New Study Links Pesticide Exposure to Prostate Cancer

(Beyond Pesticides, August 30, 2011)

A new study finds that older men living in California’s Central Valley are more likely to develop prostate cancer if they were exposed to certain agricultural pesticides than those who were not exposed. The study examines exposure via drift rather than occupational exposure, although similar results have been noted in farmworker populations. Exposure to methyl bromide or various organochlorine pesticides increased the risk of cancer by about one and a half times. The study, “Prostate cancer and ambient pesticide exposure in agriculturally intensive areas in California,” was published in the June 2011 issue of the American Journal of Epidemiology.

The researchers from the University of Southern California’s Keck School of Medicine recruited 173 men between the ages of 60 to 74 from 670 identified by the California Cancer Registry as being diagnosed with prostate cancer between August 2005 and July 2006 in California’s Central Valley. The authors used calendars and questionnaires to determine where they lived and worked between 1974 and 1999, and compared this to historical data of the corresponding area’s agricultural pesticide use from state pesticide use reports and land use records.

In comparison with unexposed persons, increased risks of prostate cancer were observed among persons exposed to compounds which may have prostate-specific biologic effects [methyl bromide (odds ratio = 1.62, 95% confidence interval: 1.02, 2.59) and a group of organochlorines (odds ratio = 1.64, 95% confidence interval: 1.02, 2.63)], but not among those exposed to other compounds that were included as controls (simazine, maneb, and paraquat dichloride).

According to the National Institutes of Health, prostate cancer is the third most common cause of death from cancer in men of all ages and is the most common cause of death from cancer in men over age 75. Prostate cancer is rarely found in men younger than 40. The prostate is a small, walnut-sized structure that makes up part of a man’s reproductive system. It wraps around the urethra, the tube that carries urine out of the body. Men who are at higher risk include those who: are African-Americans, who are also likely to develop cancer at every age; are older than 60; have a father or brother with prostate cancer; have been exposed to Agent Orange; abuse alcohol; are farmers; eat a diet high in fat, especially animal fat; work in tire plant; are painters; and, have been exposed to cadmium.

This is not the first study to link pesticide exposure to prostate cancer. In 2008, University of California Davis Cancer Center research showed that Vietnam War veterans exposed to Agent Orange have greatly increased risks of prostate cancer and even greater risks of getting the most aggressive form of the disease as compared to those who were not exposed. Based on medical evaluations conducted between 1998 and 2006, the study identified twice as many men exposed to Agent Orange with prostate cancer. In addition, Agent Orange-exposed men were diagnosed two-and-a-half years younger and were nearly four times more likely to present with metastatic disease.

For more information on the diseases linked to pesticide exposure, see Beyond Pesticides’ Pesticide-Induced Diseases Database.