EDSP Tier 1 Screening: 

Assay and Battery 

Performance

Summary

Office of Chemical Safety and Pollution Prevention

U.S. Environmental Protection Agency
Summary: Purpose of Review

Evaluate how well each Tier 1 assay test guideline can 

be consistently executed based on defined performance 

criteria and to highlight any issues associated with 

interpretation of responses within each assay;

Evaluate the complementary relationships among 

responses within the assays; and,

Evaluate the redundancy of responses across the Tier 1 

battery

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Summary: Purpose of Review

Review also considered whether or not a 

modified number of assays within the battery, 

could reduce animal usage and lower costs, 

while adequately ensuring the identification of 

potential interactions with the E, A or T 

hormonal pathways

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Summary: Case Studies

Subsample of 21 chemicals out of 52

• Represented range of chemical classes, physicochemical properties

• Represented range of biological activities

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Summary: Study Performance

With respect to whether Tier 1 assay test 

guideline can be consistently executed based 

on defined performance criteria

• Laboratory performance of each Tier 1 assay 

typically consistent

• Some performance criteria were not met, but 

deviations were not considered significant; did not 

impact the interpretation or reliability of the data

• Assays provide information useful for evaluating 

potential interaction with E, A and T signaling 

pathways

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Summary: Challenges

With respect to issues identified with the 

performance of individual assays

• Dose selection and overt toxicity were issues 

associated with performance of in vivo assays

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Summary

With respect to whether complementarity was 

demonstrated within assays and redundancy 

was demonstrated across assays, based on a 

qualitative assessment:

• Individual assay results demonstrated 

complementarity, i.e., concordance of endpoints 

within an assay

• Battery of assays demonstrated redundancy,

i.e., the concordance of endpoints across assays, 

relative to E, A or T pathways

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Summary

For the E and A pathways, there were 

complementary responses with two or more 

endpoints responding in the pubertal assays 

and in the fish short-term reproduction assay 

(FSTRA)

In some case studies, the male and female 

pubertal assays and/or the FSTRA identified 

endpoint responses along with endpoint 

responses in the relevant in vitro assays

for E and A

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Summary

There were also cases in which assay 

concordance was not observed between the 

in vivo and in vitro tests

• Emphasizes the importance of multi-parameter

in vivo assays as a component of the battery to 

evaluate HPG alterations; and,

• Potential differences between taxa

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Summary

With respect to the T pathway, less 

complementarity and redundancy were 

observed within and across assays

• Design of battery

• Emphasizes the need for AMA and rat pubertal 

assays

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Conclusions

Current analysis illustrated both 

complementarity within assays and redundancy 

across assays and generally supported the 

importance of the designed complementarity 

and redundancy in the battery for evaluating 

potential interactions with the E, A, or T 

signaling pathways across taxa

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Conclusions and Notes

With respect to the extent of redundancy and 

whether the battery of assays could be 

modified

• Chemicals that elicited a response in the 

Hershberger also elicited a response in the male 

pubertal assay and/or FSTRA

• Uterotrophic assay never showed a response with 

the subset of chemicals used to evaluate battery 

performance

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