The deterministic risk analysis consisted of comparing the EC50 or LC50 values found in the toxicological tests performed in the laboratory with the critical values obtained in the field. The coefficient of risk (CR), according to the USEPA (1999), lists the maximum concentrations found in the environment divided by the LC50 or EC50 values obtained in the tests. The riskanalysis criteria vary with the duration of the toxicity test, and for tests of short duration (maximum of 96 h) the criteria are CR > 0.1 for situations of risk mitigation, i.e. restriction of the use of the product, and CR > 0.5 for high ecological risk. The values obtained for the residues were analyzed for each river basin by adopting the maximum value recorded for a scenario of critical contamination.