Comparative 90-Day Feeding Study with Low-Viscosity White Mineral Oil in Fischer-344 and Sprague-Dawley-Derived CRL:CD Rats

Abstract

A 90-day study was conducted to compare the effects of dietary administration of a food-grade white oil in female Fischer-344 (F-344) and Sprague-Dawley-derived (CRL:CD) rats. Animals were fed a low viscosity (15 mm²/sec at 40°C) paraffinic white oil (designated as P 15[H]) at 0, 0.2, or 2.0% of the diet for 30, 61, or 92 days. There were no significant adverse clinical observations or unscheduled deaths. In the F-344 rats, occasional treatment-related changes were seen in hematology and clinical chemistry parameters. At necropsy, mesenteric lymph nodes were enlarged, and there was an increase in absolute and relative liver, mesenteric lymph node, and spleen weights as compared to controls. Histopathologic effects included hepatic and mesenteric lymph node microgranulomas and mesenteric lymph node histiocytosis. In CRL:CD rats, the only effects noted were accumulations of chronic inflammatory cells in the liver at the high dose only, without the formation of discrete microgranulomas. A dose-related increase in mineral hydrocarbon (MHC) material in the liver and mesenteric lymph nodes was observed in both F-344 and CRL:CD rats. Although increased, liver MHC content was significantly less (approximately 50%) in CRL:CD rats than the levels detected in the F-344 rats. Mesenteric lymph node MHC levels did not differ significantly between the strains. This study demonstrated strain differences among rats in histopathologic effects of white oil, with the CRL:CD rat essentially showing no response compared to the F-344 rat. The differences in the pathologic responses between the 2 strains appears to result from the higher MHC tissue content and a greater sensitivity of the F-344 rat to the presence of the MHC material.

Keywords

Hepatic granuloma microgranuloma mesenteric lymph node histiocytosis

References

American Petroleum Institute ( 1992). Mineral Oil Review. HECRL:CD Report No. 39-31651. American Petroleum Institute , Washington, D.C.

Baldwin MK , Berry PH , Esdaile DJ , Linnett SL , Martin JG , Peristianis GC , Priston RA , Simpson BJ , and Smith JD (1992). Feeding studies in rats with mineral hydrocarbon food grade white oils. Toxicol. Pathol. 20: 426-435.

Bird MG , Lewis SC , Freeman JJ , Smith JH , Hogan GK , and Scala RA (1990). Subchronic feeding study of white mineral oils in rats and dogs. Toxicologist 10: 143.

Concawe ( 1984). Assessment and Comparison of the Composition of Food-Grade White Oils and Waxes Manufactured from Petroleum by Catalytic Hydrogenation Versus Conventional Treatment. Report No. 84/60. CONCAWE , Den Haag.

Concawe ( 1993). White Oil and WaxeslSummary of 90-Day Studies. Report No. 93/56. CONCAWE, Brussels.

Dixon W. and Massey F. Jr (1969). Introduction to Statistical Analysis , 3rd ed. McGraw-Hill, New York, pp. 114-116.

Dunnett CW (1964). New tables for multiple comparisons with a control . Biometrics. 20: 482-491.

Gilman AG , Goodman LS , Rall TW , and Murad F. (1985). Goodman and Gilman's the Pharmacological Basis of Therapeutics, 7th ed. Macmillan , New York, p. 1002.

Holland M. and Wolf DA (1973). Nonparametric Statistical Methods. John Wiley and Sons, New York.

10.

McKee RH Pasternak SJ , and Traul KJ (1987). Assessment of the potential reproductive and subchronic toxicity of EDS coal liquids in Sprague-Dawley rats. Toxicology 46: 267-280.

11.

Shubik P. (1962). Studies of the toxicity of petroleum waxes. Toxicol. Pathol. 4(suppl.): 1-62.

12.

Snedecor GW and Cochran WG (1989). Statistical Methods, 8th ed. Iowa State University Press. Ames, Iowa, pp. 278-280.

13.

Walters DG Sherrington KV Worrell NR and Riley RA (1994). Formulation and analysis of food-grade mineral hydrocarbons in toxicology studies. Food Chem. Tox. 32: 549-557.

14.

Wanless JM and Geddie WR (1985). Mineral oil lipogranulomata in liver and spleen . Arch. Pathol. Lab. Med. 109: 283-286.