Exposure endpoint selection in acute dietary risk assessment

Area of Science:

• Environmental toxicology
• Risk assessment methodology
• Regulatory science

Background:

• Current US Environmental Protection Agency (USEPA) Office of Pesticide Program (OPP) methods for acute dietary risk assessment exhibit uncertainty in exposure distributional analysis.
• Regulatory decision points, particularly at the extreme cumulative output distribution (e.g., 99.9th centile), lack sufficient data confidence in food consumption and residue inputs.

Purpose of the Study:

• To evaluate the adequacy of current USEPA OPP approaches to acute dietary risk assessment, focusing on uncertainty in exposure distributional analysis.
• To advocate for statistically reliable endpoint selection in risk assessment for improved regulatory decision-making.

Main Methods:

• Analysis of uncertainty in exposure distributional analysis within current USEPA OPP risk assessment frameworks.
• Evaluation of data limitations in food consumption and pesticide residue databases.
• Comparison of extreme versus central exposure distribution endpoints for risk management.

Main Results:

• Current methods, especially those using the 99.9th centile, overestimate exposure due to data limitations and extreme consumption patterns.
• The extreme upper tails of exposure distributions are data-poor and highly uncertain.
• Regions of cumulative exposure distributions well removed from output tails offer richer data content driven by residue concentrations.

Conclusions:

• Risk management decisions do not require extreme exposure endpoints to protect sensitive populations.
• Utilizing statistically reliable endpoints away from uncertain distribution tails enhances risk assessment robustness.
• Selection of risk management decision points should consider distribution characteristics, effect severity, and data robustness.