The incidence of chromosome aberrations (CAs) was investigated in cultured lymphocytes of 109 styrene-, formaldehyde-, and phenol-exposed workers in comparison with 64 controls. There was a marked increase in the incidence of the structural chromosome aberrations in the first mitotic division metaphases of occupationally exposed workers (3.59 +/- 0.26 CAs/100 cells vs 1.47 +/- 0.14 in controls (P < 0.01). 22 occupationally-exposed workers were selected for the trial including 1-month administration of a drug Aevitum (100,000 U of retinol palmitate plus 0.1 g of alpha-tocopherol acetate dissolved in 0.2 ml of oil) at a daily dose of 1-2 capsules for 5 days a week. The frequency of chromosome aberrations before, after the administration of a cumulative Aevitum dose of 2.0, 4.0 and 8.0 ml, and 6 weeks after the cessation of vitamin intake was 5.68 +/- 0.63, 4.33 +/- 0.45, 2.67 +/- 0.34, 2.00 +/- 0.25, and 2.64 +/- 0.21 per 100 cells, respectively. Thus, Aevitum was found to cause a significant decrease in occupationally-induced chromosome damage in human lymphocytes.