Agricultural exposures to carbamate herbicides and fungicides and central nervous system tumour incidence in the cohort AGRICAN.

BACKGROUND: Pesticides exposures could be implicated in the excess of Central Nervous System (CNS) tumors observed in farmers, but evidence concerning individual pesticides remains limited. Carbamate derivative pesticides, including herbicides and fungicides (i.e. (thio/dithio)-carbamates), have shown evidence of carcinogenicity in experimental studies in animals. In the French AGRICAN cohort, we assessed the associations between potential exposures to carbamate herbicides and fungicides and the incidence of CNS tumors, overall and by histological subtype. METHODS: AGRICAN enrolled 181,842 participants involved in agriculture. Incident CNS tumors were identified by linkage with cancer registries from enrollment (2005-2007) until 2013. Individual exposures were assessed by combining information on lifetime periods of pesticide use on crops and the French crop-exposure matrix PESTIMAT, for each of the 14 carbamate and thiocarbamate herbicides and the 16 carbamate and dithiocarbamate fungicides registered in France since 1950. Associations were estimated using proportional hazard models with age as the underlying timescale, adjusting for gender, educational level and smoking. RESULTS: During an average follow-up of 6.9 years, 381 incident cases of CNS tumors occurred, including 164 gliomas and 134 meningiomas. Analyses showed increased risks of CNS tumors with overall exposure to carbamate fungicides (Hazard Ratio, HR = 1.88; 95% CI: 1.27-2.79) and, to a lesser extent, to carbamate herbicides (HR = 1.44; 95% CI: 0.94-2.22). Positive associations were observed with specific carbamates, including some fungicides (mancozeb, maneb, metiram) and herbicides (chlorpropham, propham, diallate) already suspected of being carcinogens in humans. CONCLUSIONS: Although some associations need to be corroborate in further studies and should be interpreted cautiously, these findings provide additional carcinogenicity evidence for several carbamate fungicides and herbicides.

Increased risk of central nervous system tumours with carbamate insecticide use in the prospective cohort AGRICAN.

BACKGROUND: Pesticide exposures are suspected to be implicated in the excess of central nervous system (CNS) tumours observed in farmers, but evidence concerning individual pesticides remains limited. Carbamate insecticides, used on a wide range of crops, have shown evidence of carcinogenicity in some experimental studies. In the cohort AGRICAN (AGRIculture & CANcer), we assessed the associations between potential exposures to carbamate insecticides and the incidence of CNS tumours, overall and by histological subtype. METHODS: AGRICAN enrolled 181 842 participants involved in agriculture. Incident CNS tumours were identified by linkage with cancer registries from enrolment (2005-07) until 2013. Carbamate exposure was assessed by combining information on lifetime periods of pesticide use on crop or livestock and the French crop-exposure matrix PESTIMAT, individually for each of the 19 carbamate insecticides registered in France since 1950. Associations were estimated using proportional hazards models with age as the underlying time scale, adjusting for gender, educational level and smoking. RESULTS: During a 6.9-year average follow-up, 381 incident cases of CNS tumours occurred, including 164 gliomas and 134 meningiomas. Analyses showed increased risks of CNS tumours with overall exposure to carbamate insecticides and linear trends with duration of use of each carbamate. Considering tumour subtypes, hazard ratios for gliomas ranged from 1.18 for thiofanox to 4.60 for formetanate, and for meningiomas from 1.51 for carbaryl to 3.67 for thiofanox. CONCLUSIONS: Findings reinforce carcinogenicity evidence for already suspected active ingredients and draw attention to additional active ingredients, notably used on fruit trees, vineyards, potatoes and beets.