A Reexamination of Liver Tumors in Mice Exposed to Wholly Vaporized Unleaded Gasoline

Abstract

A single lifetime inhalation study of the effects of wholly vaporized unleaded gasoline has been conducted in the mouse. An elevation of hepatocellular tumors was reported only in females and only at the high treatment level (2056 ppm). Several reports of this study have appeared previously in the scientific literature, including a comprehensive summary published in this journal. Different incidence rates were reported for mouse liver tumors in these publications without explanations of how they were calculated of why they differed. To clarify the data, we recently examined the final report of the gasoline study, the individual animal data, and slides prepared from liver tissue collected during the study. The previously reported incidence rates did not take into consideration all animals at risk for tumor development or all animals with hepatocellular tumors. Revised incidence rates are presented for hepatocellular tumors in all mice on study. These rates are approximately 20–25% lower than previously reported.

References

Brooks, P.N. , and Roe, F.J.C. (1985). Digestive System. T.C. Jones , U. Mohr , and R.D. Hunt (eds.). Springer-Verlag: Berlin, pp. 47–51.

HEALTH EFFECTS INSTITUTE. (1985). Gasoline Vapor Exposure and Human Cancer. Evaluation of Existing Scientific Information and Recommendations for Future Research. Report of the HEI Health Review Committee.

INTERNATIONAL RESEARCH AND DEVELOPMENT CORPORATION. (1983). Motor Fuel Chronic Inhalation Study. Vols. 1–6. Sponsored by the American Petroleum Institute. Sept. 15, 1983.

MacFarland, H.N. (1982). Chronic gasoline toxicity, in: The Toxicology of Petroleum Hydrocarbons, Proceedings of a Symposium, May, 1982. H.N. MacFarland , C.E. Holdsworth , J.A. MacGregor , R.W. Call , and M.L. Kane (eds.): American Petroleum Institute: Washington, D.C., pp. 78–86.

MacFarland, H.N. (1984). Xenobiotic induced kidney lesions: Hydrocarbons. The 90-day and 2-year gasoline studies, in: Advances in Modern Environmental Toxicology, Vol. 7, Renal Effects of Petroleum Hydrocarbons. M.A. Mehlman , C.P. Hemstreet , J.J. Thorpe , and N.K. Weaver (eds.): Princeton Scientific Publishers, Inc.: Princeton, NJ, pp. 51–56.

Macfarland, H.N. , Ulrich, C.R. , Holdsworth, C.E. , Kitchen, D.N. , Halliwell, W.H. , and Blum, S.C. (1984). A chronic inhalation study with unleaded gasoline vapor. J. Am. Coll. Toxicol. 3:231–248.

NORTHEAST STATES FOR COORDINATED AIR USE MANAGEMENT (NESCAUM) (1989). Evaluation of the health effects from exposure to gasoline and gasoline vapors. Air Toxics Committee.

Popp, J.A. (1985). Digestive System. T.C. Jones , U. Mohr , and R.D. Hunt (eds.): Springer-Verlag: Berlin, pp. 39–45.

Squire, R.A. , and Levitt, M.H. (1975). Report of a workshop in classification of specific hepatocellular lesions in rats. Cancer Res. 35:3214–3223.

10.

U.S. ENVIRONMENTAL PROTECTION AGENCY. (1987). Evaluation of the carcinogenicity of unleaded gasoline. Office of Health and Environmental Assessment, Washington, D.C., EPA/600/6–87–001.