Weed Killers By The Glass
September 1, 1995

Weed Killers By The Glass: Johnson County, Kansas

Citizen Monitoring Results

The Johnson County (Kansas) Water District drinking water is contaminated with cancer causing weed killers at levels that have exceeded federal standards for at least one compound. Tests of city tap water found six different pesticides or metabolites in a single sample. The most common pesticide contaminant is atrazine, which was found in every tap water sample tested between May 15 and June 5, 1995. Cyanazine was also found in 100 percent of these same samples. During this test period approximately 1,500 infants in the Johnson County Water District (serving Mission, KS) consumed infant formula reconstituted with water contaminated with 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 Kansas corn growers at a rate of $84 million per year, for a ten year total of $840 million. 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 8 tap water samples
  • Highest level found -- 1.90 ppb.
  • Average concentration -- 1.45 ppb.



Causes mammary gland cancer in rats and birth defects in rats and rabbits in repeated studies. Causes genetic mutations. According to the EPA this 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 tap water samples
  • Fifty percent of samples were above the federal health advisory.
  • Highest level found -- 1.50 ppb, above the federal health advisory.
  • Average concentration --1.00 ppb, equal to the federal health advisory.


Tests for Multiple Weed Killers


  • Six pesticides or metabolites -- atrazine, cyanazine, metolachlor, alachlor, desisopropylatrazine, and desethylatrazine -- were found in a single sample of Johnson County Water District tap water collected on June 2, 1995.
  • These six pesticides or metabolites include one pesticide classified by EPA as a probable human carcinogen, three pesticides classified as probable human carcinogens, one pesticide that causes birth defects in animal studies, and three 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 Kansas Corn Reached 3.2 Million Pounds in 1993, up 578,000 Pounds Since 1990


Herbicide Acres Treated, 1994 Use, 1994 (lbs.)
Acetochlor 0 0
Alachlor 1,580,000 556,000
Atrazine 1,778,000 1,580,000
Cyanazine 219,200 378,000
Metolachlor 1,172,000 739,800
Simazine 0 0

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