Xylenes

Overview

This draft assessment is a reevaluation of the toxicity of mixed xylenes. Mixed xylenes consists of the three isomers of xylenes and commonly contains ethylbenzene. Xylenes exposure is associated with several toxic effects including neurotoxicity, reduced body weight or body weight gain, developmental effects and effects to the liver and kidney. The critical effect selected for both the oral and inhalation route of exposure is neurotoxicity. For effects other than cancer, the oral reference dose (RfD) is 0.7 mg/kg-day and the inhalation reference concentration (RfC) is 0.1 mg/m3.

The cancer weight of evidence determination for mixed xylenes is group D- not classifiable as to human carcinogenicity by the Guidelines for Carcinogen Risk Assessment (1986) and data are inadequate for an assessment of human carcinogenic potential due to conflicting evidence by the revised draft Guidelines for Carcinogen Risk Assessment (1999).

There is limited information on the relative toxicity of the individual isomers and the results are inconsistent. Based on available data, there do not appear to be susceptible populations.

Additional Information

EPA is hereby providing for public information a draft Toxicological Review, draft IRIS Summary, and charge to external peer reviewers for EPA's health assessment of xylenes. These documents are provided for public viewing during an external scientific peer review period. While EPA is not soliciting public comments by this action, any scientific views received on the content of the Toxicological Review or IRIS Summary prior to April 8, 2002 will be considered in subsequent drafts.

To access or download the external review draft xylenes document and related IRIS Summary, please refer to the Downloads/URL Links on the left sidebar.

Please direct any correspondence to: Michael Broder, National Center for Environmental Assessment (8601D), U.S. EPA, 1200 Pennsylvania Ave., NW, Washington, DC 20460 or to broder.michael@epa.gov. Also, please send a record keeping copy to: IRIS Submission Desk, c/o ASRC, 6301 Ivy Lane, Suite 300, Greenbelt, MD 20770. Note that this is a new address for the Submission Desk., or email to
IRIS.desk@epa.gov.

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.

• IRIS Summary - Xylenes (External Review Draft) (PDF)  (19  pp, 145.5 KB, about PDF)
• Instructions to Peer Reviewers for Reviewing IRIS Summaries and Supporting Documentation for Xylenes (CAS No. 1330-20-7) (PDF)  (4  pp, 88.9 KB, about PDF)
• Toxicological Review of Xylenes (External Review Draft) The purpose of this Toxicological Review is to provide scientific support and rationale for the hazard identification and dose-response assessment in IRIS pertaining to chronic exposure to xylenes. It is not intended to be a comprehensive treatise on the chemical or toxicological nature of xylenes. (PDF)  (74  pp, 366.2 KB, about PDF)

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