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Overview of the Endocrine 

Disruptor Screening Program

Mary Manibusan, Director 

Endocrine Disruptor Screening Program

Office of Science Coordination and Policy
EDSP Program Overview:

 Mission of the Endocrine Disruptor Screening 

Program: FFDCA and SDWA 1996

 Recommendations of the Endocrine Disruptor 

Screening and Testing Advisory Committee, 

1998

 Program Implementation: Data Review 

Process “Roadmap” 

 Current State of the Science: 2013 FIFRA 

Scientific Advisory Panel Reviews 

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EDSP Mission

To protect public health and wildlife by screening 

and testing chemicals and taking appropriate 

actions for those chemicals that are found to have 

endocrine effects.

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Legislative Mandate

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 1996 Federal Food, Drug and Cosmetic Act, section 408(p)

Requires the U. S. EPA to develop a screening program using 

appropriate validated test systems and other scientifically relevant 

methods to determine whether certain substances may have an effect 

in humans that is similar to an effect produced by a naturally 

occurring estrogen, or other such endocrine effect as the 

Administrator may designate. 

 1996 Safe Drinking Water Act Amendments, section 1457

Testing of chemical substances that may be found in sources of 

drinking water, if substantial human populations may be 

exposed.
Endocrine Disruptor Screening and Testing Advisory 

Committee (EDSTAC), 1998

EDSTAC Key Recommendations:

 Expand Protection to Include Human Health and Wildlife

 Include Estrogen, Androgen and Thyroid Pathways

 Develop a Two-Tiered Screening and Testing Program: 

EDSTAC Conceptual Framework:

Tier 1 Screening for Potential to Interact

Potential to interact with the estrogen, androgen or thyroid hormone 

systems

Tier 2 Testing to determine Interaction with the endocrine system

If endocrine-mediated adverse effects then quantify dose-response 

relationship

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EDSP Tier 1 Screening Battery, 2008 

In vitro 

Estrogen Receptor (ER) Binding

Estrogen Receptor Transcriptional Activation Assay (ERTA)

Androgen Receptor (AR) Binding

Steroidogenesis

Aromatase

In vivo 

Uterotrophic (rat)

Hershberger (rat)

Pubertal Female (rat) 

Pubertal Male (rat) 

Amphibian Metamorphosis Assay (frog)

Fish Short-Term Reproduction Assay (fish)
Steroid Synthesis

Pubertal female X X X X X

In vivo

In vitro

ER Transcriptional X

Activation

X

X

HPT

X

X

HPG

Aromatase (Recombinant) X

Uterotrophic X

Hershberger X X

Pubertal male X X X

Steroidogenesis (H295R) X X

AR Binding X X

ER Binding X X

E E- A A- T E

Amphibian Metamorphosis

Fish Reproductive Screen X X X X X X

Steroid Synthesis

Pubertal female X X X X X

In vivo

In vitro

ER Transcriptional X

Activation

X

X

HPT

X

X

HPG

Aromatase (Recombinant) X

Uterotrophic X

Hershberger X X

Pubertal male X X X

Steroidogenesis (H295R) X X

AR Binding X X

ER Binding X X

E E- A A- T E

Amphibian Metamorphosis

Fish Reproductive Screen X X X X X X

EDSP Tier 1 Screening Assays

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Proposed EDSP Tier 2 Test Methods

Mammalian

Mammalian Two-Generation Reproduction (Rat)

Extended One Generation Reproduction (Rat)

Ecological

Avian Multi-Generation Reproduction (Japanese quail)

Larval Amphibian Growth and Development (Xenopus laevis)

Fish Multi-Generation Reproduction (Medaka) 

Invertebrate Multi-Generation Reproduction (Mysid and Copepod) 
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Comparison of Tier 1 and Tier 2

Tier 1 Screening

 Shorter term and Lower 

Cost

 Minimize False Negative

 Potential to Interact (y/n)

 Limited Doses

 In vitro and In vivo

 Battery – all 11 assays

Tier 2 Testing

 Longer term, definitive 

studies

 Interaction and dose

 Dose Response

 In vivo: Multiple Taxa

 Targeted testing
From Prioritization to Screening and 

Testing: EDSP Roadmap

January SAP Step1:

Prioritization of 

Chemicals for 

Tier 1 Screening 

using effects 

based chemical 

categorization 

and exposure 

data.

May and July SAPStep 2: Tier 1 

assay data 

review 

Step 3: weight 

of evidence 

determinations 

with other 

scientifically 

relevant data

June SAPStep 4: Tier 2 

Assays Data 

review

Multigeneration

reproduction 

studies 

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Step 1: Prioritization of EDSP Universe of Chemicals: SAP January 29-31st, 2013

Step 2: Tier 1 assay and battery: SAP May 21-23rd, 2013

Step 3: Weight of Evidence Review: SAP July 30-August 2, 2013

Step 4: Validation of Tier 2 test methods: SAP June 25-28, 2013
Step 1: Chemical Prioritization: 

FIFRA SAP January 29-31, 2013

 Focus and Objective:

1. Prioritization of the universe of chemicals for 

estrogen receptor adverse outcome pathway 

using computational toxicology tools

2.To obtain input and recommendations on the 

scientific concepts, principles and processes used 

to prioritize chemicals for EDSP screening.

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EDSP Universe of 

Chemicals n= 10,341

Chemical 

Lists

FIFRA Registration Review 

Schedule for Active 

Ingredients (Approx.=1500)

SDWA and INERTS 

(Approx.=9000) 

PhysicoChemical 

Properties 

(Approx 

n=5000)

Excluded

Exposure 

Potential

SDWA

Lower 

Priority 

ER Expert System

High through put 

system

Prioritized List of Chemicals 

for EDSP Tier 1 Screening

yes

No

* Mixtures will be lower priority

no

Yes

Considerations of Read 

Across and Chemical 

Categories

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Step 1: Chemical January SAP

Prioritization Method
Step 2: FIFRA SAP May 21-23, 2013

 Focus and Objective:

• 1. Performance of EDSP Tier 1 Individual Assays

• 2. Performance of the EDSP Tier 1 Battery

“Convene a panel of independent

scientists to review all the screening

data for 50-100 compounds, with an eye

towards revising the process and 

eliminating those methods that

don’t work.” (SAB/SAP panel in 1999)

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SAP 2008: Tier 1 Battery Review

 Open and transparent public process for 

independent, external scientific peer review

 Based on current state of the science, Tier 1 

assays and battery are capable of identifying 

potential E, A, T endocrine activities.

 Appropriate starting point to detect potential 

endocrine disruptors

 Multiple taxa and mode of action endpoints 

provide a range of metabolism and needed 

corroboration

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SAP 2013: Tier 1 Assay Review

 21 chemicals selected for this evaluation: a range of 

physico-chemical properties and biological activity

 Tier 1 assays provide useful information to evaluate 

potential interactions with the E, A, and T signaling 

pathways. 

 No major problems identified with the Tier 1 assays

 Laboratories were able to execute each assay protocol 

in accordance with the respective test guidelines and 

achieve the specified performance criteria. 

 Some minor deviations from the performance criteria, 

but differences were not substantial

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SAP 2013: Tier 1 Battery Review

 Thyroid: AMA and the rat pubertal studies can provide 

different types of information and it reinforces the 

importance of including both taxa in the screening battery 

to reduce the potential for false negatives.

 Androgen: in vitro assays do not consistently exhibit 

significant effects when effects are observed in the in vivo

assays. Possible redundancy across the in vivo assays 

(Hershberger, male pubertal, and FSTRA), albeit some with 

observation of overt toxicity

 Estrogen: female rat pubertal and fish assays are important 

in evaluating the E pathway across taxa. The uterotrophic

assay was consistently negative for all the chemicals. Note:

no representative estrogen agonist in the subsample.

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Fundamental Charge to the Panel

1.Overall comment on the assay (laboratory) 

performance and advice on how to address 

technical deviations and other issues 

encountered with specific assays.

2. Overall comment on the Tier 1 battery 

performance and whether there are 

unnecessary redundancies among the 11 

assays.

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“The whole is greater than the sum of its parts.” Aristotle 

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Acknowledgements:

1. Jess Rowland, OPP

2. Gregory Akerman, OPP

3. John Liccione, OPP

4. Amy Blankinship, OPP

5. Catherine Aubee, OPP

6. Thomas Steeger, OPP

7. Vicki Dellarco, OPP

8. Patience Browne, OSCP

9. Don Bergfelt, OSCP

10. Calvin Powell, OPP

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USEPA Presentations

Background: Current Validated EDSP Tier 1 Screening Assays and Battery, Leslie 

Touart, Ph.D., Exposure Assessment Coordination and Policy Division, Office of 

Science Coordination and Policy, EPA

 

In Vitro Assays, Gregory Akerman, Ph.D., Health Effects Division, Office of Pesticide 

Programs, EPA

In Vivo Mammalian Assays, John Liccione, Ph.D., Health Effects Division, Office of 

Pesticide Programs, EPA

Fish Assay, Amy Blankinship, M.S., Environmental and Fate Effects Division, Office of 

Pesticide Programs, EPA

Frog Assay, Catherine Aubee, M.P.A., Environmental and Fate Effects Division, Office of 

Pesticide Programs, EPA

 

Battery Performance, Tom Steeger, Ph.D, Catherine Aubee, M.P.A, . Amy Blankinship, 

M.S., Gregory Akerman, Ph.D., 

Overall Summary of Assay and Battery Review, Tom Steeger, Ph.D., Environmental 

and Fate Effects Division, Office of Pesticide Programs, EPA

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