Cumulative Risks and Cumulative Impacts of Environmental Chemical Exposures (Symposium Article)

As part of the California Environmental Protection Agency (Cal/EPA) effort to address environmental justice issues, the agency has been working to develop methodology to evaluate cumulative impacts of chemical exposures. Cumulative impact analysis takes into account the exposures, public health and/or environmental effects from the combined emissions and discharges of chemicals within a geographic area. Included for considerations are environmental pollution from all sources, whether from a single medium or multiple media, and releases from routine, accidental or other activities. The assessment of the impacts takes into account sensitive populations and socio-economic factors where appropriate. The assessment of cumulative risks is itself a significant undertaking because it combines health risks from multiple sources of chemical exposures. This is a timely issue as there has been increasing interest to address the concern regarding multiple chemical exposures, sensitive populations, and the methodology to conduct the assessments. In November 2006, we held a symposium at the annual meeting of the American College of Toxicology, Indian Wells, California, entitled, “Cumulative Risks and Cumulative Impacts of Environmental Chemical Exposures.” We discussed the related principles and concepts and methodology currently underway in several toxicology and health assessment program areas in California, particularly in the areas of water and air risk assessment. The presentations covered issues and concerns, cumulative impacts, multiple chemical exposures, and sensitive populations. We addressed our work in progress in the Office of Environmental Health Hazard Assessment, Cal/EPA, which included principles and concepts, methodology, environmental justice, and air-toxics and water-contaminants risk assessment. The articles that follow are based on presentations by the respective authors on the following topics: 1) Perspectives on cumulative impacts and risks; 2) Standard risk assessment procedures: Are they adequate to account for cumulative risks?; 3) Accounting for changing exposure sources in a cumulative risk assessment; and 4) Applying environmental justice principles to risk assessment.