Although the hypothesis that environmental chemicals may exhibit endocrine disrupting
effects is not new, being raised by Allen and Doisy in 1924, again by Dodds
et al. in 1938, and in the 1950s by Burlington and Lindeman, the issue has seen a
growing level of concern due to reports of increased incidences of endocrine-related
diseases in humans, including declining male fertility, and more significantly, to
adverse physiological effects observed in wildlife where cause and effect relationships
are more evident. In fact, the evidence from these effects in wildlife populations
has suggested that the changes in the reproductive health of humans, including breast
and testicular cancer, birth defects, and declining sperm counts, could be linked to
exposure to endocrine disrupting chemicals. However, no definitive cause and effect
data have yet been established.
While society has released large amounts of man-made chemicals to the environment
since the 1940s, people born between 1950 and 1960 were the first generation
to suffer exposure to these pollutants (from stores in maternal fat tissue) while
they were growing in the womb. During the 1950s and 1960s, the pesticide DDT,
which was used worldwide in vast quantities after 1945, was shown to be estrogenic
and to affect the reproductive systems of mammals and birds. These findings,
together with the publication in 1962 of
Silent Spring
by Rachel Carson, further
highlighted the health problems afflicting some wildlife (e.g., egg shell thinning,
deformities, and population declines) that were exposed to pesticides and other
synthetic chemicals. The link to pollution was also thought to be a possible cause
of the effects seen in the human reproductive system, with papers such as “Are
estrogens involved in falling sperm counts and disorders of the male reproductive
tract?”, published in
The Lancet
in May 1993 provoking wider debate within the
scientific community. In 1996, the publication of
Our Stolen Future
brought this
complex scientific issue to the attention of the general public by providing a readable
account of how man-made chemicals can disrupt hormonal systems. Society and
politicians are now asking scientists if there is a link between exposure to pollutants
and effects on the endocrine system.
