Herbicide Exposure Linked to Pancreatic Cancer

(Beyond Pesticides, May 28, 2009)

Two commonly used herbicides, pendimethalin and EPTC, show a statistically significant exposure-response association with pancreatic cancer. The new study, “Agricultural Pesticide Use And Pancreatic Cancer Risk In The Agricultural Health Study Cohort,” published earlier this month in the International Journal of Cancer, is a case-control study of pesticide applicators and their spouses in Iowa and North Carolina. After controlling for age, smoking and diabetes, the study finds a three-fold increased risk with lifetime pendimethalin use and a two-and-a-half-fold increased risk with lifetime use of EPTC when compared to those that never used the chemicals. Among the 24 pesticides examined, having ever used one of five pesticides (trifluralin, chlorimuron-ethyl, pendimethalin, EPTC or heptachlor) shows at least a 40 percent excess risk of pancreatic cancer.

According to the U.S. EPA’s pesticide sales and usage statistics, pendimethalin is the third most commonly used home and garden (and other non-agricultural use) herbicide and the 7th most commonly used herbicide in agriculture, totaling 21-30 million pounds applied annually in the U.S. Pendimethalin is listed by the U.S. EPA as a Group C – Possible Human Carcinogen and is a suspected endocrine disruptor. Pendimethalin has been found to cause central nervous system depression in mice and rats. In addition, the herbicide potentiates hypnosis caused by other drugs such as pentobarbitone, barbitone or ether, and lengthened recovery from drug effects. The percentage of apoptosis increased in mouse embryos exposed to low doses of pendimethalin, suggesting that at levels considered to be safe in humans by regulatory standards pendimethalin has adverse effects very early in development.

EPTC is also a commonly used herbicide, with more than 5-8 million pounds used annually, according to EPA. It is regularly used on feed and food crops such as alfalfa, potato, and corn as well as non-agricultural uses such as rights-of-way and landscapes. EPTC, a thiocarbamate pesticide, is a cholinesterase inhibitor and is linked to increasing the risk of developing asthma.

Pancreatic cancer is the fourth leading case of cancer-related death in the U.S. The National Cancer Institute estimates that pancreatic cancer will lead to more than 35,000 deaths in 2009 and more than 42,000 new cases will be diagnosed in 2009. There has been a slight increasing trend in pancreatic cancers since the early 1990’s, with higher rates in men than woman.

Several studies published over the past 15 years have linked pesticide exposures to pancreatic cancer:
* A 2009 study analyzing pesticide sales in different parts of Brazil and cancer mortality rates a decade later found a statistically significant correlation with the mortality rates for several cancers, including cancer of the pancreas;
* A 2007 Finnish study found a more than six-fold increased risk of pancreatic cancer for male gardeners;
* A 2007 study identifying risk factors for pancreatic cancer in Egypt found a more than two and a half increased risk for those individuals exposed to pesticides;
* A 2001 National Cancer Institute study found excess risk for occupational exposure to fungicides (odds ratio (OR) 1.5) and herbicides (OR 1.6);
* A 2000 case-control study in Spain found occupational exposure to pesticides causes a three-fold increased risk for pancreatic cancer;
* A 1999 study of aerial pesticide applicator pilots found a significantly elevated risk for pancreatic cancer;
* A 1995 case control occupational study in Finland found a 1.7 increased risk for occupational pesticide exposure; and,
* A 1993 case-referent study of Italian farmers found a significantly increased risk of pancreatic cancer among licensed pesticides users with greater than 10 years experience.

Last month, EPA announced that it will be moving forward with preliminary testing of 67 active and inert pesticide ingredients for possible endocrine disrupting effects. Yet, according to prominent researcher and author Theo Colborn, Ph.D., EPA’s testing protocol will not detect chemicals that can alter development and function of the pancreas, and its hormone, insulin, which could lead to diabetes and obesity.

Looking for information on different pesticides? Find data on more than 80 pesticides commonly used in the U.S. in the Pesticide Gateway. Beyond Pesticides created this database tool to provide decision and policy makers, practitioners and activists with easier access to current and historical information on pesticide hazards and safe pest management, drawing on and linking to numerous sources and organizations that include information related to pesticide science, policy and activism.