CANCER IN OFFSPRING OF PARENTS ENGAGED IN AGRICULTURAL ACTIVITIES IN NORWAY - INCIDENCE AND RISK-FACTORS IN THE FARM ENVIRONMENT

In this study of cancer in offspring we demonstrate that factors linke d to horticulture and use of pesticides are associated with cancer at an early age, whereas factors in animal husbandry, in particular poult ry farming, are associated with cancers in later childhood and young a dulthood. Incident cancer was investigated in offspring born in 1952-1 991 to parents identified as farm holders in agricultural censuses in Norway in 1969-1989. In the follow-up of 323,292 offspring for 5.7 mil lion person-years, 1,275 incident cancers were identified in the Cance r Registry for 1965-1991. The standardized incidence for all cancers w as equal to the total rural population of Norway, but cohort subjects had an excess incidence of nervous-system tumours and testicular cance rs in certain regions and strata of time that could imply that specifi c risk factors were of importance. Classification of exposure indicato rs was based on information given at the agricultural censuses. Risk f actors were found for brain tumours, in particular non-astrocytic neur oepithelial tumours: for all ages, pig farming tripled the risk [rate ratio (RR), 3.11; 95% confidence interval (CI), 1.89-5.13]; indicators of pesticide use had an independent effect of the same magnitude in a dose-response fashion, strongest in children aged 0 to 14 years (RR, 3.37; 95% CI, 1.63-6.94). Horticulture and pesticide indicators were a ssociated with all cancers at ages 0 to 4 years, Wilms' tumour, non-Ho dgkin's lymphoma, eye cancer and neuroblastoma. Chicken farming was as sociated with some common cancers of adolescence, and was strongest fo r osteosarcoma and mixed cellular type of Hodgkin's disease. The main problem in this large cohort study is the crude exposure indicators av ailable; the resulting misclassification is likely to bias any true as sociation towards unity. (C) 1996 Wiley-Liss, Inc.