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Judge Postpones
Trial And Appoints Mediator In Glyphosate Litigation
Epidemiology
Called “Loosey-Goosey Field”
Recent jury trials on
whether or not glyphosate causes non-Hodgkins lymphoma have rendered
verdicts in favor of plaintiffs with multi-million or even billion
dollar awards against Monsanto, the maker of the well-known Round Up,
a glyphosate-based weed killer. Now a federal judge in San Francisco
has postponed a pending federal trial and appointed an experienced
mediator to help resolve the dispute between the parties.
According to the NY
Times, that mediator is Kenneth Feinberg who has experience in
mediating conflicts over the September 11th Victim
Compensation Fund, the BP Deepwater Horizon oil spill, Volkswagen’s
diesel emissions scandal, and the General Motors ignition switch
litigation. It’s not clear what the judgment about the causal role of
glyphosate, if any, will be.
Judge Reviews
Evidence
The LA Times has reported that Vince Chhabria, the federal
judge who postponed the pending trial this month, held pre-trial
hearings before an earlier first trial last year. As a result of
those pre-trial hearings, the LA Times described the judge as openly
skeptical of some of the evidence. He called epidemiology “a bit of
a loosey-goosey field” and found that the evidence implicating
glyphosate was “pretty sparse”. According to the Times, he
questioned how “an epidemiologist could conclude, in the face of all
the evidence…that glyphosate is, in fact, causing non-Hodgkins
lymphoma in human beings.”
But he also questioned
whether you could be sure it was safe and said “There’s at least a
strong argument that the only reasonable conclusion one could draw
right now is that we don’t know yet.” He allowed the first federal
trial to proceed and the jury in that trial did make an award for $80
million. Now he has postponed a second pending trial and ordered the
parties to mediation.
New Meta Analysis
It appears that some of the controversy around glyphosate was
reignited by the publication of a meta-analysis in Mutation Research
earlier this year by Luoping Zhang and colleagues which
reported an overall meta relative risk of 1.41, (95% CI 1.13-1.75).
Combined with experimental animal and mechanistic studies, the authors
concluded that “our current meta-analysis of
human epidemiological studies suggests a compelling link between
exposures to
Glyphosate based herbicides and increased risk for Non-Hodgkins
lymphoma.”
Critique
These findings have
been scrutinized and found wanting by at least one epidemiologist.
Geoffrey Kabat, who has focused in the past on identifying weak or
flawed studies that are misleadingly reported by investigators and the
media, presented a critique of the Zhang meta-analysis. It appeared on
the website for the Genetic Literacy Project and was headlined “41%
glyphosate-cancer increase claim under fire: Did authors of new
meta-study deliberately manipulate data or just botch their analysis?”
The key points he made
in his critique were:
-
Zhang and the other
researchers set out to combine the results of studies of drastically
different quality. Yet they never question the appropriateness of
conducting a meta-analysis, which, in this case, is the weighted
average of one high-quality cohort study (Agricultural Health Study,
AHS) with five case-control studies of much poorer quality.
-
Confronted with the
choice of which risk estimate to select from the AHS, the
researchers chose the highest RR of the 5 reported in the AHS, thus,
ensuring that the resulting summary RR would reach statistical
significance.
-
In order to give
their paper the appearance of academic rigor, the authors conducted
a huge number of secondary analyses, varying different conditions,
to convince us that the 41 percent increase in risk is a solid
result that is not affected by varying different aspects of their
analysis. But these “sensitivity analyses” and subtle statistical
considerations are presented instead
of addressing more basic issues that determined the
results of the meta-analysis.
-
The authors
highlighted the 41% result, which they almost certainly realized
would grab headlines and inspire fear.
Dr Zhang, an adjunct
professor of toxicology at Berkeley, was asked if she has responded to
the Kabat criticisms but she did not respond to our inquiry.
Role of Jurors
The controversy around glyphosate not only raises questions about the
causal role, if any, of glyphosate but also of the role of juries and
mediators in sorting through conflicting scientific claims. Are the
jurors as laypersons up to the task of evaluating conflicting
scientific claims? Should the court seek an independent advisory group
separate from the plaintiffs and defendants lawyers? Should the judge
play a heavier hand in the final outcome? By appointing a mediator,
the Judge Chhabria may be affirming the uncertainty and leaving it to
the the opposing sides to work out an acceptable or just solution.
Meanwhile, the truth of the matter, that is, the causal role of
glyphosate, if any, is likely to take longer to settle, and the answer
may arrive well after the legal settlements have been reached. ■
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