INDUCTION OF CHROMOSOMAL-ABERRATIONS BY 2,4-DICHLORO-6-AMINOPHENOL INCULTURED V79 CELLS

2,4-Dichloro-6-aminophenol (DCAP) is a major metabolite of the herbici de 2,4-dichloro-6-nitrophenol ammonium (DCNPA). In our previous studie s this metabolite, but not the parent compound, was found to induce si ster chromatid exchanges (SCEs) and micronucleus (MN) formation in Chi nese hamster lung fibroblasts (V79 cells). Further studies were carrie d out to determine whether DCAP can also induce structural chromosomal aberrations (CAs) in cultured V79 cells. The assay was performed unde r three different treatment conditions: 1) 3 h treatment followed by 1 7 h post-treatment incubation, 2) 12 h treatment, and 3) 20 h treatmen t with multiple sampling times. Results showed that CAs were induced b y DCAP in V79 cells. The aberrations were mainly chromatid types (gaps , breaks, and deletions), triradials, quadriradials, and complex rearr angements. However, induction of CAs appears to be dependent on the tr eatment condition. The 3 h treatment following a 17 h posttreatment in cubation gave rise to 24% aberrant cells (excluding gaps) and a total of 44 aberrations per 100 metaphases, while the 12 h treatment only ga ve a borderline response and the 20 h treatment did not yield a signif icant increase of CAs at any concentration tested. It seems that a sho rt-term treatment with higher concentrations is a better treatment pro tocol for genotoxicity studies of certain cytotoxic chemicals such as DCAP. Results of this study further indicate that the herbicide DCNPA is potentially hazardous to the exposed population. (C) 1996 Wiley-Lis s, Inc.