The Center for Alternatives to Animal Testing is an academic center affiliated with the Division of Toxicological Sciences in the Department of Environmental Health Sciences of the Johns Hopkins University Bloomberg School of Public Health.

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TestSmart Endocrine Disruptors

February 25-26
Hyatt Fair Lakes Hotel
12777 Fair Lakes Circle
Fairfax, VA

Program Committee:
Richard A. Becker, American Chemistry Council
Alan M. Goldberg, Johns Hopkins University
Pamela J. Lein, Johns Hopkins University
Ellen K. Silbergeld, Johns Hopkins University
Gary Timm, US Environmental Protection Agency
James D. Yager, Johns Hopkins University

Proceedings for TestSmart -- Endocrine Disruptors

The Work of OECD on Testing and Assessment of Endocrine Disruptors

Herman Koeter
OECD

Task Force on Endocrine Disrupters Testing and Assessment (EDTA)

Objectives:

Provide information and co-ordinate activities;
Develop new and revise existing Test Guidelines to detect endocrine disrupters;
Harmonise hazard characterisation and assessment approaches for endocrine disrupters among Member countries;
Sharing the burden of testing and assessment

Tasks:

Enhancements and modifications of existing Test Guidelines for systemic/reproduction toxicity;
Development of new Test Guidelines for screening;
Management of validation work, as appropriate;
Development of a harmonised strategy for the screening and testing of endocrine disrupters;
Provide practical tools for sharing of testing and assessments

The work in OECD is

Directed by Member countries' priorities and preferences;
Based on consensus;
Driven by scientific/technical/policy inputs (e.g. EDSTAC, CSTEE, SCP, International workshops/meetings).

Level	Purpose	Endpoints	Test Methods
			Mammalian Toxicity	Ecotoxicity
Initial Assessment
Screening	Priority Setting for Testing Mechanism of action	In vitro: Estrogen/ androgen (ant)agonism in vivo: Male/female sexual development (weight of sex organs) in pubertal animals to cover thyroid activity, steroid synthesis and estrogen/ androgen (ant)agonism	Tests to be added (EDSTAC T1S will be considered)
Testing	Identification/ Characterization, e.g. SIDS	In vivo: Male/female sexual development (weight of sex organs) in pubertal animals to cover thyroid activity, steroid synthesis and estrogen/ androgen (ant)agonism Three elements covering: in utero exposure growing-up phase mature animal	407 and/or 408 and/or 409 415 or 421/422 (*pubertal assay including thyroid)	avian reprotox (206) fish chronic/life cycle amphibian (Xenopus)
	Definitive Tests	In utero: Long term testing; focus on reproduction and development	416 devel. neurotox (if indicated)

The OECD Conceptual Framework - Current Status of Test Development

Endocrine Disrupters Testing and Assessment

Revision of existing test methods:

TG 407: 4-week systemic toxicity study
TG 416: 2-generation reproduction study
TG 206: avian reproduction study

Endocrine Disrupters Testing and Assessment

Development of new test methods:

Uterotrophic assay
Hershberger assay
Fish screening tests (3)
Fish full life cycle test
Avian two-generation reproduction test
Amphibian screening and testing methods

Validation Work

Criteria and Principles based in ICCVAM ECVAM and OECD Solna principles;
Flexibility and transparency important(see draft GD No. 34);
Management Committees established for mammalian and ecotoxicology testing

OECD Validation Management Groups (VMGs):

VMGs report to EDTA but make technical decisions independently;
EDTA reports to the Working Group of National Co-ordinators of the Test Guidelines Programme (WNT);
Validation Management Group on Screening and Testing of Endocrine Disrupters for MammalianEffects (VMG-Mam) established: February 1999;
Validation Management Group on Screening and Testing of Endocrine Disrupters for Ecotoxicity Tests (VMG-Eco) established: March 2001

Rodent Uterotrophic Assay

Test in use since 1930's in pharmaceutical industry;
Evaluates ability of a chemical to mimic estrogen activity in intact animal;
Validation work is completed

Rodent Uterotrophic Assay

Background Review Document completed and reported;
Lead country: Japan
Phase 1 completed and reported (19 labs in 8 Member countries);
Phase 2 completed and almost reported (20 labs from 9 Member countries);
Independent peer review will be organised

Hershberger Assay

Assay developed in the 1950's;
Looks at the effect of chemicals to restore the weight of prostate gland and seminal vesicles in castrated rodents;
Validation work in phase 2;
Phase 1 completed and (almost) reported (17 labs in 6 Member countries);
Lead country: USA;
Preparatory work for Phase 2 done by Japan;
Phase 2 on the brink of starting the work

Enhancement of Repeat Dose Toxicity (OECD 407)

To evaluate suitability of sub-acute tests as screening;
Examine suitability and sensitivity of additional (endocrine related parameters);
Routinely done;
Validation work lead by industry
Phase 1 completed and almost reported (8 labs in 3 Member countries);
Phase 2 work (almost) completed (13 labs in EU, Japan, Korea and US), report expected in spring 2002

Fish Screening Assays

Three fish screening tests are considered:
- early development
- juvenile growth
- adult reproduction
Applicable to different fish species;
Intended to detect activity of oestrogen and androgen (anti-)agonists;
Validation work about to start;
New elements: Vitellogenin, Gross Morphology, Gonad Histology

Tests under consideration

Fish Full Life Cycle Test: Two expert meetings were held. Lead countries: Germany. Japan, USA
Avian Reproduction Tests: Several expert meetings were held since 1994. Lead country: USA
Frog Metamorphosis Assay: Further scientific discussions are needed

Sharing the Burden of Testing and Assessment

Vast number of chemicals;
Number of screens/tests for each chemical;
Time pressure;
Costs of testing are very high;
Different philosophies in Member countries

Estimated Numbers of Chemicals (EPA estimations, 1995)

Number of Chemicals: 5,000,000
Chemicals in Commerce: 80,000
Industrial Chemicals: 72,000 (millions of products)
New Chemicals: 2,000/year (1,000 in US)
Pesticides: 600 (21,000 products)
Food Additives: 8,700
Cosmetic Ingredients: 7,500 (40,000 products)
Human Pharmaceuticals: 3,300

Sharing the Burden of Testing and Assessment

Grouping of chemicals;
Tools for Screening and Testing;
Co-ordination of Testing;
Sharing Test Results;
Sharing Hazard/Risk Assessment Reports

Sharing the Burden of Testing and Assessment

Grouping of chemicals:

Individual chemicals that have triggered a regulatory interest;
Priority lists of chemicals of concern;
Other groupings of chemicals;
Criteria for selection of chemicals;
Details of planned action, including scheduled screening/testing

Development of Tools for Screening and Testing:

High Throughput Pre-Screen (HTPS);
DNA micro-array;
QSAR models;
Prepubertal assay;
Mammalian two-generation study

Co-ordination of Testing:

Early notice of testing plans;
Use of internationally agreed protocols

Sharing Test Results:

High throughput pre-screens (HTPS) (Japan and USA);
One-generation studies with 10-12 substances (Japan);
Reproductive Toxicity Screens for 1000-2000 HPV Chemicals (USA);
Assessment of approx. 70 chemicals in the content of the Children's Health Programme (USA)

Sharing Hazard/Risk Assessment Reports:

Differences in assessment approaches;
Underlying science and principles;
Exchange information on emerging scientific developments;
Agreement on essential elements of E.D. assessment reports;
Develop generic guidance for the assessment of EDs;
Sharing existing hazard/risk assessment reports