What areas might
they affect?
In wildlife, endocrine disruptors have been clearly shown to cause
abnormalities and impaired reproductive performance in some species,
and to be associated with changes in immunity and behaviour and skeletal
deformities.
In humans, endocrine disruptors have been suggested as being responsible
for apparent changes seen in human health patterns over recent decades.
These include declining sperm counts in some geographical regions,
increased incidences in numbers of male children born with genital
malformations, and increases in incidences of certain types of cancer
that are known to be sensitive to hormones. More controversially,
links have been suggested with impairment in neural development and
sexual behaviour.
Human studies
A number of observations of adverse effects have been made in which
endocrine disruptors could play a role, including:
- Declining sperm counts: Some studies in certain western
countries have reported decreases in sperm numbers over the last
50 years. However, other studies in different regions have failed
to detect such changes.
- Congenital malformations in children: In recent years
there has been an increase in the incidence of hypospadias (a
congenital abnormality of the urethra in the penis) and cryptorchidism
(undescended testes) in humans. However, no causal association
with chemical exposure has yet been established.
- Cancer: Increased incidences of hormone-related cancers
of both women (breast & ovary) and males (testes & prostate)
have been observed in the West and in countries adopting Western
lifestyles. Again a causal association with chemicals has not
been shown, and numerous other lifestyle factors are known to
be important.
- Retarded sexual development: A few reports have been
published suggesting that adolescents in polluted areas may take
longer to reach puberty. However, the potential mode of action
of any such effect is unknown.
- Retarded neurobehavioural development: Studies in Denmark
and USA have suggested that children born in polluted areas have
some impairment of memory and intelligence.
No clear relationship has been established between adverse health
effects and exposure to endocrine disruptors. More research is needed
on a range of topics in order to understand the potential effects
of endocrine disruption including :
- Large-scale human epidemiology studies relating specific health
effects with exposure to endocrine disruptors
- Basic research into mechanisms of endocrine disruption
- Research into the effects of different types of exposure in the
environment which may lead to unexpected effects e.g. mixtures of
endocrine disruptors, long-term low dose exposure
- Exposure at different ages to see if humans are vulnerable to
endocrine disruptors at any particular stage of life
- Exposure of individuals who may be especially susceptible
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