Does the San Francisco Jury Verdict against Monsanto Spell Doom for Roundup?

Now that jurors in a San Francisco court have awarded a man $289 million in damages in his lawsuit against Monsanto (and its parent company Bayer) claiming that his exposure to Monsanto’s Roundup weedkiller gave him cancer, some people wonder whether the Cornwall Alliance will reverse its view that Roundup (the brand name for the active ingredient glyphosate) is not a carcinogen.

The answer: No.

The reason: Because the case provides no convincing evidence that glyphosate causes cancer.

It is common for jury verdicts and awards in highly complex tort actions to be overturned on appeal. Why? Because juries, which are made up of people drawn from a pool randomly selected from the population of the jurisdiction, rarely include people with the expertise needed to comprehend complex scientific evidence of causality, and because juries are prone to make excessively large awards because they’re easily manipulated by what logicians call the fallacy of argumentum ad misericordiam (appeal to pity). Indeed, plaintiffs’ attorneys routinely reject jurors who have such scientific expertise precisely because they won’t likely be moved by junk science and appeals to pity. Appeal court judges, in contrast, are, though not infallible, nonetheless much more likely than randomly selected jurors to have the skill to comprehend complex scientific evidence and much less likely to succumb to argumentum ad misericordiam.

Ethically proper tort law requires that an actual causal connection between the defendant’s action and the plaintiff’s injury be proven. What was proven in this court case, to the jury’s satisfaction, was that there is a positive correlation between exposure to glyphosate and non-Hodgkin lymphoma, the type of cancer suffered by the plaintiff.

But correlation is not causation and does not prove causation. Indeed, most people with non-Hodgkin lymphoma have not been exposed to glyphosate, and most people exposed never develop the cancer. That is strong evidence of a lack of causation.

To get an idea of just how strong correlations can be without any causal connection—and enjoy some hearty laughs while you’re at it—you might visit https://www.tylervigen.com/spurious-correlations. Here’s just one example:

In reporting on the case, The Economist said,

The case centred on whether glyphosate, an ingredient in Roundup, causes cancer. Bayer denies that, and has the backing of many. Although the World Health Organisation declared in 2015 that glyphosate was “probably carcinogenic,” America’s Environmental Protection Agency and the European Union consider it safe to use. Most reputable scientific studies find that glyphosate poses no risk to humans. Yet there is a correlation between farming work and incidence of non-Hodgkin lymphoma. More research is needed to find whether there is a causal link to glyphosate exposure, or whether it becomes toxic when mixed with other chemicals, says Robin Mesnage, a toxicologist at King’s College London.

The award to Mr Johnson is so substantial because his lawyers persuaded the jury that Monsanto had known of links between glyphosate and cancer since 1983 and had covered this up. Bayer also denies this. It hopes the ruling will be overturned by an appeal court, where decisions are made by judges rather than a jury influenced by what a company spokesman reportedly called “junk science” and “emotional arguments.”

So, we’ll await the decision of the final court of appeals on this case, and then we’ll evaluate its reasoning to the best of our ability.