A Relative Risk Ranking of Selected Substances on Canada's National Pollutant Release Inventory

Abstract

ABSTRACT The National Pollutant Release Inventory (NPRI) provides pollutant release and transfer data from point sources to various media in the Canadian environment. While the inventory serves as Canada's community right-to-know program, the growing number of listed substances and reporting facilities makes it exceedingly difficult for the public to discern which substances are of greatest concern in their respective communities. A chemical's impact is best characterized when its environmental release data are combined with its toxicity and environmental fate properties. Presently, the NPRI does not provide a synthesis of this critical information and there is a need to provide more context with NPRI data to increase its usability. To help deliver this context, a relative risk ranking was compiled for a subset of NPRI substances using a modified Chemical Hazard and Evaluation Management Strategies (CHEMS-1) model. The model combines toxicity, chemical fate properties, and NPRI release data to yield a risk score for each substance. The resulting risk scores are ranked accordingly to provide a priority ranking of the substances. In addition to contextualizing the NPRI release data with hazard information, the ranking can also help set priorities for future risk assessment and evaluation by the Canadian government and scientific community. Limitations included the reliance on modelled data and default values to fill data gaps and uncertain reliability in reported NPRI data. In spite of its limitations, the CHEMS-1 model is a useful tool for prioritizing NPRI substances.