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US EPA's acute reference exposure methodology for acute inhalation exposures.
Judy A Strickland1, Gary L Foureman
1National Center for Environmental Assessment MD 52, US Environmental Protection Agency, Research Triangle Park, NC 27711, USA. strick12@niehs.nih.gov
The Science of the Total Environment
|May 16, 2002
Summary
The US EPA developed a new methodology for acute reference exposures (AREs) to assess health risks from short-term chemical inhalation. This approach aids in evaluating accidental and routine releases, enhancing environmental risk assessment strategies.
Area of Science:
- Environmental Health
- Toxicology
- Risk Assessment
Background:
- The US EPA National Center for Environmental Assessment is developing a methodology for risk assessments of non-cancer effects from acute inhalation exposures.
- Acute Reference Exposures (AREs) are chemical-specific benchmarks analogous to chronic Reference Concentrations (RfCs).
- AREs will be integrated into the EPA's Integrated Risk Information System (IRIS) for assessing accidental and routine chemical releases.
Purpose of the Study:
- To establish a general guidance methodology for deriving chemical-specific acute reference exposures (AREs).
- To provide a framework for selecting optimal derivation approaches based on available data.
- To enhance the assessment of potential health risks associated with acute environmental chemical exposures.
Main Methods:
- The proposed methodology offers a framework for choosing derivation approaches: no-observed-adverse-effect level (NOAEL), benchmark concentration (BMC), or categorical regression.
- Uncertainty factors are applied to the point of departure, determined by the chosen approach, to derive the ARE.
- Exposure-response analyses (BMC, categorical regression) are favored over NOAEL when data support modeling.
Main Results:
- The methodology provides a flexible framework for ARE development, accommodating different data availabilities.
- Example AREs for hydrogen sulfide (categorical regression) and hexachlorocyclopentadiene (NOAEL) illustrate the application of the proposed methods.
- The methodology has undergone review by the US EPA Risk Assessment Forum.
Conclusions:
- The developed ARE methodology offers a standardized approach for assessing non-cancer effects of acute inhalation exposures.
- The framework supports the use of more data-intensive methods like BMC and categorical regression when feasible.
- AREs will improve the evaluation of health risks from acute chemical releases, contributing to public health protection.