To improve crop yield and control weeds, many farmers apply chemical herbicides to their fields. Many homeowners also reach for herbicides to lighten the work of lawn and garden maintenance on their property. However, when improperly or excessively applied, herbicides may seep into groundwater, contaminating wells and municipal water systems.
Herbicide labels outline the dangers their active ingredients pose to people if used improperly. A few of the most commonly found herbicides are alachlor, atrazine, endothall, glyphosate and dacthal. Long-term exposure to alachlor at unsafe levels can cause eye, liver, kidney or spleen problems; anemia; and an increased risk of cancer. Long-term exposure to atrazine at unsafe levels can cause cardiovascular system or reproductive problems. Problems associated with long-term exposure to endothall at unsafe levels include stomach and intestinal problems. For glyphosate, long-term exposure at unsafe levels can promote kidney problems and reproduction difficulties. For dacthal, unsafe levels over the long term can increase incidence of thyroid tumors. (See References 1 and 3.)
The risk of danger does not stop at application. If the chemicals in the herbicide enter the groundwater supply, an entire community is affected. Because of the health threat, various laws govern the manufacture, labeling, sale and use of chemical herbicides, including the Federal Insecticide, Fungicide, and Rodenticide Act; the Federal Food, Drug, and Cosmetic Act; the Food Quality Protection Act; the Endangered Species Act; and the Clean Water Act. (See References 2 and 6.)
A team of researchers at Pennsylvania State University found that overreliance on glyphosate-type herbicides for weed control has increased the number of resistant weeds. "We do understand why farmers would use the glyphosate and glyphosate-resistant crop package. It is simple and relatively cheap, but we have to think about the long-term consequences," David Mortensen, professor of weed ecology at Penn State, explained to Penn State Live, the university's news publication (see Reference 4). Although researchers primarily studied the use of glyphosate herbicides, J. Franklin Egan, a doctoral student in ecology at Penn State, was also concerned about weeds developing resistance to multiple types of herbicides. "Several species have developed amazing biochemical ways to resist the effects of the [glyphosate] herbicide," Egan told Penn State Live. "If weed problems are addressed just with herbicides, evolution will win" (see Reference 4).
Although the U.S. Geological Survey found most pesticides in groundwater were herbicides detected in the shallow groundwater of agricultural areas (see Reference 5), the average homeowner can play a part in keeping herbicides from contaminating groundwater. To avoid herbicide usage, pull weeds when possible rather than treating them. If you must use an herbicide, do not broadcast it over an entire lawn, especially when a heavy rain is expected. Spot spray an area instead, and never spray on driveways or sidewalks. On these less or nonporous surfaces, the herbicide stays on the surface, running off with storm water during the next rainstorm.
- U.S. Environmental Protection Agency: National Primary Drinking Water Regulations
- U.S. Environmental Protection Agency: Pesticides: Regulation Pesticides: Laws and Regulations
- Agency for Toxic Substances & Disease Registry: Public Health Assessments & Health Consultations
- Penn State Live: Integrated Weed Management Best Response to Herbicide Resistance
- U.S. Geological Survey: Herbicides in Shallow Ground Water Were Most Common Beneath Agricultural Areas
- U.S. Environmental Protection Agency: Summary of the Clean Water Act
Elizabeth McNelis has been writing gardening, cooking, parenting and homeschooling articles from her St. Petersburg urban homestead since 2006. She is the editor of “The Perspective,” a homeschooling newsletter distributed in Pinellas County, Fla. and writes a blog entitled Little Farm in the Big City. McNelis holds a Bachelor of Arts in professional and technical writing from the University of South Florida.
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