The Latest Glyphosate (Roundup) Controversy

A Man  Is Spraying Herbicide
credit: Big Stock Photo

by Marty Fisher, EMGV

I think I was in high school when RoundUp first burst on the gardening scene. I hate to admit it, but that was four decades ago. I remember how excited my mother was to spray it on that hateful Bermuda grass and watch it shrivel and die—really DIE! It seemed like a miracle, and we wondered if it were too good to be true.

Glyphosate, the active ingredient in RoundUp and other herbicides, has been extensively tested in laboratory animals and humans over the years and repeatedly found to be safe—or as safe as a human-engineered chemical introduced into the natural environment can be. It is a non-selective, broad-spectrum herbicide. When applied to actively growing plants, it is absorbed into the tissues and disrupts vital biochemical processes. Annuals begin to wilt and die in two to four days, while perennials can take seven to 10 days to die.

Glyphosate’s widespread appeal is based on its effectiveness, its low toxicity, and the fact that it has a low risk of leaching into groundwater. It is absorbed onto soil particles, where it stays in place and is gradually broken down into carbon dioxide.

Agricultural use of glyphosate greatly increased when food crops were genetically modified to make them immune to it. This enabled farmers to spray entire fields without fear of damaging their crops, and, understandably, led to concerns about glyphosate’s proliferation in the environment.

A Cancer Risk?
The latest controversy over glyphosate started in 2015, when the International Agency for Research on Cancer (IARC) an arm of the World Health Organization (WHO), released a report concluding that glyphosate is a Group 2a carcinogen—meaning it “probably causes” cancer in humans.

The Group 2a classification prompted mass litigation in the United States against Monsanto Corporation, the manufacturer of RoundUp, by people claiming glyphosate gave them cancer. A number of countries have now banned or restricted the sale or use of glyphosate-based herbicides.

In California, environmental officials sought to require cancer warning labels on food products containing traces of glyphosate, but this move was recently barred by a federal judge. The ruling leaves glyphosate on the state’s Proposition 65 list as “a chemical known to the state of California to cause cancer,” but bars anyone from enforcing a requirement to warn consumers about its presence in food. Major agricultural industry groups have sued California, alleging that a warning label on food would violate First Amendment free speech protections by compelling retailers to post “false, misleading, and highly controversial statements” on their products.

The IARC study has been called “an outlier” by scientists in Europe and the United States, because glyphosate has been studied so rigorously for so long. The IARC study is the only study to have declared it a “probable carcinogen.”

A review of the IARC study by Reuters News concluded that significant revisions were made to a draft of the study before it was published. The revisions concerned animal studies, specifically the omission of conclusions by multiple scientists that there were no links between glyphosate and cancer in laboratory animals.

In 2016, a joint United Nations and WHO panel reviewed the potential for glyphosate in food to cause cancer in people. It concluded the herbicide was “unlikely to pose a carcinogenic risk to humans.” Both the U.S. Environmental Protection Agency (EPA) and the European Food Safety Authority and the European Chemicals Agency have also assessed glyphosate and ruled it safe for humans and the environment.

A Miracle, with Caveats
For home gardeners, who constantly battle increasingly prevalent, highly invasive weeds, glyphosate truly does have the impact of a small miracle. It can eliminate in minutes what would have taken hours to remove by hand. Some weed infestations pose a risk to human health, native plants and wildlife habitat, and ornamental plantings. In these cases, glyphosate-based products are a reasonable and highly effective solution.

They should be used as a weapon of last resort, and as part of an integrated pest management (IPM) strategy. IPM helps solve pest problems while minimizing risks to people and the environment. An ecosystem-based strategy, it focuses on long-term prevention and management through biological control, habitat manipulation, modification of cultural practices, and the use of resistant plant varieties.

As with any herbicide or pesticide, take appropriate precautions when using glyphosate. These include wearing protective clothing to cover all exposed skin, a breathing mask and goggles or glasses, and removable shoe covers. Never spray on a windy day, as spray may drift onto desirable plants and water surfaces. Follow manufacturer’s directions carefully.

Resources for More Information on Glyphosate
Where is Glyphosate Banned?

Reuters: U.S. EPA says Glyphosate Not Likely to be Carcinogenic to People

Gyphosate Use and Cancer Incidence in the Agricultural Health Study, NCI Journal, November 2017

National Pesticide Information Center, Glyphosate Fact Sheet

Killing Weeds in the Garden with Glyphosate, Michigan State University Extension

Safety Update from the EPA on April 30, 2019

5 thoughts on “The Latest Glyphosate (Roundup) Controversy

  1. Pingback: Glyphosate Follow Up — Danger to Pets – Durham Extension Master Gardeners

  2. No doubt glyphosate based herbicides may have some cancer risk. Cancer is apparently a malignant growth of aberrant cells which have mutated for many reasons. Many food and industrial chemical compounds have been found to pose some risk of increased cancer in laboratory animal studies. Whether this proves that the risk is posed to humans whose contact with the offending agent is low and casual is arguable, and not always supported by solid data. Nevertheless, use of any herbicide/pesticide, synthetic or “organic” should always be accompanied by careful following of all label instructions, wearing protective clothing when recommended, and avoiding overuse of the product. “Better safe than sorry.”

    Overuse includes wholesale application on very large scale to control weeds in glyphosate-resistant food strains. It’s well known that weeds may evolve to be resistant to the herbicide just as the food crop has been modified to be. Then, where are we? Do we rush to develop food crops with even more herbicide resistance, followed by another upgrade in weeds’ own coping mechanisms? This is nature’s version of a nuclear arms race, and potentially just as futile and dangerous.

    Modern agriculture has evolved (devolved?) into monocropping, with good practices such as crop rotation, multi-strain planting, etc., largely gone by the wayside. For large scale food production this seems to have been unavoidable, but it leads to necessary overuse of herbicides and pesticides which can be avoided in the home/community garden. It may be impossible now to buy a commercially produced grain, fruit, leafy green that doesn’t contain traces of some potentially dangerous chemical. The obvious exception to this is locally grown (backyard, small farm) provider, but this option is available largely, or even only, to a few buyers.

    Some states have brought lawsuits against manufacturer and growers to restrict, or even prevent, use of glyphosate herbicides on the grounds that drift from sprayed fields has damaged crops in nearby fields, and some of these suits have been successful. But, the world is faced with an ever-increasing population, many of whom are hungry from birth; decrease in arable land acreage due to drought/flooding; poor farming practices; other climate changes and war. In order to deal with these human problems food producing nations are going to have to make difficult choices in order to balance worldwide dietary needs and environmental degradation. And, as much as we may not like it, these choices are going to have to include widespread use of synthetic herbicide/pesticide products Our job is to do this as wisely as we possibly can.

  3. Robin Barth

    Good info. Marty, I appreciate and like how you tried to make sense of the varying viewpoints of Roundup safety.

  4. Doug Roach

    It’s certainly worth a mention that the US Geological Survey has determined that Glyphosate® and its degradation product AMPA (aminomethyl phosphonic acid) have been detected in increasing amounts in ponds, lakes, streams and rivers. Most unfortunate is the fact that the effect of this source of contamination on those essential sources of biological nutients remains both ignored and largely unstudied. As goes the water supply, so goes the land.
    Glyphosate, in my opinion, remains a scourge on the creatures of the planet from microbes to humans and we will rue the day we permitted the large-scale, virtually unfettered introduction of such a poison into our food supply, our water, and into the forage of our pollinators.

    But, yeah… it does make for prettier lawns.

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