Hazards of the World’s Most Common Herbicide

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Photo courtest NRCS
A farmer mixes Roundup prior to application. Roundup is widely used in yards and gardens across North America, and U.S. farmers spray millions of acres of crops with it each year.

Two new scientific studies add to concerns about the dangers posed by Roundup (glyphosate), the most widely used weedkiller in the world.

A group of scientists from the University of Caen in France found that human placental cells are very sensitive to the herbicide at concentrations lower than the agricultural use, and that it disrupts human sex hormones. The scientists concluded that the herbicide could “induce reproduction problems” in humans.

In another study, University of Pittsburgh biologist Rick Relyea looked at the effect of Roundup on other life forms. Relyea found that the herbicide caused an 86-percent decline in the total population of tadpoles.

Glyphosate is marketed under several brand names — Roundup is Monsanto’s original brand; Syngenta now markets glyphosate as Touchdown Total. These products are widely used in yards and gardens across North America, and U.S. farmers spray millions of acres of crops with them each year. Drift problems are common, where the herbicide spray lands off the targeted area, killing plants.

Use of glyphosate products has increased in recent years as a result of the introduction of genetically modified (GM) varieties of corn, soybean and cotton designed to tolerate glyphosate sprays. (Normal, non-GM crops and other plants die when they are hit with glyphosate.)

Monsanto has sold Roundup since 1974, and the company continues to argue that the weedkiller is safe. (Visit Monsanto’s Web site to read the company’s responses to these studies.) Others disagree. The Journal of Pesticide Reform published one of the most comprehensive reviews of the dangers associated with glyphosate, written by Caroline Cox, staff scientist for the Northwest Coalition for Alternatives to Pesticides. Here’s a summary of her review:

Symptoms of exposure to glyphosate include eye irritation, blurred vision, skin rashes, burning or itchy skin, nausea, sore throat and difficulty breathing, headache, lethargy, nose bleeds and dizziness.

In lab tests, glyphosate and herbicides containing glyphosate caused genetic damage to human and animal cells.

Studies of farmers and other people exposed to glyphosate herbicides link this exposure to increased risks of cancer, miscarriages and attention deficit disorder. Additional laboratory tests have confirmed the results of these studies.

Laboratory evidence indicates that glyphosate herbicides can reduce production of sex hormones.

Application of glyphosate herbicides increases the severity of a variety of plant diseases.

Studies of glyphosate contamination of water are limited, but new results indicate that it can easily contaminate streams in both agricultural and urban areas.

Glyphosate herbicides cause more off-target damage incidents than all but one other herbicide — 2, 4-D.

Glyphosate herbicides cause genetic damage and harm to the immune system in fish. In frogs, glyphosate herbicides cause genetic damage and abnormal development.

“Every time there is another scientific study showing hazards to human health, to me it’s another reason why finding alternatives to pesticides is so important,” Cox recently told Mother Earth News.

To read Cox’s entire fact sheet on glyphosate, which cites 56 references, visit the Northwest Coalition for Alternatives to Pesticides.

Cheryl Long is the editor in chief of MOTHER EARTH NEWS magazine, and a leading advocate for more sustainable lifestyles. She leads a team of editors which produces high quality content that has resulted in MOTHER EARTH NEWS being rated as one North America’s favorite magazines. Long lives on an 8-acre homestead near Topeka, Kan., powered in part by solar panels, where she manages a large organic garden and a small flock of heritage chickens. Prior to taking the helm at MOTHER EARTH NEWS, she was an editor at Organic Gardening magazine for 10 years.Connect with her on.