What You Need to Know About the EPA’s Assessment of Atrazine

The agency’s new report on the second most widely used herbicide in the U.S. shows serious risks to birds, mammals, and fish. Don't know why it matters? Here's an explainer.


Last week, the Environmental Protection Agency (EPA) released a 500-page draft report on the environmental impacts of atrazine, the second most widely used weed killer in the United States and a chemical known as a water pollutant with potentially serious adverse health effects.

Although it’s not the first time the agency has assessed atrazine—the EPA must evaluate pesticides approved for use in the U.S. at least once every 15 years—this is the first close look it has taken at the herbicide since 2003. In that time, a great deal of new data has surfaced showing that atrazine is now widespread in the environment. There’s also new evidence of how the herbicide can harm plants and wildlife.

For the first time, the agency has concluded that atrazine poses a potentially serious ongoing risk to birds, mammals, fish, frogs as well as many plants it was not designed to kill. The draft report is open for public comment and will be followed later this year by a similar report on atrazine’s human health effects.

Here’s what you should know:

Dangerous Effects Even at Low levels

Atrazine is generally sprayed on corn and other crops, but it doesn’t stay on farm fields. Instead, it often ends up in our nation’s surface and groundwater. The EPA’s report found that levels of this herbicide in the environment exceed what the agency considers “levels of concern for chronic risk” by as much as 22, 198, and 62 times for birds, mammals, and fish, respectively.

And while atrazine rarely kills these animals outright, they’re still getting a heavy dose of a substance that has been shown to adversely affect their developmental, hormonal, and reproductive systems. (In the case of the controversial research done by Tyrone Hayes, male frogs effectively became female when exposed to the herbicide.) Chronic atrazine exposure has also been shown to significantly reduce animals’ body weight and the weight of individual organs.

Also new is the agency’s acknowledgment is that these effects to animal health can occur at levels of atrazine exposure well below those that have actually been found through environmental monitoring. They’re also happening at levels below what the EPA has set as drinking water safety limits for atrazine.

When it comes to plants, the agency said that atrazine run-off and spray drift from its use on crops are likely to reduce land-based plant biodiversity. The EPA also pointed to a lack of data regarding the long-term effects on honey bees and their larvae, a data gap that could be important in ongoing efforts to reverse the recent alarming decline in pollinator health.

Two Hundred Products Used in the U.S., Zero in Europe

Farmers use about 70 million pounds of atrazine in the U.S. every year. More than 90 percent is used on corn. But atrazine is also sprayed on soybeans, sugarcane, wheat, oats, and sorghum, among other crops. Atrazine is also used to kill weeds in pastures. According to the EPA, there are approximately 200 different products containing atrazine now approved for use on farms and for a variety of landscaping purposes. Atrazine is also often mixed with other pesticides when it’s applied. The environmental and health effects of these mixtures are poorly studied and not yet well understood.

First approved in 1958, atrazine has, however, long raised concerns because of its environmental persistence and mobility. For this reason its use is banned in Europe. While not considered acutely toxic, its long-term health concerns include reproductive, developmental, hormonal, and possible carcinogenic effects.

What Could This Assessment Mean Going Forward?

This risk assessment, and the upcoming one focused on human health effects, will determine the EPA’s re-authorization of atrazine. Based on these assessments, EPA could change the requirements for how atrazine can be used—possibly adding new restrictions on how much, where, or how it can be applied. Such restrictions can lead to bans on certain uses or even to banning a pesticide entirely.

For example, the insecticide chlorpyrifos used to be approved for use in homes. Because of health concerns, especially for children, in 2000 the EPA banned that use but continued to allow agricultural use. Similarly, because EPA was concerned about the potential effects of chlorpyrifos on children’s health, the agency also decided in 2000 that the pesticide could no longer be used on tomatoes, and limited its use on apples, and grapes.

Environmental Groups Say the Writing’s on the Wall

As some environmental advocates see it, the evidence EPA has put forth points to a clear need to stop using atrazine on farms and elsewhere. The assessment, said Emily Marquez, Pesticide Action Network scientist, “reinforces that low doses are causing major impacts on aquatic life, birds, and mammals.”

“When the government’s own scientists say there’s enough atrazine in streams and rivers right now to kill frogs and other imperiled wildlife, we should be worried,” said Center for Biological Diversity scientist Nathan Donley. “Atrazine has to be used at a certain concentration to be effective against weeds. And when it’s used at that concentration, water contamination is inevitable,” Donley told Civil Eats. The information in this report suggests that EPA can’t protect wildlife by simply requiring changes in how the herbicide is used, he explained. “The only path forward is an all out ban. It’s just too toxic.”

Industry Points to Concerns About No-Till

Ultimately it’s up to the EPA to decide how and where atrazine will remain in use. But that won’t stop the pesticide industry from weighing in. Atrazine manufacturer Syngenta has called the EPA’s report “scientifically unjustified” and based on studies “previously recognized as flawed.”

In a statement, Marian Stypa, who heads Syngenta’s North American product development said atrazine safety “has been established in nearly 7,000 scientific studies over more than 50 years.” Further, Sygenta added, the herbicide is essential to maintaining U.S. corn farmers’ profitability.

If the assessment leads to a ban on atrazine, the Missouri Corn Growers Association said it would “would limit farmers’ conservation efforts, specifically no-till production practices, leading to increased soil erosion and fossil fuel use.”

Yet, as Organic Valley Crop Cooperative agricultural research manager Logan Peterman explained, no-till, organic methods of growing soybeans are now well established. And when it comes to corn, he said, “The demand is huge and we successfully grow organic corn.” While no-till organic corn farming is more challenging, he added that research is underway to make that easier, though strategic use of cover crops and timing of planting in the spring.

Agricultural scientist Charles Benbrook echoes this sentiment. “Farmers are innovators, and many are already looking for ways to be less dependent on herbicides, especially those that don’t work nearly as well as they once did (like atrazine and glyphosate)” he said. It’s also worth noting that many of the crops grown in the U.S. with atrazine are grown without the herbicide in Europe.

The EPA draft report will be open for public comment for 60 days. After reviewing those comments the EPA will revise the report, which will be reviewed by the agency’s Scientific Advisory Panel some time next year. The U.S. Fish and Wildlife Service’s also report on atrazine’s impacts on endangered species in the works.

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  1. Bob Gardner
    Monday, June 6th, 2016
    In a Wisconsin survey of well water in the 1980's, Atrazine was found to be in the water of 10% of wells. It doesn't break down like Round Up. I think Atrazine is far more worrisome than Round Up.
  2. Monday, June 6th, 2016
    Same ol' story; it happened with GMOs--I mean, DDT, it's happened with other GMOs--I mean, organophosphates, it's happening with GMO--I mean, malathion, and now it's happening with GMO--I mean, atrazine. So when exactly is it going to happen that people realize the burden of proof should not be on the public to prove than non-biologicals cause harm, but should be on the industry to show that their non-biologicals are safe?
  3. Michael Boyd
    Monday, June 6th, 2016
    And, then the compounds formed along the biodegradation path to carbon dioxide and water. The time for each to be degraded further. Fast, slow, weeks, months ...
  4. Monday, June 6th, 2016
    Let"s stop growing so much corn. A lot of corn of it is used to produce ethanol which has environmental consequences of its own. When the decision is made regarding the use of atrazine, the EPA will make the wrong one for us and the country.
  5. Ken
    Monday, June 6th, 2016
    I am quite certain that very high exposures to Atrazine as a young man caused my bladder and kidney cancer.
  6. Roto2
    Monday, June 6th, 2016
    This is why food production can not possibly keep up with the over population of the world. The US feeds much of it and this is how. We are a country of deniers willing to risk all for profits and revenue without limits. We are the stupidest country currently on this planet in that respect. But we've earned that title and position.
  7. joy babineaux
    Monday, June 6th, 2016
    and so WHY/HOW has this chemical ever been approved by our wonderful epa(EVIL POISIONOUS AGENCY)???? how can we be expected to 'trust' this self serving agency which 'picks and chooses' and controls the very air we breathe, food we eat and/or water we drink???? it has become just one more governmental INTRUSION in our lives, with NO CONCERN for our health!!! when one considers all of the regulations and restrictions placed on some industries, and then realizes that these kinds of POISON are approved, it causes wonder as to how/why this occurs!!! between the FDA and EPA, we, the folks, are further burdened by 'big brother' who is mostly interested in 'big money' from these chemical companies!!!
  8. Flyoverman
    Monday, June 6th, 2016
    The EPA is so political and stupid they declared rain water to be a pollutant. They have disqualified themselves from any serious environmental discussions.
  9. Carole Douglas
    Monday, June 6th, 2016
    What's the point of planting all this food if you poison it and destroy the earth doing it? Why does Corporate American hate the American people? Can someone just ask one of them that? I really want to know.
  10. Bill Hooven
    Monday, June 6th, 2016
    Time for the USDA to earn it's keep.....It is the large AG companies that put out the most Herbicide and not the small farmer...If the USDA can limit the amount of a certain crop and pay the farmer not to grow it why not limit the use of Herbicides and pay the farmer not to use it, by paying the difference in reduced crop yield....if any...
  11. Dean
    Monday, June 6th, 2016
    Rather than trying to fix it let's just stop it. another typical left wing government approach. forget the starving humans, protect the frogs at all cost. EPA needs to hurry and issue ban on insecticides to kill misquotes that carry viruses that causes deformities in newborns. Wonder what caused extinctions before humans? Hmmm
  12. Monday, June 6th, 2016
    atrazine safety “has been established in nearly 7,000 scientific studies over more than 50 years.”
    This is the important part and should be the basis for the article. Instead, most of the article is heresay referencing possible, unsubstantiated problems. No till farming is an environmental plus and we need to encourage farmers to do it, not set up road blocks.
  13. J Graham
    Monday, June 6th, 2016
    Atrazine enables growers, world wide, to produce food at lower cost than alternative weed control practices. Not only are alternatives more expensive, in many cases they are worse for the environment, e.g. tillage.

    The exaggerated hazards in the EPA report will keep eco-nuts happy, but proposed drastic restrictions on atrazine's use will negatively effect grower productivity and increase food costs for U.S. consumers.
  14. JAKEB SCHULT
    Monday, June 6th, 2016
    This is why the outrage against round up needs to end. Atrazine needs to be banned, along with the others toxics we used to use. Over the last 60 years many bad toxins have been retired, like DDT. When safer, less toxic compounds has been made. The outrage over glysophate is misguided since it is generally benign to animals and replaced the horrible toxins of yesteryear. We need to go with the products proven safer. And continue to develop safer products.
  15. Monday, June 6th, 2016
    Once the tree huggers take all the products needed to bring an acceptable (to the general public's consumer eye ) product to market,all of you can either starve, or learn to accept a much less Eye appealing grade of fruits and vegetables.A perfect example is corn 3 types,with bugs, B.T. and clean , or heavily sprayed and clean ; at least in large enough quantities to fulfill market demand.
  16. marshall
    Monday, June 6th, 2016
    In a statement, Marian Stypa, who heads Syngenta’s North American product development said atrazine safety “has been established in nearly 7,000 scientific studies over more than 50 years.” Perhaps Marian would be willing to drink a couple gallons and start adding a pint to her children's cereal every morning. Then I;d believe her,,,
  17. Michael
    Tuesday, June 7th, 2016
    I love how the nuts who think the fact that frogs are dying and having birth defects etc means that there is no effect on humans. Nice comments like "screw the frogs we need jobs" down below are just plain ignorant. If this stuff is causing havoc on other animals and we want to do something to save those animals, somehow that turns us into tree hugging extremists out to ruin the profit party. I suppose if you are a CEO of a large company then the death of the poor that work your fields and eat your crops has no effect on you.
  18. Gilberto Guerra
    Tuesday, June 7th, 2016
    I believe it is high time we held the FDA to its responsibility of "Safety First" for all living creatures and the environment in all rulings, instead of "corporate interest first" for the bottom line. We must break away from excessive dependency on chemicals as we must on dependence on fossil fuels.
  19. Phyl Morello
    Thursday, June 9th, 2016
    Earth NEEDS a break from chemicals!!! Has anyone noticed a great decline in wildlife? I used to see lots of frogs, birds, bats, foxes & other small wildlife near my home. Not so much any more. Drastic decline noticed. So sad.
  20. Susan Janow
    Thursday, June 9th, 2016
    Please stop allowing companies to poison the earth. We will leave nothing to future generations if we don't become caregivers of this earth, and stop using chemicals tha poison the groundwater and the animals who use that water.
  21. P J Holland
    Thursday, June 9th, 2016
    Stop the use of toxic herbicides and protect life on earth!!
  22. Cynthia D. Ward
    Thursday, June 9th, 2016
    If there is anything at all I could do (that I am not already) I am willing to learn what it is and to do it !
    These toxic chemicals put every living thing at risk.
    I do not understand how knowing this is a fact, that it can be 'allowed' to continue. I'd like to know just who is preventing this critical information from being on every News program in the World. PBS/CNN et al.
    Hope someone can figure out 'who' the devil is that is behind this curtain. And fast !
    I am an artist/75 yrs young/Namaste
  23. Steve Sample
    Friday, June 10th, 2016
    Ban atrazine!
  24. Monday, June 13th, 2016
    chilling
  25. Monday, June 13th, 2016
    YO CREO QUE ES TIEMPO DE PEDIR A LA CIENCIA FORMAS SANAS Y HONESTAS DE CONTROLAR LAS PLAGAS, DE FERTILIZAR LOS CULTIVOS O DE USAR OTROS QUÍMICOS QUE MANTENGAN BAJO CONTROL LAS SIEMBRAS. ESTOY SEGURA QUE LA CIENCIA YA TIENE LOS PROCEDIMIENTOS REQUERIDOS NO TÓXICOS PARA EL CUIDADO DE LAS PLANTAS DE TODA ESPECIE, DE MANERA QUE LOGRA EVITAR Y DETENER TODO TIPO DE CONTAMINACIÓN Y CUIDAR EVITAR TODO DAÑO HACIA INSECTOS ENCARGADOS DE POLINIZAR. INCLUSO LA CIENCIA HOY EN DÍA PUEDE INCREMENTAR MÉTODOS Y PROCEDIMIENTOS SANOS E INOFENSIVOS PARA LA AGRICULTURA.