Comparing Occupational and Environmental Risk Assessment Methodologies Using Pharmacokinetic Modeling

Abstract

Human health risks from occupational exposures are managed by limiting exposures to acceptable levels established by the American Conference of Governmental Industrial Hygienists or another similar body. Acceptable environmental exposures are benchmarked by values such as U.S. Environmental Protection Agency's Reference Doses and Reference Concentrations. The approaches to establishing these values are different, as are the groups they are intended to protect, complicating direct comparisons. Occupational limits are based on a healthy workforce in a narrow age range and do not generally consider sensitive populations. Limits for environmental exposures consider sensitive populations. In this evaluation, physiologically based pharmacokinetic modeling was used to predict tissue doses from acceptable/safe exposures as established by different organizations and agencies. Internal doses calculated for an agency's acceptable/safe exposures via oral and inhalation routes may differ substantially, but are sometimes in excellent agreement. The finding that internal doses resulting from occupational exposures are almost uniformly greater than those from environmental exposures suggests different mindsets among these groups regarding how safe is “safe.”