Herbicides in Drinking Water
Herbicides in drinking water are becoming a major health concern as the conventional water treatments used by 90% of public water utilities in this country do not remove any of the herbicides that are most commonly applied in the U.S. However, people that live in rural, agricultural areas are at the greatest risk for herbicidal drinking water contamination as the vast majority of them get their water from private wells which are not subject to routine testing.
Each year, farmers across the Midwest apply more than 150 million pounds of herbicides to their corn and soybean fields. Making matters worse, most of these are applied before the crop emerges and can absorb and reduce groundwater contamination by natural biodegradation.
How Herbicides get into Drinking Water
The two most common ways for herbicides to enter drinking water supplies are:
- Gradual accumulation in the soil where they slowly percolate down into underground water.
- Heavy rainfall and irrigation which wash herbicides off farmland and into lakes and rivers.
The amount of runoff is particularly astonishing. During peak periods of spring rainfall, it is estimated that 18,000 pounds of herbicides are washed from fields, enter the Mississippi river and flow into the Gulf of Mexico each day. What�s more, over 14 million people in the U.S. routinely drink water that is contaminated with herbicides, including an estimated 65,000 infants.
Types of Herbicides
The five most commonly used herbicides in the United States are:
They are sold under a number of different names commercially, and they are especially effective at restricting the growth of grasses and broadleaf weeds that compete with crops for water and soil nutrients. However, scientists are only beginning to discern the impact that these herbicides have on the health of humans.
Health Effects of Herbicides in Drinking Water
Studies conducted by the herbicide manufacturers� own chemists determined that the top five herbicides cause at least nine different types of cancer, various birth defects, and genetic mutations that are passed on from one generation to the next. Other health problems from herbicide contamination of drinking water include:
- Cardiovascular problems
- Impaired function of the eyes, liver, kidney, and spleen
- Reproductive problems and complications
- Gastrointestinal problems
- Premature births and low birth weight
- Growth retardation of fetuses in utero
A study conducted by the EPA in 1994 reached these conclusions about herbicides in drinking water:
- Drinking water in the Midwest is commonly contaminated with two or more of the above herbicides.
- 61% of water samples taken in Kansas City contained two or more of these herbicides.
- 47 % of samples taken from four rivers in northern Ohio contained three or more.
- 38 % of samples from 27 Midwestern reservoirs contained four or more.
- More than 3.5 million people in 120 Midwestern cities and towns face cancer risks more than 10 times the federal cancer risk benchmark.
- Over 400,000 people in 98 rural communities face cancer risks from 10 to 116 times the federal benchmark for cancer risk.
While we are still learning about the impact that herbicides in drinking water have on our environment and ourselves, the preliminary figures suggest that we�re headed for big trouble. The EPA and FDA have imposed strict controls on the allowable levels of contaminants in food, but the standards for herbicidal water contaminants are curiously lax. It may take a few more generations for us to fully grasp the impact that herbicides in drinking water have on our bodies, but unless we get serious about controlling them right now, these problems will persist for a very long time to come.