[In vivo test for endocrine disruptors].

The Endocrine Disruptor Issue has been brought up widely to the public by a book titled "Our stolen future"(Theo Colborn et al., 1996), in which the reproductive impairment of a variety of wild life was documented in relation to chemical exposures. The fear that the similar adverse effects could have been observed in humans is based on the understandings that estrogens and androgens are highly conserved signaling molecules among species. In addition, the estrogen receptors are known to have abilities to bind a variety of chemicals. Although such chemicals bind weakly to the receptor, it is also known that, at least in some assay systems, high concentration of these chemicals can elicit effects that are quite similar to those of the natural hormones. Thus, such "hermonally active agents, HAAs" can be ligands to the hormone receptors in an organism, and may cause adverse effects, namely the "receptor-mediated toxicity", which is a relatively new concept in the field of toxicology. This new aspects of toxicology is briefly discussed in relation to the reversible/irreversible effects in developing organisms and the shape of dose-response curves, both especially in the low-dose ranges, now often referred to as "low-dose effects".