Study Links Women’s Brain Cancer to Herbicide Use

(Beyond Pesticides, October 10, 2008)

A study published in the American Journal of Epidemiology [Vol. 167, No. 8] finds women who have used herbicides are twice as likely to have meningioma, a specific kind of brain tumor. The study, “Occupational exposure to pesticides and risk of adult brain tumors,” was conducted by the National Cancer Institute.

The authors examined the risk of two types of brain cancer, glioma and meningioma, associated with occupational exposure to insecticides and herbicides in a hospital-based, case-control study of brain cancer. Cases were 462 glioma and 195 meningioma patients diagnosed between 1994 and 1998 in three U.S. hospitals. Controls were 765 patients admitted to the same hospitals for nonmalignant conditions. Occupational histories were collected during personal interviews. Exposure to pesticides was estimated by use of a questionnaire, combined with pesticide measurement data abstracted from published sources.

The researchers found no overall link between brain cancer and on-the-job exposure to pesticides or herbicides. However, looking closer at the data, the researchers noticed that women who reported using herbicides had a more than doubled risk for meningioma compared with women who never used herbicides, and there were significant trends of increasing risk with increasing years of herbicide exposure and increasing cumulative. There is no association between meningioma and herbicide or insecticide exposure among men. Unfortunately, the studies used by the Environmental Protection Agency (EPA) to register pesticides are conducted on male rats.

Of the women with the highest herbicide exposure, most worked in restaurants or grocery stores, and were likely exposed by routinely handling produce treated with herbicides.

Tumors of the brain, cranial nerves, and meninges account for 95 percent of tumors of the central nervous system and include some of the most rapidly fatal types of cancer. An estimated 20,500 new cases of brain and other nervous system cancers were diagnosed during 2007 in the United States. The two most common histologic types of brain tumors are gliomas and meningiomas, and data suggest that gliomas are more common in men, while meningiomas occur more often in women.

Another study, published in 2007 in the journal Occupational and Environmental Medicine indicates that farmworkers and persons exposed to high levels of pesticides have an increased risk of developing brain tumors, especially gliomas – a tumor of the nervous system. The study, “Brain tumors and exposure to pesticides: a case-control study in southwestern France,” suggests that not only are occupational pesticide exposure risks high, but indoor domestic uses of pesticides also increase the risk of developing brain tumors.