2

Endothall Preliminary Work Plan – Table of Contents

OVERVIEW ................................................................................................................................... 4

ANTICIPATED DATA NEEDS .................................................................................................... 5

STATUTORY AND REGULATORY AUTHORITY................................................................... 8

CHEMICAL FACTS ...................................................................................................................... 8

USE AND USAGE INFORMATION............................................................................................ 9

RECENT ACTIONS..................................................................................................................... 11

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW.............................. 11

TIMELINE.................................................................................................................................... 13

NEXT STEPS ............................................................................................................................... 13

Appendix – Additional Areas Considered in the Endothall Registration Review.................... 14

References:

This Preliminary Work Plan summarizes the Environmental Protection Agency's current position 

based on the following documents:

1. EFED Registration Review Problem Formulation for Endothall. Christina Wendel, James 

Lin, Donna Kamarei. August 5, 2015.

2. Endothall: Human Health Risk Assessment in Support of Registration Review, and the 

Petition to Re-evaluate Tolerances for Livestock, and Remove the Restriction that Prohibits 

Livestock from Drinking Treated Water. Ideliz Negron- Encarnacion, John Liccione, 

Katelynn King, Seyed Tadayon. December 9, 2015

3. Bead Chemical Profile (BCP) for Registration Review: Endothall (Case 2245 PC Codes 

038901-038908). Carl Chen, Claire Paisley Jones, Derek Berwald. August 19, 2015. 

4. SLUA Endothall and Salts Case (002245). December 31, 2014.

5. Endothall (038901) EFED Table 1 Report. 8/26/2014. 
3

6. Endothall-dipotassium (038904) EFED Table 1 Report. 8/26/2014. 

7. Endothall, mono (N,N,-dimethyl alkyl amine) salt (038905) EFED Table 1 Report. 

12/3/2014. 

8. Endothall (038901) HED Master Label Report. 8/26/2014.

9. Endothall-dipotassium (038904) HED Master Label Report. 8/26/2014.

10. Endothall, mono (N,N,-dimethyl alkyl amine) salt (038905) HED Master Label Report. 

12/3/2014. 

11. Estimates of Crop Irrigation for Endothall Registration. Derek Berwald. March 26, 2015. 

These and other supporting documents for the endothall registration review case may be found in

the docket EPA-HQ-OPP-2015-0591 at http://www.regulations.gov.
4

OVERVIEW

The docket for endothall and its salts is now open, initiating the first public comment period for

this registration review (docket number EPA-HQ-OPP-2015-0591). Endothall is a dicarboxylic 

acid registered for use as an aquatic herbicide, desiccant, and biocide. Endothall acid (038901) is 

the active ingredient that forms from the breakdown of the endothall salts, and is not applied 

directly to use sites. The dipotassium salt (PC 038904) and the mono-N,N,-dimethylalkylamine 

salt (amine salt) (PC 038905) are formulated into pesticide products. The dipotassium salt is 

applied directly to water of lakes, ponds, and irrigation canals to control algae and submerged 

aquatic vegetation, and also has a use on apple blossoms as a thinner. The amine salt is also 

applied directly to water to control aquatic weeds and has desiccant uses on potatoes, cotton, 

clover, and alfalfa. In addition, the amine salt has an antimicrobial use in water cooling towers to 

control mollusks, where it also has activity against slime organisms. This Preliminary Work Plan 

(PWP) document explains what EPA's Office of Pesticide Programs knows about endothall,

highlighting anticipated data and assessment needs, identifying the types of information that 

would be especially useful to the Agency in conducting the review, and providing an anticipated 

timeline for completing the registration review for endothall. 

The registration review process was designed to include a public participation component to 

solicit input from interested stakeholders. The Agency intends, by sharing this information in the 

docket, to inform the public of what it knows about endothall and what types of new data or 

other information would be helpful for the Agency to receive as it moves toward a decision on 

endothall. The Agency encourages all interested stakeholders to review the PWP and Appendix 

and to provide comments and additional information that will help the Agency’s decisionmaking process for this chemical. In addition to general areas on which persons may wish to 

comment, there are some areas identified in the PWP and Appendix about which the Agency 

specifically seeks comments and information. Interested stakeholders could include: 

environmental non-profit or interest groups; pesticide manufacturers; agricultural labor or 

commodity groups; commercial, institutional, residential, and other users of pesticides; or the 

public at large.

The Preliminary Work Plan begins by listing the anticipated data needs for endothall. Next, it 

discusses the statutory and regulatory authority for Registration Review. Then the document 

provides chemical facts, use and usage information, recent actions, the anticipated risk 

assessments, and a projected registration review timeline for endothall. Finally, the Appendix to 

this document includes identification and discussion of some areas that are considered generally 

in Registration Review along with some additional chemical case-specific information.
5

ANTICIPATED DATA NEEDS

Table 1 below summarizes anticipated data needs for endothall. For additional discussion of the 

anticipated data needs, see the EFED Registration Review Problem Formulation for Endothall

and Endothall: Human Health Risk Assessment in Support of Registration Review, and the 

Petition to Re-evaluate Tolerances for Livestock, and Remove the Restriction that Prohibits 

Livestock from Drinking Treated Water.

Table 1: Anticipated Data Needs for the Endothall Registration Review

Guideline 

Number1 Study Title1

Test Material

Estimated 

Timeframe

(Months 

from 

receipt of 

DCI)

Data Requirements for the Conventional Uses 

835.1230 Adsorption/desorption Coco-alkylamine cation; TGAI 

or PAIRA 12

835.2120 Hydrolysis Coco-alkylamine cation; TGAI 

or PAIRA 12

835.2240 Aqueous Photolysis Coco-alkylamine cation; TGAI 

or PAIRA 12

835.4100 Aerobic Soil Metabolism Coco-alkylamine cation; TGAI 

or PAIRA 24

835.4300 Aerobic Aquatic Metabolism Coco-alkylamine cation; TGAI 

or PAIRA 24

835.4400 Anaerobic Aquatic Metabolism Coco-alkylamine cation; TGAI 

or PAIRA 24

850.1300 Freshwater invertebrate lifecycle Endothall acid and/or

dipotassium salt; TGAI 12

850.1350 Saltwater invertebrate life cycle

Endothall acid and/or

dipotassium salt; and monoN,N,-dimethylalkylamine salt; 

TGAI

12

850.1400 Saltwater fish early-life stage2 Endothall acid and/or

dipotassium salt; TGAI 12

 

1 On June 27, 2012, EPA announced certain revisions in harmonized guideline series 850 – Ecological Effects Tests 

– including renumbering and other designations or changes for some guideline studies. See “Final Test 

Guidelines; OCSPP 850 Series; Notice of Availability” 77 FR 38282, June 27, 2012. 

http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0154-0028

2 Alternatively, submission of an acceptable acute fathead minnow study for endothall acid can be used to calculate 

an acute to chronic ratio (ACR) derived estuarine/marine NOAEC for the acid, and the endpoint can be used for 

the dipotassium salt. 
6

Table 1: Anticipated Data Needs for the Endothall Registration Review

Guideline 

Number1 Study Title1

Test Material

Estimated 

Timeframe

(Months 

from 

receipt of 

DCI)

850.2100 Avian acute oral toxicity; 

passerine species

Mono-N,N,-dimethylalkylamine 

salt; Endothall acid and/or

dipotassium salt; TGAI

12

850.2300 Avian reproduction; bobwhite 

quail

Endothall acid and/or

dipotassium salt; TGAI 24

850.3020 Honeybee acute contact toxicity 

study

Dipotassium salt and monoN,N,- dimethylalkylamine salt; 

TGAI

12

850.30303 Honey bee toxicity of residues 

on foliage

dipotassium salt and monoN,N,-(dimethylalkylamine) salt; 

TEP

12

850.30403 Field testing for pollinators

Dipotassium salt and monoN,N,-dimethylalkylamine salt; 

TEP

24

Nonguideline

Honey bee adult acute oral 

toxicity 

Dipotassium salt and monoN,N,-dimethylalkylamine salt; 

TGAI

12

Nonguideline

Honey bee adult chronic oral 

toxicity 

Dipotassium salt and monoN,N,-dimethylalkylamine salt; 

TGAI

12

NonguidelineHoneybee larval acute oral 

toxicity

Dipotassium salt and monoN,N,-dimethylalkylamine salt; 

TGAI

12

NonguidelineHoneybee larval chronic oral 

toxicity

Dipotassium salt and monoN,N,-dimethylalkylamine salt; 

TGAI

12

Nonguideline3

Residues in pollen and

Nectar/field residue analysis

Dipotassium salt and monoN,N,-dimethylalkylamine salt; 

TEP

24

Nonguideline3

Semi-field testing for pollinators Dipotassium salt and monoN,N,-dimethylalkylamine salt; 

TEP

24

 

3 These studies are anticipated to be included in the DCI. However the need for this data will be determined by EPA 

based upon the results of the Tier 1 honey bee laboratory studies. 
7

Table 1: Anticipated Data Needs for the Endothall Registration Review

Guideline 

Number1 Study Title1

Test Material

Estimated 

Timeframe

(Months 

from 

receipt of 

DCI)

Data Requirements for the Antimicrobial Use 

850.3300 Activated Sludge Respiration 

Inhibition

Mono-N,N,-dimethylalkylamine 

salt; TGAI 12

835.3110 Ready Biodegradation4 Mono-N,N,-dimethylalkylamine 

salt; TGAI 12

835.3220 Porous Pot Study4 Mono-N,N,-dimethylalkylamine 

salt; TGAI 12

835.3240 Simulation Test – Aerobic 

Sewage Treatment4

Mono-N,N,-dimethylalkylamine 

salt; TGAI 12

835.3280 Simulation Test – Assess 

Biodegradability in Wastewater4

Mono-N,N, dimethylalkylamine 

salt; TGAI 12

Outstanding Data Requirements from GDCI-038905-261185

850.1350 Saltwater invertebrate life cycle Mono-N,N,-dimethylalkylamine 

salt; TGAI

Due March 

12, 2008

850.2300 Avian reproduction; mallard 

duck

Mono-N,N,-dimethylalkylamine 

salt; TGAI

Due March 

12, 2009

Outstanding Data Requirements from GDCI-038905-270066

860.1340

Residue analytical methods

(plants and livestock)

Endothall monomethyl ester Due 

September 

4, 2010

860.1500 Crop field trials (alfalfa) Mono-N,N,-dimethylalkylamine 

salt; TEP

Due 

September 

4, 2010

TGAI = technical grade active ingredient; TEP = typical end-use product; PAIRA = Pure Active Ingredient 

Radiolabeled

 

4

 Only one of the four biodegradation studies is needed (Ready Biodegradation, Porous Pot Study, or Simulation 

Test – Aerobic Sewage Treatment, or Simulation Test – Assess Biodegradability in Wastewater). All of these 

studies are anticipated to be included in the DCI, however the results of the Activated Sludge Respiration 

Inhibition (ASRI) test will determine which of biodegradation studies is needed. 

5 The studies listed in this section were previously required through a generic data call-in issued March 12, 2007 and

are still outstanding. These studies will not be included in the anticipated Registration Review DCI because they 

are already required through the earlier DCI.

6 The studies listed in this section were previously required through a generic data call-in issued September 4, 2008 

and are still outstanding. These studies will not be included in the anticipated Registration Review DCI because 

they are already required through the earlier DCI.
8

STATUTORY AND REGULATORY AUTHORITY

The Food Quality Protection Act (FQPA) of 1996 mandated a registration review program. All 

pesticides distributed or sold in the United States (U.S.) generally must be registered by the 

Environmental Protection Agency (EPA or the Agency), based on scientific data showing that 

they will not cause unreasonable risks to human health or the environment when used as directed 

on product labeling. The registration review program is intended to make sure that, as the ability 

to assess risk evolves and as policies and practices change, all registered pesticides continue to 

meet the statutory standard of no unreasonable adverse effects to human health or the 

environment. Changes in science, public policy, and pesticide use practices will occur over time. 

Through the registration review program, the Agency periodically reevaluates pesticides to make 

sure that as change occurs, products in the marketplace can be used safely. Information on this 

program is provided on EPA’s website.

7

The Agency is implementing the registration review program pursuant to Section 3(g) of the 

Federal Insecticide, Fungicide, and Rodenticide Act (FIFRA), and will review each registered 

pesticide every 15 years to determine whether it continues to meet the FIFRA standard for 

registration. The regulations governing registration review begin at 40 CFR 155.40. The 

Agency will consider benefits information and data as required by FIFRA. The public phase of 

registration review begins when the initial docket is opened for each case. The docket is the 

Agency’s opportunity to state what it knows about the pesticide and what additional risk analyses 

and data or information it believes are needed to make a registration review decision. After 

reviewing and responding to comments and data received in the docket during this initial 

comment period, the Agency will develop a Final Work Plan (FWP) and anticipated schedule for 

the registration review of endothall.

CHEMICAL FACTS

Table 2 provides a summary of the chemical facts for endothall.

Table 2: Chemical Facts for Endothall

PC code 038901 (Endothall, acid), 038904 (endothall, dipotassium salt), 

038905 (endothall, mono-N,N-dimethylalkylamine salt)

Case Number 2245

CAS Number 145-73-3 (Endothall, acid), 2164-07-0 (endothall, dipotassium salt), 

66330-88-9 (endothall, mono-N,N-dimethylalkylamine salt)

Year first registered Endothall, acid and endothall, mono-N,N-dimethylalkylamine salt 

were registered in the early 1960’s; endothall, dipotassium salt was 

registered in the early1970’s

Pesticide Type Herbicide 

Chemical class Dicarboxylic acid 

Reregistration Eligibility 

Decision (RED)

September 30, 2005

 

7 http://www2.epa.gov/pesticide-reevaluation
9

Table 2: Chemical Facts for Endothall

Tolerance Reassessment 

Eligibility Decision

(TRED)

Not applicable – the tolerance reassessment was included in the 

RED. 

Cumulative group Not applicable. Endothall has not been identified as a member of a 

cumulative group that shares a common mechanism of toxicity. 

40 CFR Citation Tolerances for endothall are established in 40 CFR 180.293 and an 

interim tolerance is established in 40 CFR 180.319. 

Dual-use Endothall mono-N,N- dimethylalkylamine salt has an antimicrobial

use as an industrial biocide-molluscicide use to control freshwater 

and saltwater mussels in water cooling towers and also has activity 

against slime organisms. 

Non-pesticidal uses There are no identified non-pesticidal uses of endothall. 

Pesticide Re-evaluation 

Division, Chemical 

Review Manager

Garland Waleko, waleko.garland@epa.gov, 703-308-8049

Antimicrobials Division, 

Chemical Review 

Manager

Donna Kamarei, kamarei.donna@epa.gov, 703-347-0443

Registration Division, 

Product Manager

Kathryn Montague, montague.kathryn@epa.gov, 703-305-1234

USE AND USAGE INFORMATION

Table 3 summarizes the use and usage information for endothall. Please see the Bead Chemical 

Profile (BCP) for Registration Review: Endothall (Case 2245 PC Codes 038901-038908) in the 

registration review docket for more details.

Table 3: Endothall Use and Usage Information

Summary of Use The endothall acid (038901) is the active ingredient that forms from 

the breakdown of the endothall salts. The dipotassium salt (PC 

038904) is applied to water to control aquatic vegetation and is used 

as an apple blossom thinner. The amine salt (PC 038905) is applied 

to water to control aquatic weeds and is used as a desiccant on 

alfalfa and clover (grown for seed), cotton, and potatoes; 

additionally there is an antimicrobial use in water cooling towers to 

control mollusks, where it also has activity against slime organisms. 

Use Sites Aquatic applications are made to lakes, ponds and canals. The 

desiccant is used on potatoes, cotton, alfalfa, and clover, and is an 

apple blossom thinner. The antimicrobial use is in water cooling 

towers to control mollusks and slime organisms.

Summary of Usage The agricultural use of endothall has decreased in recent years, to 

4,500 pounds in the period 2004-2008 on cotton and potatoes. No 

usage was reported on potatoes from 2009-2013 and only 150 

pounds on cotton. No data are available on usage on alfalfa and 
10

Table 3: Endothall Use and Usage Information

clover. EPA has very limited usage data for the aquatic uses of 

endothall, with the exception of use in golf course ponds. In 2011, 

3,000 pounds were applied, the most recent year for which EPA has 

data. The other aquatic uses comprise the majority of endothall use 

and have the potential to be large. For example, in Florida alone, 

220,000 pounds were estimated to be used in the period 2004-2005. 

Formulation Type(s) Granular, soluble concentrate

Application Method(s) Aquatic: granular formulations are applied by centrifugal or 

blower-type spreaders mounted to boats or helicopters; Liquid 

formulations by hand wands/gun sprayers, drip or metering 

systems, injection, and aerial equipment. Terrestrial: liquid 

formulations are applied as a broadcast by ground, air blast, or 

aerial equipment. 

Technical Registrant(s) United Phosphorous Inc (UPI)

No. of Registrations Section 3 registrations8: 1 technical endothall acid (PC 038901), 4 

dipotassium salts (038904), and 5 amine salts (038905).

Section 24c registrations: 4 dipotassium salts (038904) (Florida and 

New York), 3 amine salts (038905) (Florida and New York).

Section 18 registrations: 1 endothall acid (PC 038901), Idaho 

Department of Agriculture

Restricted Use No 

Guidance for Commenters: Additional areas of use and usage related information

requested for this registration review, and of particular interest to EPA, are described below.

 Confirmation of the following label information: sites of application; formulations;

application methods and equipment; maximum application rates; frequency of 

application, application intervals, and maximum number of applications per season; and 

geographic limitations on use.

 Use distribution (e.g., acreage and geographical distribution of relevant use sites).

 Median and 90th percentile reported use rates (lbs ai/A) from usage data – national, state, 

and county.

 Typical application timing (date of first application and application intervals) – national, 

state, and county.

 Usage/use information for non-agricultural uses.

 Typical application interval (days).

 State or local use restrictions.

 Foreign technical registrants not listed above who supply technical endothall to the US 

market.

 

8 Section 3 product labels can be obtained from the Pesticide Product Label System (PPLS) website 

(http://oaspub.epa.gov/pestlabl/ppls.home).
11

RECENT ACTIONS

A tolerance petition for endothall on meat, milk, poultry, and eggs to remove the livestock 

watering restrictions for aquatic uses was submitted to the Agency and announced in the January 

14, 2015 Federal Register (80 FR 1911). The Health Effects Division completed a risk 

assessment for this use, dated December 9, 2015 that will serve as the scoping document and 

registration review risk assessment. 

A new use on apple blossoms as a thinner was added and assessed by HED in an assessment 

dated March 18, 2013 (77 FR 50686). EFED also completed an assessment for this new use, 

dated March 19, 2013, with a February 4, 2014 Addendum. 

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW

The most recent comprehensive human health risk assessment for endothall was completed on 

December 9, 2015 for a tolerance petition for endothall on meat, milk, poultry, and eggs to 

remove livestock watering restrictions for aquatic uses and in support of registration review. The 

most recent ecological and environmental fate risk assessment was completed in March 2013 

updated in February 2014 for the new use on apple tree blossoms. Findings and conclusions 

from these risk assessments are summarized in the EFED Registration Review Problem 

Formulation for Endothall and Endothall: Human Health Risk Assessment in Support of 

Registration Review, and the Petition to Re-evaluate Tolerances for Livestock, and Remove the 

Restriction that Prohibits Livestock from Drinking Treated Water.

During registration review, the Agency anticipates the need to conduct a comprehensive

ecological risk assessment, including an endangered species assessment, for all uses of endothall. 

For human health, EPA has conducted a revised dietary, residential, and occupational risk 

assessments for a tolerance petition to remove livestock watering restrictions for aquatic uses and 

for registration review. If toxicological endpoints are revised based on the ecological data that 

are anticipated to be required for registration review, they will be considered in the new 

assessment, as well as any changes to the standard operating procedures or default exposure 

assumptions.

Table 4 below summarizes the anticipated registration review risk assessments based on the 

EFED Problem Formulation and the HED risk assessment.

Table 4: Anticipated/Completed Risk Assessments for the Endothall Registration Review

Type of Risk 

Assessment Conduct? Notes

Ecological and Environmental Fate
12

Comprehensive 

ecological (species to 

be assessed include 

terrestrial and aquatic 

organisms), including 

endangered species 

Yes The Agency will evaluate risks to federally listed 

threatened and endangered species from endothall 

according to the Joint Interim Approaches developed by 

EPA and the Services (U.S. Fish and Wildlife Service and 

National Marine Fisheries). The planned risk assessment 

for the registration review of endothall will describe the 

level of ESA analysis completed for this particular 

registration review case.

Incidents Will check 

for updates

For a discussion of reported ecological incidents for 

endothall, see page 19 of the Problem Formulation.

Human Health

Dietary

Food Yes Complete. Risk estimates for all food and water uses are 

Drinking water Yes below the level of concern.

Occupational

Handlers (mixers, 

loaders, applicators)

Yes Complete. Estimates for occupational handler risk for 

aquatic products indicate that some short- and 

intermediate-term inhalation risks exceed the level of 

concern at the maximum PPE (i.e., engineering controls). 

Post-application Yes A quantitative occupational post-application inhalation 

exposure assessment was not performed at this time. 

Residential

Handlers No Residential handler assessments were not conducted 

because the end-use products specify the use of PPE. 

Standard HED assumptions for residential handlers do not 

include the use of PPE. 

Post-application Yes Complete. Risk estimates for post application exposures 

are below the level of concern. 

Other

Aggregate Yes The combined risk from dietary/drinking water and 

exposure from incidental ingestion of treated water from 

swimming was evaluated. Residential short-term 

aggregate risk is not of concern; acute aggregate risk was 

not assessed, and intermediate-term exposure is not 

expected. The chronic dietary assessment serves as the 

chronic aggregate assessment. Endothall is classified as 

“Not likely to be carcinogenic to humans” through the 

oral, dermal and inhalation routes of exposure; a 

quantitative cancer aggregate assessment is not needed

Cumulative No EPA has not made a common mechanism of toxicity 

finding for endothall.

Tolerances Yes Updated/new tolerances are recommended for several 

commodities.
13

Incidents Yes Incidents for endothall and salts were last reviewed in 

2004. Based on the low frequency and severity of incident 

cases reported, there does not appear to be a concern at 

this time that would warrant further investigation. 

Guidance for Commenters: Additional ecological information requested for this 

registration review, and of particular interest to EPA, is described below.

 Ecological incidents (non-target plant damage and avian, fish, reptilian, amphibian and 

mammalian mortalities) not already reported to the Agency.

 Water quality monitoring data (see Appendix for further details)

TIMELINE

EPA has created the following estimated timeline for the completion of the endothall registration

review in Table 5 below.

Table 5: Projected Endothall Registration Review Timeline

Activities Estimated Date

Opening the Docket

Open Docket and 60-day Public Comment Period 2015 - December

Close Public Comment 2016 - February 

Case Development

Final Work Plan 2016 - May

Issue DCI 2016 - July - September

Data Submission 2018 - July - September

60-day Public Comment Period for Draft Risk 

Assessments9

2020 - January - March 

Registration Review Decision

60-day Public Comment Period for Proposed 

Registration Review Decision

2020 - October - December 

Registration Review Decision and Begin Post-Decision 

Follow-up

2021

Total (years) 6

NEXT STEPS

After the 60-day public comment period closes, the Agency will review and respond to any 

comments received in a timely manner and then issue a Final Work Plan for the registration 

review of endothall. 

 

9 The regulations governing Registration Review generally require the Agency to provide a public comment period 

of at least 30 calendar days for draft risk assessments; see 40 CFR Part 155.53(c). For conventional pesticides, the 

Agency plans to provide a 60 calendar day public comment period generally for draft risk assessments.
14

Appendix – Additional Areas Considered in the Endothall Registration 

Review

PUBLIC COMMENTS AND FEEDBACK:

Guidance for Commenters: The areas below highlight topics of special interest to the Agency 

where your comments, data submissions, or reference to sources of additional information could 

be of particular use.

Trade Irritants:

Through the registration review process, the Agency intends to solicit information on trade 

irritants and, to the extent feasible, take steps toward facilitating irritant resolution. The Agency 

will work to harmonize tolerances and international maximum residue limits (MRLs) and may 

modify tolerance levels to do so, when possible. Growers and other stakeholders are asked to 

comment on any trade irritant issues resulting from lack of MRLs or disparities between U.S. 

tolerances and MRLs in key export markets, providing as much specificity as possible regarding 

the nature of the concern. 

Water Quality:

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.

10

 In addition, no Total Maximum Daily Loads (TMDL) 

have been developed for endothall.

11

 More information on impaired water bodies and TMDLs 

can be found at the Agency’s website.

12 The Agency invites submission of water quality data 

for this pesticide. To the extent possible, data should conform to the quality standards in 

Appendix A of the OPP Standard Operating Procedure: Inclusion of Impaired Water Body and 

Other Water Quality Data in OPP’s Registration Review Risk Assessment and Management 

Process13 in order to ensure they can be used quantitatively or qualitatively in pesticide risk 

assessments.

Environmental Justice:

EPA seeks to achieve environmental justice, the fair treatment and meaningful involvement of all 

people, regardless of race, color, national origin, or income, in the development, implementation, 

and enforcement of environmental laws, regulations, and policies. To help address potential 

environmental justice issues, the Agency seeks information on any groups or segments of the 

population who, as a result of their location, cultural practices, or other factors, may have 

atypical, unusually high exposure to endothall compared to the general population. Please 

comment if you are aware of any sub-populations that may have atypical, unusually high 

exposure compared to the general population

 

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

11http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant

_group_name=PESTICIDES

12 http://www.epa.gov/owow/tmdl/

13 http://www2.epa.gov/pesticide-reevaluation/opp-guidance-submission-state-and-tribal-water-quality-monitoringdata
15

ENDANGERED SPECIES:

A risk assessment that supports a complete endangered species determination has not been 

conducted for endothall. The ecological risk assessment planned during registration review will 

allow the Agency to determine whether use of endothall has “no effect” or “may affect” federally 

listed threatened or endangered species (listed species) or their designated critical habitats. 

When an assessment concludes that a pesticide’s use “may affect” a listed species or its 

designated critical habitat, the Agency will consult with the U.S. Fish and Wildlife Service 

and/or National Marine Fisheries Service (the Services), as appropriate.

ENDOCRINE DISRUPTOR SCREENING PROGRAM:

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

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

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

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

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

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

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

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

taxonomic groups. As part of its reregistration decision for endothall, EPA reviewed these data 

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

chemicals, which contains 58 pesticide active ingredients and 9 inert ingredients. A second list 

of chemicals identified for EDSP screening was published on June 14, 201314 and includes some 

pesticides scheduled for registration review and chemicals found in water. Neither of these lists 

should be construed as a list of known or likely endocrine disruptors. 

 

14 See http://www.regulations.gov/#!documentDetail;D=EPA-HQ-OPPT-2009-0477-0074 for the final second list of 

chemicals.
16

For further information on the status of the EDSP, the policies and procedures, the lists of 

chemicals, future lists, the test guidelines and the Tier 1 screening battery, please visit our 

website.15 Endothall is on List 2. List 2 represents the next set of chemicals for which EPA 

intends to issue test orders/data call-ins in the near future. 

HUMAN STUDIES:

Occupational and Residential

Past endothall risk assessments rely in part on data from studies in which adult human subjects 

were intentionally exposed to a pesticide to determine their dermal and inhalation exposure. 

Many such studies, involving exposure to many different pesticides, comprise generic pesticide 

exposure databases such as the Pesticide Handlers Exposure Database (PHED), the Agricultural 

Handler Exposure Task Force (AHETF) Database, and HED’s SOP for Residential Exposure 

Assessments (Draft; 17-Dec-1997, pg 52-57) modified in HED’s SWIMODEL V1.0 (W. Dang et 

al., 27-March 1999). EPA has reviewed all the studies supporting these multi-pesticide generic 

exposure databases, and has found no clear and convincing evidence that the conduct of any of 

them was either fundamentally unethical or significantly deficient relative to the ethical 

standards prevailing at the time the research was conducted. All applicable requirements of 

EPA’s Rule for the Protection of Human Subjects of Research (40 CFR Part 26) have been 

satisfied, and there is no regulatory barrier to continued reliance on these studies.

 

15 http://www2.epa.gov/endocrine-disruption