Hazards of the World’s Most Common Herbicide

New scientific studies link Roundup, the world's most common herbicide, to a host of health risks, such as cancer, miscarriages and disruption of human sex hormones.


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.

Photo courtest NRCS

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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.

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 .

11/18/2013 3:43:02 PM

Jenny Rasico, I've wondered exactly the same thing. Living in suburbia exposes our "green" family to plenty of chemicals (which have made me quite ill, already). I have considered beginning a block club type of informational night at a grassroots level. There are so many seemingly small changes we can all make to improve our environment. I am thinking if the information is presented in a substantiated manner admitting the safe vs. unsafe ideologies and is presented in a non-judgmental format, it will make a difference to a handful of people at a time. .....Baby Steps

11/18/2013 3:34:01 PM

I've read quite a few articles which provided proof that round-up does not break down, quicly or otherwise. When I locate them, I will post them. My stomach churns to think that Monsanto is allowed to do what they do for money.... Lots and lots of Money. It doubly distreeses me to hear that Mr./Mrs. Joe would love to spray round-up in small areas because he/she wants to save time which for him/her will equal some profit. We as a race are destroying our earth, friends, and neighbors health for a minor convenience to ourselves. How disheartening. :(

t brandt
12/30/2011 11:41:28 PM

Excellent post, Randolph. Nannycrats are those politicians who get their election funds from The Trial Lawyers. More regulations mean more potential for law suits. Glyphosphate is a very safe chemical when used properly. The health effects listed in the article are those resulting from unusually large exposures when the chemical is used improperly out of ignorance or accident. The chemical breaks down rapidly after use and produces absolutely no health problems from eating food produced in its presence. The quote in the article about health effects in farm families is made based on studies with borderline statistical significance, at best.

randolph erickson
12/29/2011 11:02:09 PM

I own a one man company that mows grass in Florida. I would love to use round up especially around a/c units where my weed eater can't get. (I don't have time to pull weeds, nor do I want to fight fire ants.) The law in Florida is very clear. I must take a class $35. Then take a test $150. Then I must produce proof of $400,000 worth of liability insurance with more proof that it covers "environment disasters". This covers fertilizer in plant beds only, round up use, and insecticides in plant beds only. I only want to spray round up. I can't afford the $900 a year insurance, vs the $250 per year I spend now for general liability. It seems to favor very large enterprises, and discriminates against me. I want to use round up, so I don't have to use my gas powered weed eater, and the plastic string that it spits out.. Anything we put on the ground can leach and cause issues. In the modern world, round up comes premixed and idiot proof. Would you rather have someone like me spraying it only where I need to? Or an uneducated home owner just spraying where ever? I have been to college to know how to use most chemicals. My education is worthless because I have been regulated out of that part of my business. Remember, the worst pollution comes from the every day person. Not the paid professional who cares about things.

jenny rasico
4/8/2009 8:43:05 PM

this is the second article in 2 days i have read regarding this newly found old threat. Very scary. I am in my first year of organic gardening after finding out that my dad's lymphoma was triggered by pesticide exposure. How do we protect our children from this widespread threat? If we eat organic food, how do we avoid overspray from the neighbor's weed killer of choice, or the water? I am expecting a child soon , and the stats on chemicals in our environment is scary. what can we truely do? how do we stop the machine?is it possible to create a mini clean environment for ourselves?