MONITORING SAO-PAULO STATE RIVERS IN BRAZIL FOR MUTAGENIC ACTIVITY USING THE AMES TEST

Organic extracts of raw water from 11 water courses of Sao Paulo State , Brazil, were collected during one year bimonthly and tested for muta genicity using the Ames test, with strains TA98 and TA100 of Salmonell a typhimurium with and without metabolic activation. The samples were extracted with XAD(2) resin and eluted with methanol and methylene chl oride. From the 75 samples analyzed, 14 showed positive responses and 8 were considered marginal, making up 29% of mutagenic samples. The pe rcentage of mutagenic samples in October (spring) was 9%, increasing t o 64% in February (summer), and decreased to 9% again in August (winte r). Paraiba do Sul river showed the higher percentage of mutagenic sam ples (67%) and Capivari river the highest mutagenic sample (1787 and 3 265 revertants per liter for TA98 without and with S9, respectively). The amplitude of the mutagenic response was 39-3265 revertants per lit er for TA98 and 83-467 for TA100. The mutagenic samples showed direct and indirect mutagens, and TA98 detected the majority of responses, in dicating prevalence of frameshift mutagens in these samples. (c) 1993 John Wiley and Sans, Inc.