The Yokohama International Workshop on the effects of Endocrine Disruptors in Living Things was held with particular focus on effects on human beings, following the 2nd International Symposium on Environmental Endocrine Disruptors '99, hosted in Kobe on December 9 to 11, 1999 by Japan's Environment Agency.

Responding to reproductive abnormalities reported worldwide in wildlife due to exposure to manmade chemicals, the Wingspread Statement was adopted at the July 1991 meeting in Wingspread, Wisconsin, USA. This statement identified the need to initiate investigations into human health hazards caused by endocrine disruptors.

Since the 1991 Wingspread Conference, there have been several significant advances in our scientific understanding of endocrine disruption.

1. It is now clear that exposure is ubiquitous. All humans have been exposed, to varying amounts.
2. Laboratory experiments show that exposures have impacts at levels far lower than had been considered possible in traditional toxicology.
3. Many more hormone systems, perhaps all chemically-mediated message systems, are now known to be vulnerable to endocrine disruptors.
4. Many more compounds are now known to be powerful endocrine disruptors.
5. Human health effects of concern now include adult impacts of fetal exposure.

In Japan, concerned ministries and research institutes have also been conducting similar investigations since 1997. At the Yokohama Workshop held on December 13-14, 1999, twenty-five scientists from Japan, North America and Europe agreed on the urgency of investigations and actions as follows:

1. Residual organochlorine chemicals working as endocrine disruptors have already accumulated in the body and effected the health of some wildlife species. Appropriate technologies must be developed to reduce organochlorine residues in the environment and consequently there effects on wildlife.
2. Basic research is needed to identify the relationships between endocrine disruptors and their effects on developmental mechanisms. The most vulnerable period is in the developmental stage. Effective dose level and metabolic factors can conceivably vary according to animal species. Also, studies must be conducted into the species specificity of their effects.
3. Further investigations should carried out to clarify the effects of low doses of endocrine disruptors in organisms. In addition, it is desirable to conduct wildlife investigations not only at the individual level but also at the population and community level.
4. Epidemiological research must be continued to elucidate under what circumstances endocrine disruptors pose a threat to human health as well as to the intellectual development and mental health of children. Investigations must examine the compounded effects of endocrine disruptors, as exposure occurs to mixtures of substances rather than to single contaminants.
5. Because human beings are biological in nature, with varying genetic predispositions, and live in groups of individuals under diverse environmental factors including residence, occupation, lifestyle, etc., research must investigate individual variation in susceptibility to effects of endocrine disruptors. For example, study into the effects of phytoestrogens would be one such theme because Japanese ingest large amounts of phytoestrogens.
6. We need to determine an effective dose level and evaluate risks of endocrine disruptors by studying the relationship between concentration in the environment and intake. Also, study of methodologies for risk assessment should be promoted.
7. Until scientific conclusions are obtained, the "precautionary principle" should be applied to reduce the release of endocrine disruptors into the environment and the intake thereof.
8. The problem of endocrine disruptors should be addressed in all aspects of society. Information disclosure and the creation of educational curriculums on environmental problems are very critical social countermeasures.
9. The problem of endocrine disruption is a global issue. Solutions will therefore, of necessity, require international collaboration. Also, joint multidisciplinary research and conferences on the international level should be continued in order to promote research and countermeasures.
10. Yokohama City and Yokohama City University will promote both research and international conferences on endocrine disruptors. Yokohoma City University will also open its endocrine disruptor research facilities to researchers both inside and outside of the country in order to full utilize the benefits.

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