A Look at State‐Level Risk Assessment in the United States: Making Decisions in the Absence of Federal Risk Values

Abstract

State environmental agencies in the United States are charged with making risk management decisions that protect public health and the environment while managing limited technical, financial, and human resources. Meanwhile, the federal risk assessment community that provides risk assessment guidance to state agencies is challenged by the rapid growth of the global chemical inventory. When chemical toxicity profiles are unavailable on the U.S. Environmental Protection Agency's Integrated Risk Information System or other federal resources, each state agency must act independently to identify and select appropriate chemical risk values for application in human health risk assessment. This practice can lead to broad interstate variation in the toxicity values selected for any one chemical. Within this context, this article describes the decision-making process and resources used by the federal government and individual U.S. states. The risk management of trichloroethylene (TCE) in the United States is presented as a case study to demonstrate the need for a collaborative approach among U.S. states toward identification and selection of chemical risk values while awaiting federal risk values to be set. The regulatory experience with TCE is contrasted with collaborative risk science models, such as the European Union's efforts in risk assessment harmonization. Finally, we introduce State Environmental Agency Risk Collaboration for Harmonization, a free online interactive tool designed to help to create a collaborative network among state agencies to provide a vehicle for efficiently sharing information and resources, and for the advancement of harmonization in risk values used among U.S. states when federal guidance is unavailable.

Part II: Quantitative Evaluation of Choices Used in Setting Noncancer Chronic Human Health Reference Values Across Organizations

“…Based on HHRV derivation practices, this analysis included the main choices used to set HHRVs and has compared these choices across organizations for the same chemicals. Other factors not included in this analysis may also have an impact on HHRV agreement, including differences in the mathematical derivation of HHRV, adversity definition differences, organizational mission differences, problem formulation, and differences in scientific data interpretation …”

“…Only limited studies have been conducted to date on HHRV differences across international organizations. These studies have primarily focused on a single chemical or group of chemicals, specifically boron, trichloroethylene, benzo(a)pyrene, and pesticides . Observed differences in the HHRV for a specific chemical ranged from 2‐ to 1,700‐fold, with these differences primarily being attributed to the use of variable uncertainty factors and risk assessment guidance.…”

Part I––Comparing Noncancer Chronic Human Health Reference Values: An Analysis of Science Policy Choices

“…After controlling for data availability, the largest HHRV difference was 83‐fold (cyanide, free). This result is higher than the two‐fold differences previously observed for boron but lower than the 1,700‐fold differences observed for trichloroethylene . Unlike boron, where there was relative agreement on the critical study and POD values, there were a number of cases in this analysis where the HHRV differences could be attributed to scientific disagreement on these choices.…”

“…Despite the importance of noncancer HHRV differences across international organizations, there has only been limited study on their scope and origins. Studies conducted to date have focused on a single chemical or group of chemicals . Risher and DeRosa discussed the primary reasons for differences between the USEPA and the U.S. Agency for Toxic Substances and Disease Registry (ATSDR) HHRVs and provided key examples .…”

“…Effio et al . compared trichloroethylene assessments across state organizations in the United States, finding up to a 1,700‐fold difference in the HHRVs . To reduce these differences, Effio et al .…”