Atrazine is a triazine-based herbicide, and is most commonly used on corn crops in farming states. It is also sometimes applied to lawns,
gardens, parks and golf courses. Atrazine has been used as a cheap and effective broad-leaf herbicide for the last 35 years, and is today the most frequently used herbicide in the United States. More than 65 percent of the corn crop acreage in the United States is treated with atrazine. The main route of exposure to atrazine for the general population is through drinking water. Atrazine can enter drinking water sources, including the Kansas River and reservoirs such as Perry, Clinton, Milford and Tuttle, by overland runoff from agricultural fields and other areas of use. There is concern about exposure through drinking water for people living in states that use atrazine heavily. Studies have suggested possible adverse health effects resulting from exposure to atrazine, including birth defects, developmental defects, and certain cancers. There is also evidence that atrazine acts as an endocrine disruptor, resulting in lowered fertility and inhibited puberty. To limit these effects, the Environmental Protection Agency has set a Maximum contaminant level of 3 μg/L (equivalent to 3 parts per billion); the Food and Drug Administration also set a maximum allowable level for atrazine in bottled water at 3 μg/L. The EPA generally does not require water systems to notify residents unless the yearly average of atrazine in drinking water exceeds 3 μg/L, and considers one-day exposures of up to 297 μg/L safe.
The EPA has come under recent scrutiny for not addressing studies that suggest adverse human health effects occur at levels of exposure much lower than the current guideline of 3 μg/L. Recent studies found that, even at concentrations meeting current federal standards, the chemical may be associated with birth defects, low birth weights and menstrual problems. One study published in the journal Environmental Health Perspectives suggests that concentrations as small as 0.1 parts per billion may be associated with low birth weights. Officials at the EPA insisted that Americans are not exposed to unsafe levels of atrazine, and the current regulations are sufficient to protect human health. However, on October 7, 2009, officials announced that they would initiate a new inclusive study of the effects of atrazine on human health. The results of the study will be used to reevaluate the current regulatory standards. (More information may be found by clicking here)
In response to the recent studies, forty-three water systems in six states — Illinois, Indiana, Iowa, Kansas, Mississippi and Ohio — recently sued manufacturers of atrazine to force them to pay for removing the chemical from drinking water (More information may be found by clicking here). The largest manufacturer of atrazine is the Swiss agribusiness company Syngenta.
An efficient way to mitigate the amount of atrazine in our rivers and lakes (and subsequently, our drinking water) is to maintain riparian buffer zones between agricultural land and river banks. Riparian zones are areas of riverbank vegetation, including trees and native plants and grasses. These strips of vegetation act as a filter for overland runoff (rain water washing over the fields and into the river) which carries with it pesticides, soil particles, and fecal coliform bacteria. Riparian zones also stabilize streambanks and prevent erosion, and improve aquatic ecosystems by providing shelter, food, and shade to help regulate water temperature. It is common for agricultural fields along the banks of the Kansas River to have all riparian vegetation removed, so that crops may be planted all the way to the edge of the river (see picture on left). Loss of the riparian buffer can also happen when the river migrates laterally. In this type of system, there is no filter to prevent pesticides and fecal coliform bacteria from entering the river. Rivers with absent riparian zones not only have higher concentrations of pollutants, they are also more turbid (cloudier due to large amounts of soil and other particles suspended in the water column) and warmer due to the absence of shade. High turbidity and warmer water both decrease the concentration of dissolved oxygen in water, which stresses fish and other aquatic organisms. Often, riparian areas are removed to maximize the area of cropland available; however without a riparian zone the river quickly erodes away the riverbank, undermining cropland and often causing crops to fall into the river. Friends of the Kaw highly advocates restoring riparian zones along the banks of the Kansas River and its tributaries.
Sources
"Atrazine." U.S. Environmental Protection Agency. 5 Mar. 2010.
Duhigg, Charles. "Debating How Much Weed Killer Is Safe in Your Water Glass." The New York Times. 22 Aug. 2009.
"EPA Begins New Scientific Evaluation of Atrazine." Environmental Protection Agency. 7 Oct. 2009.
Ochoa-Acuña, Hugo and others. "Drinking-Water Herbicide Exposure in Indiana and Prevalence of Small-for-Gestational-Age and Preterm Delivery." Environmental Health Perspectives 117.10 (2009): 1619-624.
