In a decision that made headlines around the world, a California jury awarded $289 million dollars, a stunning amount, to a former groundskeeper for a California school district who claims that he contracted non-Hodgkins lymphoma from exposure to a commercial preparation of glyphosate, the world’s most widely used herbicide. The jury decision elicited extensive commentaries from experts and non-experts, both pro and con.
First of all, let’s point out that this trial dealt with occupational exposure to glyphosate and had nothing to do with trace amounts of the chemical in our food supply. Nevertheless, the Environmental Working Group (EWG) in Washington, an advocacy organization that is a long-standing critic of the use of glyphosate, took the opportunity to ride on the coat tails of the publicity garnered by the California lawsuit to publish a report about traces of glyphosate in oat products and suggested that these were a threat to health.
A typically “high” concentration EWG found was 760 parts per billion. That would mean that a small child eating 100 grams of the cereal would consume 0.076 milligrams of glyphosate. Most regulatory agencies have concluded that consumption up to 0.5 mg/kg body weight per day presents no problem, so that a 10 kg child could consume 5 mg per day. The 0.076 mg consumed is 1/66th of this. EWG uses its own calculation based on California’s curious Proposition 65 legislation to conclude that a concentration of glyphosate above 160 parts per billion is a health risk. By comparison, Health Canada has set a maximum residue level of glyphosate in oats at 15,000 parts per billion! What we have here is a tempest in a cereal bowl caused by an ill wind blowing from an alarmist organization.
Glyphosate is not only the world’s most widely used herbicide, it is also the most studied one, the subject of literally hundreds of publications. One would think that after such extensive research there would be consensus on the safety profile of this chemical, but such is not the case. The literature is speckled both with papers that purport to show the safety of glyphosate and ones that claim it can undermine health. By selective reporting, it is possible to convince a lay audience either that glyphosate use presents no significant concern or that the chemical should be banned. The research is full of nuances piled upon nuances, criticisms of methodologies, allegations of biases, claims of suppressed data and speculation presented as fact. It is difficult enough for someone well-versed in science to separate the glyphosate-sprayed grain from the chaff, but nigh-near impossible for twelve lay people snared for jury duty. Yet it is just these folks who were saddled with the task of determining if DeWayne Johnson’s cancer was caused by glyphosate.
Epidemiological studies can guide us towards understanding risk, but they apply to populations, not individuals. We know that colon cancer is more prevalent among populations that consume a lot of processed meats, but it is not possible to prove that any individual’s colon cancer was caused by consuming processed meats. Not everyone who consumes such foods contracts colon cancer, and there are plenty of cases of colon cancer among people who never consume processed meats.
Even if glyphosate were an established carcinogen, which it is not, it would never be possible to conclude that it caused a specific individual’s non-Hodgkins lymphoma. This particular cancer has numerous risk factors that include alcohol intake, Helicobacter pyloriinfection, exposure to hepatitis virus, various autoimmune diseases and contact with lubricating oils, benzidine dyes, wood dust, pesticides and herbicides.
The controversy over the potential carcinogenicity of glyphosate crested when the International Agency for Research on Cancer (IARC), an arm of the World Health Organization, concluded that glyphosate is “probably carcinogenic in humans.” What needs to be emphatically pointed out is that this was a hazard, not a risk analysis. Such an analysis just asks the question whether the chemical of concern can under some condition, no matter how unusual that condition may be, cause cancer. It does not address whether there is a cancer risk under conditions to which humans may reasonably be exposed. Regulatory agencies, such as the U.S. EPA, the European Food Safety Association and Canada’s Pesticide Regulatory Agency focus on risk, not hazard, and have all concluded that glyphosate does not pose a cancer risk to humans.
For a hazard analysis, it is enough to show that massive exposure in an animal can cause cancer. Some studies have shown this to be the case for glyphosate in mice, but interestingly, not in rats. For humans, as far as IARC is concerned, a hint of a slight increase in cancer under occupational exposure, is enough to label the chemical “probably carcinogenic,” even though such an association does not prove a cause and effect relationship. It should be noted that IARC’s category of “probable carcinogens” also includes red meat, wood fires, emissions from frying foods, shift work and drinking beverages hotter than 65 degrees C.
Not all studies are created equal. While some studies have shown a slight increase in non-Hodgkins lymphoma among farmers who use agricultural chemicals, the most recent and largest studies have not corroborated this. The “Agricultural Health Study” in the U.S., published in 2017, reported on monitoring the health of some 54,000 pesticide applicators, 82% of whom used glyphosate. No link was found between glyphosate use and any sort of lymphoid cancer. Arguments have been made that while glyphosate itself may not be a problem, commercial preparations contain various additives, such as surfactants, to allow for improved penetration, and that it is the combination of glyphosate and additives that poses a risk. However, it is such commercial preparations that were examined in the Agricultural Health Study. It is also noteworthy that the incidence of non-Hodgkins lymphoma has actually declined since 2000, even though glyphosate use has dramatically increased after the introduction of genetically modified crops in the 1990s.
Although there is no convincing evidence that glyphosate is carcinogenic in people, the possibility of harm when exposure is extensive cannot be ruled out. By his own admission, Mr. Johnson sprayed hundreds of gallons of herbicide every week with no protective equipment. On windy days he admits to having been coated with a chemical mist and once was even soaked from head to toe when a hose on his equipment malfunctioned. As has often been said, there are no safe or dangerous chemicals, only safe or dangerous ways to use them.
In the present case, the jury was undoubtedly influenced by information that came to light about Monsanto having known, but not having revealed, that glyphosate in huge doses may cause cancer in mice. The company claims that there was no need to publicize this because the information is not relevant to humans. Monsanto also shot itself in the foot by sponsoring some overzealous ghost-written articles about the safety of glyphosate. There was nothing fictitious about the data, but the company’s contribution to the articles was not disclosed. Monsanto is not staffed by angels, but it is certainly not unique in this regard when it comes to large companies. Whether it markets pharmaceuticals, cosmetics, cleaning agents, food or pesticides, a producer will always try to show its products in the best possible light with ethics sometimes swept under the carpet. That’s why we don’t place much emphasis on individual studies, relying rather on the preponderance of evidence. In this instance, the preponderance does not support the claim that glyphosate is a human carcinogen.
Obviously Mr. Johnson’s is a complicated legal case with lawyers on both sides demonstrating their ability to pick and choose studies that support their argument. In my opinion, science is on the side of glyphosate’s benefits outweighing its risks, but emotion is on the side of the plaintiff. And we have often seen that emotion trumps science. Furthermore, the defendant in this lawsuit, Monsanto, was essentially challenged to prove that Mr. Johnson’s lymphoma was not caused by glyphosate. That is an impossible task.
