Sister-chromatid exchanges and chromosomal aberrations in rats treated with phenacetin, phenazone and caffeine.

To study chromosomal aberrations and the frequency of sister-chromatid exchanges (SCE) a long-term chronic toxicity study was performed in rats treated with phenacetin, phenazone and caffeine, alone and in different combinations. Compared with controls, aberrations such as gaps, breaks and structural dearrangements were only increased in the group treated by phenacetin alone. After mitomycin C treatment of the blood culture, the aberrations were markedly, but not significantly, increased. All experimental groups showed a higher SCE frequency, most deviating in the rats treated with phenacetin alone. This correlates with the fact that phenacetin is a strong general carcinogen.