Endocrine disruption in wildlife: The future?
J. P. Sumpter
Department of Biological Sciences, Brunel University,
Uxbridge, Middlesex, UB8 3PH, UK
Abstract: Probably the only thing that can be said with certainty
about the future of this field of ecotoxicology is that predicting it
is foolish; the chances of being right are very slim. Instead, it seems
to me likely that unexpected discoveries will probably have more influence
on the field of endocrine disruption than the outcomes of all the planned
experiments. It is certainly true that chance discoveries, such as masculinized
fish in rivers receiving paper-mill effluent, imposex in molluscs due
to exposure to tributyltin and feminized fish in rivers receiving effluent
from sewage-treatment works, have been pivotal in the development of
the field of endocrine disruption in wildlife. I consider that further
such discoveries are likely, but I do not know which species will be
affected, what effects will be found, what chemical(s) will be the cause,
or what endocrine mechanism(s) will underlie the effects. The recent
realization that many pharmaceuticals are present in the aquatic environment
only underscores the range of effects that could, in theory at least,
occur in exposed wildlife. What is somewhat easier to predict is the
research that will be conducted in the immediate future, which will
build upon what is known already. For example, it is clear that wildlife
is rarely, if ever, exposed to single chemicals, but instead is exposed
to highly complex, ill-defined mixtures of chemicals, including many
that are endocrine active in various ways. We need to understand much
better how chemicals interact, and what overall effects will occur upon
exposure to such mixtures. We also need to move from assessing effects
at the individual organism level, to understanding the consequences
of these effects at the population level. Then, we need to determine
the significance of any population-level effects due to endocrine disruption
in comparison with the impact of many other significant stressors (e.g.,
over-exploitation, habitat loss, climate change) that also negatively
impact wildlife. Such research will be difficult, and time-consuming,
and will probably produce many surprises. All I can be fairly certain
about is that the next few years are likely to be as interesting and
exciting as the last few have been.
*Report from a SCOPE/IUPAC project: Implication of
Endocrine Active Substances for Human and Wildlife (J. Miyamoto and
J.Burger, editors). Other reports are published in this issue,
pp. 1617-2615.
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