SITEL, Integrated Wastewater Treatment System of South Petrochemical Complex, operated by CORSAN, the State Sanitation Company, has been conducting toxicity tests since 1986 in order to complement the physico-chemical analyses which had been showing unsatisfactory results. These tests were to assess the performance of the tertiary stabilization ponds where fishes have been found with deformities since 1983.

Ever since then, toxicity tests have been a routine in SITEL's monitoring procedures, and although they do not indicate the agents, they inform the effects of the discharge of petrochemical effluents on the local biota, being one further step to secure and preserve local water resources.

This paper summarizes the regular monitoring and studies SITEL has conducted until now to evaluate the full environmental impact on waters in the area of influence of the effluents of the South Petrochemical Complex.