The
International Agency for Research on Cancer (IARC) released a monograph in 1991
on the carcinogenic risks caused by coffee (Vol. 51). The monograph was an
outcome of year long study and a weak long workshop held in 1990 in Lyon, by a
working group comprising 23 experts drawn from 16 countries. Based on the published literature available from
reputed sources, the working group evaluated the reports on epidemiological and
experimental studies on the carcinogenicity ln experimental animals, Structure-activity
considerations, Absorption, distribution, excretion and metabolism, toxicity, Genetic
and related effects, and evidence for carcinogenicity in humans. The working
group in its monograph observed that,
·
There is limited evidence in humans that coffee
drinking is carcinogenic in the urinary bladder.
·
There is evidence suggesting lack of carcinogenicity
of coffee drinking in the human female breast and in the large bowel.
· There is inadequate evidence in humans that coffee
drinking is carcinogenic in the pancreas, ovary and other body sites.
·
There is inadequate evidence in experimental animals
for the carcinogenicity of coffee.
The working
group concluded that,
·
Coffee is possibly carcinogenic to the human urinary
bladder (Group 2B).
This attracted
widespread criticism on this report among the public, law makers and scientist's
world over. This triggered an in-person enquiry of officials of the U.S.
government’s health research agency, “National Institute of Health” by the Congressional
committee of United States of America (USA), on its grants to the International
Agency for Research on Cancer (IARC) (As per Reuters report dated October 6,
2016). As per the news agency Reuters, the briefing
comes after the committee’s chairman added his voice to growing concerns among
some senior U.S. lawmakers about the way IARC reviews and classification of substances
such as coffee, mobile phones, processed meat and the weed killer glyphosate as
carcinogenic. As per Reuters, the Chairman of the Committee on Oversight and
Government Reform, Mr. Jason Chaffetz wrote a letter to the NIH Director, and
alleged that “IARC’s standards and determinations for classifying substances as
carcinogenic, and therefore cancer-causing, appear inconsistent with other
scientific research, and have generated much controversy and alarm” and questioned
NIH policy to fund IARC.
In 2016, IARC
constituted a working group of 23 members drawn from 11 countries to reevaluate
the carcinogenic risk posed by Coffee. They released report in 2016 and brought out a monograph on
coffee in 2018 (Vol. 116).
The working
group observed in its monograph that,
· There is inadequate evidence in humans for the
carcinogenicity of drinking coffee.
· There is evidence suggesting lack of carcinogenicity of
drinking coffee in humans for cancers of the pancreas, liver, female breast,
uterine endometrium, and prostate. Inverse associations with drinking coffee
have been observed with cancers of the liver and uterine endometrium.
· There is inadequate evidence in experimental animals
for the carcinogenicity of coffee.
The working
group concluded that,
·
Drinking coffee is not classifiable as to its carcinogenicity
to humans (Group 3).
The working
group also observed that coffee drinking is associated with a beneficial effect
on liver fibrosis and cirrhosis.
This triggered an allegation that IARC takes decisions in haste and retract their findings due to public pressure after the publication of monograph on coffee and glyphosate. IARC’s director, Chris Wild defended IARC’s evaluation of coffee and said that “The (coffee) report in 2016 was not a ‘retraction’ but a re-evaluation based on an additional 25 years of scientific evidence” (As per Reuters report).
Nevertheless, this is a classic example where IARC has reversed its assessment on a most popular consumer item.
