Cancer risk in a cohort of licensed pesticide users.

First admissions to the hospital among 25,945 men living in southern Piedmont and holding a license authorizing them to use pesticides were analyzed in a study of the cancer risk related to exposure to pesticides. Standardized incidence ratios significantly higher than one were encountered for malignant skin cancers and lymphomas. The risk of lymphoma was particularly high in predominantly arable areas. The standardized incidence ratios for tumors of the nervous system and hematopoietic tissue showed an interesting age-related pattern and a higher risk in areas primarily devoted to forest tree plantation, but did not reach significance. Certain hypotheses are advanced to explain these findings.