Dan Charles / NPR
John Draper and I are sitting in the cabin of a tractor on the research farm he manages for the University of Maryland, next to Chesapeake Bay. Behind us is a sprayer.
"So, get away, let's go!" Draper says. He presses a button and we start to move. A fine mist emerges from nozzles on the arms of the sprayer.
We spray glyphosate and kill the soil-sparing "cover crop" of rye in this field before planting soybeans.
Farmers have often used this chemical under the Roundup brand name for about four decades.
But now it is violently attacked and accused of causing cancer. In three civil cases, the US juries have ordered the inventor of Roundup, Monsanto, now owned by Bayer, to pay enormous compensation to cancer survivors. Thousands more lawsuits have been filed.
For this chemical and for Monsanto, this is an amazing change.
Farmers felt they could spray glyphosate with a clear conscience. It does not stay around as long as DDT. It does not build up in groundwater like another widely used herbicide, atrazine. And it is certainly less toxic than some alternatives.
"If we were to spray Gramoxone [the trade name for paraquat, another herbicide] you would also need to wear a respirator to stand next to the sprayer spraying respirator even in the tractor," says Draper.
Monsanto began selling Roundup in 1974. For 20 years it did not attract much attention. That was Act 1 of the glyphosate drama: The Silent Years.
Act 2 began in the late 1990s.
In 1996 Monsanto began to sell genetically modified plants or GMOs. They were modified to tolerate glyphosate. This meant that farmers could now spray this chemical directly on their Roundup Ready soybeans, corn and cotton, and the crops would be alright, but the weeds would die.
It was a glyphosate-based agricultural revolution. Monsanto quickly became the world's largest seed company. And the farmers sprayed a lot more Roundup. The turnover of the chemical has increased more than tenfold.
It all happened so fast that it scared many people. There were protests against GMOs around the world, and glyphosate was increasingly under scrutiny.
The International Agency for Research on Cancer, which is part of the World Health Organization, decided to re-evaluate the risks of glyphosate.
On March 20, 2015, the IARC announced its conclusion: Glyphosate is "probably carcinogenic to humans."
This conclusion is based on three types of studies. First, IARC found "strong evidence" that glyphosate can damage DNA in cells. This type of damage, which causes mutations, is the first step in the development of cancer. Second, there are studies showing that when mice were eating glyphosate, mice got more tumors. Kate Guyton, a high-ranking toxicologist at IARC, told reporters at a news conference that "these two studies provided enough evidence for cancer in animals."
Finally, according to the IARC, there are "limited indications" that persons exposed to glyphosate had higher rates of glyphosate. A particular type of cancer – non-Hodgkin's lymphoma.
Guyton has been studying the causes of cancer for decades. Nothing she has ever done has reacted as violently as the glyphosate announcement. "The internet has exploded," she says.
Anti-GMO groups felt confirmed. Monsanto executives were furious and launched a public relations campaign against the IARC and its report.
In the small town of Orange, Virginia, a personal injury lawyer named Michael Miller began to line up clients with non-Hodgkin's lymphoma. "I decided that these people need a voice in the courtroom," he says.
The scientific picture, however, became more complicated. Other government agencies, including the US Environmental Protection Agency and the European Food Safety Authority, have re-examined glyphosate. And they came to the conclusion that it is probably not that people get cancer.
David Eastmond, a toxicologist from the University of California, Riverside, helped carry out one of these glyphosate tests for another part of the World Health Organization, the Joint FAO / WHO Conference on Pesticide Residues.
"If glyphosate causes cancer, it's a pretty weak carcinogen, which means you need fairly high doses to cause it," he says.
Eastmond says that there are several reasons for this apparent disagreement between IARC and the other agencies.
First, IARC only examines whether glyphosate can cause cancer ; On the other hand, supervisors have to decide if this is indeed the case, considering how much of it people are exposed to.
Second, and most importantly, according to Eastmond, various authorities considered different evidence. Eastmond's committees and regulatory agencies, such as the EPA, have considered a large number of studies that are not publicly available because Monsanto has paid them and presented them to the agencies. "I've never seen a chemical with as many animal cancer studies as glyphosate," says Eastmond.
However, IARC examined most of this research as only publicly available studies were approved. In this way, any other scientist can fully understand what the conclusions of the IARC are based on.
For his part, Eastmond believes that business-sponsored studies are credible and valuable, despite the potential conflict of interest for companies undertaking these studies. The laboratories would have to follow strict guidelines.
After all, scientists sometimes look at the same data and disagree on what that means. Eastmond says he and Guyton had "lively discussions" about some of the data. "We only rated the evidence differently, but you know that these are honest disagreements [among] that I think are well meant," says Eastmond.
Then came Act 3. Glyphosate went to court. There were three civil cases in or near San Francisco.
Lawyers from Bayer, now the owner of Monsanto, repeatedly reminded the jury that the regulators had concluded that glyphosate was not a cancer risk.
Lawyers for cancer victims. suggested that the same regulators could not be trusted because they had been manipulated or betrayed by Monsanto.
Miller and his legal team showed the juries a whole collection of internal Monsanto emails. In one, company executives reported on phone calls with an EPA official. As Miller describes it, the official said, "I do not need further studies, I declare Roundup safe and will prevent another authority from considering it."
Another Monsanto The officer discussed ghostwriting articles about the safety of glyphosate, which scientists were able to publish under their own name.
"I think the jury was rightly offended," says Miller.
All three attempts ended with resounding verdicts in favor of cancer victims. The jury imposed on Bayer a high punitive damages. In the latter case, the damage totaled $ 2 billion.
Bayer challenges these judgments – and the damage is likely to decrease. But there are more lawsuits waiting. The total value of Bayer stock has fallen by $ 40 billion since the announcement of the first judgment.
Alexandra Lahav, a professor at the School of Law at the University of Connecticut, states that one of the lessons learned so far has been making favorable decisions by regulators backfiring in court.
"Then open up for the jury and say: 'Wait a minute – you try to persuade the regulator not to regulate you, and now you want me to believe the regulator is completely objective', says Lahav.
If the regulators are considered weak or ineffective watchdogs, the seal of approval also has less weight on the public – and on the juries.
The next glyphosate attempt is scheduled for August in St. Louis.