Evaluation of the water genotoxicity from Santos Estuary (Brazil) in relation to the sediment contamination and effluent discharges.

The genotoxic activity of water samples collected in 9 different sites within the area of the Santos estuary was preliminary evaluated, and related to previous data on the genotoxicity of sediments and the contents of PAHs in both water and sediment samples. The liquid discharge of a steel mill (coke plant), known to be mutagenic, was chemically analyzed to determine its PAH content. For the water evaluation we employed the Salmonella/microsome assay with the strains TA98 and TA100 with and without S9 mix in the plate incorporation method. The water was filtered with an AP20 membrane before being extracted with XAD4 at natural and acidic pH. The industrial effluent was filtered in 0.45 microm membranes before being extracted with the liquid/liquid method. Both membranes containing the particulate material were extracted using ultrasonication. PAHs were found associated with the suspended particles present in the industrial effluent in accordance with mutagenicity data previously reported. In relation to the estuarine waters, sites 1 and 5 presented low levels of mutagenic activity only in the filtered water (liquid fraction) extracts. At site 3, both the filtered water and particulate solids presented also low mutagenicity. Results show that the mutagenic activity observed in water could not be directly related to the genotoxic activity and PAHs contents of the bottom sediments.

Exposiçäo humana a trialometanos presentes em água tratada / Human exposure to trihalomethanes in drinking water

Realizou-se uma revisäo bibliográfica do período de 1974-1998, no MEDLINE, sobre compostos orgânicos halogenados derivados de hidrocarbonetos denominados de trialometanos. Muitos deles, reconhecidamente carcinogênicos para diferentes espécies animais, podem ser encontrados, freqüentemente, inclusive entre nós, em águas tratadas e enviadas à populaçäo urbana. É o caso de compostos como o clorofórmio, bromodiclorometano, clorodibromometano e bromofórmio, resultantes da halogenaçäo de precursores, principalmente substâncias húmicas e fúlvicas presentes na água que será tratada (clorada). Assim, descreve-se sua formaçäo, fontes de exposiçäo humana bem como os aspectos toxicológicos de maior importância: disposiçäo cinética e espectro dos efeitos tóxicos (carcinogênicos, mutagênicos e teratogênicos) decorrentes de exposiçöes a longo prazo e baixas concentraçöes. Níveis seguros de exposiçäo propostos säo também fornecidos