SUMMARY OF THE NATIONAL TOXICOLOGY PROGRAM BENZIDINE DYE INITIATIVE

The benzidine dye initiative is a research program established by the National Toxicology Program to generate an integrated body of scientif ic information regarding the potential health risks associated with ex posure to beozidine- and benzidine-congener-derived dyes. Because an i n-depth evaluation of each of the hundreds of benzidine-congener-deriv ed dyes was considered impractical, the research program was designed to study the metabolism and disposition, genetic toxicity, and in vivo toxicity and carcinogenicity of two primary benzidine congeners, 3,3' -dimethylbenzidine and 3,3'-dimethoxybenzidine, and a select group of prototypical dyes derived from those amines. It was anticipated that b y applying the basic information generated in these extensive studies, it would be possible to make regulatory decisions about other dyes af ter conducting only a minimal number of experiments such as studies of disposition and metabolism, and in vitro mutagenicity. This paper sum marizes the results of studies conducted to evaluate the metabolism, d isposition, mutagenicity, toxicity, and carcinogenicity oi representat ive benzidine congeners and derived dyes.