Reports the deliberations of a working group convened to evaluate the
strength of evidence linking the drinking of coffee, tea, and mate to
the development of human cancer. Separate evaluations are also provided
for caffeine, theophylline theobromine and methylglyoxal, which are
chemical constituents of coffee, tea, and several other popular
beverages.
The first and most extensive monograph evaluates the large number of
studies designed to assess the carcinogenic potential of coffee. On the
basis of available data, the working group concluded that coffee is
possibly carcinogenic to the human urinary bladder. Evidence further
suggests that coffee may actually protect humans against cancer of the
colon and rectum. The risk for breast cancer was shown, with remarkable
consistency, to have no association with coffee drinking.
The second monograph evaluates the carcinogenicity of black and green
teas. Although available data were judged inadequate to classify tea
according to its carcinogenic risk, the analysis uncovered evidence
suggesting that the temperature at which tea is drunk may be a more
important determinant of risk than the chemical composition of the
beverage.
This observation is further supported in the monograph on mate, a South
American beverage, which is usually drunk very hot following repeated
addition of almost boiling water to the infusion. While mate could not
be classified on the basis of available data, hot mate drinking was
judged to have a probable association with the development of
oesophageal and oral cancers. Evidence was inadequate to assess the
carcinogenicity of caffeine, theophylline, theobromine, and
methylglyoxal.