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Toronto Epidemiologist Clarifies Stance On Glyphosate And Themes
Relevant For Epidemiology
[Ed. Last month we
published an article about the categorization of glyphosate as
probably carcinogenic by the International Agency for Research on
Cancer and the related controversy swirling around this issue. In the
article, we reported a quote attributed to the University of Toronto’s
John McLaughlin saying that despite unpublished negative data
he was aware of, this information had not changed his views about the
overall categorization of glyphosate as probably carcinogenic.
McLaughlin wrote the commentary below to expand on his views.]
Dear Sir,
Thank you EM for the thoughtful update on glyphosate and various media
responses, which highlights several themes relevant to the field of
epidemiology.
On
the basis of a reporter's online article (by C. Gillam), EM commented
that it was "not clear" how I had made a particular decision. I would
have gladly spoken with EM, which would have shown close agreement
with your main messages and with Dr. Blair's well-reasoned
conclusions.
To
clarify where EM was not clear, I stated that: (1) there are merits in
making decisions based on all published evidence; (2) I continued to
stand by the IARC decision, due to the rigour, comprehensiveness and
transparency of the IARC decision- making process; and (3) it is
standard practice to re-evaluate past decisions as new evidence
emerges.
This leads to a further point that the reporter did not convey, which
fits with the 'big picture perspective' noted in EM's conclusion. The
essential role for epidemiological evidence in weighing risks and
benefits is well appreciated, and EM readers know that to deliver
evidence that reliably informs decision-making, studies must meet high
quality standards (e.g., requiring strong designs, large sample sizes,
detailed exposure information, covariate adjustment, replication,
etc.). What is not widely recognized is that even with global interest
and many decades of use, there are very few human studies that can
contribute substantially to cancer hazard assessments for many
environmental exposures. Accordingly, this 'big picture perspective'
could also consider the forces that influence research investments,
and with broad stakeholder engagement and partnerships would better
support the epidemiological community in addressing society's needs,
while also delivering sustainable systems that can answer important
questions of the future.
John McLaughlin
Chief Science Officer
Ontario Public Health
And
Professor
University of Toronto
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