Sanet Post, Charles Benbrook
Cancer and Farmers
March 3, 1999

Beth's post asks if there is any evidence that farmers and their families, who face occupational as well as dietary exposure to pesticides, suffer higher rates of incidence/mortality of cancer, other health effects. The answer is --Yes, there is much evidence that a variety of cancers are elevated among those exposed to pesticides on or near farms where pesticides are routinely used, especially in areas where exposure via drinking water is common. The evidence is strongest for non-Hodgkin's lymphoma and related cancers. There must be over a dozen major epidemiological studies in the U.S. showing elevated risk ratios among farm/rural communities.

The literature also notes the consistent "healthy worker effect" in the farm population; higher rates of skin and lip cancers from exposure to the sun and smoking; elevated rates of other health effects, especially certain reproductive/birth defects; and a probable role (as initiators and/or promoters) of other chemicals farmers are exposed to routinely (fuels, hydraulic and other oils; viruses in hog and poultry sheds, etc). Pesticides rarely are the sole cause of cancer (among farmers and consumers); they are risk factors which increase the frequency and severity of disease in some portion of the exposed population. Much evidence is pointing to impaired immune system development and function as one of the most common mechanisms, i.e., pesticide exposure does not directly cause the cancer but it plays a role in disarming/weakening the body's natural defenses such that tumors gain the upper hand and are able to progress to become malignant.

The latest important epidemiological study I know of appeared in the March 1999 issue of Env. Health Perspectives (Vol. 107, Num. 3). "Cancer Mortality in Agricultural Regions of Minnesota," by Dina Schreinemachers, John Creason and Vincent Garry, confirms findings reported in an earlier study (published maybe 18 months ago), and also reached some new conclusions. They found elevated mortality ratios for 7 cancers in four regions of the state. The statistical significance of the findings were greatest in the regions with the most intensive use of pesticides.

Unlike other midwestern epi studies, this one found elevated rates of mortality to thyroid and bone cancers, in addition to various leukemias. A possible link to exposure to ETU, the oncogenic metabolite in the EBDC fungicides (maneb, mancozeb, ziram, metiram, also known as Dithane, Manzate, etc), is noted in one region, the first such finding.

There is a series of coordinated epidemiological studies underway now for 3-5 years as part of a national farm/farm family health study. Dozens of new studies will be published over the next 24 months, providing a much firmer base to quantify the contribution of pesticide exposure to increased incidence and mortality from cancers caused or promoted by pesticide exposure. The findings will no doubt be challenged, and among some labelled "junk science" just as the Consumers Union article and analysis are being attacked. Some people in the ag community now so firmly believe that pesticides are safe, period, that they appear not interested in nor willing to seriously consider new evidence of risks. In time science and better information will prevail over "conventional wisdom" and cherished mythology, but in the interim, expect a lot of name calling.

chuck

Last Updated on 3/7/99
By Karen Lutz
Email: karen@hillnet.com