Finland has kept a registry on the manufacture and use of carcinogenic agents involving occupational exposure since 1979. Employers must report annually to the labor safety authorities the employees who have been exposed to carcinogens and provide information on carcinogenic agents produced, used, or formed. Out of 131 substances or groups of agents listed as carcinogenic, occupational exposure to 78 of them was reported in 1987. About half of the agents reported were used or produced in industry and half were handled on a laboratory scale. About 15,000 employees from 1,700 work departments were reported to the registry; 17% of them were women. The number of workers reported in 1987 accounted for 0.6% of the total work force. It has been estimated that at least 60,000 workers are exposed annually to carcinogens in Finland. The three most prevalent exposures--hexavalent chromium compounds, nickel and its inorganic compounds, and asbestos--accounted for over 60% of all exposed workers; only five carcinogenic chemicals were produced in Finland in 1987.