REGULATIONS FOR COMBINED EFFECTS OF POLLUTANTS - CONSEQUENCES FROM RISK ASSESSMENT IN AQUATIC TOXICOLOGY

In the analysis of combined effects two reference concepts are current ly considered as equally valid for the assessment of mixture toxicitie s: these are LOEWE additivity (concentration addition) and BLISS indep endence (response addition) (Greco et al., 1995). The aim of this stud y of 137 binary mixtures of pesticides and surfactants using an algal biotest was to find rational procedures for the assessment of mixture toxicities in the aquatic environment. By introducing an index on pred iction quality the quantitative relationships between predicted and ob served effects are evaluated for each concept. It is shown that LOEWE additivity leads to good predictions of mixture toxicities for most co mbinations, whereas BLISS independence tends to underestimate mixture toxicities. By this it is reaffirmed that there is a solid basis for f orthcoming regulatory activities on mixtures of chemicals. Copyright ( C) 1997 Elsevier Science Ltd.