2

Mesotrione Preliminary Work Plan – Table of Contents 

 

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

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

STATUTORY AND REGULATORY AUTHORITY ................................................................... 7

CHEMICAL FACTS ...................................................................................................................... 7

USE AND USAGE INFORMATION ............................................................................................ 8

RECENT ACTIONS ....................................................................................................................... 9

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW ................................ 9

TIMELINE .................................................................................................................................... 11

NEXT STEPS ............................................................................................................................... 12

Appendix – Additional Areas Considered in the Mesotrione Registration Review ................. 13 

References: 

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

based on the following documents: 

1. Problem Formulation for the Environmental Fate, Ecological Risk, Endangered Species, 

and Drinking Water Exposure Assessments in Support of the Registration Review of 

Mesotrione. I. Maher and M. Wagman. June 3, 2014. 

2. Mesotrione. Human-Health Assessment Scoping Document in Support of Registration 

Review. S. Levy, K. Lowe, and M. Perron. June 4, 2014. 

3. Mesotrione: Tier I Review of Human Incidents. E. Evans and S. Recore. February 6, 2014 

4. BEAD Chemical Profile (BCP) for Registration Review: Mesotrione (122990). S. 

Ratnayake, D. Atwood, S. Smearman. April 9, 2014

5. Mesotrione (122990) Screening Level Usage Analysis (SLUA). March 12, 2013 

6. EFED Table 1 Report. April 15, 2014
3

7. HED Master Label Report. April 15, 2014

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

in the docket EPA-HQ-OPP-2013-0779 at http://www.regulations.gov. 

 
4

OVERVIEW 

The docket for mesotrione is now open, initiating the first public comment period for this 

registration review (docket number EPA-HQ-OPP-2013-0779). Mesotrione is a selective 

herbicide registered for use to control broadleaf weeds in many agricultural and non-agricultural 

use sites. This Preliminary Work Plan (PWP) document explains what EPA's Office of Pesticide 

Programs knows about mesotrione, 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 

mesotrione.

 

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 mesotrione and what types of new data or 

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

mesotrione. 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 

decision-making 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 PWP begins by listing the anticipated data needs for mesotrione. 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 mesotrione. 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 mesotrione. For additional discussion of 

the anticipated data needs, see the Problem Formulation for the Environmental Fate, Ecological 

Risk, Endangered Species, and Drinking Water Exposure Assessments in Support of the 

Registration Review of Mesotrione and Mesotrione. Human-Health Assessment Scoping 

Document in Support of Registration Review. 

Table 1: Anticipated Data Needs for the Mesotrione Registration Review 

Guideline 

Number1 Study Title1 

Test Material 

Estimated 

Timeframe 

(Months 

from receipt 

of DCI) 

Anticipated Data Needs for the Parent Mesotrione

835.4200 Anaerobic soil metabolism2 TGAI 24 

835.4300 Aerobic aquatic metabolism3 TGAI 24 

835.4400 Anaerobic aquatic metabolism4 TGAI 24 

835.6100 

Analytical methods with Storage Stability5

(additional information needed to support 

previously submitted water monitoring study) 

TGAI 12 

 850.1350 Estuarine/Marine Invertebrate Chronic 

Toxicity Study6

TGAI 12 

850.6100 Analytical method in soil7 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

 An anaerobic soil metabolism study is expected to be required for soils under different pH conditions characteristic 

for mesotrione use areas. 

3

 The study was conducted on two British natural water-sediment systems at two pHs. The microbial makeup of the 

studied system may not be similar to the one in the US. A new study conducted on US natural-water sediment 

systems in variety of pHs typical in mesotrione use areas is expected to be required. 4

 The results obtained in this study are essentially the same as those from the two different aerobic aquatic systems. 

This could suggest that metabolism progresses under suboxic conditions, and may be more influenced by pH than 

lower oxygen content. An additional study is expected to be required to verify this assumption. 

5

This information is needed for the purpose of upgrading an unacceptable Surface Water Monitoring study to 

supplemental. The surface water samples were stored for up to 18 months before analysis. If upgraded, the available 

surface water data could be used for qualitative characterization or even used more quantitatively (chronic exposure 

results) in the risk assessment. 

6

 Since the mysid was significantly more (~2 orders of magnitude) acutely toxic than the daphnid, chronic data are 

expected to be required. The results of this study will be used to generate an ACR and be applied to the freshwater 

invertebrate acute endpoints. 

7

 Inadequacy was noted of soil extraction methods for aged soil. As a result the extraction and separation of 

mesotrione and degradates/metabolites were not reliable and quantitatively efficient. 
6

Table 1: Anticipated Data Needs for the Mesotrione Registration Review 

Guideline 

Number1 Study Title1 

Test Material 

Estimated 

Timeframe 

(Months 

from receipt 

of DCI) 

850.6100 Analytical method in water and sediment.8 TGAI 12 

Nonguideline 

Drinking water treatment methods9

(additional information needed to support 

previously submitted water monitoring study) 

TGAI 8 

Anticipated Data Needs for the Degradates 

835.4100 Aerobic soil metabolism MBNA 24 

835.4300 Aerobic aquatic metabolism MBNA 24 

850.1035 Estuarine/Marine invertebrate acute toxicity10 MNBA 12 

850.6100 

Analytical method in soil MNBA & 

AMBA 12 

Analytical method in water and sediment. MNBA & 

AMBA 12 

850.4100 Terrestrial Plant Seedling Emergence Tier II 

Study11 MNBA 12 

TGAI = technical grade active ingredient; 

 

 

8

 The methods are expected to be required to support monitoring for mesotrione residues on current and newly 

submitted environmental fate and ecological effects data. 

9

 Information on the types of treatment that were used in surface water samples from the monitoring study (MRID 

47244503) to obtain drinking water are expected to be required. The surface monitoring study had no detections of 

mesotrione in finished water. The sampling was conducted at the same time and in the same locations as that for 

untreated water, but there is no information as to the types of treatment that were used to obtain finished water. 10 MNBA was more acutely toxic than the parent to freshwater invertebrates. An acute mysid study with the MNBA 

degradate is expected to be required. 

11 Seedling emergence data are expected to be required for MNBA’s effects. The recommended species are the most 

sensitive ones from the parent mesotrione dataset, onion (for monocot species), lettuce and cabbage (for dicot 

species). 
7

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.12

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 mesotrione. 

CHEMICAL FACTS 

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

Table 2: Chemical Facts for Mesotrione

PC code 122990 

Case Number 7256 

CAS Number 104206-82-8 

Year first registered 2001 

Pesticide Type Herbicide 

Chemical class Triketone 

Reregistration Eligibility 

Decision (RED) 

Because it was registered after November 1984, mesotrione was 

not subject to reregistration. 

Tolerance Reassessment 

Eligibility Decision (TRED) 

Because it was registered after November 1984, mesotrione was 

not subject to tolerance reassessment. 

Cumulative group Not applicable. Mesotrione has not been identified as a 

member of a cumulative group that shares a common 

mechanism of toxicity. 

 

12 http://www.epa.gov/oppsrrd1/registration_review/ 
8

40 CFR Citation Tolerances for mesotrione are established in 40 CFR Part 

180.571 (a) 

Dual-use Mesotrione is registered for conventional pesticidal uses only 

and has no registered antimicrobial or biopesticidal uses. 

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

Pesticide Re-evaluation 

Division, Chemical Review 

Manager 

Jolene Trujillo 

trujillo.jolene@epa.gov

703-347-0103 

Registration Division, 

Product Manager 

Kathryn Montague 

montague.kathryn@epa.gov

703-305-1243 

USE AND USAGE INFORMATION 

Table 3 summarizes the use and usage information for mesotrione. Please see the BEAD 

Chemical Profile (BCP) for Registration Review: Mesotrione (122990) in the registration review 

docket for more details. 

Table 3: Mesotrione Use and Usage Information

Summary of Use Mesotrione is a selective herbicide registered for use to control 

broadleaf weeds in many agricultural and non-agricultural use 

sites.

Use Sites AGRICULTURAL USE SITES: 

blueberries, caneberries, cranberries, rhubarb, popcorn, field corn, 

grass grown for seed, sod, sweet corn, okra, asparagus, millet 

(pearl and proso), oats, sorghum (grain and sweet), sugarcane, 

flax, and soybeans. 

NON-AGRICULTURAL USE SITES: 

lawns, ornamental turf (i.e. commercial lawn, golf courses, 

cemeteries, and athletic fields), ornamental flowering plants 

(cuphea), and recreational areas. 

Summary of Usage A review of total mesotrione usage data for the last 5 years 

indicates that the primary use site is corn, accounting for 

approximately 98% of both total pounds applied and total acres 

treated. Field corn represents the highest percent crop treated in 

terms of acres grown and acres treated at 20.2%. Usage data is not 

available for mesotrione use in non-agricultural sites.

Formulation Type(s) Granular, water dispersible granules, emulsifiable concentrate, 

soluble concentrate, solution-ready to use, pressurized liquid, and 

soluble concentrate/solid 

Application Method(s) Mesotrione is applied pre- and post-emergence through ground or 

aerial application equipment

Technical Registrant(s) Syngenta Crop Protection 
9

No. of Registrations 27 Section 3 registrations13

1 Experimental Use Permit 

14 Section 24c registrations 

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. 

 The Agency currently does not have information regarding total pounds active ingredient 

applied, percent crop/site treated, application rates: typical and maximum, frequency of 

application, application intervals, methods of application and target pests for the 

following registered agricultural sites: okra, oats, and flax. This information may improve 

future assessments conducted by the Agency related to the use and importance of 

mesotrione. 

 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 mesotrione to the US 

market. 

RECENT ACTIONS 

There are several pending PRIA actions under review for the following proposed new uses: 

citrus fruit, palm, stone fruit, tree nuts, almond hulls, and mesotrione-tolerant soybeans. 

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW 

The most recent comprehensive human health risk assessments for mesotrione were completed in 

2009 and 2010 for a new use request. The most recent ecological and environmental fate risk 

assessments were completed in 2008 and 2013 for the same purpose. Findings and conclusions 

from these risk assessments are summarized in the Problem Formulation for the Environmental 

Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments in 

Support of the Registration Review of Mesotrione and Mesotrione. Human-Health Assessment 

Scoping Document in Support of Registration Review. 

 

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

(http://oaspub.epa.gov/pestlabl/ppls.home). 
10

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

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

mesotrione. For human health, EPA anticipates the need to conduct revised dietary, residential, 

and occupational risk assessments during registration review. If toxicological endpoints or 

points of departure (PODs) are revised based on the data that are anticipated to be required for 

registration review, they will be considered in the new assessments, as will 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 HED Scoping Document. 

Table 4: Anticipated Risk Assessments for the Mesotrione Registration Review 

Type of Risk Assessment Conduct? Notes 

Ecological and Environmental Fate 

Comprehensive ecological 

(species to be assessed 

include terrestrial and aquatic 

organisms), including 

endangered species 

Y The stressors of concern are mesotrione and 

mesotrione’s major degradates, MNBA and AMBA. 

A total toxic residues (TTR) approach will be used for 

the ecological risk assessment. The drinking water 

assessments conducted to support future human health 

risk assessments of mesotrione will incorporate 

modeling of the parent only in surface and 

groundwater. See page 26 of the Problem Formulation 

for more detail. 

Incidents Will check for 

updates 

For a discussion of reported ecological incidents for 

mesotrione, see page 23 of the Problem Formulation. 

Human Health 

Dietary 

Food Y A revised dietary exposure analysis may be required 

to reflect the most recent dietary exposure models, 

potential revised Estimated Drinking Water 

Concentrations (EDWCs), and/or changes to the 

toxicological PODs. 

Drinking water Y 

Occupational 

Handlers (mixers, loaders, 

applicators) 

Y During registration review, updated occupational 

assessments will be conducted to reflect all currently 

registered uses. In addition, assessments for all uses 

may be updated if toxicological PODs are revised. 

Post-application Y 

Residential 

Handlers Y A higher application rate for handheld equipment was 

identified during the label review process. This 

higher rate will need to be assessed. 

Post-application N 

Other 
11

Aggregate Y New aggregate risk assessment may be required 

during registration review to incorporate revised 

dietary exposure analyses, revised residential 

exposure assessments, and/or changes to the 

toxicological PODs. 

Cumulative N Mesotrione has not been identified as a member of a 

cumulative group that shares a common mechanism 

of toxicity in mammals. 

Tolerances N Adequate methods are available for enforcement of 

the currently established tolerances. 

Incidents Will check for 

updates 

For a discussion of reported human incidents for 

mesotrione, see pages 10 and 11 of the Scoping 

Document and the Mesotrione: Tier I Review of 

Human Incidents.

TIMELINE 

EPA has created the following estimated timeline for the completion of the Mesotrione 

registration review in Table 5 below. 

Table 5: Projected Mesotrione Registration Review Timeline

Activities Estimated Date

Opening the Docket 

Open Docket and 60-day Public Comment Period 2014- June 

Close Public Comment 2014- August 

Case Development 

Final Work Plan 2014- November 

Issue DCI 2015 Jan.-March 

Data Submission 2017 Jan.-March 

60-day Public Comment Period for Draft Risk 

Assessments14

2018- July- Sept. 

Registration Review Decision 

60-day Public Comment Period for Proposed 

Registration Review Decision 

2019- April- June 

Registration Review Decision and Begin Post-Decision 

Follow-up 

2020 

Total (years) 6 

 

14 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. 
12

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 Mesotrione. 

 
13

Appendix – Additional Areas Considered in the Mesotrione 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: 

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

under section 303(d) of the Clean Water Act.15 In addition, no Total Maximum Daily Loads 

(TMDL) have been developed for Mesotrione.16 More information on impaired water bodies and 

TMDLs can be found at the Agency’s website.17 The Agency invites submission of water 

quality data for this pesticide. To the extent possible, submissions should include the key data 

elements noted in the OPP Guidance for Submission of State and Tribal Water Quality 

Monitoring Data18 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 Mesotrione 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.

ENDANGERED SPECIES: 

 

15 http://iaspub.epa.gov/tmdl_waters10/attains_nation_cy.cause_detail_303d?p_cause_group_id=885 16http://iaspub.epa.gov/tmdl_waters10/attains_nation.tmdl_pollutant_detail?p_pollutant_group_id=885&p_pollutant

_group_name=PESTICIDES 17 http://www.epa.gov/owow/tmdl/ 18 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm
14

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

conducted for Mesotrione. The ecological risk assessment planned during registration review 

will allow the Agency to determine whether use of Mesotrione 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 the most recent registration decision for mesotrione, 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), 

mesotrione 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, 201319 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. 

 

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

chemicals. 
15

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.20

HUMAN STUDIES: 

Occupational and Residential 

Past mesotrione 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 

Reentry Task Force (ARTF) Database, and the Outdoor Residential Exposure Task Force 

(ORETF) Database. 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. 

 

20 http://www.epa.gov/endo/