NOTE: Although the toxicity values presented in these toxicity profiles were correct at the time they were produced, these values are subject to change. Users should always refer to the Toxicity Value Database for the current toxicity values.September 1994
Prepared by Carol S. Forsyth, Ph.D. and Rosmarie A. Faust, Ph.D., Chemical Hazard Evaluation Group, Biomedical and Environmental Information Analysis Section, Health Sciences Research Division, *, Oak Ridge, Tennessee
Prepared for OAK RIDGE RESERVATION ENVIRONMENTAL RESTORATION PROGRAM
*Managed by Martin Marietta Energy Systems, Inc., for the U.S. Department of Energy under contract No. DE-AC05-84OR21400
Xylene (dimethylbenzene) is a colorless, flammable liquid that is used as a solvent in the printing, rubber, and leather industries and as a cleaner and paint thinner. It occurs naturally in petroleum and coal tar. Xylene is absorbed following oral, dermal, or inhalation exposure; can be stored in adipose tissue; and is eliminated in the urine after conjugation with glycine.
Human exposure to xylene by either oral or inhalation routes can cause death due to respiratory failure accompanied by pulmonary congestion (Sandmeyer, 1981). Nonlethal levels of xylene vapor may cause eye (Carpenter et al., 1975), nose, and throat (ATSDR, 1993) irritation, and contact with liquid may result in dermatitis (Sittig, 1985). Chronic occupational exposure to xylene has been associated with headaches, chest pain, electrocardiographic abnormalities, dyspnea, cyanosis of hands, fever, leukopenia, malaise, impaired lung function, and confusion (Hipolito, 1980).
Long-term gavage studies with mixed xylenes in laboratory animals resulted in decreased body weight gain in male rats given 500 mg/kg/day and hyperactivity in male and female mice given 1000 mg/kg/day (NTP, 1986). A chronic oral reference dose (RfD) of 2 mg/kg/day for mixed xylenes was calculated from a no-observed-adverse-effect level (NOAEL) of 250 mg/kg/day derived from a chronic gavage study with rats (EPA, 1994a). The critical effects were hyperactivity, decreased body weight, and increased mortality (males). An RfD of 2 mg/kg/day is also reported for the m- and o-xylene isomers (EPA, 1994b).
Inhalation of 3000 mg/m3 of the o-, p-, or m-xylene isomer by rats on gestation days 7-14 resulted in decreased fetal weights, skeletal anomalies, and altered fetal enzyme activities (Hood and Ottley, 1988). Rib anomalies and cleft palate occurred in mouse fetuses following maternal oral exposure of 2.06 g/kg/day of mixed xylenes on gestation days 6-15 (Marks et al., 1982). An inhalation reference concentration (RfC) is under review by EPA (1994a).
Oral (NTP, 1986) and topical (Berenblum, 1941; Pound, 1970) carcinogenic studies with xylene in laboratory animals gave negative results. EPA (1994a) has placed xylene in weight-of-evidence group D, not classifiable as to human carcinogenicity. No significant increase in tumor incidence was observed in rats or mice of both sexes following oral administration of technical grade xylene. Retrieve Toxicity Profiles Formal Version
Last Updated 8/29/97