Toxicological resources for cumulative risk: An example with hazardous air pollutants

Cumulative risk assessment, concerned with the multiple health effects of chemical mixtures, challenges the utility of existing single-chemical regulatory references. We compare example cumulative risk assessments for 40 HAPs; one based on single-effect toxicological data from EPA, and another based on a multiple-effect toxicological database we developed. For the 40-chemical HAP subset, the multiple effect database contains information on approximately seven effects per chemical and contains a total of 290 toxicological values. Seven health effects are represented in the IRIS data. Seventeen health effects are represented in the multiple-effect data. Respiratory and neurological effects ranked first and second in both cumulative analyses, regardless of the source data. In addition to respiratory and neurological effects, gastro-intestinal/ hepatic, renal/kidney, and immunologic effects were identified as effects of concern on the basis of the multiple effect data. Immunologic effects are not found in the 40-chemical IRIS dataset. Cumulative risk assessment has the potential to expand our understanding of the public health impacts of environmental exposures. Advancements in toxicological resources will improve cumulative risk assessment. Cumulative risk assessment will reduce risks to the extent that it can be integrated into prevention strategies to track and protect the public's health.