Picture of Emily Marquez

Emily Marquez

What’s the deal with glyphosate?

Glyphosate, the active ingredient of Monsanto's RoundUp, is the most commonly used pesticide active ingredient in the U.S. From the product's beginnings back in the 1970s, it's been touted as a relatively safe, non-toxic chemical.

But the use of glyphosate has surged dramatically since the 1990s, when genetically engineered (GE) "RoundUp Ready" corn and soybean crops were introduced. This intensive usage raises an important and increasingly urgent question: have the human health and environmental impacts of glyphosate been carefully and exhaustively evaluated? What do we know and what don't we?

I've heard a few of our community partners quoting neighbors or others assuring them that glyphosate is completely harmless. The product's familiar presence in home garden centers seems to lull people into thinking that it must be safe — so safe that some say "you could drink the stuff!"

What do we know?

We know this herbicide is in our air and water. A 2011 U.S. Geological Survey (USGS) study documented glyphosate and its breakdown product in the air and rain of agricultural areas in Mississippi and Iowa over two growing seasons. Preliminary data was also collected in Indiana. Overall, glyphosate was detected in 60-100% of the samples taken.

Another 2011 USGS study tested for the presence of glyphosate and its breakdown product in the surface water of four agricultural basins, and concluded that where glyphosate is used, it will be detected in surface water. So we know it is in our environment.

What do we know about glyphosate's potential for impacts on human health? I'll unpack this further in future blogs, but there's a growing body of evidence examining links to human health effects that raises some concern. Many of these impacts are not yet fully understood — but signal to me as a scientist that we should be paying very careful attention.

Here are a few nitty gritty details from recent studies:

  • Evidence suggests that glyphosate can activate the estrogen receptor in a breast cancer cell line, which means it may be able to mimic the function of the key sex hormone estrogen.
  • Researchers documented oxidative stress and other subchronic impacts on liver enzymes in rodent models. Oxidative stress can lead to production of compounds toxic to cells, and/or decrease the body's ability to detoxify biologically active and damaging compounds.
  • A range of other health impacts from nonmammalian models such as: retardation of larval development in oysters, adverse developmental effects affecting head formation in frog and chicken embryos and altered gene activity in fish livers suggesting potential for damage.

We know that glyphosate doesn't pose the same immediate threat to human health that neurotoxic organophosphate insecticides like chlorpyrifos do. But given the ubiquitous nature of glyphosate in our environment — and the concerns raised by some of the studies I've been looking at — I'd vote for knowing more about potential health and environmental harms. And I'd definitely vote against drinking it.

More questions

A few "big picture" questions come to mind too. What happens to our agricultural system when we continue to rely so heavily on pesticides like glyphosate as our solution?

Average Glyphosate Rate per Crop Year on Corn, Soybeans, and Cotton.

Source – Impacts of Genetically Engineered, Crops on Pesticide Use in the United States: The First Thirteen Years, by Charles Benbrook, November 2009.

In 2011, the increase in overall pesticide use in GE crops was 77.9 million pounds from the previous year. Glyphosate-resistant crops comprise the "overwhelming majority" of the herbicide-tolerant varieties so widely used today.

Also in 2011, an estimated 94% of soybean and 72% of corn area planted was devoted to herbicide resistant varieties. The dominance of herbicide-resistant crops in our agricultural system (take a look at this graphic on seed companies owned by the Big 6) tells me that the agricultural system is heading down a path that leaves precious few options for farmers who are interested in reducing their reliance on pesticides.

Then there's the uptick in glyphosate resistant weeds, which tells us that herbicides as a solution don't work in the long term, and may even end up negatively impacting agricultural productivity.

Will there be a tipping point at which the chemical inputs into our environment stress so many aspects of the ecosystem that we see unwanted and/or permanent changes? How will this, in the longterm, impact both human health and the environment?

I'd like to see Monsanto and the other pesticide companies answer that question truthfully.  Meanwhile, stay tuned for more updates and analysis on the emerging science of glyphosate and other pesticides.

Photo Credit: efwp/Flickr

Picture of Emily Marquez

Emily Marquez

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