Risk Assessment of PAH Containing Petroleum Substances

Abstract

An approach is proposed for the environmental risk assessment of complex mixtures like petroleum substances based on the identification of clusters (“blocks”) of components with similar environmental fate and ecotoxicological properties. The risks of these blocks are assessed individually and multiplied with their proportional distribution in the substance discharged and summed in order to arrive at a total environmental risk for a specific petroleum substance, assuming additivity. This paper addresses the matter of identifying such blocks for PAH and heterocyclics present in petroleum substances. So-called regional intrinsic PEC/PNECs (Predicted Environmental Concentration divided by Predicted No Effect Concentration) are calculated for individual PAH-components for a fixed release of 1 tonne/year to water. These intrinsic PEC/PNECs are calculated from a data-set with component specific physico-chemical, fate and ecotoxicity properties and follow the EU risk assessment procedure. This paper shows that the use of intrinsic PEC/PNECs as a basis for the identification of blocks is feasible and that the identification of PAH blocks with similar environmental risks is mainly driven by log Kow. Differences between PAH and log Kow-comparable heterocyclics were mainly found in the low log Kow range, in which heterocyclics tended to have somewhat higher PEC/PNECs.

Key words::

• PAH
• heterocyclics
• environmental risk assessment
• aquatic toxicity