It shows contamination of well water by Volatile Organic Compounds (VOCs). "VOCs come from a wide variety of sources, including gasoline, plastics, paints, dyes, solvents, adhesives, insecticides, and spot removers."
This study only tested 2401 wells, between 1991 and 2002. A pittance, since "about 400,000 new wells are drilled every year." Of those 2401:
"65% had detectable levels of VOCs, and 1% had levels above the EPA [limit]."Exposure to VOCs is a known risk factor for cancer: EPA: Drinking water Contaminants.
So, except for California and the Northwest, there does seem to be a gross correlation between this and the map of colon cancer rates in my previous post.
This doesn't let public water off the hook. Municipal water is chlorinated to kill microorganisms. Byproducts of chlorination include a group of compounds called trihalomethanes:
"Studies conducted at NIEHS have shown that administration of certain trihalomethanes, by-products of water chlorination, and several brominated chemicals cause colorectal cancer in experimental animals. Epidemiologic studies now suggest a link between the consumption of chlorinated water and increased human risk for colorectal cancer."Yep, that water guess has merit.
- Trihalomethanes and Colorectal Cancer, and Trihalomethanes and Other Environmental Factors That Contribute to Colorectal Cancer, Environmental health Perspective, 1994.