Review of suggested testing methods for endocrine-disrupting chemicals

Recent concern about the possible impact of exposure to endocrine-disrupting chemicals (EDCs) on humans and wildlife has led to a need for the development of regulatory test methods to facilitate identification of endocrine- disrupting substances and their effects, both at the stage of product development, and when they are present in the environment. Whilst structural activity relationships (SARs) and in vitro tests have potential utility for the rapid identification of suspect chemicals, they do not accurately mimic effects in whole animals and are therefore complementary to, not substitutes for, in vivo tests on whole animals. A tiered structure for testing has been suggested by scientists at various workshops and is reiterated here. Prioritisation screens involving in vitro and in vivo short-term tests should be followed by partial or whole life-cycle studies on whole animals with a variety of reproductive and developmental end-points. Whilst existing in vivo mammalian test methods are broadly suitable as screens for assessing potential endocrine-disrupting effects in mammalian wildlife, it is uncertain if these assays would be of use as screens for other classes of vertebrate wildlife, due to differences in endocrine function. Existing full and partial life-cycle tests with some avian and fish species could also identify endocrine disrupters; however, these long term tests are not suitable for routine screening without modification. Several non-regulatory tests are suitable for development and could be applied for regulatory purposes after modification and standardisation. Despite the absence of properly validated internationally agreed test methods, several countries have already taken action to restrict or prevent the use/discharge of certain endocrine-disrupting chemicals.