Image courtesy of the Mailman School of Public Health at Columbia University

Can companies be held responsible for cancer caused by their herbicides? Courts have been saying yes, and the latest verdict came from a jury in state court in Oakland, California. Last week, they ordered Bayer to pay more than $2 billion in damages for the medical bills and suffering, on top of punitive damages, to a couple who claimed they got cancer because of using Roundup—a glyphosate-based weedkiller—for about 30 years. This is the largest jury award so far this year.

The jurors agreed that the design of Roundup was a “substantial factor” in causing harm to the Pilliods, in both Alberta and Alva Pilliod’s verdicts. In turn, Bayer continues to argue that Roundup is safe for use and does not cause cancer, maintaining that “glyphosate-based products can be used safely and that glyphosate is not carcinogenic.” The company also states there is no reliable scientific evidence to conclude its herbicide was the “but for” cause of the Pilliods’ cancer, “as the jury was required to find in this case.” Though these verdicts just came out, the core question seems somewhat familiar: to what extent is the use of a certain product the cause of a disease?

Judges all around the world have faced similar questions throughout the years, even if applied to different contexts—for instance, tobacco litigation. In Brazil, the courts have been deciding for years that tobacco companies are not liable for the harms to smokers. In 2010, for example, the Superior Tribunal of Justice (one of the high courts in the country) issued a decision that struck down the plaintiffs’ claim by pointing out that other factors could have contributed to their disease, among other arguments. In this sense, according to the judges, compensation would only be due if it were possible to establish causation (understood as the cause that necessarily led to the harm) in the individual cases brought before the court. Other decisions have followed this line of reasoning, in one way or another.

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Nonetheless, not all judges agree. Last year, a court in the South of Brazil held a tobacco company accountable for the harm caused by its product. Regarding causation, specifically, the judges highlighted the overall inconsistency of the reasoning indicated above. Basically, they said that science has already demonstrated that certain diseases are necessarily linked to smoking in a percentage around 80 to 90%. This means that only 10 to 20% of individuals develop these diseases due to factors other than smoking. The judges did acknowledge that it is almost impossible to assert categorically which of these hundred people are in one group or the other, but asserted that this does not subvert the certainty that 80-90% of them actually developed the disease because of smoking. In spite of this, if these hundred people were to file actions individually and all of their claims were to be denied on the grounds of multi-factorial causation, the system would fail eighty to ninety individuals whose disease was indeed caused by smoking. In other words, to avoid that the tobacco industry be unjustly convicted in 10 to 20% of the cases, the courts end up failing 80 to 90% of the plaintiffs—rightful plaintiffs.

Tobacco and glyphosate-based weedkillers are, of course, very different, as are the circumstances under which they are produced, commercialized, and used. Such differences show in court, including in topics of discussion such as whether or not the scientific evidence is irrefutable; whether or not it is a defective product; whether or not the manufacturers withheld information; etc. These are all interesting points, but what really catches the eye is that causation remains a big issue in tobacco litigation in Brazil, despite the consensus that exists in the scientific community that smoking causes a number of diseases, while courts in the United States have no problem reviewing and accepting epidemiological data as evidence in all sorts of cases (even those in which data are less established than that relating to tobacco, for now).

This is the third loss for Bayer in California since August 2018; the first of an estimated 13,000 plaintiffs with pending lawsuits against Monsanto (owned by Bayer) throughout the country. It will be interesting to track them as they make their way to the courts of appeals, and even more interesting to follow whether other countries will move forward in the discussion or will remain closing their eyes to the wonders of epidemiology.