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European Workshop
on the impact of endocrine disrupters on human health and wildlife
Conclusions and recommendations
One of the main outcomes of this workshop was agreement of
a definition of an ED
- "An endocrine disrupter is an exogenous substance that
causes adverse health effects in an intact organism, or its
progeny, secondary to changes in endocrine function."
A further definition was also agreed, concerning potential
ED:
- "A potential endocrine disrupter is a substance that
possesses properties that might be expected to lead to endocrine
disruption in an intact organism."
1) Conclusions
Main conclusions reached at the meeting were as follows:
- Sufficient evidence exists for increasing testicular cancer
rates, and the apparent decline in sperm counts in some areas
was unlikely to be attributable to the known confounding variables;
existing exposure information was generally insufficient to
definitely associate the human changes seen with chemical
exposure.
- For wildlife, few cases within the EU were known where effects
could be clearly ascribed to endocrine disrupters. In any
event, the critical factor for survival of wildlife populations
and for maintaining biodiversity was considered to be reproductive
efficiency (including offspring survival). The need to obtain
adequate background data and to use a broad testing strategy
in field studies using a range of sentinel (marker) species
and biomarkers was stated.
- The subgroup considering mechanisms concluded that some
animal models were available that could allow detection of
many endocrine disrupting substances, based upon well characterized
adverse reproductive effects. However, further development
work and validation was needed. It was suggested that priority
should initially be given to detecting effects rather than
understanding the underlying mechanism of toxicity.
- Exposure monitoring studies would need to be integrated
with studies on human or wildlife effects, and there was a
need for national specimen banks to be set up and more use
made of existing information.
- There was a need to agree on experimental methods, and a
tiered screening strategy was proposed to facilitate this
process.
- Overall, the workshop noted that measures to reduce exposure
to endocrine disrupters should be in line with the Precautionary
Principle, [LINK TO DEFINITION IN OTHER SECTION OF WEBSITE]
as described in Principle 15 of the 1992 Rio declaration.
2) Recommendations
Numerous recommendations for future areas of research or action
were identified by the workshop:
- General areas:
- Studies on effects in humans (epidemiology): Give priority
to human epidemiology studies on compounds shown to be
active in intact animal studies
- In all studies look to see if there are effects due
to exposures before and after birth
- Collect tissue and body fluid samples during epidemiology
studies to allow for possible future investigations
- Look for effects in groups of people (cohorts) that
have different levels of exposure to environmental pollutants,
at work, or to naturally-occurring substances, and also
look at the effects of "lifestyle" factors (e.g.
diet and socio-cultural differences)
- In situations where action is taken that results in
a reduced exposure to particular chemicals, then undertake
follow-up epidemiology studies to check if there is any
change in human reproductive health
- Current investigations into known changes in reproductive
health should be continued, and work should be done to
establish 'baseline' measurements and investigate geographical
differences (e.g.investigations across Europe into levels
of testicular cancer, semen quality, cryptorchidism and
hypospadias [congenital abnormalities of the testes and
penis of boys] and breast cancer in women)
- Use common standards for measuring end-points to aid
cross-study comparisons
- Include additional, easy to measure end-points (e.g.
testis, penis and clitoral size in new borns, twinning
rates, ratio of males to females)
- Find chemical markers in the blood that predict sperm
and ovarian function in humans and animals
- Studies on effects in wildlife
- There is a need to conduct field studies at locations
where endocrine disruption has been suggested to occur.
Such studies need to look at a wide range of aspects,
including gonadal function, behaviour and offspring sex
ratio, numbers and survival. To be understandable, it
is important that studies also look at control (unimpacted)
areas
- The basic endocrinology of many species is not understood
and needs to be investigated
- Need to identify which species should be looked at to
see if the environment is being affected (i.e. can act
as sentinels)
- Biomarkers are needed to predict effects on reproduction
- The environmental fate and availability to animals of
known endocrine disrupters should be studied
- Regional variations in the distribution of endocrine
disrupting substances and in effects in wildlife populations
should be looked at
- ensure that all available data are fully utilised
- Understanding the mechanisms by which effects occur, and
developing models to use in research
- Basic knowledge is still needed on the hormonal systems
of various organisms and of how the endocrine system interacts
with other stystems in the case of disease or injury
- The current animal models used in testing need to be
validated to ensure that they are relevant to humans for
endocrine effects, and new, more meaningful animal models
are needed for testicular cancer and control of testicular
descent
- Basic research is needed into the mechanisms of testicular
descent, hypospadias and polycystic ovaries in humans
- Urgently investigate the aetiologies of persistent oestrus
in rodents and polycystic ovaries in humans to se if they
have similar causes
- Non- or minimally-invasive biomarkers are needed to
check endocrine and testicular function that are valid
and consistent across species
- Investigate techniques to study neurodevelopmental and
neurobehavioural effects and to relate animal and human
systems
- Exposure
- Look for effects in wildlife populations (both aquatic
and terrestrial) known to be exposed, and use well-defined
end-points where it is possible to determine what is "normal"
as a baseline
- Conduct effects-driven studies into exposure assessment
in humans comprising epidlemiological (including case-control)
studies linked to evaluation of exposure and other lifestyle
factors at critical life-stages
- Develop validated environmental fate and behaviour models
- Improve current risk assessment methodologies so that
the potential interactive effects of multiple exposures
(i.e. exposure to several chemicals at a time) can be
taken into account
- There is a need for a Europe-wide strategy for monitoring
the environment for endocrine disrupting substances
- Undertake studies of the cost and effectiveness of reductions
in exposure to recognised endocrine disrupters
- Methods for testing and screening chemicals
- Develop computer based structure-activity relationship
(SAR) models to predict the activity of chemicals
- Assess if it is possible to use assays that do not involve
the use of live animals, allowing replacement or reductions
in the use of intact animals during the testing of chemicals
- Develop new whole animal assays in fish and birds as
possible replacements for rodent studies
- Determine whether endocrine disruption effects in neonates
(new born) or weanlings can be predicted by measurements
made in exposed parent; if this does not prove possible,
then any testing processes will need to look at the effects
of exposures during gestation and lactation
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