A Case-Control Study of Brain Gliomas and Occupational Exposure to Chemical Carcinogens: The Risk to Farmers

Abstract

During 1983 and 1984, 240 newly diagnosed cases of brain glioma and 742 controls (465 non-glioma nervous system tumors and 277 patients with other neurologic diseases) were recruited and interviewed in the neurologic and neurosurgical departments of two hospitals in Milan, Italy. The occupational histories of cases and controls were compared, and relative risk estimates, adjusted for sex, age, residence, and socioeconomic status, were computed using the Mantel-Haenszel method. A statistically significant risk increase was found for farmers (relative risk (RR) = 1.6, p = 0.0025). This risk increase was attributable to those farmers who reported the use of chemicals (insecticides or fungicides, herbicides, and fertilizers). Among the three groups of investigated agrochemicals, only the use of insecticides or fungicides was associated with a significant increase in relative risk (RR = 2.0, p = 0.006). Many farmers exposed to fungicides reported the use of commercial compounds of copper sulfate. Some of these compounds contain methyl urea, which has a specific carcinogenic effect on the nervous system in animals. These data suggest that the occupational exposure of farmers to agrochemicals might be responsible for the observed excess risk of brain glioma in farmers.

Incidence and risk factors of cancer among men and women in Norwegian agriculture

“…The associatioll between grain farming and brain tumors among the men is in agreement with the results of a previous report (54), but we found no risk increase in combination with pesticide exposure indicators, as earlier reports indicate (55,56).…”

Cluster of brain cancers spuriously suggesting occupational risk among glassworkers.

“…Occupations that ha ve been reported as associated with increase d risks are dent ists (16), chemists (17), and electr icians and workers exposed to electromagnetic fields (18,19), but also artists, teachers and physician s (15). An excess risk has also been reported for farmers (20)(21)(22), and thi s risk has been especially relat ed to the use of insecticides and fungicide s (23). These chemicals, used in farming , can po ssibly also be an en vironmental risk facto r for person s other than farm ers.…”

Epidemiology of Glioma

“…Interestingly, therapeutic immunity to intracranial tumors has been induced in the laboratory by peripheral immunization with interleukin-4 (IL-4) transduced glioma cells [Okada et al 2001;Benedetti et al 1998]. Farmers have been found to have an increased risk for brain cancer in some studies (Kristensen et al 1996;Reif et al 1989;Wingren et al 1992;Ahlbom et al 1986;Musicco et al 1982;Musicco et al 1988;Brownson et al 1990;Heineman et al 1995), although they generally are healthier than the population-at-large (Kristensen et al 1996;Bråbäck 2002;Population and Public Health Branch (PPHB) 1995;Blair et al 2005;Ronco et al 1992), live longer (Alavanja 1996), and die less frequently from cancer overall (Blair et al 1993). Being raised on a farm ( (Godfrey 1975) has been shown to protect against asthma, hay fever, and atopic sensitization.…”