In re Roundup Prods. Liab. Litig.

• Decision Date: 10 July 2018
• Docket Number: Case No. 16-md-02741-VC,MDL No. 2741
• Parties: IN RE: ROUNDUP PRODUCTS LIABILITY LITIGATION This document relates to: All Actions
• Court: U.S. District Court — Northern District of California

390 F.Supp.3d 1102

IN RE: ROUNDUP PRODUCTS LIABILITY LITIGATION

This document relates to: All Actions

MDL No. 2741

Case No. 16-md-02741-VC

United States District Court, N.D. California.

Signed July 10, 2018

PRETRIAL ORDER NO. 45: SUMMARY JUDGMENT AND DAUBERT MOTIONS

Re: Dkt. Nos. 545, 647

VINCE CHHABRIA, United States District Judge

The question at this early phase in the proceedings—the "general causation" phase—is whether a reasonable jury could conclude that glyphosate, a commonly used herbicide, can cause Non-Hodgkin's Lymphoma

("NHL") at exposure levels people realistically may have experienced. If the answer is yes, the case moves to the next phase, which addresses whether each particular plaintiff's NHL was caused by glyphosate. If the answer is no, none of the plaintiffs' cases may proceed. And the answer must be no unless the plaintiffs can present at least one reliable expert opinion in support of their position.

There are two significant problems with the plaintiffs' presentation, which combine to make this a very close question. First, the plaintiffs (along with some of their experts) rely heavily on the decision by the International Agency for Research on Cancer ("IARC") to classify glyphosate as "probably carcinogenic to humans." This classification is not as helpful to the plaintiffs as it might initially seem. To render a verdict for a plaintiff in a civil trial, a jury must conclude, applying the "preponderance of the evidence" standard, that the plaintiff's NHL was more likely than not caused by exposure to glyphosate. And at this general causation phase, the question is whether a reasonable jury could conclude by a preponderance of the evidence that glyphosate can cause NHL at exposure levels people realistically could have experienced. The IARC inquiry is different in kind—it is a public health assessment, not a civil trial. Public health assessments generally involve two steps: (1) an effort to identify hazards ; and (2) an evaluation of the risk that the hazard poses at particular exposure levels. The first step essentially asks whether a substance is cause for concern, while the second step asks how concerned we should be. As IARC takes pains to point out, its decision that a substance is "probably carcinogenic to humans" is a hazard assessment—merely the first step in determining whether the substance currently presents a meaningful risk to human health. IARC leaves the second step—risk assessment—to other public health entities. Moreover, even with its hazard assessment, IARC makes clear that although it uses the word "probably," it does not intend for that word to have any quantitative significance. Therefore, the public health inquiry does not map nicely onto the inquiry required by civil litigation. And the hazard assessment IARC undertakes is too limited and too abstract to fully serve the plaintiffs' purposes here. A substance could be cause for concern, such that it can and should trigger preventive public health measures and further study, even when it is not so clearly dangerous as to allow a verdict in favor of a plaintiff.

The second problem with the plaintiffs' presentation is that the evidence of a causal link between glyphosate exposure and NHL in the human population seems rather weak. Some epidemiological studies suggest that glyphosate exposure is slightly or moderately associated with increased odds of developing NHL. Other studies, including the largest and most recent, suggest there is no link at all. All the studies leave certain questions unanswered, and every study has its flaws. The evidence, viewed in its totality, seems too equivocal to support any firm conclusion that glyphosate causes NHL. This calls into question the credibility of some of the plaintiffs' experts, who have confidently identified a causal link.

However, the question at this phase is not whether the plaintiffs' experts are right. The question is whether they have offered opinions that would be admissible at a jury trial. And the case law—particularly Ninth Circuit case law—emphasizes that a trial judge should not exclude an expert opinion merely because he thinks it's shaky, or because he thinks the jury will have cause to question the expert's credibility. So long as an opinion is premised on reliable scientific principles, it should not be excluded by the trial judge; instead the weaknesses in an unpersuasive expert opinion can be exposed at trial, through cross-examination or testimony by opposing experts.

The three expert opinions most helpful to the plaintiffs at this phase in the proceedings were offered by Dr. Christopher Portier, Dr. Beate Ritz, and Dr. Dennis Weisenburger. A jury may well reject these opinions at trial, finding the opinions too results-driven or concluding that the evidence behind those opinions is too weak. But applying the standard set forth in the case law for admission of expert testimony, the Court cannot go so far as to say these experts have served up the kind of junk science that requires exclusion from trial. And the testimony of these three experts is directly on topic, because they (in contrast to some other experts) went beyond the inquiry conducted by IARC, offering independent and relatively comprehensive opinions that the epidemiological and other evidence demonstrates glyphosate causes NHL in some people who are exposed to it. Accordingly, their opinions are admissible, which means the plaintiffs have presented enough evidence to defeat Monsanto's summary judgment motion. These proceedings thus move on to the next phase, which will involve an attempt by individual plaintiffs to present enough evidence to warrant a jury trial on whether glyphosate caused the NHL they developed. Given how close the question is at the general causation phase, the plaintiffs appear to face a daunting challenge at the next phase. But it is a challenge they are entitled to undertake.

This ruling is organized as follows: Section I provides background information relevant to these lawsuits. Section II describes the legal standard that applies to the admissibility of expert testimony, and explains why the IARC classification is insufficient to get the plaintiffs over the general causation hurdle. Section III provides an overview of the important epidemiological studies, highlighting the strengths and weaknesses of those studies and explaining why Monsanto's criticisms of the studies more helpful to the plaintiffs are not fatal to the plaintiffs' case. Section IV introduces the evidence addressing the carcinogenic effects of glyphosate on rodents. Section V briefly discusses evidence on the effects of glyphosate at the cellular level. Section VI examines each of the plaintiffs' experts' opinions, and analyzes whether those opinions synthesize all this evidence reliably enough to be admissible at trial. Finally, Section VII addresses the plaintiffs' motion to exclude some of Monsanto's experts.

I. BACKGROUND

Glyphosate is the active ingredient in Roundup, an herbicide manufactured by Monsanto. Roundup became commercially available in 1974, and glyphosate-based herbicides are now widely used across the United States and much of the world, on large-scale farms and in backyards. The U.S. Environmental Protection Agency does not currently consider glyphosate likely to cause cancer

.¹

In 2015, IARC, which is the specialized cancer

agency of the World Health Organization, convened a "working group" to assess whether several pesticides, including glyphosate, can cause cancer. Since 1971, IARC has regularly convened working groups to evaluate whether chemicals or other environmental factors are capable of causing cancer in humans. These working groups compile "Monographs" that examine the available scientific evidence and then come to conclusions about the carcinogenic potential of these different agents. The working group examining glyphosate concluded that the pesticide is "probably carcinogenic to humans," a designation whose meaning will be discussed later in this ruling.²

IARC's designation addressed cancer

in general, but the working group's report paid particular attention to human studies concerning a particular cancer, NHL, in reaching its conclusion. NHL is a cancer that affects lymphocytes, a type of white blood cell that is part of the immune system. Farmers have long had an elevated risk of NHL, even before glyphosate went on the market.³

After IARC classified glyphosate as a probable carcinogen, a wave of lawsuits followed. These lawsuits, which now number in the hundreds, were dispersed among state and federal courts across the country, but the claims against Monsanto raised similar issues. In particular, a central question in all these cases is whether Monsanto's glyphosate-based herbicides can cause NHL.

The Judicial Panel on Multidistrict Litigation, a panel of judges empowered to coordinate proceedings in federal cases where doing so "will be for the convenience of parties and witnesses and will promote the just and efficient conduct" of the cases, determined that coordination in these cases was warranted. 28 U.S.C. § 1407(a). The Panel therefore created this Multidistrict Litigation to centralize management of all the federal cases, and assigned to this Court all pretrial proceedings in the Multidistrict Litigation. As is common in such proceedings, the Court appointed a group of plaintiffs' counsel to serve as leaders and to represent all the plaintiffs' interests. Dkt. No. 62. Many additional cases have since been transferred to this district as part of the Multidistrict Litigation, and more than 400 cases are now pending.

The Court decided to bifurcate the pretrial proceedings. Dkt. No. 25. The motions at issue here arise during the first phase, which addresses "general causation." As noted, the question at the general causation phase is whether glyphosate is capable of causing NHL at exposure levels humans might have experienced. The second phase will involve, among...