PROSPECTS FOR REDUCTION AND REPLACEMENT ALTERNATIVES IN REGULATORY TOXICOLOGY

There is a considerable impetus to developing alternative methods in r egulatory toxicity testing from the introduction of legislation requir ing alternative methods to be used whenever possible. Some progress ha s been made in the search for and validation of alternative methods in regulatory toxicology. When replacement and reduction alternatives ar e considered, the absolute reduction in the number of animals used in testing is a good indicator of the progress that is being made. Attemp ts at replacing existing animal methods have focused on acute studies where the endpoints are simple and the mechanism of toxic action under stood. The majority of animal studies rely on non-specific endpoints f rom chronic studies and where there is little understanding of the mec hanism of toxic action; these studies are much more difficult to repla ce. The conclusion is that the methods that are currently under valida tion to replace regulatory toxicology studies will only reduce the num ber of animals used to test a chemical (such as a pesticide) by about 3%. The process of validation is likened to technology, where addition al resources can improve and hasten the process; however, the rate-lim iting step in the overall objective of reducing animal use is the deve lopment of suitable tests for validation, a scientific process which d raws on the full range of biomedical research and hence will be slow t o reveal the necessary data for test development. (C) 1997 Elsevier Sc ience Ltd.