LONDON — A UN-related International Agency for Research on Cancer decided the most popular weedkiller used by South Dakota farmers - and one of the most popular around the world - which is best known as Roundup around here but generically as glyphosate, is a "probable carcinogen," according to news sources Friday.
The IARC, the France-based cancer research arm of the United Nations' World Health Organization, announced it considered the status of five insect and weed killers including glyphosate, which is used globally in industrial farming. The results were published in a well-known British medical journal, Lancet.
Nearly all farmers in South Dakota use Roundup, especially as more crops have been given immunity to it, or made "Roundup Ready," the past decade or more. Through genetic tweaking since the mid-1990s, corn, soybeans and sugar beets are made resistant to the herbicide so it can be easily applied to fields, killing weeds but not the crops.
It's especially important in controlling weeds for farmers who use "no-till" techniques to avoid disturbing the soil, losing moisture and nutrients, which is how most farmers in central South Dakota operate.
The U.S. Environmental Protection Agency, which is not bound by the French panel's study, said it would study the study's results, according to The Associated Press.
The French agency has four levels of risks for possible cancer-causing agents: known carcinogens, probable or possible carcinogens, not classifiable and probably not carcinogenic, AP reported. Glyphosate now falls in the second level of concern.
It's the industrial use of it that poses the risk, not the gardening kind of use and glyphosate was put in the same risk level as things like anabolic steroids and shift work.
The French panel's decision was published online Thursday in the British medical journal, Lancet Oncology.
According to the French agency, glyphosate is used in more than 750 different herbicide products and its use has been detected in the air during spraying, in water and in food. Experts said there was "limited evidence" in humans that the herbicide can cause non-Hodgkins lymphoma and there is convincing evidence that glyphosate can also cause other forms of cancer in rats and mice. IARC's panel said glyphosate has been found in the blood and urine of agricultural workers, showing the chemical has been absorbed by the body.
Monsanto, which produces the glyphosate-containing herbicide, Roundup, strongly disagreed with the decision. "All labeled uses of glyphosate are safe for human health," said Phil Miller, a Monsanto spokesman, in a statement.
The EPA's 2012 assessment of glyphosate concluded that it met the statutory safety standards and that the chemical could "continue to be used without unreasonable risks to people or the environment."
Worldwide, sales of herbicides total more than $6 billion, according to the Financial Times of London. Malathion, a mosquito killer, also was labeled at the same level of risk.
Whatever the scientific value of the new study, the news of it is sure to be a topic of discussion if not concern in South Dakota.
Roundup, or the same glyphosate herbicide now available from a host of other brands other than Monsanto, is used on most acres farmed in South Dakota every year, Sharon Clay, a professor of weed science at South Dakota State University in Brookings, told the Capital Journal on Friday.
Monsanto patented the herbicide and started selling it about 1975, Clay said. But for the first two decades, since it killed crops as well as weeds, it was used to “burn down” weeds after harvest or before seeding and in ditches.
Not the 1990s when genetic tweaking of crop seeds led to putting resistance to Roundup into crops did Roundup begin to be ubiquitous on corn and soybean fields, especially, across the United States, Clay said. Federal officials even quit their annual surveys of farmers' herbicide choices some years ago, simply because they all were using Roundup nearly all the time, Clay said.
“In corn, 99 percent (of the acres) have Roundup, and 95 percent of the soybeans,” she said.
It’s one factor, in fact - other than rising prices and better seed varieties for northern climes- that has pulled South Dakota and North Dakota nearly into the Corn and Soybean Belt.
So far, there is not a Roundup Ready variety of wheat, Clay said.
The dominance of Roundup, or glyphosates in general, is great enough that it's led, naturally, to an unintentional breeding program of weeds that are resistant to the herbicide.
In the past two years or so in South Dakota, farmers are seeing kochia and ragweed and other weeds that can't be killed by glyphosates, she said. The answer is to use other herbicides, often mixed with glyphosates, she said.
Clay hasn’t seen the new French study.
But she said she’s skeptical that glyphosates pose a real threat of cancer for humans.
“There are some herbicides that have been shown to be carcinogenic and they are no longer on the market,” she said. Roundup, however, has been “tested so many times, fed to rats, probably fed to mice and fed to dogs” that she's confident it doesn't pose a human health risk.
It's a famous stunt one hears not infrequently over the years from farmers who have ag degrees that they have, or would, drink a tumbler of Roundup with no concern.
Of course, one dynamic in play with the new study is that European scientists, farmers and consumers generally are leery or even vehemently opposed to the sort of genetic modification to crops that adds, say, herbicide resistance, Clay said. But there's growing concern stateside, too. Last year Vermont passed the first U.S. mandatory labeling law for foods from genetically modified crops, Reuters reported.
Several years ago, Monsanto’s patents expired on Roundup and many companies now offer a form of the glyphosate herbicide that works so well, including foreign companies, some from China, Clay said.
Monsanto issued a lengthy response Friday on its website, saying there’s nothing new or significant in the French study.
Relevant scientific datat that shows glyphosate is not a heath risk for humans was excluded from the IARC study, according to Monsanto.
The IARC’s way of classifying glyphosate “does not establish a link” between the chemical “and an increase in cancer,” Monsanto said. “IARC has classified numerous everyday items in (the same Catetory 2) including coffee, cell phones, aloe vera extract and pickled vegetables, as well as professions such as a barber and fry cook,” according to Monsanto’s news release.
A four-year German study, reported in January, concluded “glyphosate was unlikely to pose a carcinogenic risk in humans,” according to Monsanto.
The French agency's experts said the cancer risks of the weed killer were mostly from occupational exposure.
"I don't think home use is the issue," said Kate Guyton of IARC. "It's agricultural use that will have the biggest impact. For the moment, it's just something for people to be conscious of."
(Capital Journal reporter Stephen Lee contributed to this article.)