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Azo dyes and related compounds as important aquatic contaminants: a ten-year case study
Citation:
UMBUZEIRO, G. AND L. D. CLAXTON. Azo dyes and related compounds as important aquatic contaminants: a ten-year case study. Presented at Society of Environmental Toxicology and Chemistry Annual Meeting (SETAC-EU), Seville, SPAIN, May 23 - 27, 2010.
Impact/Purpose:
Mutagenicity has been found in several aquatic systems in the world; however, this activity usually is not associated with any of the compounds that are currently regulated. Attempting to identify these hazardous compounds, an integrated study was conducted, employing several different bioassays and chemical analysis.
Description:
Mutagenicity has been found in several aquatic systems in the world; however, this activity usually is not associated with any of the compounds that are currently regulated. Attempting to identify these hazardous compounds, an integrated study was conducted, employing several different bioassays and chemical analysis. The study was carried out in Brazil, in a river that is used as drinking water source for 60,000 people. This place was selected because it was considered as a hot spot for mutagenic activity in the surface water quality-monitoring program carried out by the Sao Paulo Environmental Agency. The pollution sources were investigated using different strains of Salmonelfa typhimurium, and other ancillary genetic toxicology studies also were done. An effluent of a dye processing plant, located -6 km upstream from the Drinking Water Treatment Plant (DWTP) intake, was identified as responsible for the mutagenic activity. The river sediment and the sLudge of the DWTP were also mutagenic. The compounds that were at least partially responsible for the observed effect were identified as: CI Disperse Blue 373, CI Disperse Violet 93, and CI Disperse Orange 37. Several mutagenic and carcinogenic aromatic amines were detected in the effluent and water samples analyzed. Unknown direct-acting nitro-polycyclic compounds apparently generated during the chlorination of the cited azo-compounds were found in the drinking water. Other biological assays, such as the T. palfida (micronuclei), A. cepa (chromosome aberration), and Wistar rats (ACF), provided positive results. From the results, we concluded that the combination of chemical analysis, selective water extraction procedures, and toxicological assays are powerful tools for the evaluation of the water quality. [Abstract does not necessarily reflect the views of the U.S. EPA.]