A cohort mortality study of leather tanners in Tuscany, Italy

Background Work in leather tanning may involve exposure to a wide range of chemicals. Some of these are carcinogens or suspected carcinogens. Increased risk for a number of cancers have been reported, although there are considerable inconsistencies between studies. The present study investigates the mortality of leather tanners in Tuscany, Italy. Methods Tanneries were selected from the 1996 Valdarno Inferiore Tanneries Census and were in operation since December 31, 1970. Employees were followed until December 31, 1998 through company records, and the National and Regional Death Index. Demographic and work history data were abstracted from company payrolls. Regional mortality rates were used to calculate Standardized Mortality Ratio (SMR). Analyses were completed for the overall cohort (men and women) and for men who ever worked as of finisher chrome tanners, and vegetable tanner (only men). Results The cohort consisted of 4,874 workers (4,150 males and 724 females) employed in 92 tanneries active in 1996 and operating on December 31, 1970. Ascertainment of vital status and cause of death were completed for all individuals by the end of follow-up, December 31, 1998. Males showed increases for cancer of the endocrine glands (SMR 5.67, 4 observed (obs), 90% Confidence Intervals (Cl) 195-1,308), blood diseases (SMR 3.29, 4 obs, 90% CI 112-753), mental disorders (SMR 1.95, 6 obs, 90% Cl 85-385), violence and accidents (SMR 1.30, 54 obs, 90% CI 102-163). Mortality from myeloid leukemia was increased in males (SMR 2.08, 5 obs, 90% CI 82-437) and in females (SMR 5.99, 2 obs, 90% CI 106-1,887). One death from nasal cancer was observed versus 0.2 expected. Mortality from lung cancer was increased among finishers (SMR 1.45, 19 obs, 90% CI 95-212), an increase was observed also for bladder cancer (SMR 1.25, 2 obs, 90% CI 22-393) and pancreatic cancer (SMR 1.20, 2 obs, 90% CI 21-379). Conclusions The study confirms previous observations among tanners of increased mortality from lung, bladder, and pancreatic cancer. Noteworthy are the increased mortality from myeloid leukemia together with the new findings of an increased mortality from endocrine glands tumors, blood diseases, and psychiatric disorders which should be considered with caution because of the small number of cases and the novelty of the observation.