Weed Killers By The Glass
September 1, 1995

Weed Killers By The Glass: Baltimore, Maryland

Citizen Monitoring Results

Baltimore drinking water is contaminated with the cancer causing weed killer atrazine at trace levels. Tests of city tap water found at least two different pesticides or metabolites in a single sample. The most common pesticide contaminant is atrazine, which was found in 40 percent of tap water samples collected between May 15 and July 1, 1995. Desethylatrazine, a breakdown product of atrazine, was also found in Baltimore drinking water. During this test period approximately 8,500 infants in Baltimore consumed infant formula reconstituted with water contaminated with trace levels of 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 the nation's corn growers at a rate of $3 billion per year, for a ten year total of $30 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 40 percent of 15 tap water samples
  • Highest level found -- 0.19 ppb.
  • Average concentration -- 0.06 ppb.


The Presence of Multiple Weed Killers


  • Atrazine and one of its breakdown products, desethylatrazine, were both found at trace levels in a sample of Baltimore tap water collected on July 3, 1995.
  • Federal drinking water standards do not account for exposure to pesticide metabolites.


Approximately 5.6 Million Pounds of Herbicides Are Used On Corn In The Chesapeake Bay Watershed


Herbicide Acres Treated, 1994 Use, 1994 (lbs.)
Acetochlor n/a n/a
Alachlor 445,750 802,655
Atrazine 1,767,300 2,306,548
Cyanazine 248,250 399,688
Metolachlor 1,044,700 1,897,258
Simazine 260,700 266,638

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