Weed Killers By The Glass
September 1, 1995

Weed Killers By The Glass: Decatur, Illinois

Citizen Monitoring Results

Decatur drinking water is contaminated with cancer causing weed killers at levels that frequently exceed federal standards. A total of six different pesticides or metabolites were found in city tap water, with up to five found in a single sample. The most common pesticide contaminant was atrazine, which was found in every tap water sample tested between May 15 and July 1, 1995. Cyanazine was also found in 100 percent of these same samples. During this test period over 500 infants in Decatur consumed infant formula reconstituted with water contaminated with up to six toxic weed killers (Note 1: Ershow, Abby G., and Cantor, Kenneth P. 1989. Total Water and Tapwater Intake in the United States: Population-Based Estimates of Quantities and Sources. Life Sciences Research Office; Federation of American Societies for Experimental Biology. Bethesda, MD).

Most of these weed killers are used in corn production. Since 1985, taxpayers have subsidized Illinois corn growers at a rate of $607 million per year, for a ten year total of $6.07 billion. Farmers in turn pay nothing to clean up the water. The pesticide industry claims that farmers' weed control cost would double if these polluting herbicides were banned. Assuming the industry claim is true, the added costs to farmers would amount to just 11 percent of the value of the subsidy taxpayers pay to these corn farmers each year.



Causes mammary gland cancer in female rats in repeated studies.(Note 2: Copley, Marion. 1989. Follow-up to the Third Peer Review of Atrazine. EPA. Washington, D.C.; International Agency for Research on Cancer. 1991. World Health Organization. IARC Monographs on the Evolution of Cancer Risk to Humans. Vol. 53.) Classified by the EPA as a possible human carcinogen. Federal health standard in drinking water -- 3 parts per billion (ppb), European Drinking Water Standard -- 0.1 ppb.


  • Found in 100 percent of 16 tap water samples
  • 63 percent of samples were above the federal health standard
  • Highest level found -- 7.20 ppb, more than twice the federal health standard.
  • Average concentration -- 3.45 ppb, also above the federal health standard.



Causes mammary gland cancer in rats and birth defects in rats and rabbits in repeated studies. Causes heritable genetic mutations in mammalian cells, which according to the EPA makes cyanazine a potent carcinogen.(Note 3: Dykstra, William. 1991. Peer Review of Cyanazine (Bladex). EPA. Washington, D.C.) Classified by the EPA as a possible human carcinogen, required birth defects warning on the product label. Federal health guideline in drinking water -- 1 ppb. European Drinking Water Standard -- 0.1 ppb.


  • Found in 100 percent of samples
  • 81 percent of samples were above the federal health advisory.
  • Highest level found -- 6.20 ppb, six times the federal health advisory.
  • Average concentration -- 2.19 ppb, more than twice the federal health advisory.


Tests for Multiple Weed Killers


  • Six pesticides or metabolites -- atrazine, cyanazine, metolachlor, desisopropylatrazine, desethylatrazine, and acetochlor -- were found in Decatur tap water samples. Up to five of these were found in a single sample.
  • These six pesticides or metabolites include one pesticide classified by the EPA as a probable human carcinogen, three classified as possible human carcinogens, one pesticide that causes birth defects in animal studies, and two pesticides that disrupt the normal functioning of the hormone system.
  • Federal drinking water standards do not account for this simultaneous exposure to multiple pesticides (or other contaminants) in drinking water, and allow cancer risks from these weed killers up to 29 times higher than the federal government allows from the same chemicals in food.


Use of 6 Major Herbicides on Illinois Corn Reached 32.4 Million Pounds in 1994, up by 6 Million Pounds Since 1990


Herbicide Acres Treated, 1994 Use, 1994 (lbs.)
Acetochlor 580,000 973,000
Alachlor 1,972,000 5,041,000
Atrazine 9,628,000 11,345,000
Cyanazine 2,668,000 6,933,000
Metolachlor 3,712,000 7,713,000
Simazine 348,000 415,000

(Note 4: USDA 1995. Agricultural Chemical Usage: 1994 Field Crops Summary.)