In vitro mutagenicity of rubber chemicals and their nitrosation products.

14 chemicals employed in rubber manufacture were assayed in the Salmonella reversion test with the strains TA98 and TA100. Mixed diaryl-p-phenylenediamines were weakly mutagenic in TA98 after metabolic activation; poly-p-dinitrosobenzene was active in TA98 without as well as with S9. After in vitro reaction with nitrite at low pH, mixed diaryl-p-phenylenediamines became directly mutagenic in both strains, whereas poly-p-dinitrosobenzene retained its activity unchanged. Furthermore, 4 of the remaining chemicals acquired mutagenic characteristics: in the presence of S9, N,N'-dimethylpentyl-p-phenylenediamine reverted TA98 and hexamethylenetetramine reverted both TA98 and TA100; N-isopropyl-N'-phenyl-p-phenylenediamine was mutagenic in TA98 with and without S9; N-nitrosodiphenylamine was active in both strains without S9 and weakly mutagenic in TA98 after metabolic conversion.