US EPA

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.

U.S. EPA. IRIS TOXICOLOGICAL REVIEW AND SUMMARY DOCUMENTS FOR XYLENES (EXTERNAL REVIEW DRAFT). U.S. Environmental Protection Agency, Washington, DC, NCEA # S-1203, 2002.

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, 149 KB, about PDF)
• Instructions to Peer Reviewers for Reviewing IRIS Summaries and Supporting Documentation for Xylenes (CAS No. 1330-20-7) (PDF)  (4 pp, 91 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, 375 KB, about PDF)

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