Derivation of An Acute Reference Concentration for Inhalation Exposure to Naphthalene (Final Report)

Abstract

EPA is announcing the availability of this final report, Derivation of an Acute Reference Concentration for Inhalation Exposure to Naphthalene, prepared by the Center for Public Health and Environmental Assessment. Naphthalene is a volatile organic compound that occurs naturally and is also manufactured for commercial use. Naphthalene has been detected in ambient air due to industrial emissions, biomass combustion, and use of fossil fuels, and may be present in indoor air due to wood burning, tobacco smoking, and use of naphthalene-containing moth repellents (ATSDR, 2005). Inhalation exposure to naphthalene has been found to induce respiratory inflammation and cytotoxicity, with neoplastic lesions resulting from chronic exposure in animal models (ATSDR, 2005).
The following report was developed via ORD’s Superfund Health Risk Technical Support Center (STSC) in response to a technical support request to review the scientific information relevant to derive an acute inhalation reference value for naphthalene. Based on the STSC evaluation, it was determined that EPA would develop an acute reference concentration (RfC) for inhalation exposure to naphthalene using Agency guidelines and best practices, including the use of systematic review methods, the application of a PBPK model for naphthalene (Kapraun et al., 2020), and the use of benchmark dose modeling to identify and evaluate the available human and animal health effect studies.

Impact/Purpose

This document contains scientific evaluations provided in response to a request for site technical support with limited scope. The evaluations herein are intended to address specific scientific questions posed to assessors with applicable experience. Therefore, the evaluations are written for a specific scientific audience. The observations provided are intended to assist EPA assessors with relevant and innovative science to help meet site-specific environmental goals. The observations are provided in good faith, and due to the limited scope of technical support requests include potential uncertainty. This memorandum is not to be considered the only source of information for decision making, nor should the information provided here be parsed. It would be advisable to consider this memorandum in conjunction with multiple lines of evidence, including history, experience of site managers, and other pertinent information available to EPA staff that retain the duties and responsibilities of all decisions and regulatory actions at the site.

Citation

U.S. EPA. Derivation of An Acute Reference Concentration for Inhalation Exposure to Naphthalene (Final Report). U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-21/292, 2022.

Date	Description
02- May 2022	EPA finalized the report.
03- July 2022	EPA released the final report on the EPA website.

This document has been reviewed in accordance with U.S. Environmental Protection Agency policy and approved for publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.

• Derivation of an Acute Reference Concentration for Inhalation Exposure to Naphthalene [CASRN 91-20-3] (PDF)  (97  pp, 2.7 MB, about PDF)