2

Aluminum Phosphide, Magnesium Phosphide, and Phosphine Preliminary 

Work Plan – Table of Contents 

Overview 4 

Anticipated Data Needs 5 

Statutory and Regulatory Authority 6 

Chemical Facts 6 

Use and Usage Information 7 

Recent Actions 9 

Anticipated Risk Assessments for Registration Review 9 

Timeline 12 

Next Steps 12 

Appendix – Additional Areas Considered in the Aluminum Phosphide, Magnesium 

Phosphine, and Phosphine Registration Review 13 

References:

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

based on the following documents: 

1. Registration Review: Preliminary Problem Formulation for Environmental Fate, 

Ecological Risk, Endangered Species, and Drinking Water Exposure Assessments for 

Aluminum Phosphide, Magnesium Phosphide, and Phosphine. Lowit, M. and S. Wente. 

September 12, 2013. 

2. Phosphide (Al, Mg) and Phosphine: Human-Health Assessment Scoping Document 

Supporting Registration Review. King, M. T. Morton, and S. Miller. September 11, 2013. 

3. Aluminum Phosphide, Magnesium Phosphide and Phosphine: Review of Human Incidents. 

Recore, S. and E. Evans. May 8, 2013.

4. PRD Label Report: Aluminum Phosphide. April 22, 2013.

5. PRD Label Report: Magnesium Phosphide. December 31, 2012. 

6. PRD Label Report: Phosphine. January 29, 2013. 
3

7. BEAD Chemical Profile for Registration Review Phosphine (066500),

Aluminum Phosphide (066501) and Magnesium Phosphide (066504). Cook, C. August 6, 2012. 

These and other supporting documents for the aluminum phosphide, magnesium phosphide, and 

phosphine registration review case may be found in the docket EPA-HQ-OPP-2013-0081 at 

http://www.regulations.gov. 
4

OVERVIEW

The docket for aluminum phosphide, magnesium phosphide, and phosphine is now open, 

initiating the first public comment period for this registration review (docket number EPA-HQOPP-2013-0081). This case includes the following active ingredients: aluminum phosphide and 

magnesium phosphide (hereafter referred to as “metal phosphides”) and phosphine. Zinc 

phosphide is not included in this registration review case. 

Phosphine is a colorless gas registered for use against stored-product insect pests and vertebrate 

pests, mainly rodents. It is formulated as a pressurized gas and it is also the active ingredient for 

the metal phosphides. The metal phophides are formulated as impregnated materials, 

pellets/tablets, and granules which release phosphine gas upon exposure to atmospheric 

moisture. 

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

knows about the metal phosphides and phosphine, 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 the metal phosphides and phosphine. 

 

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 the metal phosphides and phosphine and 

what types of new data or other information would be helpful for the Agency to receive as it 

moves toward a decision on the metal phosphides and phosphine. 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 Preliminary Work Plan begins by listing the anticipated data needs for the metal phosphides 

and phosphine. 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 the metal 

phosphides and phosphine. 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 the metal phosphides and phosphine. For 

additional discussion of the anticipated data needs, see the Registration Review: Preliminary 

Problem Formulation for Environmental Fate, Ecological Risk, Endangered Species, and 

Drinking Water Exposure Assessments for Aluminum Phosphide, Magnesium Phosphide, and 

Phosphine and Phosphide (Al, Mg) and Phosphine: Human-Health Assessment Scoping 

Document Supporting Registration Review. 

Table 1: Anticipated Data Needs for the Aluminum Phosphide, Magnesium Phosphide 

and Phosphine Registration Review 

Guideline 

Number1 Study Title1 

Test Material 

Estimated 

Timeframe 

(Months from 

receipt of DCI) 

Anticipated Data Needs for the Parent Aluminum Phosphide, Magnesium Phosphide, and 

Phosphine

875.1700 Product use information TEP 12 

875.1400 Inhalation exposure for applicators TEP 24 

875.2500 Post-application inhalation exposure 2 TEP 24 

NonGuideline Extended one-generation reproduction study via 

inhalation route phosphine 36 

NonGuideline Special acute inhalation study phosphine 24 

NonGuideline Ambient air monitoring study TEP 36 

NonGuideline Monitoring data on fumigated commodities TEP 24 

NonGuideline Terrestrial plant toxicity phosphine 12 

NonGuideline Avian acute inhalation toxicity phosphine 24 

NonGuideline Honeybee acute vapor exposure study phosphine 24 

TGAI = technical grade active ingredient; TEP = typical end-use product; 

 

 

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

 This study is needed to assess post-application exposures for workers within and near structural fumigation 

facilities/operations or who work with treated commodities/materials. 
6

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.3

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 the metal phosphides and phosphine. 

CHEMICAL FACTS

Table 2 provides a summary of the chemical facts for the metal phosphides and phosphine. 

Table 2: Chemical Facts for Aluminum Phosphide, Magnesium Phosphide, and Phosphine

Aluminum 

Phosphide 

Magnesium 

Phosphide 

Phosphine 

PC code 066501 066504 066500 

Case Number 0025 0645 7608 

CAS Number 20859-73-8 12-057-74-8 7803-51-2 

Year first registered 1958 1979 1999 

Pesticide Type Insecticide, rodenticide 

Chemical class Fumigant 

Reregistration 

Eligibility Decision 

(RED) 

1998 1998 Registered after 

1984. Not subject to 

review under 

reregistration. 

 

3

 http://www.epa.gov/oppsrrd1/registration_review/ 
7

Table 2: Chemical Facts for Aluminum Phosphide, Magnesium Phosphide, and Phosphine

Tolerance 

Reassessment 

Eligibility Decision 

(TRED) 

Not applicable. 

Cumulative group Not applicable. The metal phosphides and phosphine have not been 

identified as a member of a cumulative group that shares a common 

mechanism of toxicity. 

40 CFR Citation Tolerances are established for residues of the metal phosphides and 

phosphine in 40 CFR §180.225 

Dual-use The metal phosphides and phosphine are registered for conventional 

pesticidal uses only and have no registered antimicrobial or 

biopesticidal uses. 

Non-pesticidal uses There are no identified non-pesticidal uses of the metal phosphides or 

phosphine. 

Pesticide Re-evaluation 

Division, Chemical 

Review Manager 

Dana Friedman, friedman.dana@epa.gov, (703) 347-8827 

Registration Division, 

Product Manager 

Venus Eagle, eagle.venus@epa.gov, 703-308-8045

USE AND USAGE INFORMATION

Table 3 summarizes the use and usage information for the metal phosphides and phosphine. 

Please see the BEAD Chemical Profile for Registration Review Phosphine (066500), 

Aluminum Phosphide (066501) and Magnesium Phosphide (066504) in the registration review 

docket for more details. 

Table 3: Aluminum Phosphide, Magnesium Phosphide, and Phosphine 

Use and Usage Information

Summary of Use Phosphine is a colorless gas registered for use against storedproduct insect pests and vertebrate pests, mainly rodents. It is the 

active ingredient for the metal phosphides, which emit phosphine 

after contact with atmospheric moisture. Phosphine is one of the 

major chemical alternatives to post-harvest uses of methyl bromide, 

which has been phased out under the Montreal Protocol except for 

some special exemptions.

Use Sites Agricultural Uses: Phosphine is registered for use on numerous 

stored raw commodities (i.e. tree nuts, dried fruits, cereal grains), 

animal feed and feed ingredients, and processed foods (i.e. candy, 

bakery mixes, crackers, cheese, meat products). 

Non-Agricultural Uses: 

Phosphine may be used as a space fumigation (mills, food plants, 

warehouses); as a vehicle fumigation (railcars, trucks, vans, 
8

Table 3: Aluminum Phosphide, Magnesium Phosphide, and Phosphine 

Use and Usage Information

containers);; and as a vessel or ship fumigation. Phosphine is also 

registered for use on numerous non-food commodities and other 

non-food items. These include tobacco, cloth fibers, feathers, hair, 

wood and wood products, paper, tires, and beehives.. 

In addition, metal phosphine pellets/tablets are registered for use for 

rodent control, especially burrowing pests. 

Summary of Usage EPA has very limited usage data for the metal phosphides and 

phosphine. According to Kline and Company, during the 2002-

2003 time periods, aluminum phosphide was the leading active 

ingredient used on stored grains (wheat, com, rice, and soybeans) 

with 791,000 pounds sold, which was 43% of the market. 

Based on information from California’s Department of Pesticide 

Regulation’s use reports, use of these fumigants in recent years has 

been above average, particularly that of phosphine. This increase is 

explained by two major factors, a new phosphine product was 

introduced that allows for better control and target fumigations and 

the reduction of availability of methyl bromide in this market 

because of the Montreal Protocol obligations. 

Formulation Type(s) Phosphine is formulated as a pressurized gas. The metal phosphides 

are formulated as impregnated materials, pellets/tablets, and 

granules.

Application Method(s) Cylinderized canisters of phosphine may be pre-blended or blended 

on site, and dispensed with carbon dioxide or forced air using 

blending equipment. 

Pellets/tablets may be spread along the surface of 

a commodity, through a probe/pipe into the commodity, or using a 

dispensing machine. They may also be placed in a tray near the 

commodity. 

Pellets or tablets are placed into the rodent burrows. These 

products may not be used in burrows that are within 100 feet of a 

building that is, or may be, occupied by humans and/or domestic 

animals.

Technical Registrant(s) Aluminum Phosphide: All registrations are end-use products. Enduse registrants are: Bernardo Chemicals, Inc., D&D Holdings, Inc., 

Douglas Products and Packaging Company, ROC Enterprises, LLC, 

and United Phosphorus, Inc. 

Magnesium Phosphide: All registrations are end-use products. 

End-use registrants are: D&D Holdings, Inc. and United 

Phosphorus, Inc. 
9

Table 3: Aluminum Phosphide, Magnesium Phosphide, and Phosphine 

Use and Usage Information

Phosphine: All registrations are end-use products. The end-use 

registrant is Cytec Industries. 

No. of Registrations Aluminum Phosphide: 

Section 3 products: 20 

Magnesium Phosphide:

Section 3 products: 5 

Phosphine: 

Section 3 products: 2 

Restricted Use Yes 

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. 

 Usage/use information for agricultural and non-agricultural uses including: indoor 

fumigation of raw agricultural commodities, animal feeds, processed food commodities, nonfood commodities in sealed containers or structures, and outdoor fumigation of burrows to 

control rodents and moles in non-domestic areas, non-cropland, and agricultural areas.

 Information about the characteristics of the treatment facilities in which phosphine is 

used including building size (dimensions), emission control devices (if any), and the 

number, size, and relative location of stacks and vents that serve as the release points 

during phosphine aeration operations. 

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

application methods and equipment; aeration methods and equipment; maximum 

application rates; frequency of application, and application intervals. 

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

 Median and 90th percentile reported use rates from usage data – national, state, and 

county. 

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

state, and county. 

 State or local use restrictions. 

 Foreign technical registrants not listed above who supply technical metal phosphides or 

phosphine to the US market. 

RECENT ACTIONS

In 2010, the Agency expanded and clarified restrictions on aluminum and magnesium phosphide 

products to better protect bystanders from exposure. The new restrictions prohibit all uses of the 

metal phosphide products around residential areas and increase buffer zones for treatment around 

non-residential buildings that could be occupied. Additional information on these restrictions is 

located at http://www.epa.gov/oppsrrd1/reregistration/alphosphide/aluminum-magnsm-phosfs.html.
10

On March 21, 2013, the Agency accepted a label amendment to the phosphine products for an 

increase in the use rate and to add certain food and non-food commodities that were already on 

the metal phosphide labels. 

ANTICIPATED RISK ASSESSMENTS FOR REGISTRATION REVIEW

The most recent comprehensive human health risk assessment for the metal phosphides was 

completed in June 1998 in preparation for the Reregistration Eligibility Decision (RED) and 

subsequently updated in December 1998 to provide dietary exposure and risk estimated with the 

Dietary Exposure Evaluation Model (DEEM). The most recent ecological and environmental 

fate risk assessments were completed in 1998 for RED and in 2010 concerning the risk to several 

federally threatened and endangered species. Findings and conclusions from these risk 

assessments are summarized in the Registration Review: Preliminary Problem Formulation for 

Environmental Fate, Ecological Risk, Endangered Species, and Drinking Water Exposure 

Assessments for Aluminum Phosphide, Magnesium Phosphide, and Phosphine and Phosphide 

(Al, Mg) and Phosphine: Human-Health Assessment Scoping Document Supporting Registration 

Review. 

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

ecological risk assessment, including an endangered species assessment, for the metal 

phosphides and phosphine. 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 are revised based on the data that are anticipated to 

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

Table 4: Anticipated Risk Assessments for the Aluminum Phosphide, Magnesium Phosphide, and 

Phosphine 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 will be the metal phosphides 

and phosphine. Phosphine released from structures or 

within burrows comprise the primary exposure 

pathways of concern for terrestrial organisms. 

Aquatic exposure to phosphine is assumed minimal. 

Terrestrial (above ground) and aquatic exposure to the 

metal phosphides is not expected. 

Incidents Will check for 

updates 

For a discussion of reported ecological incidents for 

the metal phosphides and phosphine, see page 12 of 

the Problem Formulation. 

Human Health 

Dietary 
11

Food Y A new dietary exposure and risk assessment may be 

required during Registration Review to incorporate 

potential changes to the phosphine toxicological 

points of departure (PODs). 

Drinking water N Given the use pattern and the physical/chemical 

properties of the metal phosphides and phosphine, 

there is a low exposure potential for ground and 

surface water.

Occupational 

Handlers (mixers, loaders, 

applicators) 

Y A new occupational handler risk reassessment will 

incorporate new data, updated PODs, and, to the 

extent that they are available, policies currently under 

development regarding assessment of fumigant 

chemicals. 

Post-application Y A new occupational post-application risk 

reassessment will incorporate new data, updated 

PODs, and, to the extent that they are available, 

policies currently under development regarding 

assessment of fumigant chemicals. 

Residential 

Handlers N The metal phosphides and phosphine are restricted 

use pesticides, so residential handlers are prohibited 

from applying these products. 

Post-application N Metal phosphide and phosphine exposure to 

occupants of fumigated structures is expected to be 

negligible given proper aeration procedures. 

Bystander Y Bystander risk (anyone not part of the fumigation) 

from metal phosphide and phosphine emissions from 

treated commodities and structures will need to be 

evaluated based label prescribed use conditions, and if 

the PODs or uncertainty factors (UFs) change based 

on acute toxicological data identified. 

Other 

Aggregate Y Evaluates the combined risk from dietary and 

residential exposures. 

Cumulative N The metal phosphides and phosphine are not members 

of a cumulative group, so no cumulative risk 

assessment is planned. 

Tolerances Y Tolerances are established for residues of the 

fumigants aluminum phosphide, magnesium 

phosphide and phosphine gas in 40 CFR §180.225. 

Incidents Will check for 

updates 

For a discussion of reported human incidents for the 

metal phosphides and phosphine see page 12 of the 

Scoping Document and the Aluminum Phosphide, 

Magnesium Phosphide and Phosphine: Review of 

Human Incidents. 
12

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 metal phosphides and 

phosphine registration review in Table 5 below. 

Table 5: Projected Aluminum Phosphide, Magnesium Phosphide, and Phosphine 

Registration Review Timeline

Activities Estimated Date

Opening the Docket 

Open Docket and 60-day Public Comment Period 2013 – September

Close Public Comment 2013 – November

Case Development 

Final Work Plan 2014 – February

Issue DCI 2014 April - June

Data Submission 2017 April - June

60-day Public Comment Period for Draft Risk 

Assessments4

2018 Oct. – Dec.

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) 7

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 the metal phosphides and phosphine. 

 

 

4

 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. 
13

Appendix – Additional Areas Considered in the Aluminum Phosphide, 

Magnesium Phosphide, and Phosphine 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: 

The metal phosphides and phosphine are not identified as a cause of impairment for any water 

bodies listed as impaired under section 303(d) of the Clean Water Act.5

 In addition, no Total 

Maximum Daily Loads (TMDL) have been developed for the metal phosphides or phosphine.6 

More information on impaired water bodies and TMDLs can be found at the Agency’s website.7

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 Process8 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 the metal phosphides or phosphine 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.

 

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

6

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

group_name=PESTICIDES

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

8 http://www.epa.gov/oppsrrd1/registration_review/water_quality_sop.htm
14

ENDANGERED SPECIES:

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

conducted for the metal phosphides or phosphine. The ecological risk assessment planned 

during registration review will allow the Agency to determine whether use of the metal 

phosphides or phosphine “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 most recent registration decision for the metal phosphides and 

phosphine, 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), the metal phosphides and phosphine are 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, 20139

 and includes some 

 

9

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

chemicals. 
15

pesticides scheduled for Registration Review and chemicals found in water. 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.10 

In the interim, EPA is making no human health or environmental safety findings associated with 

the EDSP screening of the metal phosphides and phosphine. Before completing this Registration 

Review, the Agency will make an EDSP FFDCA section 408(p) determination. 

HUMAN STUDIES:

Chemical-specific Human Studies 

Past metal phosphide and phosphine risk assessments have relied in part on human studies which 

may have involved intentional exposure to the metal phosphides and phosphine. In the course 

of registration review EPA will reconsider these studies, as well as any other research involving 

intentional exposure of human subjects to the metal phosphides and phosphine brought to its 

attention. If EPA decides to rely on any of these studies, EPA will ensure that all applicable 

regulatory requirements are met, including, but not limited to, the requirements for EPA ethics 

review and Human Studies Review Board review of certain research involving intentional 

exposure of human subjects. 

AGRICULTURAL HEALTH STUDY:

Aluminum phosphide is among several agricultural chemicals included in the Agricultural 

Health Study (AHS). The AHS began in 1993 and is a collaboration of the National Institute of 

Environmental Health Sciences (NIEHS), the National Cancer Institute (NCI), the EPA, and the 

National Institute for Occupational Safety and Health (NIOSH). Designed as a large long-term 

epidemiological study, the AHS collects and analyzes data on the health and work practices of 

nearly 90,000 farmers and their families in Iowa and North Carolina who enrolled in the study 

before any disease developed. The study focuses particularly on farmers' exposure to 50 

chemicals including many of the most widely used pesticides. As data are collected over a 

period of years, scientists can compare overall health outcomes for people who differ in whether 

they have had exposure to various chemicals. While these comparisons cannot conclusively 

demonstrate how exposure affects health, they can show some statistical associations. More 

information on the AHS can be found at: http://aghealth.nci.nih.gov. EPA is monitoring the 

results of the AHS and will consider this study in the registration review of aluminum phosphide 

as appropriate. 

 

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