Risk Assessment 1 Thanks to Paul R. Harp, Ph.D., NH Department of Health & Human Services, US EPA Air Quality Planning & Standards Division, and the DOE Risk Assessment Information System. Crispin Pierce, Ph.D. University of Washington

The hazard identification process determines whether exposure to a chemical can increase the incidence of a particular adverse health effect and determines the likelihood of occurrence in humans. Hazard Identification ?

Exposure Assessment

The dose-response assessment describes the relationship between the magnitude of exposure and the appearance and duration of adverse effects. Dose-Response Assessment

Review toxicity and exposure assessment output Quantify risks Combine risks across all pathways Assess & present uncertainties Consider site-specific human studies, if available Summarize & present baseline risk assessment characterization results Risk Characterization

? How would you sort out the incidence of disease related to toxicant exposure vs. the background incidence? Should people who have both personal and occupational exposure to the same toxicants have different standards than those who don’t? (e.g., should smokers have lower occupational formaldehyde exposure limits?)

Should pregnant women be excluded from jobs where reproductive toxicant exposure occurs?

Activities Perceived as Higher Risk by:the United States Environmental Protection Agency (EPA)  Global warming  Indoor air pollution, including radon (high health risk)  Exposure to chemicals in consumer products (high health risk)  Surface water pollution (high ecological risk) by the Public  Chemical waste disposal  Water pollution  Chemical plant accidents Perception of Risk

Activities Perceived as Lower Risk by: the EPA  Hazardous waste sites - active and inactive  Underground storage tanks the Public  Indoor air pollution  Exposure to chemicals in consumer products  Global warming

? Should taxpayer dollars be spent on reducing the highest risks determined by experts (e.g., the EPA) or by the public?

Cancer vs. Non-Cancer Endpoints

No (or Lowest) Observed Adverse Effect Level

Additional UF between 1 and 10. Allows professional assessment of additional uncertainties not accounted for by the UF. Default is 1. Modifying Factor

? How would you set exposure standards for simultaneous exposure to two chemicals that targeted the same organ?

Weight of Evidence for Cancer Risk

? In 1763, Reverend Edmund Stone effectively treated fever with the bark from willow trees. The effective ingredient turned out to be salicylic acid. This drug has been used in different forms since then, and has shown good efficacy and low toxicity in treating fever, pain, and arthritis. However, acetylsalicylic acid is teratogenic in mice, rats, and hamsters. How do you approach this controversy in deciding whether or not to approve this drug for use?