Address for correspondence: Lorenzo Tomatis, M.D., Cave 25/r, 34011 Aurisina (Trieste), Italy. Fax: 39 040 202549.
ltomatis{at}hotmail.com
Ann. N.Y. Acad. Sci. 982: 190-197 (2002).
It is widely accepted that epidemiological data provide the
only reliable evidence of a carcinogenic effect in humans, but
epidemiology is unable to provide early warning of a cancer
risk. The experimental approach to carcinogenicity can ascertain
and predict potential cancer risks to humans in time for primary
prevention to be successful. Unfortunately, only in rare instances
were experimental data considered sufficiently convincing per
se to stimulate the adoption of preventive measures. The experimental
testing of environmental agents is the second line of defense
against potential human carcinogens. The first line is the testing
of synthesized agents, be these pesticides, medical drugs, or
industrial chemical/physical agents, at the time of their development.
We do not know, however, how many substances have been prevented
from entering the environment because most tests are carried
out by commercial or private laboratories and results are rarely
released. A better understanding of the mechanisms underlying
the sequence of events of the carcinogenesis process will eventually
lead to a more accurate characterization and quantification
of risks. However, the ways that mechanistic data have been
used lately for evaluating evidence of carcinogenicity have
not necessarily meant that the evaluations were more closely
oriented toward public health. A tendency has surfaced to dismiss
the relevance of long-term carcinogenicity studies. In the absence
of absolute certainty, rarely if ever reached in biology, it
is essential to adopt an attitude of responsible caution, in
line with the principles of primary prevention, the only one
that may prevent unlimited experimentation on the entire human
species.
