Chronic (8-month) Feeding Studies with Dc 360 Fluids in Rabbits with Cover Letter dated 04/20/94

摘要

This study evaluated the toxic effects of polydimethylsiloxane (PDMS) fluid under the conditions of normal and high cholesterol levels following chronic exposure. Four groups of 3 male and 3 female albino rabbits were given 1.0% PDMS, 350 cs.; 1.0% PDMS, 350 cs., and 0.8% cholesterol; 1.0% PDMS, 50 cs.; or 0.8% cholesterol in addition to the basal diet. An additional group of 6 male and 6 female albino rabbits were fed only the basal diet and served as controls. The animals were observed daily for appearance, behavior, and survival. Body weights were observed weekly. Hematological evaluations and urinalysis were conducted after 0,4, and 8 months. Clinical chemistry parameters were also examined after 8 months of exposure. After 8 months of exposure the animals were sacrificed and necropsied. Organ to body weight ratios were calculated and selected tissues were examined histopathologically. No significant effects were observed in body weights, organ to body weight ratios, or urinalysis. Males receiving PDMS fluid and cholesterol had a significant decrease in hemoglobin paralleled by a decrease in hematocrit. Females in the same group developed low hemoglobin values and an anemic state that is typical of hemoglobin values below 10 g per 100 ml. Clinical chemistry data at 8 months revealed 5 of the 6 animals in the group given PDMS and cholesterol had increased serum cholesterol. Increased serum cholesterol was also observed in all the animals receiving only cholesterol and in 3 of the 12 control animals. The livers of some animals receiving cholesterol revealed cirrhotic changes. Also observed in this group were enlarged adrenals and chronic hypercholesterolemia of the cardiovascular system. Histopathological observation of the liver revealed cholesterol related changes including fibrosis, cirrhosis, and biliary obstruction. Administration of as much as 1 percent PDMS at viscosities of either 50 or 350 cs. had no effect on development of the rabbit or on activity of the various organs and systems. Administration of increased sterol seriously impairs most organ functions. A mixture of cholesterol and the siloxane has the same effect as administration of the sterol alone.