Effect of long-term ingestion of asbestos fibres in rats

The effects of ingested asbestos fibres were studied in Wistar Han rats. Chrysotile and a mixture of chrysotile/crocidolite (75%/25%) in palm oil were given for 24 months to 70 males and 70 females per group (daily doses 10, 60 and 360 mg); one control group was fed with normal diet, a second with normal diet plus palm oil. The animals were observed for a further 6 months after the end of the treatment. The results indicate that ingestion of asbestos fibres at high doses had no toxic effects and did not affect animal survival; in addition, there was no evidence of carcinogenic effects.