surrounding the dose of one of the 

available acute oral studies for the 

mono salt (emesis in all treatment 

levels). Data are needed for the 

dimethylalkylamine salt and either 

the dipotassium salt or the free 

acid. 

42359601 Supplemental 

850.2200 Avian dietary 

toxicity 

43167901 Acceptable Yes None

43167902 Acceptable 
37 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data Need 

850.2300 Avian 

reproduction 

47861102 Acceptable 

No

The mallard study (MRID 

47861101) was classified as 

supplemental (not upgradable) 

because a definitive NOAEC could 

not be established (treatment-related 

effects were observed in the lowest 

test concentration). Toxicity data 

are needed for the mallard duck for 

the dimethylalkylamine salt; but a 

study for bobwhite quail is needed 

for either the free acid or the 

dipotassium salt. 

47861101 Supplemental 

870.1100 Mammalian 

acute oral 42774001 Acceptable Yes None

870.1300 

Mammalian 

acute 

inhalation 

42560901 Acceptable Yes None

870.3800 

Mammalian 2- 

generation 

Reproduction 

(None) (Not applicable) Yes

None with the mono (N,Ndimethylalkylamine) salt of 

endothall; the test substance is 

only the disodium salt of 

endothall; MRID #’s 43152101 

and 43629301 (see above). 

850.3020 

Honey bee 

adult acute 

contact toxicity 

44038201 Acceptable No

Based on classification in paper by 

Atkins, E.L. Division of 

Agricultural Sciences, University 

of California. MRID 44038201. A 

LD50 of >11 ȝg/bee was classified 

as practically non-toxic. Although 

the test product was given 

(Hydrothol 191 23.4% ae); it is 

not clear if any additional 

adjustments are needed to present 

the data as ae. A new acute contact 

toxicity study is needed based on 

the new guideline methods. 

Special 

study 

OECD 

213

Honey bee 

adult acute oral 

toxicity 

(None) (Not applicable) No 

An acute oral toxicity study with 

the adult honey bee is needed; 

testing should be completed using 

the salts, as that is what the bees 

will be exposed to. 

Special 

Study 

(NG) 

Honey bee 

adult chronic 

toxicity

(None) (Not applicable) No 

A chronic oral toxicity study with 

the adult honey bee is needed; 

testing should be completed using 

the salts, as that is what the bees 

will be exposed to. 
38 

OCSPP 

Guideline 

Data 

Requirement 

Submitted 

Studies 

(MRID) 

Study 

Classifications 

Sufficient 

for risk 

assessment? 

Current Additional Data Need 

Special 

study 

OECD 

237

Honey bee 

larvae acute 

oral toxicity 

(None) (Not applicable) No 

An acute oral toxicity study with 

the honey bee larvae is needed; 

testing should be completed using 

the salts, as that is what the bees 

will be exposed to. 

Special 

Study 

(NG) 

Honey bee 

larvae chronic 

toxicity 

(None) (Not applicable) No 

A repeat dose toxicity study with 

honey bee larvae is needed; testing 

should be completed using the 

salts, as that is what the bees will 

be exposed to. 

Special 

Study 

(NG) 

Field trial of 

residues in 

pollen and 

nectar

(None) (Not applicable) No 

A field trial measuring the 

residues of Endothall in pollen and 

nectar is needed; testing should be 

completed using the salts, as that 

is what the bees will be exposed 

to. 

Special 

Study 

OECD 75 

Semi-field 

testing for 

pollinators 

(None) (Not applicable) Tiered 

Approach 

Results of the Tier I studies could 

trigger the higher Tier studies 

(Tier II and III), see below; testing 

should be completed using the 

salts, as that is what the bees will 

be exposed to. 

850.3040 Field testing 

for pollinators (None) (Not applicable) Tiered 

approach 

Results of the Tier I studies could 

trigger the higher Tier studies 

(Tier II and III), see below; testing 

should be completed using the 

salts, as that is what the bees will 

be exposed to. 

850.4100 Seedling 

Emergence 43870401 Acceptable Yes None

850.4150 Vegetative 

Vigor 43870401 Acceptable Yes None

Data Gaps 

 Acid and/or Dipotassium salt 

x OCSPP 850.1300: Freshwater invertebrate life cycle

x OCSPP 850.1350: Saltwater invertebrate life cycle

x OCSPP 850.1400: Saltwater fish early-life stage (sheepshead minnow)

o or OCSPP 850.1075 Freshwater fish acute toxicity with fathead minnow (acid only) 

for calculation of an ACR

x OCSPP 850.2100: Avian acute oral toxicity with passerine species 

x OCSPP 850.2300: Avian reproduction – bobwhite quail 
39 

Dipotassium salt (only) 

x OCSPP 850.3020: Honeybee acute contact toxicity study

x OECD TG 213 and Non-guideline special studies: Honey bee adult acute and chronic 

oral toxicity studies 

x OECD TG 237 and Non-guideline special studies: Honeybee larval acute and chronic 

oral toxicity studies 

x Non-guideline special studies: Field trial measuring residues of endothall in pollen and 

nectar 

x Special study OECD TG 75 and OSCPP 850.3040: Semi-field testing for pollinators and 

Field testing for pollinators (both studies are conditionally required pending the results of 

the Tier I – laboratory based studies listed above; if needed protocols for each study must 

be submitted for review prior to study initiation). 

Mono (N,N-dimethylalkylamine) salt

x OCSPP 850.1350: Saltwater invertebrate life cycle

x OCSPP 850.2100: Avian acute oral toxicity with passerine species 

x OCSPP 850.2300: Avian reproduction – mallard duck 

x OCSPP 850.3020: Honeybee acute contact toxicity study

x OECD TG 213 and Non-guideline special studies: Honey bee adult acute and chronic 

oral toxicity studies 

x OECD TG 237 and Non-guideline special studies: Honeybee larval acute and chronic 

oral toxicity studies 

x Non-guideline special studies: Field trial measuring residues of endothall in pollen and 

nectar 

x Special study OECD TG 75 and OSCPP 850.3040: Semi-field testing for pollinators and 

Field testing for pollinators (both studies are conditionally required pending the results of 

the Tier I – laboratory based studies listed above; if needed protocols for each study must 

be submitted for review prior to study initiation). 

Honeybee Toxicity: 

Although endothall is categorized as practically non-toxic to adult honeybees on contact exposure 

basis, and by extension, to other beneficial terrestrial invertebrates on an acute exposure basis, there 

is considerable uncertainty regarding the potential effects of the compound on honeybee larval 

development and survival as well as potential for chronic effects. Therefore, additional data on 

pollinators is needed to fully characterize the risk associated with endothall use to all developmental 

stages of honeybees, as sensitivity may vary according to life-stage and length of exposure (adult 

vs. larval and acute vs. chronic, respectively). Endothall is an herbicide so exposure via pollen and 

nectar is possible; and therefore, residues of pollen and nectar of crops are an additional set of data 

that is needed. Open literature data can be used to help better characterize some uncertainties 

regarding potential effects to bees and other non-target terrestrial invertebrates. In addition, higher 

tier effects toxicity tests (i.e., semi-field and/or field studies – Tier II and Tier III, respectively) may 

also be needed, based on the results of the larval and chronic adult toxicity studies. Higher tier 

studies are recommended if the ratio of the EEC and larval or adult bee acute LD50>0.4 or the ratio 

of the EEC and the chronic NOAEC>1. Incident data and/or compelling open literature studies can 

also be used to support the need for higher tier studies. Should the screening level risk assessment 

identify that there are risk concerns to bees, mitigation measures may need to be considered or the 

registrant may need to conduct Tier II or Tier III effects studies (e.g. OECD Guideline 75 and/or 
40 

850.3040 guideline studies) that reduce uncertainty by characterizing endothall’s effects at the 

whole-colony level1

. 

Study Title: Honey bee Adult Acute Oral Toxicity 

Guideline Number: Special Study – OECD 213; 

Test Substance: Endothall – Dipotassium Salt and Mono (N,N-dimethylalkylamine) Salt

Rationale for Requiring the Data 

No data are available with which to assess the toxicity of endothall to honey bees on an acute oral exposure 

basis. Terrestrial invertebrates are likely to be impacted if exposed to pesticides in various use settings. With 

eusocial bees, pesticide residues may be transferred to pollen and/or nectar of treated plants and subsequently 

brought back to the hive. Therefore, potential acute effects to adult honey bees and other insect pollinators 

from oral exposure to some pesticides could exist. Currently available toxicity studies do not address possible 

effects of oral exposure on adult terrestrial insect survival. Because of the potential for pollen and nectar to be 

contaminated with pesticide residues, and subsequently brought back to the hive, it is important to determine 

the acute oral toxicity of this compound to adult honey bees and other insect pollinators. 

The Office of Pesticide Programs has made available a guidance regarding ecological testing for bees using 

the honey bee as a surrogate test species. The guidances discusses Tier 1 laboratory-based acute oral toxicity 

studies of individual adult bees as a critical component of the screening-level risk assessment process for 

examining potential adverse effects from specific routes of exposure. The guidance can be found at: 

http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. Additional guidance on the 

honey bee oral toxicity test design can be found in OECD Test Guideline 213 (http://www.oecdilibrary.org/docserver/download/9721301e.pdf?expires=1423074617&id=id&accname=guest&checksum=2F

0764FCB4DCF01D32382952A2E995C3) 

Practical Utility of the Data 

How will the data be used?

The Tier 1 acute oral toxicity data on adult honey bees serve as a foundation for the screening-level 

assessment of potential risk non-target organisms such as federally listed threatened or endangered and nonlisted terrestrial invertebrate insects, including pollinators, from acute oral exposures to pesticides. The data 

will be used to reduce uncertainties associated with the risk assessment for terrestrial invertebrates and will 

improve EPA’s understanding of the potential direct and indirect effects on a broad range of taxa. This study 

will also provide information with which to compare whether oral toxicity estimates differ from contact 

toxicity estimates obtained from other Tier 1 studies. If acute oral effects data for adult honey bees are not 

available, risks to terrestrial insects from acute oral exposure will be assumed. Risk estimates based on these 

data will be considered along with other lines of evidence to determine whether higher-tier studies are needed 

at the whole colony level.

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether continued registration 

of a pesticide is likely to result in unreasonable adverse effects to non-target species or is likely to adversely 

affect listed threatened or endangered species and/or modify their designated critical habitat. Without these 

data, EPA may need to presume risk, which will limit the flexibility of pesticide products to comply with 

FIFRA and the ESA, and could result in use restrictions. 

 

 

1 http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance.
41 

Study Title: Honey Bee Acute Larvae Oral Toxicity Study; 

Guideline Number: Special Study – OECD 237; 

Test Substance: Endothall – Dipotassium Salt and Mono (N,N-dimethylalkylamine) Salt

Rationale for Requiring the Data 

No data have been submitted on the toxicity of endothall to honey bee larvae. Terrestrial invertebrates are 

likely to be impacted if exposed to pesticides in various use settings. With eusocial bees, pesticide residues 

may be transferred to pollen and/or nectar of treated plants and subsequently brought back to the hive where 

developing larvae and pupae may be exposed. Therefore, potential adverse effects to developing bees could 

result from exposure to pesticide residues. Available toxicity studies do not address possible effects on brood 

(larvae and pupae) survival/development. Because of the potential for pollen and nectar to be contaminated 

with pesticide residues, and subsequently brought back to the hive, it is important to determine the acute 

toxicity of this compound to bee brood. 

The Office of Pesticide Programs has made available a guidance regarding ecological testing for bees using 

the honey bee as a surrogate test species. The guidances discusses Tier 1 laboratory-based acute toxicity studies 

of individual honey bee larvae as a critical component of the screening-level risk assessment process for 

examining potential risks from specific routes of exposure. The guidance be found at: 

http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. Additional guidance on 

larval honey bee toxicity test design can be found in OECD Test Guideline 237 (http://www.oecdilibrary.org/docserver/download/9713171e.pdf?expires=1422485600&id=id&accname=guest&checksum=D

8E07C2B1DF77BF096C3B29F55BF86A7). In some cases, information pertaining to acute toxicity to honey 

bee larvae may be obtained with the chronic honey bee larval test thereby negating the need for separate acute 

and chronic larval toxicity tests. 

Practical Utility of the Data 

How will the data be used? 

The Tier 1 acute toxicity data on honey bee larvae serve as a foundation for the screening-level assessment of 

potential risk to non-target organisms including federally listed threatened or endangered and non-listed 

terrestrial invertebrates, including pollinators, and/or modify their designated critical habitat from acute 

exposures to pesticides. The data will be used to reduce uncertainties associated with the risk assessment for 

terrestrial invertebrates and will improve EPA’s understanding of the potential effects on terrestrial species 

and whether there is a differential sensitivity of larval bees relative to adult bees. If acute effects data for 

larvae are not available, risks to terrestrial insects from acute exposure will be assumed. Risk estimates 

based on these data will be considered along with other lines of evidence to determine whether higher-tier 

studies are needed at the whole colony level.

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether continued registration 

of a pesticide is likely to result in unreasonable adverse effects to non-target species or is likely to adversely 

affect listed threatened or endangered species and/or modify their designated critical habitat. Without these 

data, EPA may need to presume risk which will limit the flexibility of pesticide products to comply with FIFRA 

and the ESA, and could result in use restrictions. 

 
42 

Study Title: Honey Bee Adult Chronic Oral Toxicity 

Guideline Number: Special Study – Non-guideline; 

Test Substance: Endothall – Dipotassium Salt and Mono (N,N-dimethylalkylamine) Salt 

Rationale for Requiring the Data 

No data have been submitted on the chronic toxicity of endothall to adult honey bees. A study is needed to 

determine the chronic toxicity of the compound to adult honey bees, including mortality and sublethal effects. 

Terrestrial invertebrates are likely to be impacted if exposed to pesticides in various use settings. With eusocial 

bees, pesticide residues may be transferred to pollen and/or nectar of treated plants and subsequently brought 

back to the hive. Therefore, potential chronic effects to adult honey bees and other pollinators from oral 

exposure to some pesticides could exist. Currently available toxicity studies do not address possible lethal and 

sublethal effects of chronic oral exposure on adult terrestrial invertebrates and will assist in determining 

whether the sensitivity of adult bees differs from that of earlier life stages. Because of the potential for pollen 

and nectar to be contaminated with pesticide residues, and subsequently brought back to the hive, it is important 

to determine the chronic oral toxicity of this compound to adult honey bees and other pollinators. 

The Office of Pesticide Programs has made available a guidance regarding ecological testing for bees using 

the honey bee as a surrogate test species. The guidances discusses Tier 1 laboratory-based chronic oral 

toxicity studies of individual adult honey bees as a critical component of the screening-level risk assessment 

process for examining potential risks from specific routes of exposure. The guidance can be found at: 

http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. Although study design 

elements for the chronic 10-day oral toxicity test with honey bees are similar to the OECD TG 213 acute oral 

toxicity test ( http://www.oecdilibrary.org/docserver/download/9721301e.pdf?expires=1422484908&id=id&accname=guest&checksum=C

38495D2A570AC2216CFB1F223D24AA7), EPA requires that the proposed protocol for this study be 

submitted for review and approval by EPA prior to initiating the test.

Practical Utility of the Data 

How will the data be used? 

The Tier 1 chronic toxicity data on adult bees serve as a foundation for the screening-level assessment of 

potential risk to non-target organisms including federally listed threatened or endangered species and nonlisted terrestrial invertebrates, including pollinators, from chronic oral exposures to pesticides. The data will 

be used to reduce uncertainties associated with the risk assessment for terrestrial invertebrates and will 

improve EPA’s understanding of the potential direct and indirect lethal and sublethal effects on a broad range 

of terrestrial species, particularly insect pollinators and to determine whether adult toxicity differs 

substantially from other life stages evaluated in other Tier 1 tests. If chronic oral effects data for adults are 

not available, risks to terrestrial insects from chronic exposure will be assumed. Risk estimates based on 

these data will be considered along with other lines of evidence to determine whether higher-tier studies are 

needed at the whole colony level.

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether continued registration 

of a pesticide is likely to result in unreasonable adverse effects to non-target species or is likely to adversely 

affect listed threatened or endangered species and/or their designated critical habitat. Without these data, EPA 

may need to presume risk which will limit the flexibility of pesticide products to comply with FIFRA and the 

ESA, and could result in use restrictions. 

 
43 

Study Title: Honey Bee Larvae Chronic Oral Toxicity 

Guideline Number: Special Study –Non-Guideline; 

Test Substance: Endothall – Dipotassium Salt and Mono (N,N-dimethylalkylamine) Salt

Rationale for Requiring the Data 

No data have been submitted on the toxicity of endothall to honey bee larvae. Terrestrial invertebrates are 

likely to be impacted if exposed to pesticides in various use settings. For eusocial bees, pesticide residues may 

be transferred to pollen and/or nectar of treated plants and subsequently brought back to the hive where larvae 

and pupae may be exposed. Therefore, potential effects to developing bees could result from chronic exposure 

to pesticide residues. Available toxicity studies do not address possible chronic effects on brood (larvae and 

pupae) survival. Because of the potential for pollen and nectar to be contaminated with pesticide residues, and 

subsequently brought back to the hive, it is important to determine chronic larval/pupal toxicity and whether 

adult emergence is adversely affected. This study will provide information on whether honey bee larvae differ 

in sensitivity from adult bees following chronic exposure.

The Office of Pesticide Programs has made available a guidance regarding ecological testing for bees using 

the honey bee as a surrogate test species. The guidances discusses Tier 1 laboratory-based chronic toxicity 

studies of individual honey bee larvae as a critical component of the screening-level risk assessment process 

for examining potential risks from specific routes of exposure. The guidance can be found at: 

http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. Additional information on 

larval honey bee toxicity repeat exposure test design can be found in the OECD draft guidance 

(http://www.oecd.org/env/ehs/testing/Draft_GD_honeybees_rep_exp_for_2nd_CR_25_November_2013.pdf. 

Although study design elements for the chronic 21-day toxicity test with honey bee larvae have been drafted, 

EPA requires that the proposed protocol for this study be submitted for review and approval by EPA prior to 

initiating the test. 

Practical Utility of the Data 

How will the data be used? 

The Tier 1 chronic toxicity data on bee larvae serve as a foundation for the screening-level assessment of 

potential risk to non-target organisms including federally listed threatened or endangered and non-listed 

terrestrial invertebrates, including insect pollinators, from chronic exposures to pesticides. These data will be 

used to reduce uncertainties associated with the risk assessment for terrestrial invertebrates and will improve 

EPA’s understanding of the potential direct and indirect lethal and sublethal effects on a broad range of 

terrestrial species, particularly insect pollinators. These data will also assist in determining whether early life 

stages of the bee differ in their sensitivity to pesticides relative to adults. If chronic effects data for larvae are 

not available, risks to terrestrial insects from chronic exposure will be assumed. Risk estimates based on 

these data will be considered along with other lines of evidence to determine whether higher-tier studies are 

needed at the whole colony level.

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether continued registration 

of a pesticide is likely to result in unreasonable adverse effects to non-target species or is likely to adversely 

affect listed threatened or endangered species and/or modify their designated critical habitat. Without these 

data, EPA may need to presume risk which will limit the flexibility of pesticide products to comply with FIFRA 

and the ESA, and could result in use restrictions. 

 
44 

Study Title: Residues in Pollen and Nectar 

Guideline Number: Special Study – Non-guideline; 

Test Substance: Endothall – Dipotassium Salt and Mono (N,N-dimethylalkylamine) Salt 

Rationale for Requiring the Data 

Measurements of residues in the pollen/nectar are needed based upon lower-tiered tests and/or other lines of 

evidence, and the need for a refined pollinator risk assessment. Terrestrial invertebrates are likely to be 

impacted if exposed to pesticides residues in various use settings. Pesticide residues may be transferred to 

pollen and/or nectar of treated plants and subsequently brought back to hive all life stages may be exposed. 

For some pesticides, the quantification of pollinator-relevant residues in treated flowering plants is needed, 

since pollinators will be exposed to residues from either current or prior season applications (due to the 

potential for residues to accumulate in plants and trees). Residues in edible/transportable-to-hive parts of 

treated trees and plants, including (where appropriate), but not limited to, guttation water, sap/resins, whole 

plant tissue (e.g., leaves, stems), as well as blooming, pollen-shedding, and nectar producing parts (i.e., 

flowers and, if present, extra-floral nectaries) of plants may inform the potential for risk. Studies should be 

designed to provide residue data for crops and application methods of concern.

The Office of Pesticide Programs has made available a guidance regarding ecological testing for bees using 

the honey bee as a surrogate. This can be found at: http://www2.epa.gov/pollinator-protection/pollinatorrisk-assessment-guidance. Since residue studies are intended to provide exposure data in multiple matrices 

and under specific application conditions, EPA requires that the protocol is submitted for review and 

approval by EPA prior to initiation of the study.

Practical Utility of the Data 

How will the data be used? 

Measured residue data will be used to refine conservative estimates of pesticide exposure and reduce 

uncertainties associated with the Tier 1 exposure assessment by providing direct measurements of pesticide 

concentrations resulting from actual use settings. Measured residues may provide a more realistic 

understanding of exposure through contact or ingestion with which to calculate risk quotients for individual 

bees as well as to characterize exposure to the colony. If measured residue data are not available, risk 

estimates for terrestrial insects will be based on model generated or default values used to support the 

screening-level assessment.

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether continued registration 

of a pesticide is likely to result in unreasonable adverse effects to non-target species or is likely to adversely 

affect federally listed threatened or endangered species or their designated critical habitat. Without these 

data, EPA will have to rely on conservative estimates of exposure which may limit the flexibility of pesticide 

products to comply with FIFRA and the ESA, and could result in use restrictions. 

 
45 

Study Title: Semi-field Testing for Pollinators (tunnel or colony feeding studies) 

Guideline Number: Special Study – Non-guideline, OECD 75; 

Test Substance: Endothall – Dipotassium Salt and Mono (N,N-dimethylalkylamine) Salt

Rationale for Requiring the Data 

Should the screening level risk assessment identify that there are risk concerns to bees, mitigation measures 

may need to be considered or the registrant may need to conduct Tier 2 or Tier 3 effects studies. For eusocial 

bees, pesticide residues may be transferred to pollen and/or nectar of treated plants and subsequently brought 

back to the hive and may adversely affect developing brood (egg, larvae, and pupae) and adult bees. Tier 2 

feeding studies are conditional on the outcome of the screening-level assessment where acute and/or chronic 

risk levels of concern have been exceeded for terrestrial invertebrates based on Tier 1 studies of individual 

bees. Feeding studies utilize free foraging bee colonies that are “dosed” with specific quantities of test material 

and represent a means of ensuring exposure to the test material through spiked pollen and/or sugar solutions 

fed to the colony while still allowing the bees to forage freely. Since bee colonies are not confined to 

enclosures, colonies can be exposed for longer duration periods without subjecting the bees to stress that 

typically results from Tier 2 tunnel studies. Available toxicity studies of individual bees (Tier 1) conducted to 

support screening-level assessments do not address possible effects and/or exposure to pesticide residues at 

the colony-level. It is therefore important to determine whether bee colonies may be negatively affected where 

bees are free foraging and have the option to collect/consume alternative forage items beyond the spiked food. 

Since multiple dose levels can be more readily tested, feeding studies can help to define dose-response 

relationships at the whole colony level. 

The Office of Pesticide Programs has made available a guidance regarding ecological testing for bees using 

the honey bee as a surrogate. This guidance describes the tiered testing process and can be found at: 

http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. Additional information on honey 

bee colony feeding studies can be found in the EPPO Guidance 170 

(www.nationalbeeunit.com/downloadDocument.cfm?id=191). Formal guidelines for semi-field tests do not yet 

exist; however, information that can help guide the development of either a semi-field tunnel test protocol 

can be found at OECD 75

(http://www.oecd.org/officialdocuments/publicdisplaydocumentpdf/?cote=env/jm/mono(2007)22&doclanguage=en).

Although study design elements for the feeding study are available through the EPPO Guidance 170 and 

OECD 75, EPA requires that the proposed protocol for this study be submitted for review and approval by 

EPA prior to initiating the test. 

Practical Utility of the Data 

How will the data be used? 

Tier 2 colony feeding data will be used to assess potential risk to non-target organisms including listed and 

non-listed terrestrial social invertebrate species. The colony feeding study is designed to represent potential 

field-level exposure and account for hive dynamics using longer duration exposure periods than are possible 

in Tier 2 tunnel studies. This study will be used to determine whether potential adverse effects to insect 

pollinators at the whole colony level when bees are able to forage naturally beyond the spiked food. Results 

from the feeding study will help to refine the screening-level risk assessment for beneficial terrestrial 

invertebrates that were based on Tier 1 studies on individual bees. Since feeding studies can help to define a 

dose-response relationship at the colony level, the studies can provide a means of determining exposure 

thresholds below which the likelihood of adverse effects on colonies may be low. 

How could the data impact the Agency’s future decision-making?

The Tier 2 colony-level data will be used to refine screening-level risk estimates derived using Tier 1 

laboratory-based data on individual bees. The Tier 2 data will help to inform the determination required under 

FIFRA or the ESA as to whether continued registration of a pesticide is likely to result in unreasonable adverse 

effects to non-target species or is likely to adversely affect federally listed threatened or endangered species 

or their designated critical habitat. Without these data, EPA may need to presume risk which will limit the 

flexibility of pesticide products to comply with FIFRA and the ESA, and could result in significant use 

restrictions. 
46 

Study Title: Field Testing for Pollinators 

Guideline Number: Special Study – 850.3040, 850.2500 (design elements); 

Test Substance: Endothall – Dipotassium Salt and Mono (N,N-dimethylalkylamine) Salt 

Rationale for Requiring the Data 

Should the screening level risk assessment identify that there are risk concerns to bees, mitigation measures 

may need to be considered or the registrant may need to conduct Tier 2 or Tier 3 effects studies. Tier 3 studies 

are conditional on the outcome of the screening-level assessment (Tier 1) where acute and/or chronic risk 

levels of concern have been exceeded for terrestrial invertebrates and where Tier 2 studies either under semifield tunnel conditions and/or feeding studies have indicated potential adverse effects at the colony level. 

Available toxicity studies from lower-tier studies do not address possible effects and/or exposure to pesticide 

residues at the colony-level under actual pesticide use conditions and where specific uncertainties regarding 

the likelihood of exposure and/or effects remain. Full-field studies also provide an opportunity to measure 

residues in pollen and nectar as well as various matrices (beebread, honey, wax) within the colony to obtain 

a more realistic understanding of exposure.

The Office of Pesticide Programs has made available a guidance regarding ecological testing for bees using 

the honey bee as a surrogate. This guidance describes the tiered testing process and can be found at: 

http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. Additional information on 

honey bee colony studies under full-field conditions can be found in the OCSPP 850.3040 

(http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0154-0018). Useful guidance is 

also available through OCSPP 850.2500 (Field Testing of Terrestrial Wildlife; 

http://www.epa.gov/ocspp/pubs/frs/publications/Test_Guidelines/series850.htm) Although design elements 

for the full-field colony-level study are available through the 850.3040 and 850.2500, EPA requires that the 

proposed protocol for this study be submitted for review and approval by EPA prior to initiating the test; the 

protocol should attempt to address specific uncertainties identified in lower-tier studies.

Practical Utility of the Data 

How will the data be used? 

Tier 3 colony-level data will be used to further characterize potential risk to non-target organisms including 

listed and non-listed terrestrial social invertebrate species and to refine screening-level risk estimates that 

were based on individual bee responses. The semi-field test is a controlled study that is designed to represent 

potential field-level exposure under relatively controlled conditions and account for hive dynamics, which 

are not achievable from lower-tier pollinator studies. This study will be used to determine whether adverse 

effects to insect pollinators at the whole colony level, may result for the use of pesticides and will help to 

refine the screening-level risk estimates for beneficial terrestrial invertebrates. This study will also be used 

to determine whether more refined (Tier 3) studies are needed to characterize risk. 

How could the data impact the Agency’s future decision-making?

The data will inform the determination required under FIFRA or the ESA as to whether continued registration 

of a pesticide is likely to result in unreasonable adverse effects to non-target species or is likely to adversely 

affect federally listed threatened or endangered species or their designated critical habitat. Without these 

data, EPA may need to presume risk which will limit the flexibility of pesticide products to comply with 

FIFRA and the ESA, and could result in significant use restrictions. 

 
47 

10. References 

Keller, A. E., Dutton, R. J., Bitton, G., and Crisman, T. L. 1988. Chronic Toxicity of Hydrothol 191 

to Ceriodaphnia dubia at 25 and 15 Degrees C. Bull.Environ.Contam.Toxicol. 41[2], 233 

240. E012941. MRID 49660201. 

United States Environmental Protection Agency (USEPA). 2004. Overview of the Ecological Risk 

Assessment Process in the Office of Pesticide Programs. U.S. Environmental Protection 

Agency, Office of Pesticide Programs, Environmental Fate and Effects Division. Available 

at http://www.epa.gov/espp/consultation/ecorisk-overview.pdf

USEPA. 2004. Memorandum “Environmental Fate and Ecological Risk Assessment of 

 Endothall (PC Code 038901, 038903, 038904, 038905, DP Barcode D236807, D240095, 

 D263581, D288190, D287268, and D307700)” to Registration Division. Dated September 

 30, 2004. Office of Prevention, Pesticides, and Toxic Substances, U.S. Environmental 

 Protection Agency, Washington, D.C. 

USEPA. 2005. Memorandum “Environmental Fate and Ecological Risk Assessment of 

 Endothall – Revised (PC Code 038901, 038903, 038904, 038905, DP Barcode D315240)” to 

 Registration Division. Dated April 22, 2005. Office of Prevention, Pesticides, and Toxic 

 Substances, U.S. Environmental Protection Agency, Washington, D.C. 

USEPA. 2005. Memorandum “Environmental Fate and Effects Division Error-only corrections of 

 the Endothall RED (PC Code 038901, 038904, 038905, DP Barcode D316102)” to 

 Registration Division. Dated April 22, 2005. Office of Prevention, Pesticides, and Toxic 

 Substances, U.S. Environmental Protection Agency, Washington, D.C. 

USEPA. 2009. Memorandum “Ecological Risk Assessment Addressing the Proposed Registration 

 of Endothall Applied as Irrigation Water for New Use Crops under IR-4 (PC Code 038901, 

 038904, 038905, DP Barcode D356316)” to Registration Division. Dated October 29, 2009. 

 Office of Pesticide Programs, U.S. Environmental Protection Agency, Washington, D.C. 

USEPA. 2013. Memorandum “Endothall - Dipotassium salt: Ecological Risk Assessment for 

 Proposed New Formulation and New Use on Apple trees (PC Code 038904, DP Barcode 

 D403244)” to Registration Division. Dated March 19, 2013. Office of Pesticide Programs, 

 U.S. Environmental Protection Agency, Washington, D.C. 

USEPA. 2014. Memorandum “Endothall - Dipotassium salt: Addendum to the “Ecological Risk 

Assessment for Proposed New Formulation and New Use on Apple trees, DP 403244” (PC 

Code 038904, DP Barcode D417414)” to Registration Division. Dated February 4, 2014. 

Office of Pesticide Programs, U.S. Environmental Protection Agency, Washington, D.C. 

USEPA. 2007a. ECOTOXicology Database. Office of Research and Development National Health 

and Environmental Effects Research Laboratory’s (NHEERL’s) Mid-Continent Ecology 

Division (MED). http://cfpub.epa.gov/ecotox/ 
48 

USEPA. 2014a. Guidance for Assessing Pesticide Risks to Bees. U.S. Environmental Protection 

Agency, Office of Pesticide Programs; Health Canada Pest Management Regulatory 

Agency; and California Department of Pesticide Regulation. Jun. 23, 2014. Available at 

http://www2.epa.gov/pollinator-protection/pollinator-risk-assessment-guidance. 

a. Submitted Environmental Fate Studies 

MRID: 124624 Oregon State Univ. (1963). Progress Report on the Soil Behavior of Endothal. 

(Unpublished study received Dec 1, 1970 under 1F1105; submitted by Agchem Div., Pennwalt 

Corp., Philadelphia, PA; CDL:094511-D). 

MRID: 124626 Oregon State Univ. (19??). Preliminary Investigations of the Behavior of Endothal 

in Water. (Unpublished study received Dec 1, 1970 under 1F1105; submitted by Agchem Div., 

Pennwalt Corp., Philadelphia, PA; CDL:094511-G) 

MRID: 147122 Carlson, R. (1985). The Hydrolysis of Endothall in Water: Project No. WT-3-85. 

Unpublished study prepared by Pennwalt Corp. 18 p. 

MRID: 44578401 Mao, J. (1997). Endothall Amine Salt- Determination of pH Dependent 

Hydrolysis: Lab Project Number: 12442.0396.6209.715: KP-96-01: 96-6-6537. Unpublished study 

prepared by Springborn Laboratories, Inc. 79 p. 

MRID: 147123 Pennwalt Corp. (1985). Photodegradation of Endothall in Water. Unpublished 

study. 9 p. 

MRID: 42289205 Saxena, A.; Marsh, S.; Koebel, D. (1991). Photodegradation of carbon-14 

Endothall in a Buffered Aqueous Solution Under Artificial Sunlight: Final Report: Lab Project 

Number: SC910024: BR-91-25. Unpublished study prepared by Battelle. 55 p. 

MRID: 42289206 Zwick, T.; Kazee, B.; Marsh, S. (1990). Photodegradation of (carbon-14) 

Endothall in Water Under Artificial Light: Final Report: Lab Project Number: SC890059. 

Unpublished study prepared by Battelle. 92 p. 

MRID: 42641201 Zwick, T.; Kazee, B.; Marsh, S. (1992). Photodegradation of (carbon-14) 

Endothall in Water under Artificial Light: Amended Final Report: Lab Project Number: SC890059: 

N0758-4400. Unpublished study prepared by Battelle. 92 p. 

MRID: 113974 Oregon State Univ. (1962). Progress Report on the Endothal Project. Progress rept., 

no. 2. (Unpublished study received Jul 8, 1965 under 4581-232; submitted by Agchem Div., 

Pennwalt Corp., Philadelphia, PA; CDL:121844-B). 

MRID: 147124 Pennwalt Corp. (1985). Photodegradation of Endothall on Soil. Unpublished study. 

10 p. 

MRID: 42289207 Saxena, A.; Zwick, T.; Marsh, S.; et al. (1991). Photodegradation of (carbon-14) 

Endothall on Sandy Loam Soil Under Artificial Light: Final Report: Lab Project Number: 

SC890060: BR-90-02. Unpublished study prepared by Battelle. 67 p. 
49 

MRID: 42641202 Saxena, A.; Zwick, T.; Marsh, S.; et al. (1992). Photodegradation of (carbon-14) 

Endothall on Sandy Loam under Artificial Light: Amended Final Report: Lab Project Number: 

SC890060: BR-90-02. Unpublished study prepared by Battelle. 67 p. 

MRID: 113974 Oregon State Univ. (1962). Progress Report on the Endothal Project. Progress rept., 

no. 2. (Unpublished study received Jul 8, 1965 under 4581-232; submitted by Agchem Div., 

Pennwalt Corp., Philadelphia, PA; CDL:121844-B). 

MRID: 113979 Temby, F. (1963). Biological Breakdown of Endothal Compounds. (Unpublished 

study received Jul 8, 1965 under 4581-232; submitted by Agchem Div., Pennwalt Corp., 

Philadelphia, PA; CDL: 121844-N). 

MRID: 124624 Oregon State Univ. (1963). Progress Report on the Soil Behavior of Endothal. 

(Unpublished study received Dec 1, 1970 under 1F1105; submitted by Agchem Div., Pennwalt 

Corp., Philadelphia, PA; CDL:094511-D). 

MRID: 124625 Freed, V. (1963). Progress Report on the Study of the Degradation Products of 

Endothal in Soil. (Unpublished study received Dec 1, 1970 under 1F1105; prepared by Oregon 

State Univ., submitted by Agchem Div., Pennwalt Corp., Philadelphia, PA; CDL: 094511-F) 

MRID: 162920 Dykeman, R. (1986). Aerobic/Anaerobic Soil Metabolism of Endothall: Final 

Report: Project No. WT-86-C-1. Unpublished study prepared by Agchem Div., Pennwalt Corp. 

185 p. 

MRID: 44949401 Atkins, R.; Peel, D.; Marsh, D. (1999). Aerobic Soil Metabolism of (carbon-14) 

Endothall: Lab Project Number: 1134: 2045: KP-97-24. Unpublished study prepared by PTRL East, 

Inc. 167 p. 

MRID: 162920 Dykeman, R. (1986). Aerobic/Anaerobic Soil Metabolism of Endothall: Final 

Report: Project No. WT-86-C-1. Unpublished study prepared by Agchem Div., Pennwalt Corp. 

185 p. 

MRID: 79977 Sikka, H.C.; Saxena, J. (1973). Metabolism of endothall by aquatic microorganisms. 

Journal of Agricultural and Food Chemistry 21 (3):402-406. (Also In unpublished submission 

received Feb 1, 1975 under 4581-EX-21; submitted by Pennwalt Corp., Philadelphia, Pa.; 

CDL:094575-G). 

MRID: 113974 Oregon State Univ. (1962). Progress Report on the Endothal Project. Progress rept., 

no. 2. (Unpublished study received Jul 8, 1965 under 4581-232; submitted by Agchem Div., 

Pennwalt Corp., Philadelphia, PA; CDL:121844-B). 

MRID: 113975 Montgomery, M. (1962). Letter sent to O. Keckemet dated Oct 16, 1962 Endothal 

in soil. Progress rept., no. 3. (Unpublished study received Jul 8, 1965 under 4581-232; prepared by 

Oregon State Univ., Dept. of Agricultural Chemistry, Agricultural Experiment Station, submitted 

by Agchem Div., Pennwalt Corp., Philadelphia, PA; CDL:121844-C). 

MRID: 113977 Comes, R.; Bohmont, D.; Alley, H. (1961). Movement and persistence of endothal 

... as influenced by soil texture, temperature, and moisture levels. Journal of the A.S.S.B.T. XI 
50 

(4):287-293. (Also In unpublished submission received Jul 8, 1965 under 4581-232; submitted by 

Agchem Div., Pennwalt Corp., Philadelphia, PA; CDL:121844-L). 

MRID: 113978 Agchem (19??). Movement and Persistence of Endothal under Controlled 

Conditions. (Unpublished study received Jul 8, 1965 under 4581- 232; CDL:121844-M). 

MRID: 113980 Temby, F. (1963). Soil Movement Studies with Endothal Compounds. 

(Unpublished study received Jul 8, 1965 under 4581-232; submitted by Agchem Div., Pennwalt 

Corp., Philadelphia, PA; CDL: 121844-O). 

MRID: 113981 Temby, F. (1963). Soil Adsorption Studies- Endothal Compounds. (Unpublished 

study received Jul 8, 1965 under 4581-232; submitted by Agchem Div., Pennwalt Corp., 

Philadelphia, PA; CDL:121844-P). 

MRID: 113986 Freed, V.; Montgomery, M.; Fang, S. (1958). The Absorption and Translocation of 

C14 Labelled Endothal in Red Beets and Spinach. (Unpublished study received Sep 8, 1958 under 

unknown admin. no.; prepared by Pennsylvania Salt Mfg. Co. of Washington, submitted by 

Agchem Div., Pennwalt Corp., Philadelphia, PA; CDL: 124421-A). 

MRID: 113987 Agchem (1970). The Results of Tests on the Amount of Residue Remaining 

Including a Description of the Analytical Method Used: Endothall. (Compilation; unpublished 

study received Jun 27, 1971 under unknown admin. no.; CDL:124882-A). 

MRID: 114521 Freed, V.; Montgomery, M. (1963). Progress Report on the Study of the 

Degradation Products of Endothal in Soil. (Unpublished study received Mar 15, 1966 under 4581-

139; prepared by Oregon State Univ., Agricultural Experiment Station, Dept. of Agricultural 

Chemistry, submitted by Agchem Div., Pennwalt Corp., Philadelphia, PA; CDL:007441-X). 

MRID: 114523 Agchem (1961) Chemical Study: Endothall. (Compilation; unpublished study 

received Mar 15, 1966 under 4581-139; CDL: 007441-AB) 

MRID: 124624 Oregon State Univ. (1963) Progress Report on the Soil Behavior of Endothall. 

(Unpublished study received Dec 1, 1970 under 1F1105; submitted by Agchem Div., Pennwalt 

Corp., Philadelphia, PA; CDL:094511-D) 

MRID: 124627 Horowitz, M. (1966). Breakdown of Endothal in soil. Weed Research 6(2):168-

171. (Also In unpublished submission received Dec 1, 1970 under 1F1105; submitted by Agchem 

Div., Pennwalt Corp., Philadelphia, PA; CDL:094511-H). 

MRID: 156635 Dykeman, R. (1985). Adsorption/Desorption of Endothall on Soils by Batch 

Equilibrium Method: Final Report: Project No. WT-7-85. Unpublished study prepared by Pennwalt 

Corporation, Agchem Division. 71 p. 

MRID: 41616404 Vigon, B. (1989). Adsorption/Desorption of 14C (Carbon 14) ring (2,3) 

Endothall on Soils by the Batch Equilibrium Method: Lab Project Number: NO962/6200. 

Unpublished study prepared by Battelle. 68 p. 
51 

MRID: 38645 Van Horn, S.L. (1975). Dissipation of the Herbicides Endothall, Diquat, and a 1:1 

Mixture in Water, Sediment, and Egeria densa. Master's thesis, Virginia Polytechnic Institute and 

State Univ. (Unpublished study received Jun 13, 1975 under 5E1648; submitted by Chevron 

Chemical Co., Richmond, Calif.; CDL:095428-AA). 

MRID: 113927 Agchem (1966). Description of Analytical Methods and Results of Analyses for 

Dimethylcocoamine Endothall (Accelerate) in Cotton-seed. (Compilation; unpublished study 

received Feb 14, 1966 under 4581-284; CDL:007456-A). 

MRID: 113974 Oregon State Univ. (1962). Progress Report on the Endothal Project. Progress rept., 

no. 2. (Unpublished study received Jul 8, 1965 under 4581-232; submitted by Agchem Div., 

Pennwalt Corp., Philadelphia, PA; CDL:121844-B). 

MRID: 118549 Amchem Products, Inc. (1971). Fenac Residue Data- Total Water Treatment. 

(Compilation; unpublished study received Jul 7, 1972 under 2F1213; CDL:091039-T). 

MRID: 162921 Jacobson, S. (1986). Terrestrial Field Dissipation Studies for Endothall (Herbicide 

273 and Des-I-Cate Harvest Aid Formulations): Final Report: Project WT-1-85 and WT-2-85. 

Unpublished study prepared by Agchem Div., Pennwalt Corp. 125 p. 

MRID: 38645 Van Horn, S.L. (1975). Dissipation of the Herbicides Endothall, Diquat, and a 1:1 

Mixture in Water, Sediment, and Egeria densa. Master's thesis, Virginia Polytechnic Institute and 

State Univ. (Unpublished study received Jun 13, 1975 under 5E1648; submitted by Chevron 

Chemical Co., Richmond, Calif.; CDL:095428-AA). 

MRID: 84382 Seaman, D.E.; Berkenkotter, P.; Chen, T.M.; et al. (1966). Persistence of Residues 

and Fates of Herbicides in Rice Fields and in Rice-field Effluents: Progress rept. WRC Project No. 

W 3 02 67. For the period Mar 1, 1965 to Jan 31, 1966. (Unpublished study received Oct 8, 1981 

under 476-2107; prepared by Univ. of California--Davis, Dept. of Botany, submitted by Stauffer 

Chemical Co., Richmond, Calif.; CDL:246011-M) 

MRID: 113982 Hiltibran, R. (19??). Duration of toxicity of endothal in water. Source unknown. 

(Also In unpublished submission received Jul 8, 1965 under 4581-232; submitted by Agchem Div., 

Pennwalt Corp., Philadelphia, PA; CDL:121844-Q). 

MRID: 113987 Agchem. (1970). The Results of Tests on the Amount of Residue Remaining 

Including a Description of the Analytical Method Used: Endothall. (Compilation; unpublished 

study received Jun 27, 1971 under unknown admin. no.; CDL:124882-A). 

MRID: 114554 3M Co. (1974). Residue Studies and Methods: System E. (Unpublished study 

received Dec 19, 1975 under 6H5112; CDL:225291-J). 

MRID: 116739 Chevron Chemical Co. (1977). Residue Chemistry Data and Data Reference List to 

Support Label Amendment for Diquat Water Weed Killer. (Compilation; unpublished study 

received Aug 22, 1977 under 239-1663; CDL:231427-A). 

MRID: 118549 Amchem Products, Inc. (1971). Fenac Residue Data--Total Water Treatment. 

(Compilation; unpublished study received Jul 7, 1972 under 2F1213; CDL:091039-T). 
52 

MRID: 44820101 Keckemet, O.; Sharp, J. (1999). Historical Aquatic Residue and Dissipation Data 

for Endothall Aquatic Products Aquathol K Aquatic Herbicide and Hydrothol 191 Aquatic Algicide 

and Herbicide: Lab Project Number: KP-99-02: WT-86-C-11. Unpublished study prepared by Elf 

Atochem. 316 p. {OPPTS 860.1400} 

MRID: 44820103 Biever, R. (1998). Hydrothol 191: An Aquatic Dissipation Study for Aquatic 

Non-Crop Uses: Final Report: Lab Project Number: KP-96-14: 98-1-7215: 12442-0896-6214-330. 

Unpublished study prepared by Elf Atochem and Springborn Laboratories, Inc. 164 p. 

MRID: 44828801 Singh, P.; Ritter, A.; Sharp, J. et al. (1999). Aquatic Dissipation Modeling of 

Endothall Acid: Aquathol K Aquatic Herbicide and Hydrothol 191 Aquatic Algicide and Herbicide: 

Lab Project Number: ATO KP-97-16: WEI 286.01. Unpublished study prepared by Waterborne 

Environmental, Inc. 363 p. 

MRID: 44828802 Williams, W.; Ritter, A.; Sharp, J. et al., (1999). An Evaluation of the Aquatic 

Dissipation of Endothall Aquatic Product: Aquathol, K Aquatic Herbicide and Hydrothol 191 

Aquatic Algicide and Herbicide: Lab Project Number: ATOKP-98-32: WEI-286.06. Unpublished 

study prepared by Waterborne Environmental, Inc. 69 p. 

b. Submitted Ecological Toxicity Studies 

Acid 

MRID Citation Reference 

71131 Bodden, R.M. (1979) Avian Single-dose Oral LDI50: Study No. W-910. (Unpublished 

study, including letter dated Jul 8, 1980 from R.M. Bodden to Obren Keckemet, received 

Jan 23, 1981 under 4581- 174; prepared by Ralston Purina Co., submitted by Pennwalt 

Corp., Philadelphia, Pa.; CDL:244131-B) 

72455 Bodden, M.R. (1979) Avian Single-dose Oral LD50: Study No. W-910. Final rept. 

(Unpublished study, including letter dated Jul 8, 1980 from R.M. Bodden to Obren 

Keckemet, received Jan 23, 1981 under 1F1105; prepared by Ralston Purina Co., submitted 

by Pennwalt Corp., Philadelphia, Pa.; CDL:099883-B) 

74220 Bodden, R.M. (1979) Avian Single-dose Oral LD50. (Unpublished study received Jan 23, 

1981 under 4581-282; prepared by Ralston Purina Co., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244122-B) 

42359701 Pedersen, C.; Helsten, B. (1992) Endothall Technical: 21-Day Acute Oral LD50 Study in 

Mallard Ducks: Lab Project Number: 106-004-04. Unpublished study prepared by Bio-Life 

Associates, Ltd. 50 p. 

92057001 Shellenberger, T. (1990) Agchem Division-Pennwalt Corp. Phase 3 Summary of MRID 

00072455. Endothall Technical--Single Dose Oral LD50 Value to Bobwhite Quail: Project 

W-910. Prepared by Hazleton Laboratories America, Inc. 10 p. 

92057002 Shellenberger, T. (1990) Agchem Division-Pennwalt Corp. Phase 3 Summary of MRID 

00035237. Hydrothol 191 - Acute Oral LD50 Test - Bobwhite Quail: Project No. 110-115. 

Prepared by Wildlife International Ltd. 11 p. 
53 

00160000 Hudson, R.; Tucker, R.; Haegele, M. (1984) Handbook of toxicity of pesticides to wildlife: 

Second edition. US Fish and Wildlife Service: Resource Publication 153. 91 p Ring-necked 

pheasant and Mallard duck tested 

35233 Fink, R. (1975) Final Report: Eight-Day Dietary LC50--Mallard Ducks: Project No. 110-

106. (Unpublished study received Oct 21, 1975 under 4581-EX-18; prepared by Truslow 

Farms, Inc., submit- ted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; CDL: 

096340-B) 

116271 Fink, R. (1975) Eight-day Dietary LC50--Mallard Ducks: Technical Endothal: Project No. 

110-106. Final rept. (Unpublished study received Jul 9, 1975 under 1F1105; prepared by 

Truslow Farms, Inc., submitted by Pennwalt Corp., Tacoma, WA; CDL:094702-G) 

52229 Fink, R. (1975) Final Report: Eight-Day Dietary LC50--Bobwhite Quail: Project No. 110-105

(Unpublished study received Oct 21, 1975 under 4581-EX-18; prepared by Truslow Farms, 

Inc., submit- ted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; CDL: 096340-A) 

CDL:094702-F) 

116270 Fink, R. (1975) Eight-day Dietary LC50--Bobwhite Quail: Technical Endothal: Project No. 

110-105. Final rept. (Unpublished study received Jul 9, 1975 under 1F1105; prepared by 

Truslow Farms, Inc., submitted by Pennwalt Corp., Tacoma, WA; CDL:094702-F). 

96299 Menzie, C.M. (1964) Letter sent to H.L. Lindaberry dated Oct 15, 1964 Toxicity to 

mallards|. (U.S. Fish and Wildlife Service, Patuxent Wildlife Research Center, Section of 

Chemical and Physiological Studies; unpublished study; CDL:090719-K). 

43167701 Pedersen, C.; Solatycki, A. (1994) Endothall Technical: 8-Day Acute Dietary LC 50 Study 

in Bobwhite Quail: Lab Project Number: 106-011-01. Unpublished study prepared by BioLife Associates, Ltd. 96 p. 

43167702 Pedersen, C.; Solatycki, A. (1994) Endothall Technical: 8-Day Acute Dietary LC 50 Study 

in Mallard Ducklings: Lab Project Number: 106-015-02. Unpublished study prepared by 

Bio-Life Associates, Ltd. 94 p. 

42507301 Pedersen, C.; Fletcher, D. (1992) Endothall Technical: Toxicity and Reproduction Study 

in Mallard Ducks: Lab Project Number: 89 DR 37. Unpublished study prepared by BioLife Associates, Ltd. 300 p. 

42507302 Pedersen, C.; Fletcher, D.; Lesar, C. (1992) Endothall Technical: Toxicity and 

Reproduction Study in Bobwhite Quail: Lab Project Number: 89 QR 41. Unpublished 

study prepared by Bio-Life Associates, Ltd. 301 p. 

43558201 Rose, S.; Goin, L. (1994) Endothall Technical: 28-Day Dietary Toxicity and 

Reproduction Pilot Study in Mallard Ducks: Addendum: Diet Analyses: Final Report: 

Lab Project Number: 89 DRP 37: 33400. Unpublished study prepared by NPC, Inc.; 

Columbia Labs, Inc.; and Bio-Life Associates, Ltd. 49 p. 

43558301 Rose, S.; Goin, L. (1994) Endothall Technical: 28-Day Dietary Toxicity and 

Reproduction Pilot Study in Bobwhite Quail: Addendum: Diet Analyses: Final Report: 

Lab Project Numbers: BLAL 89 QRP 41: 33400: 153-144. Unpublished study prepared 

by Columbia Labs, Inc.; NPC, Inc.; Bio-Life Associates, Ltd. 49 p. 

43558202 Rose, S.; Goin, L. (1994) Endothall Technical: Toxicity and Reproduction Study in 

Mallard Ducks: Addendum: Diet Analyses: Final Report: Lab Project Number: 89 DR 37: 

0660: 09356. Unpublished study prepared by NPC, Inc.; Columbia Labs, Inc.; and BioLife Associates, Ltd. 47 p. 
54 

96298 Walker, C.R. (1963) Endothal derivatives as aquatic herbicides in fishery habitats. 

Weeds 11(3):226-232. (Also In unpublished submission received Feb 17, 1967 under 

7F0570; submitted by Pennsalt Chemicals Corp., Bryan, Tex.; CDL:090719-J) 

67174 Schreck, C.B. (1974) Aquatic Plant Control Using Herbicides in a Large Potable Water 

Supply Reservoir: Contract No. DACW65-74- C-0013. (Virginia Polytechnic Institute 

and State Univ., Dept. of Fisheries and Wildlife Sciences for U.S. Dept. of the Army, 

Corps of Engineers; unpublished study; CDL:231433-D). 

69192 Bond, C.E.; Lewis, R.H.; Fryer, J.L. (1960) Toxicity of various herbicidal materials to 

fishes. Pages 96-101, In Transactions of the 1959 Seminar of Biological Problems in 

Water Pollution. By Robert A. Taft Engineering Center. Cincinnati, Ohio: U.S. Public 

Health Service. (Technical report W60-3; published study; CDL:230691-H) 

71143 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Endothall (Acid 

Monohydrate) Technical 89.5% Acid Equivalent to the Common Mummichog 

Fundulus heteroclitus (Linnaeus): UCES Project No. 11056-41-12. (Unpublished study 

received Jan 23, 1981 under 1F1105; prepared by Union Carbide Corp., submitted by 

Pennwalt Corp., Philadelphia, Pa.; CDL:244131-P) 

72465 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Endothall (Acid 

Monohydrate) Technical 89.5% Acid Equivalent to the Common Mummichog 

Fundulus heteroclitus (Linnaeus): UCES Project No. 11056-41-12. (Unpublished study 

received Jan 23, 1981 under 1F1105; prepared by Union Carbide Corp., submitted by 

Pennwalt Corp., Philadelphia, Pa.; CDL:099883-P). 

74225 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Endothall (Acid 

Monohydrate) Technical 89.5% Acid Equivalent to the Common Mummichog 

Fundulus heteroclitus (Linnaeus): UCES Project No. 11506-41-12. (Unpublished study 

received Jan 23, 1981 under 4581-282; prepared by Union Carbide Corp., submitted by 

Pennwalt Corp., Philadelphia, Pa.; CDL:244122-P). 

114549 Economon, P. (1967) Letter sent to W. Paterson dated Nov 3, 1967 Results of bioassay 

on aquatic herbicide compounds|. (Minnesota, Dept. of Conservation, Div. of Game 

and Fish, Technical Services; unpublished study; CDL:225291-D) 

114551 Whitley, J. (1968) Letter sent to W. Paterson dated Nov 18, 1968 Four-day fish 

toxicity tests on bluegill sunfish, black bull- head and mosquitofish. (Missouri, Dept. 

of Conservation, Fisheries Research Laboratory, Water Quality Investigations; 

unpublished study; CDL:225291-F) 

114552 Bionomics, Inc. (1971) The Acute Toxicity of System E (T-350) to Bluegill ..., 

Rainbow Trout ..., and Largemouth Bass (Micropterus salmoides). (Unpublished study 

received Dec 19, 1975 under 6H5112; submitted by 3M Co., St. Paul, MN; 

CDL:225291-G) 

116465 Paterson, W. (1969) Aquatic Herbicide System S. (Unpublished study received Mar 6, 

1969 under 7182-EX-6; submitted by Medical Products Div., 3M Co., St. Paul, MN; 

CDL:127050-A) 

43558302 Rose, S.; Goin, L. (1994) Endothall Technical: Toxicity and Reproduction Study in 

Bobwhite Quail: Addendum: Diet Analyses: Final Report: Lab Project Numbers: BLAL 

89 QR 41: 0660: 09356. Unpublished study prepared by Columbia Lab, Inc.; NPC, Inc.; 

Bio-Life Associates, Ltd. 47 p. 
55 

118536 Hughes, J.; Davis, J. (1963) Comparative Toxicity to Bluegill Sunfish of Granular and 

Liquid Herbicides. (Unpublished study received Nov 26, 1963 under unknown admin. 

no.; prepared by Louisiana, Wildlife & Fisheries Commission, submitted by Union 

Carbide Agricultural Products Co., Inc., Research Triangle Park, NC; CDL:129700-A) 

42327701 Bettencourt, M. (1992) Endothall Technical-Acute Toxicity to Bluegill Sunfish 

(Lepomis macrochirus) under Flow-through Conditions: Lab Project Number: 91-9-

3917: 12442.0591.6121.105. Unpublished study prepared by Springborn Laboratories, 

Inc. 62 p. 

42327702 Bettencourt, M. (1992) Endothall Technical-Acute Toxicity to Rainbow Trout 

(Oncorhynchus mykiss) Under Flow-through Conditions: Lab Project Number: 91-9-

3918: 12442.0591.6120.108. Unpublished study prepared by Springborn Laboratories, 

Inc. 63 p. 

69192 Bond, C.E.; Lewis, R.H.; Fryer, J.L. (1960) Toxicity of various herbicidal materials to 

fishes. Pages 96-101, In Transactions of the 1959 Seminar of Biological Problems in 

Water Pollution. By Robert A. Taft Engineering Center. Cincinnati, Ohio: U.S. Public 

Health Service. (Technical report W60-3; published study; CDL:230691-H) 

38629 Surber, E.W.; Pickering, Q.H. (1962) Acute toxicity of Endothal, Diquat, Hyamine, 

Dalapon, and Silvex to fish. Progressive Fish- Culturist (?/Oct):164-171. (U.S. Public 

Health Service, Robert A. Taft Sanitary Engineering Center, published study; 

CDL:095428-F) 

71137 Vilkas, A.G.; Hughes, J.S. (1979) The Acute Toxicity of Endothall to the Water Flea 

Daphnia magna Straus: UCES Project No. 11506- 41-09. (Unpublished study received 

Jan 23, 1981 under 4581-174; prepared by Union Carbide Corp., submitted by 

Pennwalt Corp., Philadelphia, Pa.; CDL:244131-I) 

42359702 McNamara, P. (1992) Endothall Technical--Acute Toxicity to Daphnids (Daphnids 

magna) Under Flow-through Conditions: Final Report: Lab Project Number: 91-10-

3946: 12442.0591.6122.115. Unpublished study prepared by Springborn Labs., Inc. 64 

p. 

5001624 Nebeker, A.V.; Gaufin, A.R. (1964) Bioassays to determine pesticide toxicity to the 

amphipod crustacean, Gammarus lacustris. Pages 64-67, In Utah Academy of Sciences 

Proceedings. Vol. 41, Part I. Salt Lake City, Utah: Utah Academy of Sciences, Arts 

and Letters. 

ACC 

094509 

05001465 

Crosby, D.G.; Tucker, R.K. (1966) Toxicity of Aquatic Herbicides to Daphnia magna. 

Science 154(3746):289-291. Study conducted at the Agricultural Toxicology and 

Residue Research Laboratory, University of California, Davis. Submitted by Pennwalt 

Corp., Pet#1F1105, Acc# 094509 (exhibit C-109), 12/01/70). Test ID# ES-H2. 

05001497 Sanders, H.O. (1970) Toxicities of some herbicides to six species of freshwater 

crustaceans. Journal of the Water Pollution Control Federation 42(8):1544-1550. 

71142 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Endothall (Acid 

Monohydrate) Technical 89.5% Acid Equivalent to the Fiddler Crab, Uca pugilator: 

UCES Project No. 11506-41-11. (Unpublished study received Jan 23, 1981 under 

4581-174; prepared by Union Carbide Corp., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244131-O) 

72464 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Endothall (Acid 

Monohydrate) Technical 89.5% Acid Equivalent to the Fiddler Crab, Uca pugilator: 
56 

UCES Project No. 11506-41-11. (Un- published study received Jan 23, 1981 under 

1F1105; prepared by Union Carbide Corp., submitted by Pennwalt Corp., Philadelphia, 

Pa.; CDL:099883-O) 

74224 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Endothall (Acid 

Monohydrate) Technical 89.5% Acid Equivalent to the Fiddler Crab, Uca pugilator: 

UCES Project No. 11506-41-11. (Unpublished study received Jan 23, 1981 under 

4581-282; prepared by Union Carbide Corp., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244122-O). 

71145 

ACC# 

244122 

Bailey, H.C. (1980) Letter sent to Bernalyn D. McGaughey dated Sep 19, 1980 

(Summary of results of 48-hour mussel embryo bio- assay performed on Endothall): 

SRI Project LSC-1514-6. (Unpublished study, including letter dated Jun 20, 1980 from 

H.C. Bailey to Bernalyn D. McGaughey, received Jan 23, 1981 under 4581-174; 

prepared by SRI International, submitted by Pennwalt Corp., Philadelphia, Pa.; 

CDL:244131-R) Toxicity of 89.5 acid equiv. to mussel embryos. 1980 study SRI 

Labs. 

74227 Bailey, H.C. (1980) Letter sent to Bernalyn D. McGaughey dated Sep 19, 1980 Results 

of 48-hour mussel embryo bioassay performed on Endothal|: SRI Project LSC-1514-6. 

(Unpublished study received Jan 23, 1981 under 4581-282; prepared by SRI 

International, submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244122-R). 

83026 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Endothall (Acid 

Monohydrate), 89.5% Acid Equivalent, to the Grass Shrimp Palaemonetes pugio: 

UCES Project No. 11506-41-10. (Unpublished study received Jan 23, 1981 under 

4581-174; prepared by Union Carbide Corp., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244131-L) 

83108 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Endothall (Acid 

Monohydrate), 89.5% Acid Equivalent, to the Grass Shrimp Palaemonetes pugio: 

UCES Project No. 11506-41-10. (Unpublished study received Jan 23, 1981 under 

1F1105; prepared by Union Carbide Corp., submitted by Pennwalt Corp., Philadelphia, 

Pa.; CDL:099883-L) 

84151 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Endothall (Acid 

Monohydrate), 89.5% Acid Equivalent, to the Grass Shrimp Palaemonetes pugio: 

UCES Project No. 11506-41-10. (Unpublished study received Jan 23, 1981 under 

4581-282; prepared by Union Carbide Corp., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244122-L) 

42895201 Dionne, E. (1993) Endothall Technical--Acute Toxicity to Eastern Oyster (Crassostrea 

virginica) Under Flow-through Conditions: Final Report: Lab Project Number: 93-4-

4715: 12442.0591.6125.504. Unpublished study prepared by Springborn Laboratories, 

Inc. 68 p. 

42914101 Bettencourt, M. (1993) Endothall Technical-Acute Toxicity to Mysid Shrimp 

(Mysidopsis bahia) Under Flow-Through Conditions: Final Report: Lab Project 

Number: 12442.0591.6124.515: 93-3-4711. Unpublished study prepared by Springborn 

Labs, Inc. 67 p. 

42914102 Bettencourt, M. (1993) Endothall Technical-Acute Toxicity to Sheepshead Minnow 

(Cyprinodon variegatus) Under Flow-Through Conditions: Final Report: Lab Project 

Number: 92-1-4901: 12442.0591.6123.505. Unpublished study prepared by Springborn 

Labs, Inc. 65 p. 
57 

25816 Davis, H.C.; Hidu, H. (19??) Effects of pesticides on embryonic development of Clams 

and Oysters and on survival and growth of the Larvae. Fishery Bulletin 67(2):393-

400,403. (Also In unpublished submission received Jan 2, 1980 under 2217-485; 

submitted by PBI-Gordon Corp., Kansas City, Kans.; CDL:241581-W) 

26244 Miller, C.W.; Lowe, J.I. (19??) Toxicity of Herbicides to Estuarine Animals. (U.S. 

Bureau of Commercial Fisheries, unpublished report.) 

40228401 Mayer, F.L. (1986). Acute Toxicity Handbook of Chemicals to Estuarine Organisms. 

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

Agency (USEPA), Prepared by Environmental Research Laboratory, Office of 

Research and Development, USEPA, Gulf Breeze, FL 32561. 274p. 

43007801 Putt, A. (1993) Endothall Technical (Acid)--The Chronic Toxicity to Daphnia magna 

Under Flow-Through Conditions: Final Report: Lab Project Number: 92-11-4525: 

12442.0692.6148.130. Unpublished study prepared by Springborn Labs, Inc. 99 p. 

43295401 Bettencourt, M. (1994) Endothall Technical (Acid)--The Toxicity to Fathead Minnow 

(Pimephales promelas) During an Early Life-stage Exposure: Final Report: Lab 

Project Number: 93-1-4567: 12442.0692.6149.120. Unpublished study prepared by 

Springborn Labs, Inc. 84 p. 

48157201 Paul, E.; Simonin, H.; Symuyla, J. (2010) The Toxicity of Diquat, Endothall, and 

Fluridone to Early Life Stages of Fish. Project Number: FLURIDONE/01/10/04. 

Unpublished study prepared by SePRO Corporation. 23 p. (E014903 Open Literature 

Study) 

45088229 Hiltibran, R. (1967) Effect of Some Herbicides on Fertilized Fish Eggs and Fry. Trans. 

Am. Fish. Soc. 96:414-416. (ACC#094509) 

44949201 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191 (Endothall): A 96-Hour 

Toxicity Test with the Freshwater Diatom (Navicula pelliculosa): Final Report: Lab 

Project Number: 299A-102. Unpublished study prepared by Wildlife International 

Ltd. 38 p. {OPPTS 850.5400} 

44949202 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191 (Endothall): A 96-Hour 

Toxicity Test with the Freshwater Alga (Anabaena flos-aquae): Final Report: Lab 

Project Number: 299A-101. Unpublished study prepared by Wildlife International 

Ltd. 36 p. {OPPTS 850.5400} 

44949402 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191 (Endothall): A 7-Day 

Toxicity Test with Duckweed (Lemna gibba G3): Final Report: Lab Project Number: 

299A-105. Unpublished study prepared by Wildlife International Ltd. 34 p. {OPPTS 

850.4400} 

44949403 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191 (Endothall): A 7-Day 

Toxicity Test with The Freshwater Alga (Selenastrum capricornutum): Final Report: 

Lab Project Number: 299A-103. Unpublished study prepared by Wildlife International 

Ltd. 36 p. {OPPTS 850.5400} 

44976701 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191: A 96-Hour Toxicity 

Test with the Marine Diatom (Skeletonema costatum): Final Report: Lab 

Project Number: 299A-104. Unpublished study prepared by Wildlife 

International , Ltd. 38 p. {OPPTS 850.5400} 
58 

113952 Walsh, G. (1971) Effects of Herbicides on Photosynthesis and Growth of 

Marine Unicellular Algae. (Environmental Protection Agency, Gulf Breeze 

Laboratory; unpublished study; CDL:094506-F) 

111488 Moffett, J.; Morton, H.; MacDonald, R. (1972) Toxicity of some herbicidal sprays 

to honey bees. Journal of Economic Entomology 65(1):32-36. (Also In 

unpublished submission received Sep 26, 1974 under 464-323; submitted by Dow 

Chemical U.S.A., Midland, MI; CDL:120345-H) 

35245 Pennwalt Corporation (1970) Beneficial Insect Safety. (Unpublished study 

received Jan 5, 1978 under 1F1105; CDL:096705-K) 

ACC 

094509 

Morton, H.T. Letter to E.J. Bowles regarding preliminary honeybee feeding 

studies. 1p. Submitted by Pennwalt Corp., Pet. #1F1105, Acc#094509 (Exhibit C38). Test ID#ES-GG6. 

40960 MacEwen, J.D. (1963) Toxicity Studies on Endothal acid: Development File No. 

342.44-11/1. (Unpublished study received Apr 10, 1966 under 6G0503; prepared 

by Wayne State Univ., Dept. of Industrial Medicine and Hygiene, submitted by 

Pennsalt Chemical Corp., Bryan, Tex.; CDL:090587-C) 

75236 Brieger, H. (1950) Preliminary Toxicity Studies on Endothal. (Jefferson Medical 

College, Div. of Industrial Medicine for U.S. Food and Drug Administration; 

unpublished study; CDL: 109911-A) 

114548 Kohn, F.; Kay, D. (1968) Report to Minnesota Mining and Manufacturing Co: 

Acute Toxicity Studies on 3ME68H: Lifestream Laboratories Project Nos. 984 

through 988. (Unpublished study received Dec 19, 1975 under 6H5112; prepared 

by Lifestream Laboratories, Inc., submitted by 3M Co., St. Paul, MN; 

CDL:225291-C) 

40109202 Smith, S. (1986) Acute Oral LD50 Study in Rats with Pelletted Endothall: Project 

ID: 480-2553. Unpublished study prepared by American Biogenics Corp. 32 p. 

42289201 Mallory, V. (1991) Acute Exposure Oral Toxicity in Rats with Endothall 

Technical: Lab Project Number: PH 402-ANA-002-91. Unpublished study 

prepared by Pharmakon Research International, Inc. 53 p. 

42169501 Cracknell, S. (1988) Endothall Technical: Acute Inhalation Toxicity Study in the 

Rat: Final Report: Lab Project Number: 88/0598: PSV/024. Unpublished study 

prepared by Life Science Research Ltd. 109 p. 

42221501 Cracknell, S. (1988) Endothall Technical: Acute Inhalation Toxicity Study in the 

Rat: Lab Project Number: 90/PSV024/0970: 88/0598. Unpublished study prepared 

by Life Science Research Ltd. 5 p. 

42408701 Hoffman, G. (1992) An Acute Inhalation Toxicity Study of Endothall Technical in 

the Rat: Lab Project Number: 91-8355. Unpublished study prepared by 

Bio/dynamics, Inc. 132 p. 

42169502 

42200101 

Hallifax, D. (1990) Endothall Technical: Absorption, Distribution, Metabolism 

and Excretion Study in the Rat: Final Report: Lab Project Number: 89/0122: 

PSV/026/ENDOTHALL. Unpublished study prepared by Life Science Research 

Ltd. 381 p. 
59 

42169503 Johnson, J.; Mahon, C.; Killinger, J. (1990) Dermal Absorption of Carbon 14-

Endothall Monohydrate Using Sprague-Dawley Rats: Lab Project Number: 

N4900-1000. Unpublished study prepared by Battelle Columbus Division. 225 p. 

43152101 Trutter, J. (1993) Two-Generation Reproduction Study in Rats with Disodium Salt 

of Endothall: Final Report: Lab Project Number: 153/142. Unpublished study 

prepared by Hazleton Washington, Inc. 1479 p. 

43629301 Trutter, J. (1995) Two-Generation Reproduction Study in Rats with Disodium Salt 

of Endothall: Addendum to MRID 43152101: Lab Project Number: 153-142. 

Unpublished study prepared by Hazleton Washington, Inc. 21 p. 

31855 Blackburn, R.D.; Weldon, L.W. (1964) Control of Southern Naiad in Florida drainage 

and irrigation channels. Weeds 12(4):295-298. (Also In unpublished submission 

received Sep 15, 1972 under 1F1101; submitted by Chevron Chemical Co., 

Richmond, Calif.; CDL:090862-AE) 

36529 Carlson, R.E.; Sandeno, J.L. (1970) Effect of Endothall on the Growth of Several 

Fungi. (Unpublished study received Jan 5, 1978 under 1F1105; submitted by 

Pennwalt Corp., Agchem Div., King of Prussia, Pa.; CDL:096704-B) 

114556 Carlson, R.; Sandeno, J. (1970) Effect of Endothall on the Growth of Several Fungi. 

(Unpublished study received Oct 26, 1978 under 4581-282; submitted by Agchem 

Div., Pennwalt Corp., Philadelphia, PA; CDL:235432-B) 

72467 U.S. Department of Interior, Bureau of Reclamation (1964?) Results of Algaecidal 

Evaluation Tests of Selected Compounds: Report No. WC-21. Annual progress rept. 

of 1964, lab. Studies. (Unpublished study; CDL:099883-U) 

74228 Pennwalt Corporation (19??) Toxicity Testing Protocols: Mussel Embryo Test. 

(Unpublished study received Jan 23, 1981 under 4581-282; CDL:244122-S) 

80439 Montgomery, M.L.; Freed, V.H. (1964) Preliminary Study on Microbial Effect on 

Endothal. (Unpublished study received Feb 4, 1966 under 6G0503; prepared by 

Oregon State Univ., Dept. of Agricultural Chemistry, submitted by Pennsalt 

Chemicals Corp., Tacoma, Wash.; CDL:090585-D) 

86622 Scribner, J.D. (1981) Evaluation of Studies on Genetic Toxicity of Endothall. 

(Unpublished study received Jul 29, 1981 under 4581-204; submitted by Pennwalt 

Corp., Philadelphia, Pa.; CDL:245680-D) 

114492 Pennwalt Corp. (1972) Responses of Plankton and Macrofauna Communities To Test 

Application of Chemical Herbicides. (Unpublished study received Jul 9, 1975 under 

1F1105; CDL:094702-H) 

114493 Walker, C. (1971) The toxicological effects of herbicides and weed control on fish 

and other organisms in the aquatic ecosystem. By U.S. Fish and Wildlife Service, Div. 

of Fishery Research, Branch of Pest Control Research. Pages 119-126, In Proc. Eur. 

Weed Res. Coun. 3rd Int. Symp. Aquatic Weeds; 1971. S.l.: s.n. (Also In unpublished 

submission received Jul 9, 1975 under 1F1105; submitted by Pennwalt Corp., 

Tacoma, WA; CDL: 094702-I) 

136298 House, W.; Goodson, L.; Gadberry, H.; et al. (1967) Assessment of Ecological Effects 

of Extensive or Repeated Use of Herbicides: MRI Project No. 3103-B; Contract No. 

DAHC15-68-C-0119. Final rept. (Unpublished study received Aug 12, 1970 under 

1E1046; submitted by Department of the Army, N. Fort Mead, MD; CDL: 093358-C) 
60 

138449 Sikka, H.; Saxena, J. (19??) Metabolism of endothall by aquatic microorganisms. J. 

Agr. Food Chem. 21(3). (Also In unpublished submission received Feb 1, 1975 under 

4581-EX-21; submitted by Agchem Div., Pennwalt Corp., Philadelphia, PA; 

CDL:094726-B) 

44820104 Giddings, J. (1999) Ecological Risk Assessment of Aquatic Herbicides Containing 

Endothall: Final Report: Lab Project Number: KP-98-31: 98-11-7564: 12442-0898-

6271-251. Unpublished study prepared by Elf Atochem and Springborn Laboratories, 

Inc. 64 p 

67174 Schreck, C.B. (1974) Aquatic Plant Control Using Herbicides in a Large Potable 

Water Supply Reservoir: Contract No. DACW65-74- C-0013. (Virginia Polytechnic 

Institute and State Univ., Dept. of Fisheries and Wildlife Sciences for U.S. Dept. of 

the Army, Corps of Engineers; unpublished study; CDL:231433-D) 

38643 Schreck, C.B.; Berry, C.R.; Strange, R.J.; et al. (1974) Ecosystem Studies on the Use 

of Diquat and Endothal for Aquatic Plant Control in a Large Potable Water Supply 

Reservoir: Contract No. DAW-65-74-C-0013. (Virginia, Commission of Game and 

Inland Fisheries and Virginia Polytechnic Institute and State Univ., Dept. of Fisheries 

and Wildlife Sciences for U.S. Dept. of the Army, Office of the Chief of Engineers, 

Aquatic Plant Control Program, Interagency Technical Advisory Committee, 

unpublished study; CDL:095428-Y) 

114495 Schreck, C. (1974) Aquatic Plant Control Using Herbicides in a Large Potable Water 

Supply Reservoir: Contract No. DACW65-74-C-0013. Annual rept., Jul 1, 1973-Jun 

30, 1974. (Virginia Polytechnic Institute and State Univ., Dept. of Fisheries and 

Wildlife Sciences for U.S. Dept. of the Army, Corps of Engineers; unpublished study; 

CDL:094702-L)

46269 Swabey, Y.H.; Schenk, C.F. (1963) Report on Algicides and Aquatic Herbicides. 

(Ontario, Water Resources Commission, Laboratory Division, Biology Branch, 

unpublished study; CDL:107773-B) 

55714 Silvo, O.E.J. (1967) Alustavia Tutkimuksia Eraiden Herbisidien Myrkyllisyydesta 

Nuorille Karpin Poikasille (Cyprinus carpio L.). N.P. (Suomen Kalatalous 32 Finlands 

Fiskerier; incomplete; also in unpublished submission received Jul 11, 1961 under 

1E1046; submitted by U.S. Dept. of the Army, Washington, D.C.; CDL:093359-X) 

102855 Silvo, O. (1967) Alustavia Tutkimuksia Eraiden Herbisidien Myrkyllisyydesta 

Nuorille Karpin Poikasille (Cyprinus catpio L.). Helsinki, Fin.:s.n.|. (Suomen 

Kalatalous 32; also In unpublished submission received Feb 3, 1976 under 960-163; 

submitted by Balcom Chemicals, Inc., Greeley, CO; CDL:228944-V). 

100609 Schreck, C.; Corning, R.; Berry, C.; et al. (1974) Aquatic Plant Control Using 

Herbicides in a Large Potable Water Supply Reservoir. Annual rept., Jul 1, 1973--Jun 

30, 1974: Contract No. DACW65-74-C-0013. (Virginia Polytechnic Institute and 

State Univ., Dept. of Fisheries and Wildlife Sciences for U.S. Dept. of the Army, 

Corps of Engineers; unpublished study; CDL:247354-B) 

113925 Agchem (1959) Environmental Studies on Endothall. (Compilation; unpublished 

study received Dec 3, 1959 under 4581-139; CDL: 007440-A) 

113971 Pennwalt Corp. (1970) Full Reports of Investigations Made with Respect to the Safety 

of the Product: Endothall|. (Compilation; unpublished study received on unknown 

date under 1F1105; CDL:094509-A) 
61 

Disodium Salt of Endothall

MRID Citation Reference 

85213 Inglis, A.; Davis, E.L. (1972) Effects of Water Hardness on the Toxicity of Several 

Organic and Inorganic Herbicides to Fish. By U.S. Fish and Wildlife Service, FishPesticide Research Laboratory. Washington, D.C.: USFWS. (Technical papers of the 

Bureau of Sport Fisheries and Wildlife 67; published study; CDL: 232666-L) 

96298 Walker, C.R. (1963) Endothal derivatives as aquatic herbicides in fishery habitats. Weeds 

11(3):226-232. (Also In unpublished submission received Feb 17, 1967 under 7F0570; 

submitted by Pennsalt Chemicals Corp., Bryan, Tex.; CDL:090719-J) 

99330 Applied Biochemists, Incorporated (1972) The Effect of Various Concentrations of Copper 

from Cutrine and Various Concentrations of Endothal (Dipotassium Salt) on Bluegills 

(Lepomis macrochirus Rafinesque). (Unpublished study received Dec 21, 1972 under 

unknown admin. no.; CDL:127670-E) 

102626 Inglis, A.; Davis, E. (1968) The Effect of Water Hardness on the Toxicity to Fish of 

Several Organic and Inorganic Herbicides. (Unpublished paper presented at the 8th 

meeting of the Weed Society of America, Feb 5-8,1968, New Orleans, LA; unpublished 

study received Jul 18, 1972 under 2E1221; submitted by U.S. Dept. of the

Army, Washington, DC; CDL:091051-R) 

107923 Walder, C. (1964) Toxicological effects of herbicides on the fish environment. Water & 

Sewage Works 111 (3):113-116. (Also In unpublished submission received Jul 18, 1972 

under 2E1221; submitted by U.S. Dept. of the Army, Washington, DC; CDL:091051-V) 

113925 Agchem (1959) Environmental Studies on Endothall. (Compilation; unpublished study 

received Dec 3, 1959 under 4581-139; CDL: 007440-A) 

113971 Pennwalt Corp. (1970) Full Reports of Investigations Made with Respect to the Safety of 

the Product: Endothall|. (Compilation; unpublished study received on unknown date under 

1F1105; CDL:094509-A) 

114508 Hiltibran, R. (1959) Letter sent to H. Lindaberry dated May 28, 1959 AUR 466-W-10 

toxicity to bluegills. (Illinois, Natural History Survey Div.; unpublished study; 

CDL:007441-H) 

114509 Walker, C. (1958) Letter sent to H. Lindaberry dated May 13, 1958 (Study: Endothall 

toxicity to fathead minnow). (Missouri, Conservation Commission; unpublished study; 

CDL:007441-I) 

115756 Inglis, A.; Davis, E. (1972) Effects of Water Hardness on the Toxicity of Several Organic 

and Inorganic Herbicides to Fish. By U.S. Fish and Wildlife Service, Fish-Pesticide 

Research Laboratory. Washington, DC: USFWS. (Technical papers of the Bureau of Sport 

Fisheries and Wildlife 67; published study; CDL: 248614-P) 

114493 Walker, C. (1971) The toxicological effects of herbicides and weed control on fish and 

other organisms in the aquatic ecosystem. By U.S. Fish and Wildlife Service, Div. of 

Fishery Research, Branch of Pest Control Research. Pages 119-126, In Proc. Eur. Weed 

Res. Coun. 3rd Int. Symp. Aquatic Weeds; 1971. S.l.: s.n. (Also In unpublished submission 

received Jul 9, 1975 under 1F1105; submitted by Pennwalt Corp., Tacoma, WA; CDL: 

094702-I) 

36547 Latven, A.R. (1975) Ripenthol N.B. 58-188-3 (Isopropyl-butanol Formulation). 

(Unpublished study received Jan 5, 1978 under 1F1105; prepared by Pharmacology 
62 

Dipotassium Salt of Endothall

42359501 Pedersen, C.; Helsten, B. (1992) Aquathol K Aquatic Herbicide: 21-Day Acute Oral 

LD50 Study in Mallard Ducks: Lab Project Number: 106-006-04. Unpublished study 

prepared by Bio-Life Associates, Ltd. 54 p. 

99204 Applied Biochemists, Incorporated (1973) Toxicity Data for Copper-triethanolamine 

Complex on Ring-necked Pheasant and Mallard Duck. (Unpublished study received Nov 

21, 1973 under 8959-12; CDL:010116-B) 

35238 Fink, R.; Beavers, J.B.; Brown, R. (1977) Final Report: Eight-Day Dietary LC50--

Bobwhite Quail: Project No. 110-111. (Unpublished study received Jan 5, 1978 under 

1F1105; prepared by Wildlife International, Ltd. in cooperation with Washington 

College, sub- mitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL:096705-C) 

35239 Fink, R.; Beavers, J.B.; Brown, R. (1977) Final Report: Eight-Day Dietary LC50--

Mallard Duck: Project No. 110-113. (Unpublished study received Jan 5, 1978 under 

1F1105; prepared by Wildlife International, Ltd. in cooperation with Washington 

College, sub- mitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL:096705-D) 

99448 Schmidt, J. (1974) Subacute Toxicities of Cutrine and Weedtrine- Plus to Ring-necked 

Pheasants (Phasianus colchicus) & Mallard Ducks (Anus platyrhynchos): Dietary LC50. 

(Unpublished study received Jun 14, 1976 under 8959-11; submitted by Applied Biochemists, Inc., Mequon, WI; CDL:224874-B) 

43167801 Pedersen, C. (1994) Aquathol K Aquatic Herbicide: 8-Day Acute Dietary LC50 Study 

in Bobwhite Quail: Lab Project Number: 106-013-01: HWA 153-150. Unpublished 

study prepared by Bio-Life Associates, Ltd. 102 p. 

43167802 Pedersen, C. (1994) Aquathol K Aquatic Herbicide: 8-Day Acute Dietary LC50 Study 

in Mallard Ducklings: Lab Project Number: 106-017-02: HWA 153-150. Unpublished 

study prepared by Bio-Life Associates, Ltd. 97 p. 

71134 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Aquathol K to the Bluegill 

Sunfish, Lepomis macrochirus Rafinesque: UCES Project No. 11506-41-16. 

(Unpublished study received Jan 23, 1981 under 4581-174; prepared by Union Carbide 

Corp., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244131-F) 

72457 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Aquathol K to the Bluegill 

Sunfish, Lepomis macrochirus Rafinesque: UCES Project No. 11506-41-16. 

(Unpublished study received Jan 23, 1981 under 1F1105; prepared by Union Carbide 

Corp., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:099883-F) 

113695 Davis, J.; Hughes, J. (1963) Further Observations on the Toxicity of Commercial 

Herbicides to Bluegill Sunfish. (Louisiana, Wild Life and Fisheries Commission; 

unpublished study; CDL: 098334-F) 

83025 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Aquathol K to the Rainbow 

Trout, Salmo gairdneri Richardson: UCES Project No. 11506-41-15. (Unpublished 

Research, Inc., submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL:096704-Y) 

MRID Citation Reference 
63 

study received Jan 23, 1981 under 4581-174; prepared by Union Carbide Corp., 

submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244131-C) 

83106 Vilkas, A.J.; Seminara, J. (1979) The Acute Toxicity of Aquathol K to the Rainbow 

Trout, Salmo gairdneri~Richardson: UCES Project No. 11506-41-15. (Unpublished 

study received Jan 23, 1981 under 1F1105; prepared by Union Carbide Corp., submitted 

by Pennwalt Corp., Philadelphia, Pa.; CDL:099883-C) 

96295 Walker, C.R. (1963) Letter sent to Harold L. Lindaberry dated Nov 8, 1963 Fish toxicity 

studies|. (U.S. Fish and Wildlife Service, Fish Control Laboratory; unpublished study; 

CDL:090719-G) 

113971 Pennwalt Corp. (1970) Full Reports of Investigations Made with Respect to the Safety 

of the Product: Endothall. (Compilation; unpublished study received on unknown date 

under 1F1105; CDL:094509-A) 

114494 Folmar, L. (19??) Letter sent to E. Bowles circa Dec 13, 1974 Aquathol K. (U.S. Dept. 

of the Interior, Bureau of Reclamation, Engineering and Research Center, Denver Fish 

Pesticide Unit; unpublished study; CDL:094702-K) 

114511 Cope, O. (1965) Letter sent to E. Bowles dated Jul 23, 1965 Toxicity study of several 

Pennsalt herbicides against rainbow trout. (U.S. Fish and Wildlife Service, FishPesticide Research Laboratory; unpublished study; CDL:007441-K) 

114513 U.S. Fish and Wildlife Service, Fish Control Laboratory (19??) Toxicity Study of 

Selected Test Chemicals on Rainbow Trout, Goldfish, Black Bullhead, and Bluegill|. 

(Unpublished study; CDL:007441-M) 

116471 McCann, J. (1969) Aquathol Plus Granular: Bluegill (Lepomis macrochirus)|. (U.S. 

Agricultural Research Service, Pesticides Regulation Div., Animal Biology Laboratory; 

unpublished study; CDL:132041-A) 

42695401 Bettencourt, M. (1993) Aquathol K (Dipotassium Salt of Endothall)--Acute Toxicity to 

Bluegill Sunfish (Lepomis macrochirus) under Flow-through Conditions: Final Report: 

Lab Project Number: 92-3-4192: 1244.0591.6133.105. Unpublished study prepared by 

Springborn Labs, Inc. 62 p. 

42695402 Bettencourt, M. (1993) Aquathol K (Dipotassium Salt of Endothall)--Acute Toxicity to 

Rainbow Trout (Oncorhynchus mykiss) under Flow-through Conditions: Final Report: 

Lab Project Number: 92-3-4163: 12442.0591.6132.108. Unpublished study prepared by 

Springborn Labs, Inc. 63 p. 

71138 Vilkas, A.G.; Browne, A.M. (1979) The Acute Toxicity of Aquathol K 28.6% Acid 

Equivalent Lot No. ACC- 06M8-04, NB84-5-10 to the Water Flea, Daphnia magna 

Straus: UCES Project No. 11506-41-14. (Unpublished study received Jan 23, 1981 

under 4581-174; pre- pared by Union Carbide Corp., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244131-J) 

83107 Vilkas, A.G.; Browne, A.M. (1979) The Acute Toxicity of Aquathol K 28.6% Acid 

Equivalent Lot No. ACC-06M8-04, NB84-5-10 to the Water Flea, Daphnia magna 

Straus: UCES Project No. 11506-41-14. (Unpublished study, including letter dated Feb 

7, 1980 from O. Keckemet to Agchem File, received Jan 23, 1981 under 1F1105; 

prepared by Union Carbide Corp., submitted by Pennwalt Corp., Philadelphia, 

Pa.;CDL:099883-J) 
64 

84150 Vilkas, A.G.; Browne, A.M. (1979) The Acute Toxicity of Aquathol K 28.6% Acid 

Equivalent Lot No. ACC-06M8-04, NB84-5-10 to the Water Flea, Daphnia magna 

Straus: UCES Project No. 11506-41-14. (Unpublished study received Jan 23, 1981 

under 4581-282; pre- pared by Union Carbide Corp., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244122-J) 

42695403 Putt, A. (1993) Aquathol K (Dipotassium Salt of Endothall)--Acute Toxicity to 

Daphnids (Daphnia magna) under Flow-through Conditions: Final Report: Lab Project 

Number: 92-3-4153: 12442.0591.6134.115. Unpublished study prepared by Springborn 

Labs, Inc. 69 p. 

42695404 Dionne, E. (1993) Aquathol K (Dipotassium Salt of Endothall)--Acute Toxicity to 

Eastern Oyster (Crassostrea virginica) under Flow-through Conditions: Final Report: 

Lab Project Number: 92-3-4149: 12442.0591.6137.504. Unpublished study prepared by 

Springborn Labs, Inc. 66 p. 

42695405 Bettencourt, M. (1993) Aquathol K (Dipotassium Salt of Endothall)--Acute Toxicity to 

Sheepshead Minnow (Cyprinodon variegatus) under Flow-through Conditions: Final 

Report: Lab Project Number: 92-2-4110: 12442.0591.6135.505. Unpublished study 

prepared by Springborn Labs, Inc. 64 p. 

42695406 Bettencourt, M. (1993) Aquathol K (Dipotassium Salt of Endothall)--Acute Toxicity to 

Mysid Shrimp (Mysidopsis bahia) under Flow-through Conditions: Final Report: Lab 

Project Number: 92-9-4411: 12442.0591.6136.515. Unpublished study prepared by 

Springborn Labs, Inc. 66 p. 

41149 Davis, J.T.; Hughes, J.S. (1963) Further observations on the toxicity of commercial 

herbicides to bluegill sunfish. Proceedings of the Southern Weed Control Conference: 

337-340. (Also In unpublished submission received on unknown date under 8F0660; 

submitted by Dow Chemical U.S.A., Midland, Mich.; CDL:094930-M) CDL: 098334-F) 

Louisiana, Wild Life and Fisheries Commission 

46269 

ACC 094509 

Swabey, Y.H.; Schenk, C.F. (1963) Report on Algicides and Aquatic Herbicides. 

(Ontario, Water Resources Commission, Laboratory Division, Biology Branch, 

unpublished study; CDL:107773-B). 22p. 

48769 Berry, C.R. (1974) Acute Toxicity of Diquat, Endothal, and a Mixture of the Two to 

Bluegill Sunfish: Contract No. DACW65-74-C- 0013. (Virginia Polytechnic Institute 

and State Univ., Dept. of Fisheries and Wildlife Sciences for U.S. Dept. of the Army, 

Corps of Engineers, unpublished study; CDL:231436-E) 

48770 Berry, C.R. (1974) Effect of Diquat and Endothall Separately and Combined on Bluegill 

Ventilation Rate: Contract No. DACW65-74- C-0013. (Virginia Polytechnic Institute 

and State Univ., Dept. of Fisheries and Wildlife Sciences for U.S. Dept. of the Army, 

Corps of Engineers, unpublished study; CDL:231436-F) 

84991 Landolt, M.L.; Felton, S.P.; Liguori, V.M.; et al. (1981) Toxicity of Endothall to 

Juvenile Chinook Salmon (Oncorhynchus tshaw-ytscha). Final rept. (Washington, Dept. 

of Fisheries for U.S. Army Corps of Engineers, Waterways Experiment Station, Aquatic 

Plant Control Research Program; unpublished study, including published data and letters 

dated Aug 5, 1981 from B.D. Gaughey to Gary Wedemeyer and Aug 27, 1981 from 

G.A. Wedemeyer to Bernalyn D. McGaughey; CDL:246080-A) 
65 

113971 Pennwalt Corp. (1970) Full Reports of Investigations Made with Respect to the Safety 

of the Product: Endothall. (Compilation; unpublished study received on unknown date 

under 1F1105; CDL:094509-A) Dragonfly, Damselfly aquatic larvae stage toxicity 

36568 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E-5656. 

(Unpublished study received Jan 5, 1978 under 1F1105; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL: 096704-AW) 

36576 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E-5686. 

(Unpublished study received Jan 5, 1978 under 1F1105; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL: 096704-BE) 

40959 Eibert, J., Jr. (1966) Acute Oral Toxicity (LD50) Study in Rats: S.A. No. 106319. 

(Unpublished study received Apr 10, 1966 under 6G0503; prepared by Scientific 

Associates, Inc., submitted by Pennsalt Chemical Corp., Bryan, Tex.; CDL:090587-B) 

78209 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Aquathol K: Lab No. 

7E-5656. (Unpublished study received Jan 5, 1978 under 4581-174; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, PA; CDL:232580-AJ) 

78216 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E-5686. 

(Unpublished study received Jan 5, 1978 under 4581-174; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:232580-AR) 

81407 Eibert, J., Jr. (1966) Acute Oral Toxicity (LD50) Study in Rats: S.A. No. 106319. 

(Unpublished study received Apr 14, 1966 under 4581-70; prepared by Scientific 

Associates, Inc., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:051133-K) 

84612 Ralston Purina Company (1981) Aquathol Granular Aquatic Herbicide: RT Lab No. 

844059. (Unpublished study received Sep 14, 1981 under 4581-349; submitted by 

Pennwalt Corp., Philadelphia, Pa.; CDL:246012-J) 

97831 Reagan, E.L.; Becci, P.J.; Parent, R.A. (1981) Acute Oral Toxicity in Rats: FDRL Study 

No. 6915A. (Unpublished study received Sep 14, 1981 under 4581-349; prepared by 

Food and Drug Research Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, 

Pa.; CDL:246012-L) 

97832 Reagan, E.L.; Becci, P.J.; Parent, R.A. (1981) Acute Oral Toxicity in Rats: FDRL Study 

No. 6915A. (Unpublished study received Sep 14, 1981 under 4581-349; prepared by 

Food and Drug Research Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, 

Pa.; CDL:246012-M) 

97833 Reagan, E.L.; Becci, P.J.; Parent, R.A. (1981) Acute Oral Toxicity in Rats: FDRL Study 

No. 6915A. (Unpublished study received Sep 14, 1981 under 4581-349; prepared by 

Food and Drug Research Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, 

Pa.; CDL:246012-N) 

104758 Reagan, E.L.; Becci, P.J.; Parent, R.A. (1981) Acute Oral Toxicity in Rats: FDRL Study 

No. 6915A. (Unpublished study received Sep 14, 1981 under 4581-349; prepared by 

Food and Drug Research Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, 

Pa.; CDL:246012-K) 
66 

113939 Van Duuren, B. (1972) Gastric Feeding in Rats: Beta-Propiolactone and Endothall. 

(Unpublished study received May 31, 1972 under 1F1105; prepared by New York 

Medical Center, submitted by Pennwalt Corp., Tacoma, WA; CDL:094506-C) 

42289101 Mallory, V. (1991) Acute Exposure Oral Toxicity in Rats with Pelletized Aquathol K: 

Lab Project Number: PH 402-ANA-008-91. Unpublished study prepared by Pharmakon 

Research International, Inc. 42 p. 

42338901 Mallory, V. (1991) Acute Exposure Oral Toxicity in Rats with Aquathol K: Lab Project 

Number: PH 402-ANA-004-91. Unpublished study prepared by Pharmakon Research 

Intl. 55 p. 

44319605 Wnorowski, G. (1997) Acute Oral Toxicity Defined LD50 (in Rats): ThinRite: Lab 

Project Number: 5071:P320. Unpublished study prepared by Product Safety Labs. 25 p. 

44320104 Wnorowski, G. (1996) Acute Oral Toxicity Defined LD50 (in Rats): Aquathol Super K 

Granule: Lab Project Number: 4878: P320. Unpublished study prepared by Product 

Safety Labs. 26 p. 

49074404 Lowe, C. (2012) Acute Oral Toxicity Up and Down Procedure in Rats. Project Number: 

34449, P320. Unpublished study prepared by Eurofins/Product Safety Laboratories. 15p. 

36561 Wise, M.T. (1977) Acute Inhalation Toxicity of a) Aquathol® K (N.B. 77-100-4) b) 

Hydrothol® 191 Liquid (N.B. 77-100-2) c) Hydrothol® 47 Liquid (N.B. 77-100-3) d) 

Aquathol® (N.B. 77-99-7) e) Des-I-Cate® Accelerate (N.B. 77-99-6) f) Knox-Out® 2 

FM (N.B. 4414-94): Laboratory Nos. a) 7E-5660 b)7E-5665 c) 7E-5670 d) 7E-5675 e) 

7E-5680 f) 7E-5685. (Unpublished study received Jan 5, 1978 under 1F1105; prepared 

by Cannon Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of 

Prussia, Pa.; CDL:096704-AO) 

36592 Zeigler, R.L. (1977) Acute Inhalation Toxicity of 1. Aquathol® Granular (N.B. 77-99-4) 

2. Hydrothol® 191 Granular (N.B. 77- 99-2) 3. Hydrothol® 47 Granular (N.B. 77-99-3) 

4. HydoutTM (N.B. 77-99-5): Laboratory Nos. 1. 7E-5690 2. 7E-5695 3. 7E-5700 4. 7E5705. (Unpublished study received Jan 5, 1978 under 1F1105; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL: 096704-BU) 

78202 Wise, M.T. (1977) Acute Inhalation Toxicity of Aquathol® K (N.B. 77-100-4); 

Hydrothol® 191 Liquid (N.B. 77-100-2); Hydrothol® 47 Liquid (N.B. 77-100-3); 

Aquathol® (N.B. 77-99-7); Des-i-cate® Accelerate (N.B. 77-99-6); Knox-out® 2 FM 

(N.B. 4414-94): Laboratory Nos. 7E-5660; 7E-5665; 7F- 5670; 7E-5675; 7E-5680; 7E5685. (Unpublished study received Jan 5, 1978 under 4581-174; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL: 232580-AB) 

78610 Zeigler, R.L. (1977) Acute Inhalation Toxicity of 1. Aquathol® Granular (N.B. 77-99-

4); 2. Hydrothol® 191 Granular (N.B. 77-99-2); 3. Hydrothol® 47 Granular (N.B. 77-

99-3); 4. HydoutTM (N.B. 77-99-5): Laboratory Nos. 7E-5690; 7E- 5695; 7E-5700; 7E5705. (Unpublished study received Jan 5, 1978 under 4581-174; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:232580-BH) 

42407101 Hoffman, G. (1992) An Acute Inhalation Toxicity Study of Aquathol K in the Rat: Lab 

Project Number: 91/8357. Unpublished study prepared by Bio/dynamics, Inc. 133 p. 

42407102 Hoffman, G. (1992) An Acute Inhalation Toxicity Study of Pelletized Aquathol K in the 

Rat: Lab Project Number: 91-8345: Unpublished study prepared by Bio/dynamics, Inc. 

124 p. 
67 

44319607 Wnorowski, G. (1997) Acute Inhalation Toxicity Limit Test (in Rats): ThinRite: Lab 

Project Number: 5076: P330. Unpublished study prepared by Product Safety Labs. 24 p. 

49074406 Lowe, C. (2012) Acute Inhalation Toxicity Study in Rats - Limit Test. Project Number: 

P330, 34451. Unpublished study prepared by Eurofins/Product Safety Laboratories. 25p. 

43152101 Trutter, J. (1993) Two-Generation Reproduction Study in Rats with Disodium Salt of 

Endothall: Final Report: Lab Project Number: 153/142. Unpublished study prepared by 

Hazleton Washington, Inc. 1479 p. 

43629301 Trutter, J. (1995) Two-Generation Reproduction Study in Rats with Disodium Salt of 

Endothall: Addendum to MRID 43152101: Lab Project Number: 153-142. Unpublished 

study prepared by Hazleton Washington, Inc. 21 p. 

42396401 Hoberg, J. (1992) Dipotassium Salt of Endothall--Toxicity to the Freshwater Bluegreen 

Alga Anabaena flos-aquae: Final Report: Lab Project Number: 91-12-4035. 

Unpublished study prepared by Springborn Laboratories, Inc. 59 p. 

42396402 Hoberg, J. (1992) Dipotassium Salt of Endothall--Toxicity to the Freshwater Diatom 

Navicula pelliculosa: Final Report: Lab Project Number: 91-12-4049. Unpublished 

study prepared by Springborn Laboratories, Inc. 61 p. 

42396403 Hoberg, J. (1992) Dipotassium Salt of Endothall--Toxicity to the Freshwater Green 

Alga, Selenastrum capricornutum: Final Report: Lab Project Number: 91-12-4053. 

Unpublished study prepared by Springborn Laboratories, Inc. 61 p. 

42396404 Hoberg, J. (1992) Dipotassium Salt of Endothall--Toxicity to the Marine Diatom, 

Skeletonema costatum: Final Report: Lab Project Number: 92-1-4063. Unpublished 

study prepared by Springborn Laboratories, Inc. 60 p. 

44392801 Hoberg, J. (1997) Dipotassium Salt of Endothall--Toxicity to the Freshwater Green 

Alga, Selenastrum capricornutum: Supplemental Information to Final Report (MRID 

#423964-03): Lab Project Number: 91-12-4053A: 12442.0391.6118.430A: BR-91-58A. 

Unpublished study prepared by Springborn Labs, Inc. 49 p. 

44392802 Hoberg, J. (1997) Dipotassium Salt of Endothall--Toxicity to the Freshwater Diatom, 

Navicula pelliculosa: Supplemental Information to Final Report (MRID #426964-02): 

Lab Project Number: 91-12-4049A: 12442.0391.6118.440A: BR-91-57A. Unpublished 

study prepared by Springborn Labs, Inc. 49 p. 

44408801 Hoberg, J. (1997) Dipotassium Salt of Endothall--Toxicity to the Freshwater Blue-Green 

Alga, Anabaena flos-aquae: Final Report: Lab Project Number: 91-12-4035A: 

12442.0391.6118.420A: BR-91-56A. Unpublished study prepared by Springborn Labs, 

Inc. 46 p. 

42396405 Hoberg, J. (1992) Dipotassium Salt of Endothall--Determination of Effects on Seed 

Germination, Seedling Emergence and Vegetative Vigor of Ten Plant Species: Final 

Report: Lab Project Number: 91-11-4015: 12442.0391.6117.610: BR-91-55. 

Unpublished study prepared by Springborn Laboratories, Inc. 353 p. 

44392803 Hoberg, J. (1997) Dipotassium Salt of Endothall--Determination of the Effects on Seed 

Germination, Seedling Emergence and Vegetative Vigor of Ten Plant Species: 

Supplemental Information to Final Report (MRID #423964-05): Lab Project Number: 

91-114015A: 12442.0391.6117.610A: BR-91-55A. Unpublished study prepared by 

Springborn Labs, Inc. 153 p. 
68 

42396406 Hoberg, J. (1992) Dipotassium Salt of Endothall--Toxicity to the Duckweed Lemna 

gibba: Final Report: Lab Project Number: 92-2-4097: 12442.0391.6118.410: BR-91-54. 

Unpublished study prepared by Springborn Laboratories, Inc. 45 p. 

44392801 Hoberg, J. (1997) Dipotassium Salt of Endothall--Toxicity to the Freshwater Green 

Alga, Selenastrum capricornutum: Supplemental Information to Final Report (MRID 

#423964-03): Lab Project Number: 91-12-4053A: 12442.0391.6118.430A: BR-91-58A. 

Unpublished study prepared by Springborn Labs, Inc. 49 p. 

44392802 Hoberg, J. (1997) Dipotassium Salt of Endothall--Toxicity to the Freshwater Diatom, 

Navicula pelliculosa: Supplemental Information to Final Report (MRID #426964-02): 

Lab Project Number: 91-12-4049A: 12442.0391.6118.440A: BR-91-57A. Unpublished 

study prepared by Springborn Labs, Inc. 49 p. 

44408801 Hoberg, J. (1997) Dipotassium Salt of Endothall--Toxicity to the Freshwater Blue-Green 

Alga, Anabaena flos-aquae: Final Report: Lab Project Number: 91-12-4035A: 

12442.0391.6118.420A: BR-91-56A. Unpublished study prepared by Springborn Labs, 

Inc. 46 p. 

44976701 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191: A 96-Hour Toxicity Test 

with the Marine Diatom (Skeletonema costatum): Final Report: Lab Project Number: 

299A-104. Unpublished study prepared by Wildlife International , Ltd. 38 p. {OPPTS 

850.5400} 

71149 Morton, H.L.; Moffett, J.O.; MacDonald, R.H. (1972) Toxicity of herbicides to newly 

emerged honey bees. Environmental Entomology 1(1):102-104. (Also In unpublished 

submission received Jan 23, 1981 under 4581-04; submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244128-A) 

ACC 

094509

Morton, H.T. Letter to E.J. Bowles regarding preliminary honeybee feeding studies. 1p. 

Submitted by Pennwalt Corp., Pet. #1F1105, Acc#094509 (Exhibit C-38). Test ID#ESGG6. 

42644001 Dionne, E. (1992) Dipotassium Salt of Endothall: Bioconcentration and Elimination of 

(carbon 14)-residues with Bluegill Sunfish: Final Report: Lab Project Number: 92-5-

4269: 12442.0391.6115.140. Unpublished study prepared by Springborn Labs, Inc. 92 p. 

43315801 Dionne, E. (1994) Metabolism of Endothall Dipotassium Salt in Bluegill Sunfish 

(Lepomis macrochirus): Identification and Characterization of Metabolites in Fillet and 

Viscera: Lab Project Number: 12442.0391.6115.180: BR-91-53: 94-2-5168. 

Unpublished study prepared by Springborn Labs, Inc. and XenoBiotic labs Inc. 155 p. 

44820102 Dionne, E.; Sharp, J.; Formella, T. (1999) Dipotassium Salt of Endothall: A Freshwater 

Fish and Shellfish Magnitude of Residues Study in a Static Aquatic System: Lab Project 

Number: KP-97-14: 52897/171.4/FIFRA: EN1115.95. Unpublished study prepared by 

Elf Atochem and ABC Laboratories, Inc. 213 p. {OPPTS 860.1400} 

26244 Miller, C.W.; Lowe, J.I. (19??) Toxicity of Herbicides to Estuarine Animals. (U.S. 

Bureau of Commercial Fisheries, unpublished report.) 

30123 Davis, J.T.; Hughes, J.S. (1963) Further Observations on the Toxicity of Commercial 

Herbicides to Bluegill Sunfish. (Unpublished study received Jan 2, 1980 under 2217-

641; prepared by Louisiana, Wild Life and Fisheries Commission, submitted by PBIGordon Corp., Kansas City, Kans.; CDL:241577-S) 
69 

35236 Pennwalt Corporation (1975) Fish and Wildlife Safety. (Unpublished study received 

Jan 5, 1978 under 1F1105; CDL:096705-A 

35243 Vilkas, A.G. (1977) The Acute Toxicity of Aquathol® K to the Fiddler Crab, 

Uca pugilator: UCES Project # 11506-41-04. (Unpublished study received Jan 

5, 1978 under 1F1105; prepared by Union Carbide Corp., submitted by 

Pennwalt Corp., Agchem Div., King of Prussia, Pa.; CDL:096705-H) 

35245 Pennwalt Corporation (1970) Beneficial Insect Safety. (Unpublished study 

received Jan 5, 1978 under 1F1105; CDL:096705-K) 

35443 Pennwalt Corporation (1974) Results of Residue Determinations: Fish and 

Other Aquatic Organisms (Oysters, Clams, Crayfish, etc.). (Unpublished study 

received Jan 5, 1978 under 1F1105; CDL:096703-T) 

35442 Pennwalt Corporation (1974) Results of Residue Determinations: 

Disappearance of Endothall in Water. (Unpublished study received Jan 5, 

1978 under 1F1105; CDL:096703-S) 

35453 Pennwalt Corporation (1954?) Toxicology: Endothall. (Unpublished study 

received Jan 5, 1978 under 1F1105; CDL:096703-AE) 

36529 Carlson, R.E.; Sandeno, J.L. (1970) Effect of Endothall on the Growth of 

Several Fungi. (Unpublished study received Jan 5, 1978 under 1F1105; 

submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL:096704-B) 

114556 Carlson, R.; Sandeno, J. (1970) Effect of Endothall on the Growth of Several 

Fungi. (Unpublished study received Oct 26, 1978 under 4581-282; submitted 

by Agchem Div., Pennwalt Corp., Philadelphia, PA; CDL:235432-B) 

36536 Serns, S.L. (1977) Effects of Dipotassium endothall on rooted aquatics and 

adult and first generation bluegills. Water Resources Bulletin 13(1):71-80. 

(Also In unpublished submission received Jan 5, 1978 under 1F1105; 

submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL:096704-K) 

36539 Miller, H. (1975) Phytotoxicity: Phototoxicity to Irrigated Crops. 

(Unpublished study received Jan 5, 1978 under 1F1105; submitted by 

Pennwalt Corp., Agchem Div., King of Prussia, Pa.; CDL: 096704-N) 

48110 Davis, J.T.; Hughes, J.S. (1963?) Further Observations on the Toxicity of 

Commercial Herbicides to Bluegill Sunfish. (Louisiana, Wildlife and Fisheries 

Commission, unpublished study; CDL: 241577-R) 

56036 White, R.L.; Bounds, R.L.; Lowman, F.G.; et al. (1967) Experimental Control 

of Submerged Vegetation in Clear Water Lakes: Federal Aid Project No. F-2-

R-14. (Texas, Parks and Wildlife Dept., Wildlife Services, unpublished study; 

CDL:132475-A) 

95812 Folmar, L.C. (1976) Letter sent to Edward J. Bowles dated Jun 9, 1976. 

Results from toxicity tests conducted on rainbow trout fertilized eggs and sac 

fry with Aquathol K®. (U.S. Fish and Wildlife Service, Bureau of 

Reclamation, Denver Fish-Pesticide Research Unit; unpublished study; 

CDL:096705-J) 
70 

116458 Rock, L. (1963) Letter sent to unknown recipient dated Jan 8, 1963 Potassium 

Endothal: Toxicity to fish. (Illinois, Dept. of Conservation; unpublished study; 

CDL:110609-B) 

138446 Serns, S. (1974) The Effects of a Dipotassium Endothall Treatment on the 

Ecology of a Small Pond. (Wisconsin, Dept. of Natural Resources, Water 

Resources Research Section; unpublished study; CDL:094702-J) 

138964 Folmar, L. (1976) Overt avoidance reaction of rainbow trout fry to nine 

herbicides. Bulletin of Environmental Contamination & Toxicology 

15(5):509-514. (Also In unpublished submission received Feb 6, 1984 under 

239-2424; submitted by Chevron Chemical Co., Richmond, CA; 

CDL:252355-D) 

138965 Folmar, L. (1978) Avoidance chamber responses of mayfly nymphs exposed 

to eight herbicides. Bulletin of Environmental Contamination & Toxicology 

17:312-318. (Also In unpublished submission received Feb 6, 1984 under 239-

2424; submitted by Chevron Chemical Co., Richmond, CA; CDL:252355-E) 

44820104 Giddings, J. (1999) Ecological Risk Assessment of Aquatic Herbicides 

Containing Endothall: Final Report: Lab Project Number: KP-98-31: 98-11-

7564: 12442-0898-6271-251. Unpublished study prepared by Elf Atochem 

and Springborn Laboratories, Inc. 64 p. 

96295 Walker, C.R. (1963) Letter sent to Harold L. Lindaberry dated Nov 8, 1963 

Fish toxicity studies. (U.S. Fish and Wildlife Service, Fish Control 

Laboratory; unpublished study; CDL:090719-G) 

ACC 094509 Lowe, J.I. and P.D. Wilson. (1970) Two letters regarding accumulation and 

retention. 5 p. Study conducted at Gulf Breeze Laboratory, FL. Submitted by 

Pennwalt Corp., Pet. #1F1105, Acc#094509, (exhibit C-106), 12/01/70. 

45088229 Hiltibran, R. (1967) Effect of Some Herbicides on Fertilized Fish Eggs and 

Fry. Trans. Am. Fish. Soc. 96:414-416. (ACC#094509) 

ACC 221750 Hagen, H.K. (undated) Long and Short Term Effects of Endothall in a Colorado 

Mountain Lake. Submitted by Pennwalt Corp., Pet.#221750 (exhibit C-122), undated. 

ACC 094702 Walker, C.R. 1971. The Toxicological Effects of Herbicides and Weed 

Control on Fish and Other Organisms in the Aquatic Ecosystem. Proc. Eur. 

Weed Res. Coun. 3rd Int. Symp. Aquatic Weeds, pp. 119-126. Submitted by 

Pennwalt Corp., Pet. #1F1105, Acc#094702, (exhibit C-129), 07/09/75. Test ID 

ES-GG1. 

40228401 Mayer, F.L. (1986). Acute Toxicity Handbook of Chemicals to Estuarine 

Organisms. Prepared for Office of Pesticides and Toxic Substances, U.S. 

Environmental Protection Agency (USEPA), Prepared by Environmental 

Research Laboratory, Office of Research and Development, U.S. 

Environmental Protection Agency (USEPA), Gulf Breeze, FL 32561. 274 p. 

Acc 221750 Sikka, H.C. 1971. Fate of Herbicides in the aquatic environment. Annual 

Report Contract. #DACW31-71-C-0026. (Endothall Acc#221750 Sect. D 

Exhibit 37). 

96298 Walker, C.R. (1963) Endothal derivatives as aquatic herbicides in fishery 

habitats. Weeds 11(3):226-232. (Also In unpublished submission received Feb 
71 

17, 1967 under 7F0570; submitted by Pennsalt Chemicals Corp., Bryan, Tex.; 

CDL:090719-J) 

ACC 221750 Whitley, J.R. Letter to F.E. Temby of Pennwalt Corp. 4 p. Submitted by 

Pennwalt Corp., Pet# 221750 (exhibit C-120). Test ID ES-GG2. 

ACC 094509 Roby, R.E. 1961. Report on use of Aquathol and effects to microorganisms. 6p. 

Study Conducted by Passaic Valley Water Commission, N.J. Submitted by Pennwalt 

Corp., Pet. #1F1105, Acc.#094509 (exhibit C—114), 12/01/70. Test ID# ES-GG3. 

40098001 Mayer, F.L. Jr, and Ellersieck, M.R. (1986) Manual of Acute Toxicity: Interpretation 

and Data Base for 410 Chemicals and 66 Species of Freshwater Animals. U.S. Fish 

and Wildlife Service. Resource Publication 160. Washington, D.C. 579 p. 

05009242 Sanders, H.O. 1969. Toxicity of Pesticides to the Crustacean Gammarus lacustris. 

Washington, D.C. U.S. Bureau of Sport Fisheries and Wildlife. (U.S. Bureau of Sport 

Fisheries and Wildlife technical paper 25). 

114493 Walker, C. (1971) The toxicological effects of herbicides and weed control on fish 

and other organisms in the aquatic ecosystem. By U.S. Fish and Wildlife Service, Div. 

of Fishery Research, Branch of Pest Control Research. Pages 119-126, In Proc. Eur. 

Weed Res. Coun. 3rd Int. Symp. Aquatic Weeds; 1971. S.l.: s.n.. (Also In unpublished 

submission received Jul 9, 1975 under 1F1105; submitted by Pennwalt Corp., 

Tacoma, WA; CDL: 094702-I) 

ACC 094509 Nebecker, A.V. and A.R. Gaufin. (1964). Bioassays to determine pesticide toxicity to 

the amphipod crustacean Gammarus lacustris. Utah Academy Proceedings, Vol. 

41:64-67. Submitted by Pennwalt Corp., Pet. #1F1105, Acc#094509 (exhibit C-111), 

12/01/70. 

Mono (N,N-dimethylalkylamine) Salt of Endothall 

35237 Fink, R.; Beavers, J.B.; Brown, R. (1977) Final Report: Acute Oral LD50--Bobwhite 

Quail: Project No. 110-115. (Unpublished study received Jan 5, 1978 under 1F1105; 

prepared by Wildlife International, Ltd. in cooperation with Washington College, 

submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; CDL: 096705-B) 

42359701 

42359601 on 

DER 

Pedersen, C.; Helsten, B. (1992) Endothall Technical: 21-Day Acute Oral LD50 Study in 

Mallard Ducks: Lab Project Number: 106-004-04. Unpublished study prepared by Bio-Life 

Associates, Ltd. 50 p. 

92061001 Shellenberger, T. (1990) Agchem Division-Pennwalt Corp. Phase 3 Summary of MRID 

00035237. Hydrothol 191-Acute Oral LD50 Test-Bobwhite Quail: Project No. 110-115.: 

11 p. 

35240 Fink, R.; Beavers, J.B.; Brown, R. (1977) Final Report: Eight-Day Dietary LC50--

Bobwhite Quail: Project No. 110-112. (Unpublished study received Jan 5, 1978 under 

1F1105; prepared by Wildlife International, Ltd. in cooperation with Washington College, 

sub- mitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; CDL:096705-E) 

35241 Fink, R.; Beavers, J.B.; Brown, R. (1977) Final Report: Eight-Day Dietary LC50--Mallard 

Duck: Project No. 110-114. (Unpublished study received Jan 5, 1978 under 1F1105; 

MRID Citation Reference 
72 

prepared by Wildlife International, Ltd. in cooperation with Washington College, submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; CDL:096705-F) 

43167901 Pedersen, C.; Thompson, S. (1994) Hydrothol 191 Aquatic Algicide and Herbicide: 8-Day 

Acute Dietary LC50 Study in Bobwhite Quail: Lab Project Number: 106-012-01: HWA 

153-148. Unpublished study prepared by Bio-Life Associates, Ltd. 100 p. 

43167902 Pedersen, C.; Thompson, S. (1994) Hydrothol 191 Aquatic Algicide and Herbicide: 8-Day 

Acute Dietary LC50 Study in Mallard Ducklings: Lab Project Number: 106-016-02: HWA 

153-148. Unpublished study prepared by Bio-Life Associates, Ltd. 96 p. 

92061002 Shellenberger, T. (1990) Agchem Division-Pennwalt Corp. Phase 3 Summary of MRID 

00035240. Eight-day Dietary LC50 of Hydrothol 191 to Bobwhite Quail: Project No. 110-

112.: 12 p. 

47861101 Stafford, J. (2009) Endothall Amine: Reproductive Toxicity Test with the Mallard Duck 

(Anas platyrhynchos), Following FIFRA Guideline. Project Number: 13845/4104. 

Unpublished study prepared by Springborn Smithers Laboratories. 254 p. 

47861102 Stafford, J. (2009) Endothall Amine: Reproductive Toxicity Test with Northern Bobwhite 

(Colinus virginianus) Following FIFRA Guideline. Project Number: 13845/4105. 

Unpublished study prepared by Springborn Laboratories, Inc. 294 p. 

71132 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydrothol 191 to the Rainbow 

Trout, Salmo gairdneri Richardson: UCES Project No. 11506-41-17. (Unpublished study 

received Jan 23, 1981 under 4581-174; prepared by Union Carbide Corp., submitted by 

Pennwalt Corp., Philadelphia, Pa.; CDL:244131-D) 

72456 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydrothol 191 to the Rainbow 

Trout, Salmo gairdneri Richardson: UCES Project No. 11506-41-17. (Unpublished study 

received Jan 23, 1981 under 1F1105; prepared by Union Carbide Corp., submitted by 

Pennwalt Corp., Philadelphia, Pa.; CDL:099883-D) 

84147 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydrothol 191 to the Rainbow 

Trout, Salmo gairdneri Richardson: UCES Project No. 11506-41-17. (Unpublished study, 

including letters dated Jan 18, 1980 from A.G. Vilkas to B.D. McGaughey and Feb 7, 1980 

from O. Keckemet to Agchem File, received Jan 23, 1981 under 4581-282; prepared by 

Union Carbide Corp., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244122-D) 

71133 

Acc#244122 

Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hyd- out(TM) Aquatic Weed 

Killer Code AHE 09H901, N.B. No. 84-112-1 to the Rainbow Trout Salmo gairdneri 

Richardson: UCES Project No. 11506-41-20. (Unpublished study, including letters dated 

Feb 7, 1980 from O. Keckemet to Agchem File and Jan 18, 1980 from A.G. Vilkas to B.D. 

McGaughey, received Jan 23, 1981 under 4581-174; prepared by Union Carbide Corp., 

submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244131-E) 

71135 

Acc#244122 

Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydrothol 191 to the Bluegill 

Sunfish, Lepomis macrochirus Rafinesque: UCES Project No. 11506-41-18. (Unpublished 

study received Jan 23, 1981 under 4581-174; prepared by Union Carbide Corp., submitted 

by Pennwalt Corp., Philadelphia, Pa.; CDL:244131-G) 

72458 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydrothol 191 to the Bluegill 

Sunfish, Lepomis macrochirus Rafinesque: UCES Project No. 11506-41-18. (Unpublished 

study received Jan 23, 1981 under 1F1105; prepared by Union Carbide Corp.; submitted 

by Pennwalt Corp., Philadelphia, Pa.; CDL:099883-G) 
73 

84148 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydrothol 191 to the Bluegill 

Sunfish, Lepomis macrochirus Rafinesque: UCES Project No. 11506-41-18. (Unpublished 

study received Jan 23, 1981 under 4581-282; prepared by Union Carbide Corp., submitted 

by Pennwalt Corp., Philadelphia, Pa.; CDL:244122-G) 

71136 

Acc#244122 

Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydout(TM) Aquatic Weed Killer 

Code AHE 09H901, N.B. No. 84-112-1 to the Bluegill Sunfish, Lepomis macrochirus 

Rafinesque: UCES Project No. 11506-41-19. (Unpublished study, including letter dated 

Feb 7, 1980 from O. Keckemet to Agchem File, received Jan 23, 1981 under 4581-174; 

prepared by Union Carbide Corp., submitted by Pennwalt Corp., Philadelphia, Pa.; 

CDL:244131-H) 

72459 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of HydoutTM Aquatic Weed Killer 

Code AHE 09H901, N.B. No. 84-112-1 to the Bluegill Sunfish Lepomis macrochirus 

Rafinesque: UCES Project No. 11506-41-19. (Unpublished study, including letter dated 

Feb 7, 1980 from O. Keckemet to Agchem File, received Jan 23, 1981 under 1F1105; 

prepared by Union Carbide Corp., submit- ted by Pennwalt Corp., Philadelphia, Pa.; 

CDL:099883-H) 

84149 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of HydoutTM Aquatic Weed Killer 

Code AHE 09H901, N.B. No. 84- 112-1 to the Bluegill Sunfish Lepomis macrochirus 

Rafinesque: UCES Project No. 11506-41-19. (Unpublished study, including letter dated 

Feb 7, 1980 from O. Keckemet to Agchem File, received Jan 23, 1981 under 4581-282; 

prepared by Union Carbide Corp., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL: 

CDL:244122-H) 

71144 

Acc#244122 

Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Hydout, 22.6% Active Ingredient 

to the Common Mummichog Fundulus heteroclitus (Linnaeus): UCES Project No. 11506-

41-21. (Unpublished study, including letter dated Feb 7, 1980 from O. Keckemet to 

Agchem File, received Jan 23, 1981 under 4581-174; prepared by Union Carbide Corp., 

submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244131-Q) 

71148 Pennwalt Corporation (1980) Hydout(TM) Aquatic Algicide and Herbicide--Pellet State 

versus Toxicity: Project No. WT-4-80. (Unpublished study received Jan 23, 1981 under 

4581-174; CDL: 244131-V) 

72466 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Hydout, 22.6% Active Ingredient 

to the Common Mummichog Fundulus heteroclitus (Linnaeus): UCES Project No. 11506-

41-21. (Unpublished study, including letter dated Feb 7, 1980 from O. Keckemet to 

Agchem File, received Jan 23, 1981 under 1F1105; prepared by Union Carbide Corp., 

submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:099883-Q) 

74226 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Hydout, 22.6% Active Ingredient, 

to the Common Mummichog Fundulus heteroclitus (Linnaeus): UCES Project No. 11506-

41-21. (Unpublished study, including letter dated Feb 7, 1980 from O. Keckemet to 

Agchem File, received Jan 23, 1981 under 4581-282; prepared by Union Carbide Corp., 

submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244122-Q) 

ACC 

090719

Hughes, J.S. and J.T. Davis. 1962. Toxicity of Selected Herbicides to Bluegill Sunfish. 8 p. 

Submitted by Pennwalt Corp., Pet. #7F0570, Acc # 090719 (exhibit C-18), 03/23/67. Test 

ID # ES-F1. 

85213 Inglis, A.; Davis, E.L. (1972) Effects of Water Hardness on the Toxicity of Several 

Organic and Inorganic Herbicides to Fish. By U.S. Fish and Wildlife Service, Fish-
74 

Pesticide Research Laboratory. Washington, D.C.: USFWS. (Technical papers of the 

Bureau of Sport Fisheries and Wildlife 67; published study; CDL: 232666-L) 

96295 Walker, C.R. (1963) Letter sent to Harold L. Lindaberry dated Nov 8, 1963 Fish toxicity 

studies|. (U.S. Fish and Wildlife Service, Fish Control Laboratory; unpublished study; 

CDL:090719-G) 

96296 Cope, O.B. (1966) Letter sent to Edward J. Bowles dated Sep 1, 1966 Fish toxicity of 

Desiccate (Accelerate)|. (U.S. Fish and Wildlife Service, Fish-Pesticide Research 

Laboratory; unpublished study; CDL:090719-H) 

96297 Pennsalt Chemicals Corporation (1967) Toxicity to Fish: Accelerate, Accelerate + Folex, 

and Accelerate + Sodium Chlorate. (Unpublished study received Feb 17, 1967 under 

7F0570; CDL:090719-I) 

102626 Inglis, A.; Davis, E. (1968) The Effect of Water Hardness on the Toxicity to Fish of 

Several Organic and Inorganic Herbicides. (Unpublished paper presented at the 8th 

meeting of the Weed Society of America, Feb 5-8, 1968, New Orleans, LA; unpublished 

study received Jul 18, 1972 under 2E1221; submitted by U.S. Dept. of the Army, 

Washington, DC; CDL:091051-R) 

113971 Pennwalt Corp. (1970) Full Reports of Investigations Made with Respect to the Safety of 

the Product: Endothall. (Compilation; unpublished study received on unknown date under 

1F1105; CDL:094509-A) 

114511 Cope, O. (1965) Letter sent to E. Bowles dated Jul 23, 1965 Toxicity study of several 

Pennsalt herbicides against rainbow trout|. (U.S. Fish and Wildlife Service, Fish-Pesticide 

Research Laboratory; unpublished study; CDL:007441-K) 

114513 U.S. Fish and Wildlife Service, Fish Control Laboratory (19??) Toxicity Study of Selected 

Test Chemicals on Rainbow Trout, Goldfish, Black Bullhead, and Bluegill|. (Unpublished 

study; CDL:007441-M) 

114514 Walker, C. (1963) Letter sent to H. Lindaberry dated Apr 24, 1963 Toxicity study of 

selected pesticides on test animals. (U.S. Fish and Wildlife Service, Fish Control 

Laboratory; unpublished study; CDL:007441-N) 

114515 Howell, J. (1963) Letter sent to H. Lindaberry dated Jan 23, 1963 Toxicity of specific 

Pennsalt chemicals to the sea lamprey and rainbow trout|. (U.S. Fish and Wildlife Service, 

Bureau of Commercial Fisheries, Hammond Bay Biological Station; unpublished study; 

CDL:007441-O) 

115756 Inglis, A.; Davis, E. (1972) Effects of Water Hardness on the Toxicity of Several Organic 

and Inorganic Herbicides to Fish. By U.S. Fish and Wildlife Service, Fish-Pesticide 

Research Laboratory. Washington, DC: USFWS. (Technical papers of the Bureau of Sport 

Fisheries and Wildlife 67; published study; CDL: 248614-P) 

43196901 Bettencourt, M. (1994) Hydrothol 191--Acute Toxicity to Rainbow Trout (Oncorhynchus 

mykiss) Under Flow-Through Conditions: Final Report: Lab Project Number: 93-8-4891: 

12442.0591.6138.108. Unpublished study prepared by Springborn Laboratories, Inc. 75 p. 

43472801 Bettencourt, M. (1994) Hydrothol 191--Acute Toxicity to Bluegill Sunfish (Lepomis 

macrochirus) Under Flow-Through Conditions: Final Report: Lab Project Numbers: 94-4-

5253: 12442.0394.6169.105. Unpublished study prepared by Springborn Labs, Inc. 74 p. 
75 

40098001 Mayer, F.L. Jr, and Ellersieck, M.R. (1986) Manual of Acute Toxicity: Interpretation and 

Data Base for 410 Chemicals and 66 Species of Freshwater Animals. U.S. Fish and 

Wildlife Service. Resource Publication 160. Washington, D.C. 579 p. 

40094602 Johnson, W.; Finley, M. (1980) Handbook of Acute Toxicity of Chemicals to Fish and 

Aquatic Invertebrates: Resource Publication 137. USDI Fish and Wildlife Service, 

Washington, D.C. 98 p. 

49658 Pennwalt Corporation (1966) Toxicity Study: Hydrothol on Fish. (Reports by various 

sources; unpublished study received Jun 25, 1971 under unknown admin. no.; 

CDL:132475-F) 

ACC 

094702

Schreck, Carl B. 1974. Aquatic Plant control Using Herbicides in a Large Potable Water 

Supply Reservoir. pp 90-99. Study contracted by the Army Corps of Engineers. Submitted 

by Pennwalt Corp. Pet. #1F1105 Acc# 094702 (exhibit C-132), 07/09/75). Test ID ES-F2. 

71139 

Acc#244122 

Vilkas, A.G.; Browne, A.M. (1979) The Acute Toxicity of Hydout (22.6% Active) 

(Sample Code 84-112-1; Lot AHE 09H9-01) to the Water Flea Daphnia magna 

Straus: UCES Project No. 11506-41-22. (Unpublished study, including letter 

dated Feb 7, 1980 from O. Keckemet to Agchem File, received Jan 23, 1981 under 

4581- 174; prepared by Union Carbide Corp., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244131-K) 

72460 Vilkas, A.G.; Hughes, J.S. (1979) The Acute Toxicity of Endothall (Acid 

Monohydrate) to the Water Flea Daphnia magna Straus: UCES Project No. 

11506-41-09. (Unpublished study received Jan 23, 1981 under 1F1105; prepared 

by Union Carbide Corp., submitted by Pennwalt Corp., Philadelphia, Pa.; 

CDL:099883-I) 

72461 Vilkas, A.G.; Browne, A.M. (1979) The Acute Toxicity of Hydout (22.6% Active) 

(Sample Code 84-112-1; Lot AHE 09H9-01) to the Water Flea Daphnia magna 

Straus: UCES Project No. 11506-41-22. (Unpublished study received Jan 23, 1981 

under 1F1105; prepared by Union Carbide Corp., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:099883-K) 

74221 Vilkas, A.G.; Browne, A.M. (1979) The Acute Toxicity of Hydout (22.6% Active) 

(Sample Code 84-112-1; Lot AHE 09H9-01) to the Water Flea Daphnia magna 

Straus: UCES Project No. 11506-41-22. (Unpublished study, including letter 

dated Feb 7, 1980 from O. Keckemet to Agchem File, received Jan 23, 1981 under 

4581-282; prepared by Union Carbide Corp., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:244122-K) 

43196902 Putt, A. (1994) Hydrothol 191--Acute Toxicity to Daphnids (Daphnia magna) 

Under Flow-Through Conditions: Final Report: Lab Project Number: 93-9-4932: 

12442.0591.6139.115. Unpublished study prepared by Springborn Laboratories, 

Inc. 87 p. 

35242 Union Carbide Corporation (1977) The Acute Toxicity of Hydrothol®191 to the 

Water Flea, Daphnia magna Straus: UCES Project # 11506-41-05. (Unpublished 

study received Jan 5, 1978 under 1F1105; submitted by Pennwalt Corp., Agchem 

Div., King of Prussia, Pa.; CDL:096705-G) 

71140 

Acc#244122 

Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Hydout, 22.6% Active 

Ingredient to the Grass Shrimp Palaemonetes pugio: USES Project No. 11506-41-23. 

(Unpublished study, including letter dated Feb 7, 1980 from O. Keckemet to Agchem 
76 

File, received Jan 23, 1981 under 4581-174; prepared by Union Carbide Corp., 

submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244131-M) 

72462 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Hydout, 22.6% Active 

Ingredient to the Grass Shrimp Palaemonetes pugio: UCES Project No. 11506-41-23. 

(Unpublished study, including letter dated Feb 7, 1980 from O. Keckemet to Agchem 

File, received Jan 23, 1981 under 1F1105; prepared by Union Carbide Corp., submitted 

by Pennwalt Corp., Philadelphia, Pa.; CDL: 099883-M) 

74222 Vilkas, A.G.; Seminara, J. (1980) The Acute Toxicity of Hydout, 22.6% Active 

Ingredient to the Grass Shrimp Palaemonetes pugio: UCES Project No. 11506-41-23. 

(Unpublished study, including letter dated Feb 7, 1980 from O. Keckemet to Agchem 

File, received Jan 23, 1981 under 4581-282; prepared by Union Carbide Corp., 

submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244122-M) 

71141 

Acc#244122 

Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydout(TM) Aquatic Weed 

Killer Code AHE 09H901, N.B. No. 84-112-1 to the Fiddler Crab, Uca pugilator: 

UCES Project No. 11506-41- 24. (Unpublished study, including letters dated Jan 18, 

1980 from A.G. Vilkas to B.D. McGaughey and Feb 7, 1980 from O. Keckemet to 

Agchem File, received Jan 23, 1981 under 4581-174; pre- pared by Union Carbide 

Corp., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244131-N) 

72463 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydout(TM) Aquatic Weed 

Killer Code AHE 09H901, N.B. No. 84-112-1 to the Fiddler Crab, Uca pugilator: 

UCES Project No. 11506-41- 24. (Unpublished study, including letters dated Feb 7, 

1980 from O. Keckement to Agchem File and Jan 18, 1980 from A.G. Vilkas to B.D. 

McGaughey, received Jan 23, 1981 under 1F1105; prepared by Union Carbide Corp., 

submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:099883-N) 

74223 Vilkas, A.G.; Seminara, J. (1979) The Acute Toxicity of Hydout(TM) Aquatic Weed 

Killer, Code AHE 09H901, N.B. No. 84- 112-1, to the Fiddler Crab, Uca pugilator: 

UCES Project No. 11506-41-24. (Unpublished study, including letters dated Jan 18, 

1980 from A.G. Vilkas to B.D. Mc Gaughey and Feb 7, 1980 from O. Keckemet to 

Agchem File, received Jan 23, 1981 under 4581-282; prepared by Union Carbide Corp., 

submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:244122-N) 

43196903 Bettencourt, M. (1994) Hydrothol 191--Acute Toxicity to Sheepshead Minnow 

(Cyprinodon variegatus) Under Flow-Through Conditions: Final Report: Lab Project 

Number: 93-10-4980: 12442.0591.6140.505. Unpublished study prepared by 

Springborn Laboratories, Inc. 70 p. 

43210001 Putt, A. (1994) Hydrothol 191--Acute Toxicity to Mysid Shrimp (Mysidopsis bahia) 

Under Flow-Through Conditions: Final Report: Lab Project Number: 93-10-5000: 

12442.0591.6141.515. Unpublished study prepared by Springborn Labs., Inc. 72 p. 

43550201 Dionne, E. (1995) Hydrothol 191--Acute Neurotoxicity to Eastern Oyster (Crassostrea 

virginica) Under Flow-through Conditions: Final Report: Lab Project Number: 

12442.0591.6142.504: 93-8-4896. Unpublished study prepared by Springborn Labs, 

Inc.108 p. 

28442 Inglis, A.; Davis, E.L. (1971) Technical Report on the Effect of Water Hardness on the 

Toxicity to Fish of Several Organic and Inorganic Herbicides. (Unpublished study 

received Jul 13, 1971 under 1E1046; prepared by U.S. Fish and Wildlife Service, Div. 

of Fishery Research, Fish-Pesticide Research Laboratory in cooperation with National 
77 

Museum, Bird and Mammal Laboratory, sub- mitted by U.S. Dept. of the Army, Office 

of the Chief of Engineers, Washington, D.C.; CDL:091865-G) 

34907 Inglis, A.; Davis, E.L. (1965) The Effect of Water Hardness on the Toxicity to Fish of 

Several Organic and Inorganic Herbicides. (U.S. Fish and Wildlife Service, FishPesticide Research Laboratory, unpublished study; CDL:091752-A) 

43276501 Bettencourt, M. (1994) Hydrothol 191: The Toxicity to Fathead Minnow (Pimephales 

promelas) During an Early Life-Stage Exposure: Final Report: Lab Project Number: 

94/1/5121: 12442/0692/6151/120. Unpublished study prepared by Springborn 

Laboratories, Inc. 84 p. 

43437901 Putt, A. (1994) Hydrothol 191--The Chronic Toxicity to Daphnia magna Under FlowThrough Conditions: Final Report: Lab Project Number: 93-11-5014: 

12442.0692.6150.130. Unpublished study prepared by Springborn Labs, Inc. 117 p. 

44700401 Serdar, D.; Johnson, A.; Stinson, M. (1995) Seawater Challenge of Chinook Salmon 

Smolts (Oncorhynchus tshawytscha) Exposed to the Aquatic Herbicide Hydrothol 191: 

Lab Project Number: 95-358. Unpublished study prepared by Washington State 

Department of Ecology. 30 p. 

51466 Lapham, V.T. (1966) Letter sent to W. Harry Culver dated Jun 24, 1966 Fish Kills. 

(Louisiana, Wild Life and Fisheries Commission, Aquatic Vegetation Control 

Research, unpublished study; CDL:132475-B) 

51467 Frank, P.A. (1964) Letter sent to Edward J. Bowles dated Oct 30, 1964 Hydrothol 

treatment of aquatic weeds|. (U.S. Agricultural Research Service, Crops Research Div., 

Crop Protection Research Branch, unpublished study; CDL:132475-C) 

51468 Zarbock, W.M. (1961) Letter sent to Harold Lindaberry dated Sep 20, 1961 TD191 on 

weeds and fish. (Ohio, Div. of Wildlife, Dept. of Natural Resources, unpublished study; 

CDL: 132475-D) 

36560 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E5661. (Unpublished study received Jan 5, 1978 under 1F1105; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL: 096704-AN) 

36580 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E5691. (Unpublished study received Jan 5, 1978 under 1F1105; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL: 096704-BI) 

36588 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E5701. (Unpublished study received Jan 5, 1978 under 1F1105; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL: 096704-BQ) 

36591 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E5676. (Unpublished study received Jan 5, 1978 under 1F1105; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of Prussia, Pa.; 

CDL: 096704-BT) 

51589 Latven, A.R. (1975) Letter sent to Obren Keckemet dated Jun 26, 1975 Toxicological 

findings with alcoholic Ripenthol and aqueous Ripenthol. (Unpublished study received 
78 

Oct 5, 1976 under 4581-173; prepared by Pharmacology Research, Inc., submitted by 

Pennwalt Corp., Philadelphia, Pa.; CDL:226503-B) 

58572 Latven, A.R. (1971) Accelerate. (Unpublished study, including letter dated Sep 29, 

1971 from A.R. Latven to Harold L. Linda- berry, received Feb 1, 1975 under 3F1416; 

prepared by Pharmacology Research, Inc., submitted by Pennwalt Corp., Tacoma, 

Wash.; CDL:093785-K) 

61919 Latven, A.R. (1975) Toxicology Report for Pennwalt Agchem Division: Ripenthol N.B. 

58-188-3 (Isopropylbutanol Formulation). (Unpublished study received Oct 5, 1976 

under 4581-174; prepared by Pharmacology Research, Inc., submitted by Pennwalt 

Corp., Philadelphia, Pa.; CDL:227610-C) 

61920 Latven, A.R. (1975) Toxicology Report for Pennwalt Agchem Division: Ripenthol N.B. 

58-191-2 (Water Only Formulation). (Unpublished study received Oct 5, 1976 under 

4581-174; prepared by Pharmacology Research, Inc., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:227610-D) 

78188 Latven, A.R. (1975) Toxicology Report for Pennwalt, Agchem Division: Ripenthol 

N.B. 58-188-3 (Isopropylbutanol Formulation). (Unpublished study received Jan 5, 

1978 under 4581-174; prepared by Pharmacology Research, Inc., submitted by 

Pennwalt Corp., Philadelphia, Pa.; CDL:232580-K) 

78189 Latven, A.R. (1975) Toxicology Report for Pennwalt, Agchem Division: Ripenthol 

N.B. 58-191-2 (Water Only Formulation). (Unpublished study received Jan 5, 1978 

under 4581-174; prepared by Pharmacology Research, Inc., submitted by Pennwalt 

Corp., Philadelphia, Pa.; CDL:232580-L) 

78220 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E5691. (Unpublished study received Jan 5, 1978 under 4581-174; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:232580-AV) 

78606 Terrell, Y.; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E5701. (Unpublished study received Jan 5, 1978 under 4581-174; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:232580-BD) 

78609 Terrell, Y; Parke, G.S.E. (1977) Report on Oral LD50 in Rats: Laboratory No. 7E5676. (Unpublished study received Jan 5, 1978 under 4581-174; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL:232580-BG) 

113972 Latven, A. (1971) Accelerate: Summary--Acute Oral Toxicity in Starved Rats: LD50 = 

650 MG/KG (0.57 ML/KG). (Unpublished study received Nov 29, 1971 under 4581-

284; prepared by Pharmacology Research, Inc., submitted by Agchem Div., Pennwalt 

Corp., Philadelphia, PA; CDL:100915-A) 

114491 Latven, A. (1971) Accelerate: Summary--Acute Oral Toxicity in Starved Rats: LD50 = 

650 Mg/Kg (0.57 Ml/Kg). (Unpublished study received Jul 9, 1975 under 1F1105; 

prepared by Pharmacology Research, Inc., submitted by Pennwalt Corp., Tacoma, WA; 

CDL: 094702-D) 

42774001 Mallory, V. (1993) Acute Exposure Oral Toxicity in Rats with Hydrothol 191 

(Endothall): Lab Project Number: PH 402-ANA-002-92. Unpublished study prepared 

by Pharmakon Research International, Inc. 169 p. 
79 

43242301 Mallory, V. (1994) Acute Exposure Oral Toxicity with Accelerate: Lab Project 

Number: PH 402-ANA-003-93. Unpublished study prepared by Pharmakon Research 

International, Inc. 170 p. 

36561 Wise, M.T. (1977) Acute Inhalation Toxicity of a) Aquathol® K (N.B. 77-100-4) b) 

Hydrothol® 191 Liquid (N.B. 77-100-2) c) Hydrothol® 47 Liquid (N.B. 77-100-3) d) 

Aquathol® (N.B. 77-99-7) e) Des-I-Cate® Accelerate (N.B. 77-99-6) f) Knox-Out® 2 

FM (N.B. 4414-94): Laboratory Nos. a) 7E-5660 b) 7E-5665 c) 7E-5670 d) 7E-5675 e) 

7E-5680 f) 7E-5685. (Unpublished study received Jan 5, 1978 under 1F1105; prepared 

by Cannon Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of 

Prussia, Pa.; CDL:096704-AO) 

36592 Zeigler, R.L. (1977) Acute Inhalation Toxicity of 1. Aquathol® Granular (N.B. 77-99-

4) 2. Hydrothol® 191 Granular (N.B. 77- 99-2) 3. Hydrothol® 47 Granular (N.B. 77-

99-3) 4. HydoutTM (N.B. 77-99-5): Laboratory Nos. 1. 7E-5690 2. 7E-5695 3. 7E-5700 

4. 7E-5705. (Unpublished study received Jan 5, 1978 under 1F1105; prepared by 

Cannon Laboratories, Inc., submitted by Pennwalt Corp., Agchem Div., King of 

Prussia, Pa.; CDL: 096704-BU) 

78202 Wise, M.T. (1977) Acute Inhalation Toxicity of Aquathol® K (N.B. 77-100-4); 

Hydrothol®191 Liquid (N.B. 77-100-2); Hydrothol®47 Liquid (N.B. 77-100-3); 

Aquathol® (N.B. 77-99-7); Des-i-cate®Accelerate (N.B. 77-99-6); Knox- out®2 FM 

(N.B. 4414-94): Laboratory Nos. 7E-5660; 7E-5665; 7F-5670; 7E-5675; 7E-5680; 7E5685. (Unpublished study received Jan 5, 1978 under 4581-174; prepared by Cannon 

Laboratories, Inc., submitted by Pennwalt Corp., Philadelphia, Pa.; CDL: 232580-AB) 

78610 Zeigler, R.L. (1977) Acute Inhalation Toxicity of 1. Aquathol® Granular (N.B. 

77-99-4); 2. Hydrothol® 191 Granular (N.B. 77-99-2); 3. Hydrothol® 47 Granular 

(N.B. 77-99-3); 4. HydoutTM (N.B. 77-99-5): Laboratory Nos. 7E-5690; 7E- 5695; 

7E-5700; 7E-5705. (Unpublished study received Jan 5, 1978 under 4581-174; 

prepared by Cannon Laboratories, Inc., submitted by Pennwalt Corp., 

Philadelphia, Pa.; CDL:232580-BH) 

42560901 Hoffman, G. (1992) An Acute Inhalation Toxicity Study of Hydrothol 191 in the 

Rat: Final Report: Lab Project Number: 91-8356. Unpublished study prepared by 

Bio/dynamics, Inc. 126 p. 

43152101 Trutter, J. (1993) Two-Generation Reproduction Study in Rats with Disodium 

Salt of Endothall: Final Report: Lab Project Number: 153/142. Unpublished study 

prepared by Hazleton Washington, Inc. 1479 p. 

43629301 Trutter, J. (1995) Two-Generation Reproduction Study in Rats with Disodium 

Salt of Endothall: Addendum to MRID 43152101: Lab Project Number: 153-142. 

Unpublished study prepared by Hazleton Washington, Inc. 21 p. 

101734 Pennwalt Corp. (1954) Full Reports of Investigations Made with Respect to the 

Safety of the Product: Disodium Endothall. (Unpublished study received Oct 30, 

1963 under 4581-284; CDL: 007455-C) 

44127801 Hoberg, J. (1993) Hydrothol 191--Determination of Effects on Seed 

Germination of Ten Plant Species: Summary Report: Lab Project Number: 93-

9-4942: 12442.0593.6159.610: 050892. Unpublished study prepared by 

Springborn Labs., Inc. 56 p. 
80 

44127802 Hoberg, J. (1994) Hydrothol 191--Toxicity to the Marine Diatom, Skeletonema 

costatum: Summary Report: Lab Project Number: 93-11-5025: 

12442.0593.6162.450: 040692. Unpublished study prepared by Springborn 

Labs., Inc. 33 p. 

44127803 Hoberg, J. (1994) Hydrothol 191--Toxicity to the Freshwater Alga, Anabaena 

flos-aquae: Summary Report: Lab Project Number: 93-11-5023: 

12442.0593.6163.420: 040692. Unpublished study prepared by Springborn 

Labs., Inc. 36 p. 

44127804 Hoberg, J. (1994) Hydrothol 191--Toxicity to the Freshwater Alga, Selenastrum 

capricornutum: Summary Report: Lab Project Number: 93-11-5022: 

12442.0593.6160.430: 040692. Unpublished study prepared by Springborn Labs.

Inc. 33 p. 

44127805 Hoberg, J. (1994) Hydrothol 191--Toxicity to the Freshwater Diatom, Navicula 

pelliculosa: Summary Report: Lab Project Number: 93-11-5021: 

12442.0593.6161.440: 040692. Unpublished study prepared by Springborn 

Labs., Inc. 33 p. 

44127806 Hoberg, J. (1994) Hydrothol 191--Toxicity to Duckweed, Lemna gibba: 

Summary Report: Lab Project Number: 93-11-5024: 12442. 0593.6164.410: 

040692. Unpublished study prepared by Springborn Labs., Inc. 32 p. 

43870401 Hoberg, J. (1995) Hydrothol 191--Determination of Effects on Seedling 

Emergence and Vegetative Vigor of Ten Plant Species: Final Report: Lab 

Project Number: 12442.0195.6185.610: BR-94-20: 95-8-6045. Unpublished 

study prepared by Springborn Labs, Inc. 339 p. 

44127801 Hoberg, J. (1993) Hydrothol 191--Determination of Effects on Seed 

Germination of Ten Plant Species: Summary Report: Lab Project Number: 93-

9-4942: 12442.0593.6159.610: 050892. Unpublished study prepared by 

Springborn Labs., Inc. 56 p. 

44976701 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191: A 96-Hour Toxicity 

Test with the Marine Diatom (Skeletonema costatum): Final Report: Lab 

Project Number: 299A-104. Unpublished study prepared by Wildlife 

International , Ltd. 38 p. {OPPTS 850.5400} 

44820102 Dionne, E.; Sharp, J.; Formella, T. (1999) Dipotassium Salt of Endothall: A 

Freshwater Fish and Shellfish Magnitude of Residues Study in a Static Aquatic 

System: Lab Project Number: KP-97-14: 52897/171.4/FIFRA: EN1115.95. 

Unpublished study prepared by Elf Atochem and ABC Laboratories, Inc. 213 p. 

{OPPTS 860.1400} 

47563701 York, D. (2008) Endothall Mono (N,N-Dimethyl Alkylamine) Salt - Life-Cycle 

Toxicity Test with Mysids (Americamysis bahia). Project Number: 13845/6109, 

051507/OPPTS/FIFRA/MYSID/FLC. Unpublished study prepared by 

Springborn Smithers Laboratories. 92 p. 

47563702 York, D. (2008) Endothall Mono (N,N-Dimethyl Alkylamine) Salt - Early LifeStage Toxicity Test with Sheepshead Minnow (Cyprinodon variegatus). Project 

Number: 13845/6110, 062707/OPPTS/ELS/SHM. Unpublished study prepared 

by Springborn Smithers Laboratories. 69 p. 
81 

35244 

Acc#232582 

Vilkas, A.G. (1977) The Acute Toxicity of Hydrothol(®) 191 to the Fiddler 

Crab, Uca pugilator: UCES Project # 11506-41-05. (Unpublished study received 

Jan 5, 1978 under 1F1105; prepared by Union Carbide Corp., submitted by 

Pennwalt Corp., Agchem Div., King of Prussia, Pa.; CDL:096705-I) 

71147 U.S. Department of Interior, Bureau of Reclamation (1963) Results of 

Algaecidal Evaluation Tests of Selected Compounds: Report No. WC-21. 

(Pages 26-32 only, In Annual Progress Report of 1964 Lab. Studies; 

unpublished study; CDL:244131-U) 

44949201 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191 (Endothall): A 96-

Hour Toxicity Test with the Freshwater Diatom (Navicula pelliculosa): Final 

Report: Lab Project Number: 299A-102. Unpublished study prepared by 

Wildlife International Ltd. 38 p. {OPPTS 850.5400} 

44949202 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191 (Endothall): A 96-

Hour Toxicity Test with the Freshwater Alga (Anabaena flos-aquae): Final 

Report: Lab Project Number: 299A-101. Unpublished study prepared by 

Wildlife International Ltd. 36 p. {OPPTS 850.5400} 

44949402 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191 (Endothall): A 7-

Day Toxicity Test with Duckweed (Lemna gibba G3): Final Report: Lab 

Project Number: 299A-105. Unpublished study prepared by Wildlife 

International Ltd. 34 p. {OPPTS 850.4400} 

44949403 Drottar, K.; Martin, K.; Krueger, H. (1999) Hydrothol 191 (Endothall): A 7-

Day Toxicity Test with The Freshwater Alga (Selenastrum capricornutum): 

Final Report: Lab Project Number: 299A-103. Unpublished study prepared by 

Wildlife International Ltd. 36 p. {OPPTS 850.5400}. 

47742801 Picard, C. (2008) Endothall Mono (N,N-Dimethyl Alkylamine) Salt- Life-Cycle Toxicity 

Test Exposing Midges (Chironomus tentans) to a Test Substance Applied to Sediment 

Under Static-Renewal Conditions Following EPA Test Methods. Project Number: 

13845/6113, 031907/EPA/MIDGE/CHRONIC. Unpublished study prepared by Springborn 

Smithers Laboratories. 118 p. 

47742802 Picard, C. (2009) Endothall Mono (N,N-Dimethyl Alkylamine) Salt- 28-Day Toxicity Test 

Exposing Estuarine Amphipods (Leptocheirus plumulosus) to a Test Substance Applied to 

Sediment Following EPA Test Methods. Project Number: 13845/6114, 

031907/EPA/28D/LEPTOCHEIRUS. Unpublished study prepared by Springborn Smithers 

Laboratories. 79 p. 

44820104 Giddings, J. (1999) Ecological Risk Assessment of Aquatic Herbicides Containing 

Endothall: Final Report: Lab Project Number: KP-98-31: 98-11-7564: 12442-0898-6271-

251. Unpublished study prepared by Elf Atochem and Springborn Laboratories, Inc. 64 p. 

36539 Miller, H. (1975) Phytotoxicity: Phototoxicity to Irrigated Crops. (Unpublished 

study received Jan 5, 1978 under 1F1105; submitted by Pennwalt Corp., Agchem 

Div., King of Prussia, Pa.; CDL: 096704-N) 

35245 Pennwalt Corporation (1970) Beneficial Insect Safety. (Unpublished study 

received Jan 5, 1978 under 1F1105; CDL:096705-K) 

40986 Bowles, E.J.; Keckemet, O; Boyle, W.D.; et al. (1964) Hydrothol 191 as an 

Aquatic Herbicide in Flowing Water. (Unpublished study received Apr 10, 
82 

1966 under 6G0503; submitted by Pennsalt Chemical Corp., Bryan, Tex.; 

CDL:090587-AE) 

55700 Frank, P.A.; Comes, R.D. (1967) Herbicidal residues in pond water and 

hydrosoil. Weeds 15(3):210-213. (Also in unpublished submission received 

Aug 4, 1976 under 876-222; submitted by Velsicol Chemical Corp., Chicago, 

Ill.; CDL:229172-F) 

56395 Hestand, R.S., III; Carter, C.C. (1967?) Herbicide Effects on Aquatic Plants. 

(Unpublished study received Dec 19, 1975 under 6H5112; submitted by 3M 

Co., St. Paul, Minn.; CDL:230414-C) 

56396 Hestand, R.S., III; Carter, C.C. (1968?) Herbicide Effects on Phytoplankton. 

(Unpublished study received Dec 19, 1975 under 6H5112; submitted by 3M 

Co., St. Paul, Minn.; CDL:230414-D) 

74229 U.S. Department of the Interior, Bureau of Reclamation (1964) Results of 

Algaecidal Evaluation Tests of Selected Compounds: Report No. WC-21. 

(Unpublished study; CDL:244122-U) 

101733 Pennwalt Corp. (1966) Efficacy of Accelerate, Desicate and Other 

Compounds for Defoliation of Cotton|. (Compilation; unpublished study 

received on unknown date under 4581-284; CDL:007455-B) 

114517 Bowles, E.; Keckemet, J.; Boyle, W.; et al. (1965) Hydrothol 191 as an 

Aquatic Herbicide in Flowing Water. (Unpublished study received Mar 15, 

1966 under 4581-139; submitted by Agchem Div., Pennwalt Corp., 

Philadelphia, PA; CDL:007441-Q) 

114492 Pennwalt Corp. (1972) Responses of Plankton and Macrofauna Communities 

To Test Application of Chemical Herbicides. (Unpublished study received 

Jul 9, 1975 under 1F1105; CDL:094702-H) 

ACC 

244122

The Acute Toxicity of Hydout to Mussel (Mytilus edulis) embryos. Prepared 

by SRI International, Menlo Park, CA, June 20, 1980. Exhibit 30 in Fish and 

Wildlife Safety Section IX for Hydout (acc#244122). 

ACC 

094509

Linn, J.D. (1967). Experiments on the Effects of Field Application of 

Hydrothol 191 on Fish. 17 p. Study conducted by California Department of 

Game and Fish. Submitted by Pennwalt Corp., Pet. #1F1105, Acc # 094509 

(exhibit C-99), 12/1/70. Test ID # ES-BB3. 

ACC 

094509

Swabey, Y.H. and C.F. Schneck. (1963). Algicides and Aquatic Herbicides. 

22 p. Study conducted by Ontario Water Resources Commission. Submitted 

by Pennwalt Corp., Pet. #1F1105, Acc # 094509 (exhibit C-61), 12/1/70. 

Test ID # ES-F4. 

ACC 

094509

McCraren, J.P. (undated). Some chronic effects of Hydrothol 191 on Redear Sunfish in two 

diverse aquatic environments. 38 p. Study conducted by USDI at Tishomongo National 

Fish Hatchery, Oklahoma in 1966. Submitted by Pennwalt Corp., Pet. #1F1105, Acc# 

094509 (exhibit C-72), 12/01/70. Test ID # ES-BB4. 

96295 Walker, C.R. (1963) Letter sent to Harold L. Lindaberry dated Nov 8, 1963 Fish toxicity 

studies|. (U.S. Fish and Wildlife Service, Fish Control Laboratory; unpublished study; 

CDL:090719-G) 
83 

114493 Walker, C. (1971) The toxicological effects of herbicides and weed control on fish and other 

organisms in the aquatic ecosystem. By U.S. Fish and Wildlife Service, Div. of Fishery 

Research, Branch of Pest Control Research. Pages 119-126, In Proc. Eur. Weed Res. Coun. 

3rd Int. Symp. Aquatic Weeds; 1971. S.l.: s.n. (Also In unpublished submission received Jul 

9, 1975 under 1F1105; submitted by Pennwalt Corp., Tacoma, WA; CDL: 094702-I) 

E012941 

MRID

49660201 

Keller, A. E., Dutton, R. J., Bitton, G., and Crisman, T. L. 1988. Chronic Toxicity of 

Hydrothol 191 to Ceriodaphnia dubia at 25 and 15 Degrees C. Bull. Environ. Contam. 

Toxicol. 41[2], 233-240. 
84 

APPENDIX A. SLUA Summary Table for Endothall 

Date: December 31, 2014 

Screening Level Estimates of Agricultural Uses of 

Endothall Case (002245) 

Sorted Alphabetically

Reporting Years: 2004-2012 

Average Percent Crop Treated 

Crop Lbs. A.I. Average Maximum 

1 Alfalfa 3,000 < 1 < 2.5 

2 Cotton 2,000 < 1 < 2.5 

3 Potatoes 4,000 < 2.5 < 2.5 

All numbers are rounded. 

 <2.5: less than 2.5 percent of crop is treated. 

 <1: less than 1 percent of crop is treated. 

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) 

These results reflect amalgamated data developed by the Agency and are releasable to the public. 
85 

APPENDIX B. Endothall Incidents

A search for ecological incidents related to endothall use, (looking under all PC codes related to endothall; endothall acid, disodium dipotassium and mono (N,N-dimethylalkylamine) salts of endothall; 038901, 038903, 038904 and 038905, respectively) conducted on

April 7, 2015; yielded three (3) incidents; two (2) involving aquatic animals and one (1) terrestrial plants listed under endothall acid (PC 

code 038901); and two (2) incidents; one (1) involving aquatic animals and one (1) terrestrial plants, under the mono (N,Ndimethylalkylamine) salt of endothall (PC code 038905). There were no incidents were listed for either the disodium or dipotassium 

salts of endothall (PC codes 038903 and 038904, respectively); all of this is summarized below. 

Table B-1. Endothall Incidents, as Reported in the EIIS Database

Incident ID # 

State, 

County Magnitude Year Description Legality Certainty 

I015726-001 Hernand o, FL Unknown 2004 

To comply with 6(a)2 requirements, Cerexagri reported an incident in Lake Tarpon, FL, when the Southwest Florida Water Management District sprayed the lake as part of its program to rid the lake of hydrilla. The herbicide used was Aquathol Super K (endothall – dipotassium salt) and the targeted concentration was 2.5 ppm; 47 acres were treated @ 55 lbs/acre. The herbicide was applied on September 28/29 and, by October 3, dead mussels were reported floating on the surface. There were no analyses included. To comply with 6(a)2 requirements, DuPont reported a claim from a landowner in western Kentucky that, for two years in a row, an application of DuPont Oust XP Herbicide plus Diuron to an area around a utility substation resulted in runoff that damaged his corn crop. The landowner had a soil test made which found traces of Diuron. No symptoms of the affected crop were given. 

Unknown Possible 

B0000-231-03 Butte, CA 1000 fish (mostly carp) 1971 

A 5-gallon can of Hydrothol 191 (endothall – mono salt) was found dripping in a drain near Richvale on Sept. 7, 1971. Over 1000 fish were killed, mostly carp (Cyprinus carpio). No tissue analyses were made and the warden investigating the incident did not file a complaint. No analytical data were given but the supposition is that a dripping Hydrothol 191 can was responsible for the fish kill. 

Misuse 

(Accidental) 

Highly 

Probable 

I013884-031 Grant, WA Not given 1998 

This is from the 1999 Annual Report from the Washington State Department of Health Pesticide Incident Reporting and Tracking Review Panel, November 2000, from the 1998 PIRT Data. Plane spraying on potato field drifted on to alfalfa (Medicago sativa). Observed Diquat injury to alfalfa. No 

information supplied regarding endothall related damage resulting from spray drift. 

Registered 

Use Possible 
86 

Incident ID # 

State, 

County Magnitude Year Description Legality Certainty 

I010688-001 MN 75,000 2000 

To comply with 6(a)2 regulations, Elf Atochem reported a fish kill in the cooling water effluent of the North States Power's Prairie Island Nuclear Generating Station on August 16, 2000. The information sent by Elf Atochem had been supplied by Nalco Chemical Co. (Naperville, IL) which had conducted a mission to kill the zebra mussels infesting the cooling chambers of the power plant. The product used was EVAC biocide (EPA Registration No. 4581-380, Shaughnessy No. 038905) which is a dimethyl 

cocoamine salt of endothall. Typically, the product is highly diluted within short distances of the application site to levels far below the LC50s for nontarget organisms. A potential factor, also, is the water temperature; in the previous year's treatment, the water temperature was 84.2qF and there were 

no fish kills but in the year 2000 the water temperature was 92qF. Elf 

Atochem feels that the concentration of EVAC applied was too high and the water temperature was too high. Another factor was that the screens designed to prevent the entry of fish from the Mississippi River allow small fish to enter but as their growth progresses they have no way to leave the system and thus are killed by the pesticide in the cooling water effluent. Thousands of catfish (Ictaluridae), Green sunfish (Lepomis cyanellus), and shiner (Cyprinidae) were killed. Concentrations in the water ranged from 7.57-9.94 

ppb (mono (N,N- dimethylcocoamine salt of endothall). 

Misuse 

(Accidental) Probable 

I014385-001 WV 2 birds 2003 

This is from the Cerexagrl Aggregate Report for June 1, 2003 to August 31, 2003. A remote 200 acre pond used to cool water used in a mining operation. Application was made to the pond and one Egret (Arteidae) was found dead 3 

days later and 1 dead Pelican (Pelecansus sp.) was found 7 days later. 

Chemical analysis on the birds or the pond were not reported. Chemical analysis was not performed on the birds or water. Hydrothol 191 was the product that was used; and it was a water soluble packet. 

Registered 

Use Possible 

Uncertainties Related to the Use of Incident Information from the Ecological Incident Information System Incident data are used in risk assessments to provide evidence that the risk predictions from the screening level assessment are supported by actual effects in the field. Incident reports submitted to EPA since approximately 1994 have been tracked by assignment of incident numbers in an Incident Data System (IDS), microfiched, and then entered to a second database, the Ecological Incident Information System (EIIS). Additionally, there is an on-going effort to enter information to EIIS on incident reports received prior to establishment 

of current databases. Incident reports are not received in a consistent format (e.g., states and various labs usually have their own 
87 

formats), may involve multiple incidents involving multiple chemicals in one report, and may report on only part of a given incident investigation (e.g., residues). 

Incidents entered into EIIS are categorized into one of several certainty levels regarding the likelihood that a particular pesticide is associated with the incident: highly probable, probable, possible, unlikely, or unrelated. In brief, “highly probable” incidents usually require carcass residues and/or clear circumstances regarding the exposure. “Probable” incidents include those where residues were not available and/or circumstances were less clear than for “highly probable.” “Possible” incidents include those where multiple chemicals may have been involved and it is not clear what the contribution was of a given chemical. The “unlikely” category is used, for example, where a given chemical is practically nontoxic to the category of organism killed and/or the chemical was tested for but not detected in samples. “Unrelated” incidents are those that have been confirmed to be not pesticide-related. Incidents entered into the EIIS are also categorized as to use/misuse. Unless specifically confirmed by a state or federal agency to be misuse, or there was very clear misuse such as intentional baiting to kill wildlife, incidents are not typically considered misuse. The number of documented kills in EIIS is believed to be a small fraction of total mortality caused by pesticides. Mortality incidents must be seen, reported, investigated, and have investigation reports submitted to EPA to have the potential for entry into the database. Incidents often are not seen, due to scavenger removal of carcasses, decay in the field, or simply because carcasses may be hard to see on many sites and/or few people are systematically looking. Poisoned animals may also move off-site to less conspicuous areas before 

dying. Incidents may not get reported to appropriate authorities capable of investigating the incident for a variety of reasons including the finder may not know of the importance of reporting incidents, may not know who to call, may not feel they have the time or desire to call, or may hesitate to call because of their own involvement in the kill. Incidents reported may not get investigated if resources are limited or may not get investigated thoroughly, with residue analyses, for example. Also, if kills are not reported and investigated promptly, there will be little chance of documenting the cause, since tissues and residues may deteriorate quickly. Reports ofinvestigated incidents often do not get submitted to EPA, since reporting by states is voluntary. 

Furthermore, the database relies heavily on registrant-submitted incident reports, and registrants are currently only required to submit 

detailed information on ‘major’ ecological incidents, while ‘minor’ incidents are reported aggregately. 

Based on the 40 CFR (§159.184 Toxic or adverse effect incident reports), an ecological incident is considered ‘major’ if any of the following criteria are met: 

Fish or wildlife:(A) Involves any incident caused by a pesticide currently in Formal Review for ecological concerns. 

(B) Fish: Affected 1,000 or more individuals of a schooling species or 50 or more individuals of a non-schooling species. 
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(C) Birds: Affected 200 or more individuals of a flocking species, or 50 or more individuals of a songbird species, or 5 or more individuals of a predatory species. 

(D) Mammals, reptiles, amphibians: Affected 50 or more individuals of a relatively common or herding species or 5 or more individuals of a rare or solitary species. (E) Involves effects to, or illegal pesticide treatment (misuse) of a substantial tract of habitat (greater than or equal to 10 acres, 

terrestrial or aquatic). 

Plants: (A) The effect is alleged to have occurred on more than 45 percent of the acreage exposed to the pesticide. 

All other ecological incidents are considered ‘minor’ and only need to be aggregately reported. ‘Minor’ incidents reported by the registrants are not included in the EIIS database. Therefore, for example, an incident could affect 900 fish, 150 birds, 45 mammals, and 

40% of an exposed crop and not be included in the EIIS database [unless is it reported by a non-registrant (e.g., an incident submitted by 

a state agency – which are not systematically collected)]. Therefore, because the number of documented kills in EIIS is believed to be a small fraction of total mortality caused by pesticides, absence of reports does not necessarily provide evidence of an absence of incidents. 

In addition to the incidents recorded in EIIS and AIMS, additional incidents have been reported to the Agency in aggregated incident 

reports. 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 endothall, registrants have reported one minor fish and wildlife incident for dipotassium salt of endothall, 

and three minor fish and wildlife incidents and one minor plant incident for the mono (N,N-dimethylalkylamine) salt of endothall. 

Unless additional information on these aggregated incidents become available, they will be assumed to be representative of registered uses of endothall in the risk assessment.
89 

APPENDIX C. SIP & STIR Inputs and Outputs for Endothall Acid, and the 

dipotassium and mono (N,N-dimethylalkylamine) salts of endothall 

SIP Inputs/Outputs 

Table 1. Inputs

Parameter Value

Chemical name Endothall Acid (as ae)

Solubility (in water at 25oC; mg/L) 11000000

Mammalian LD50 (mg/kg-bw) 44.4

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg-bw) 9.4

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Avian LD50 (mg/kg-bw) 229

Avian test species mallard duck

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 50

Bobwhite quail NOAEC (mg/kg-diet) 0

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

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 1892000 1892000

Adjusted toxicity value (mg/kg-bw) 34.2 7.23

Ratio of exposure to toxicity 55401 261683

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for mammals

Exposure through drinking 

water alone is a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 8910000 8910000

Adjusted toxicity value (mg/kg-bw) 119 2.48

Ratio of exposure to acute toxicity 74935 3591832

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for birds

Exposure through drinking 

water alone is 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.
90 

 

Table 1. Inputs

Parameter Value

Chemical name

Endothall (dipotassium salt 

as ae)

Solubility (in water at 25oC; mg/L) 65000000

Mammalian LD50 (mg/kg-bw) 24.3

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg-bw) 9.4

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Avian LD50 (mg/kg-bw) 61.6

Avian test species mallard duck

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 0

Bobwhite quail NOAEC (mg/kg-diet) 0

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

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 11180000.0000 11180000.0000

Adjusted toxicity value (mg/kg-bw) 18.6906 7.2301

Ratio of exposure to toxicity 598161.5856 1546311.3330

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for mammals

Exposure through drinking 

water alone is a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 52650000.0000 52650000.0000

Adjusted toxicity value (mg/kg-bw) 31.9843 0.0000

Ratio of exposure to acute toxicity 1646120.8927 0.0000

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for birds

Due to insufficient data, 

risk cannot be precluded

*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.
91 

Table 1. Inputs

Parameter Value

Chemical name Endothall (mono salt as ae)

Solubility (in water at 25oC; mg/L) 50000000

Mammalian LD50 (mg/kg-bw) 49.1

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Mammalian NOAEL (mg/kg-bw) 9.4

Mammalian test species laboratory rat

Body weight (g) of "other" mammalian species

Avian LD50 (mg/kg-bw) 91

Avian test species mallard duck

Body weight (g) of "other" avian species

Mineau scaling factor 1.15

Mallard NOAEC (mg/kg-diet) 82.4

Bobwhite quail NOAEC (mg/kg-diet) 613

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

Table 2. Mammalian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 8600000.0000 8600000.0000

Adjusted toxicity value (mg/kg-bw) 37.7658 7.2301

Ratio of exposure to toxicity 227719.3566 1189470.2561

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for mammals

Exposure through drinking 

water alone is a potential 

concern for mammals

Table 3. Avian Results

Parameter Acute Chronic

Upper bound exposure (mg/kg-bw) 40500000.0000 40500000.0000

Adjusted toxicity value (mg/kg-bw) 47.2495 4.0881

Ratio of exposure to acute toxicity 857151.7074 9906862.8392

Conclusion*

Exposure through drinking 

water alone is a potential 

concern for birds

Exposure through drinking 

water alone is 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.
92 

STIR Inputs/Outputs 

 

Input

Application and Chemical Information

Enter Chemical Name Endothall Acid

Enter Chemical Use cotton

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) 186.2

Enter Chemical Vapor Pressure (mmHg) 3.92E-05

Enter Application Rate (lb a.i./acre) 0.2859

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 229

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 1.58

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 44.4

Enter Lowest Rat Inhalation LC50 (mg/L) 1.27

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) 3.93E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 4.94E-02

Adjusted Inhalation LD50 2.63E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.88E-03 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 2.75E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 1.04E-03 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 3.93E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 6.21E-02

Adjusted Inhalation LD50 7.56E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 8.21E-04 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 3.45E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 4.57E-04 Exposure not Likely Significant

**NOTE**: When entering values, pres

in order to update linked cells.
93 

Input

Application and Chemical Information

Enter Chemical Name Dipotas Salt(as ae)

Enter Chemical Use apples

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) 262.31

Enter Chemical Vapor Pressure (mmHg) 3.92E-05

Enter Application Rate (lb a.i./acre) 0.3

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 61.6

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 1.58

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 24.3

Enter Lowest Rat Inhalation LC50 (mg/L) 0.53

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) 5.53E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 6.96E-02

Adjusted Inhalation LD50 5.40E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.29E-02 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 2.88E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 5.34E-03 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 5.53E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 8.74E-02

Adjusted Inhalation LD50 3.16E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 2.77E-03 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 3.62E-02

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 1.15E-03 Exposure not Likely Significant

**NOTE**: When entering values, pres

in order to update linked cells.
94 

Input

Application and Chemical Information

Enter Chemical Name Mono Salt (as ae) 

Enter Chemical Use potato

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) 228.109779

Enter Chemical Vapor Pressure (mmHg) 2.09E-05

Enter Application Rate (lb a.i./acre) 2.3

Toxicity Properties

Bird

Enter Lowest Bird Oral LD50 (mg/kg bw) 91

Enter Mineau Scaling Factor 1.15

Enter Tested Bird Weight (kg) 1.58

Mammal

Enter Lowest Rat Oral LD50 (mg/kg bw) 49.1

Enter Lowest Rat Inhalation LC50 (mg/L) 0.5

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) 2.57E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 3.23E-02

Adjusted Inhalation LD50 3.72E+00

Ratio of Vapor Dose to Adjusted Inhalation LD50 8.66E-03 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 2.21E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 5.93E-02 Exposure not Likely Significant

Results Mammalian (0.015 kg )

Maximum Vapor Concentration in Air at Saturation (mg/m3) 2.57E-01

Maximum 1-hour Vapor Inhalation Dose (mg/kg) 4.05E-02

Adjusted Inhalation LD50 2.98E+01

Ratio of Vapor Dose to Adjusted Inhalation LD50 1.36E-03 Exposure not Likely Significant

Maximum Post-treatment Spray Inhalation Dose (mg/kg) 2.78E-01

Ratio of Droplet Inhalation Dose to Adjusted Inhalation LD50 9.33E-03 Exposure not Likely Significant

**NOTE**: When entering values, pres

in order to update linked cells.