GENOTOXICITY STUDY OF A LEATHER TANNERYS WASTE-WATERS

Effluents of tanning industries were recognized as one of the main con taminants of rivers in the Buenos Aires area. Recently, Argentinian le gislation, prescribed that the effluents must be submitted to toxicolo gical tests before their release to the rivers. Among these tests the detection of genotoxicity was considered a good choice for the determi nation of long term ecotoxicity of the treated waste waters. In this w ork, we report the results obtained when liquid effluents from differe nt processes of leather tanning and finishing were assayed for mutagen icity with the Ames test. We selected an industry that processes 43 to ns of leather per day (Curtiembre Giboud Hnos, Buenos Aires, Argentina ). Recovery of chromium by precipitation and secondary waste water tre atment is also practiced in this plant. Samples of liquid effluents we re obtained from the liming and tanning processes, chromium recuperati on plant and from waters released to the river. These samples were eit her sterilized by filtration with Millipore 0.22 mu m membranes or con centrated with XAD2 resins before the biological assay. Concentration was carried out as described in a previous paper (Moretton et al. 1991 ). Two strains of Salmonella typhimurium, TA 98 and TA 100, kindly sup plied by Dr Bruce Ames, were used in the biological tests. Detection o f mutagenic activity was made using incorporation plate assay (Maron a nd Ames 1983) for these samples. An in vitro activation system, S9 mix , was incorporated in the assay for the determination of promutagenic activity (Ames et al. 1973). A highly unspecific toxicity for Salmonel la typhimurium was detected in raw water samples from the liming and t anning processes. This effect could be the result of the elevated conc entration of contaminants. Nevertheless no mutagenicity was found in t he samples. When the concentrates were tested, only the one correspond ing to the tanning process resulted in a toxic effect but neither this extract nor the one obtained from waste waters of the liming process were mutagenic in the Salmonella test. In conclusion, treatment of the tannery waste waters is considered very important to decrease the eco toxicity of these waters, however the genotoxicity was in general a mi nor problem.