Chromosomal effects of newly identified water pollutants PBTA-1 and PBTA-2 and their possible mother compounds (AZO DYEs) and intermediates (non-C1PBTAs) in two Chinese hamster cell lines

We performed the in vitro micronucleus (MN) test on 2-[2-(acetylamino) -4-[bis(2-methoxyethyl)amino]-5-methoxyphenyl] -5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1) and 2- [2-(acetylamino)-4-[N-(2-cyanoethyl)-ethylamino]-5-methoxyphenyl]-5 -amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-2), which are newly identified water pollutants from the Nishitakase river in Kyoto, Japan, and on their possible mother compounds (AZO DYE) and intermediates (non-CIPBTAs). We tested these compounds in the absence and presence of S9 mix in two Chinese hamster cell lines CHL and V79-MZ and scored MN, polynuclear and karyorrhectic (PN), and mitotic (M) cells. PBTA-2 in the absence of S9 mix induced the strongest responses in both cell lines. It was also a strong inducer of binucleate cells in PN cells in both cell lines, which suggested that it induced polyploidy. PBTA-1 showed clear positive results only in the absence of S9 mix and only in V79-MZ cells, inducing aneuploidy. In CHL cells AZO DYE-1 significantly induced MN cells in the presence of S9 mix, and AZO DYE-2 induced MN and PN cells, including binucleate cells and cells with a multilobed nucleus, in the absence of S9 mix. In V79-MZ cells, AZO DYE-1 and -2 induced primarily M cells in the presence of S9 mix. 9% of the M cells heated with 50 mug/ml AZO DYE-1 showed endoreduplication. AZO DYE-2 at 200 mug/ml condensed the chromatin in 100% of the cells. The non-CIPBTAs were a bit more cytotoxic than the other compounds and induced a slight increase in MN cells in both cell lines. Some of the chemicals tested induced a characteristic karyomorphology that might reflect abnormal cell division. Abnormalities of cell division could be detected in PN and M cells as well as in MN cells. Structure-activity relationships have also been discussed. (C) 2001 Elsevier Science B.V. All rights reserved.