New Controversy Swirls Around IARC’s Categorization Of Herbicide
Glyphosate As “Probably Carcinogenic”
Epidemiologist
Accused Of “Withholding” Data Showing
No Increased Risk of Cancer
The
International Agency for Research on Cancer (IARC) is in the news
again in connection with its determination in 2015 that glyphosate, an
ingredient in the widely used Roundup weed killer by Monsanto, is
“probably carcinogenic”. Different issues have arisen since the IARC
determination was made. The reason for the latest stir up is a special
report published in June 2017 by Kate Kelland, a Reuters
journalist, declaring that epidemiologic data relevant to the IARC’s
review of glyphosate were not considered.
Impacts
The
stakes surrounding this controversy are high since Monsanto’s popular
weed killer has many benefits and advantages described in a Science
report as “cheap,
highly effective, and is generally regarded as one of the safest and
most environmentally benign herbicides ever discovered.”
The
IARC conclusion has triggered lawsuits against Monsanto alleging that
exposure to Roundup has caused non-Hodgkins lymphoma, and the release
of previously confidential documents associated with the lawsuits (the
“Monsanto papers”) has given rise to allegations of cover up and
catalyzed other accusations on both sides of the dispute.
Current controversy
The
data not considered by IARC were updated results from the large NIH-sponsored
Agricultural Health Study which reportedly show no connection between
glyphosate and non-Hodgkins lymphoma. Earlier but more limited data
from the same study also showed negative results. Those published
negative data were reviewed and considered by IARC, but not the
updated negative findings which include additional cases and follow-up
from the same study.
The
Reuters report accused Aaron Blair, former NCI investigator and
chair of the IARC panel, of withholding the latest information which
it claims could have changed or downgraded the IARC’s risk
categorization of glyphosate. To be more precise, Blair and the panel
did not technically “withhold” data since by the rules of the IARC
process only published, in press, or readily available findings such
as government reports are suitable for consideration.
Issues
There are a number of issues raised by the various
media accounts of this controversy. The first is whether or not
relying only on published data to conduct IARC reviews is a good
policy. Asked about this question, Blair told one reporter “The rule
is you only look at things that are published. What would it be like
if everyone on the working group whispered things they knew but
weren’t published and made decisions on that?” This view contrasts
with others described in media accounts which consider the ban on
unpublished data as unjustified or even “absurd”.
However, the IARC has defended its policy saying the
cancer evaluation program “does not base its evaluations on opinions
presented in media reports”, but on the “systematic assembly and
review of all publicly available and pertinent scientific studies, by
independent experts, free from vested interests.” This has not
satisfied everyone and other criticisms of the IARC process have been
voiced, including the selection of workgroup members and even the
quality of the data included in the review and the interpretations
made.
Blair Reactions
In an interview with The Epidemiology Monitor, Blair
made clear that any data must be considered provisional until
published. There is always the possibility that analyses could change
or be interpreted differently until the investigators are finished
with it, he told the Monitor.
Other reasons for considering only published results are that they
often contain a fuller description of the study and its findings and
have undergone peer review. Adopting a policy to consider unpublished
and non-reviewed data would raise a host of thorny practical problems
such as how to locate the unpublished work and how to avoid being
biased by the direction of the findings. It is sound policy according
to Blair for the IARC or any review group to consider only published
data or completed papers “in press”.
Consequences
Some media accounts report that Blair stated that the unpublished data
would have changed the IARC’s classification had they been considered,
while another article reports Blair saying in his leaked deposition
that nothing has changed his opinion about glyphosate and non-Hodgkins
lymphoma. Asked directly
about this by the Epi Monitor, Blair clarified that nothing contained
in the totality of the evidence in the IARC review has changed his
mind about glyphosate. He did not address specifically whether the
unpublished AHS data would change his mind since for Blair those data
are not final and therefore not qualified to be considered at this
time. He emphasized that change is always possible before the final
analyses are completed and that relying exclusively on “finished” work
is the best approach. It does not preclude reconsideration of an issue
after significant new relevant information has been published.
Another member of the Blair IARC panel, John McLaughlin, an
epidemiologist at the University of Toronto, told EcoWatch that the
unpublished work did not alter his view about the validity of the IARC
conclusion on glyphosate. It is not clear how he learned of these
findings or in what form.
Hard to Fathom
The
contrasting media and other accounts illustrate how complicated it is
for consumers to find truthful and reliable information about health
risks related to chemical exposures. The Reuters reporter Kate Kelland,
who first surfaced the accusations against Blair, has been criticized
by Carey Gillam from U.S. Right to Know for cherry-picking
information and being susceptible to the public relations efforts of
large companies such as Monsanto. According to Gillam who is referring
to all the publicity surrounding the Reuters article, “Follow up the
hand-fed story with a press release from an industry-funded outlet and
calls for an investigation from the industry group American Chemistry
Council and you have propaganda gold. What you don’t have is the
truth.”
Big Picture
Perspective
Asked for his perspective as an epidemiologist on these disputes,
Blair told the Monitor that investigators working on similar topics
must be prepared for the heat of battle. He takes a big picture view
that we live in a democratic society where information must be made
public and regulators and representatives must decide what precautions
are needed, if any. Sometimes decisions are made to tolerate risks for
the benefits conferred, and he cited the more than 30,000 deaths per
year due to motor vehicles. Society must go through the process of
debating these risks and benefits as it has for asbestos, tobacco, and
other exposures. Eventually a decision we are willing to live with as
a society is arrived at. We are still in that process regarding
glyphosate, he said. ■
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