Nucleic acid metabolism in the rat following short-term and prolonged ingestion of chrysotile asbestos or cigarette-smoke condensate.

Rats which have ingested a natural diet containing chrysotile asbestos (50 mg/day) both in the short (one week) and long term (5-15 months) show a statistically significant increase in the incorporation of [3H]-thymidine into DNA in the small intestine mucosa, colon and rectum, stomach and spleen and a significant decrease in the incorporation of this radiolabel into liver DNA. However, short-term ingestion of similar quantities of chrysotile produced no significant change in the incorporation of [3H]-uridine into RNA in any tissues, although prolonged ingestion of the mineral induced alterations in RNA metabolism in the lung and liver. By contrast, animals ingesting a natural diet containing cigarette-smoke condensate show a significantly high incorporation of [3H]-uridine into RNA in the mucosa, submucosa, spleen and heart following short-term exposure. Long-term ingestion of this diet produces similar changes in the submucosa, spleen and lung. The apparent specificity and the mechanism whereby ingested chrysotile interferes with DNA metabolism in some body tissues is discussed.