Daily News Archive
From March 3, 2006
Pesticide Poisoning of Water Focus of Landmark Government Study
When pesticides are applied on fields, gardens, parks and lawns, a percentage of the chemicals ends up running off the treated site. More than 80 percent of urban streams and more than 50 percent of agricultural streams have concentrations in water of at least one pesticide, mostly those in use during the study period, that exceed a water-quality benchmark for aquatic life. Water-quality benchmarks, set by EPA, are estimates of pesticide concentrations that the agency says may have adverse effects on human health, aquatic life, or fish-eating wildlife. Insecticides, particularly diazinon, chlorpyrifos, and malathion frequently exceed aquatic-life benchmarks in urban streams. Most urban uses of diazinon and chlorpyrifos, such as on lawns and gardens, have been phased out since 2001 because of an EPA-industry agreement. In agricultural streams, the pesticides chlorpyrifos, azinphos-methyl, p,p'-DDE, and alachlor are among those most often found above benchmarks. While the standard benchmarks were not exceeded for human health, recent studies and decades of incomplete risk assessments suggest that EPA benchmarks are severely underestimated.
The USGS study also reports that pesticides seldom occur alone, rather almost always as complex mixtures. Most stream samples and about half of the well samples contain two or more pesticides, and frequently more. Robert Gilliom, Ph.D., the lead USGS researcher, explains that, “The potential effects of contaminant mixtures on people, aquatic life, and fish-eating wildlife are still poorly understood and most toxicity information, as well as the water-quality benchmarks used in this study, has been developed for individual chemicals. The common occurrence of pesticide mixtures, particularly in streams, means that the total combined toxicity of pesticides in water, sediment, and fish may be greater than that of any single pesticide compound that is present.
Studies of the effects of mixtures are still in the early stages, and it may take years for researchers to attain major advances in understanding the actual potential for effects. Our results indicate, however, that studies of mixtures should be a high priority.” A recent study by researchers at the University of California, Berkeley (see “Toxic Effects of Pesticides Amplified When Combined” in the February 2006 issue of Technical Report, Vol. 21, No. 2) finds that pesticide mixtures harm frogs at levels that do not produce the same effects alone, often levels 10 to 100 times below EPA standards.
“This report underscores the need to strengthen, not weaken, water quality protections from toxic pesticides that pollute rivers, streams, lakes and our underground water supplies,” said Paul Schwartz, National Policy Coordinator of Clean Water Action. “Drinking water providers are then faced with a dilemma about how to deal with the twin problem of killing dangerous bacteria while not increasing the chemical health risks for pregnant women and healthy infants.” The USGS report shows pesticides and their degradates are getting into the drinking water sources for millions of Americans. These contaminants combine with disinfectants, such as chlorine (added by drinking water providers to kill dangerous viruses, bacteria and pathogens), form disinfectant by-products that are associated with increases in birth defects and miscarriages. “The toxic cocktail of pesticides in our drinking water can’t be addressed by the chemical-by-chemical regulatory approach of government,” said Jane Nogaki, pesticide program coordinator of NJ Environmental Federation. “Citizens can take action at the local level to reduce or eliminate pesticides in their own back yard, in their local parks and schools.”
Take Action: Stop water contamination by pesticides and other lawn chemicals in your community. Help reduce and eliminate the use of unnecessary chemicals on lawns and public property, such as parks and athletic fields. Join the Coalition for Pesticide-Free Lawns and order copies of the new doorknob hanger, which helps to educate neighbors that pesticides are not necessary for a healthy, green lawn. For more information on pesticides in water, see Beyond Pesticides' article, “Threatened Water: Turning the Tide on Pesticide Contamination,” in the Winter 2005-2006 edition of Pesticides and You (Vol. 25, No. 4). For more information on pesticides in water, see Beyond Pesticides' article, Threatened Water: Turning the Tide on Pesticide Contamination from the Winter 2005-2006 edition of Pesticides and You.
USGS scientist Pixie Hamilton will be presenting the results and participating in a water and pesticides discussion at Building the Movement, the 24th National Pesticide Forum, May 18-20 in Washington, DC. See www.beyondpesticides.org/forum for details.