Predicted No Effect Concentration (PNEC)

This article focuses on the procedures utilized to characterize the concentration of a substance below which adverse effects, in an environmental sphere of concern, are unlikely to occur (predicted no effect concentration (PNEC)). PNEC assessment follows a tiered approach with different levels of refinement. The fist tier is based on single-species toxicity test. PNECs are estimated by dividing the lowest relevant effect value selected from the toxicity studies by an appropriate assessment factor chosen in function of the uncertainty degree. At higher tiers, the assessment can be done using either multispecies toxicity tests or the species sensitivity distribution approach.