RESUMO
Semicarbazide (SEM) belongs to the hydrazine family of chemicals, some members of which are known to possess carcinogenic potential. Information on the potential hazard of SEM itself is incomplete and the possibility that it is genotoxic cannot be ruled out. SEM is widely used as a residue marker for the banned veterinary drug nitrofurazone. Also, it occurs as a break-down product of azodicarbonamide (ADC), a chemical used as a flour treatment. Furthermore, it may form as a reaction product of hypochlorite action on food additives. In the present study, we investigated the possible genotoxic effects of SEM with respect to the following cytogenetic end-points: (1) in vitro micronucleus (MN) formation and sister-chromatid exchange (SCE) induction in human lymphocytes and (2) in vivo micronucleus induction on rat bone marrow polychromatic erythrocytes (PCEs). Comparing MN and SCE frequencies on control and examined concentrations (0.5, 2.5, 5, 10 and 20 microg ml(-1)) did not reveal statistically significant differences except, marginally, the highest concentration (20 microg ml(-1)) in SCE analysis. On the other hand, oral administration of 50, 100 and 150 mg kg(-1) b.w. of SEM showed a statistically significant effect in MN frequencies on Wistar rats' bone marrow PCEs, with no dose-response pattern.