Improvement of a practical method for priority selection and risk assessment among existing chemicals

In a previous paper (A. Sampaolo and R. Binetti (1986). Regul. Toxicol. Pharmacol. 6, 129-154) an original pragmatic approach for priority setting and risk assessment among existing chemicals was presented. The experience subsequently acquired in the use of the method suggested some improvements, relevant for an easier application. The priority coefficient R has been redefined so that now it can range between zero (all data available) and 1 (no data available). In order to make the final figures more comparable with each other, the indexes are now expressed as percentage with reference to the maximum score obtainable if all parameters of the equation used had reached the maximum score. New general priority index and general risk index formulas, both for personal direct and environmental exposure, are also defined. Another modification concerns the application of the method to specific aspects, such as irreversible effects, immediate and delayed toxic effects, and so on. The method has then been validated on 80 known substances obtaining the respective ranking according to the specific kind of risk.