Fumonisin B(1) (FB(1)), a mycotoxin produced by Fusarium moniliforme, is a contaminant of cereals with various and complex cellular effects. FB(1) induces liver cancer in rats and has been linked to esophageal cancer in South Africa and China. The mechanisms of FB(1)-induced carcinogenesis are uncertain and the information on FB(1) mutagenic properties is limited and controversial. FB(1) contamination levels in maize and wheat from Chile were found to be similar to those in other countries. FB(1) was devoid of activity in gene mutation assays with Salmonella typhimurium strains TA100, TA102 and TA98. However, i.p. injection of FB(1) induced an increased frequency of micronuclei in mouse bone marrow polychromatic erythrocytes at 25 and 100 mg/kg. We conclude that FB(1) induces in vivo genotoxicity in the absence of in vitro mutagenicity in Salmonella.

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Although alcohol is known to be a carcinogen for humans, ethanol-genotoxicity studies are incomplete. Ethanol seems not to be a bacterial mutagen, but the results are confl icting in rodent assays. We investigate the genotoxicity in the bone marrow micronucleus (MN) test and in the dominant lethal mutation (DLM) assay using two long-term ethanol exposure protocols. In the MN test, mice consumed three doses (5, 10 and 15% v/v) for 32 weeks. MN induction was compared to two control groups of 5-and 38-week-old mice (the ages of the treated mice when the treatment was initiated and when they were killed, respectively). For the three groups treated with ethanol there was no signifi cant increase in MN induction as compared to the fi rst control group, but observed MN frequencies were signifi cantly lower than in the 38-week-old control group. This suggests a protective effect against genotoxic damage caused by aging, probably due to ethanol action as a hydroxyl radical scavenger. In the DLM assay, male mice drank ethanol at 15% or 30% (v/v) for 20 weeks. In both groups the number of dead implants was similar to the control, but there was a signifi cant reduction in total implants, indicating a pre-implantation loss.

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