The Salmonella mutagenicity assay in a surface water quality monitoring program based on a 20-year survey

Since 1979, the Environmental Agency of Sao Paulo State in Brazil, CETESB, has been using the Salmonella mutagenicity assay to assess the quality of n atural waters. This paper is a compilation of data obtained during the last 20 years from more than a thousand samples. Potencies up to 30,000 reverta nts/l were observed in 137 positive samples. The Salmonella typhimurium str ain TA98 was more sensitive than TA100: 79% of the mutagenicity was detecte d by this strain, regardless of the presence of S9-mix. A classification of the mutagenic response was proposed to facilitate in the dissemination of the information to the public. The classification was low, moderate, high a nd extreme for samples with mutagenic potency (revertants/l equivalent) of <500, 500-2500, 2500-5000 and >5000, respectively. As a result of this effo rt to standardize methodologies, compile and classify the mutagenic effect of water pollution, in 1998, the Salmonella mutagenicity assay was official ly and systematically included in the Sao Paulo State Water Quality Monitor ing Program. This assay has proven to be a useful tool in the identificatio n of important pollution sources. Correction and prevention actions in Wate r Pollution Control Programs were generated as a result. (C) 2001 Elsevier Science B.V. All rights reserved.