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Advisory Committee on Health Effects of Endocrine Disruptors
The Supplement II to the Intermediary Report
1.3.1 |
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Section 3: |
The low-dose issue 1 Background
The low-dose issue has attracted attention as one of the key
issues of the endocrine disruptor problem since the publication
of "Global Assessment of the State-of-the-Science of Endocrine
Disruptors"1 ("Global
Assessment" hereinafter) by World Health Organization's
International Programme on Chemical Safety.
Global Assessment notes that various cases have been reported
which indicate effects on wildlife of chemical substances with
hormonal activities existing in the environment, although within
a certain limit of space and time.
It also points out that mammals have inherently a large amount
of endogenous hormones in the body and are equipped with the
defense mechanism against those hormones, and consequently
long-term tests on adult animals have found no significant
effects of hormone-like substances; it concludes that effects of
such substances on adults are not the focus of adverse effects.
This conclusion is based on the recognition that usual test
methods have failed to detect the low-dose effects of
hormone-like substances on organisms, as agreed upon in a
workshop on the low-dose issue in North Carolina in October 20002.
The endogenous hormones can, on the other hand, have deleterious
effects. Hormones are also administered for medical purposes
with acceptance of certain risks3.
Data have been accumulated indicating that effects of hormonal
activity are significant in morphogenetic stages including the
embryo, fetus and neonate, where physiological functions are
unstable. This also applies certainly to the adolescent stage4. |
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1 WHO/International
Programme on Chemical Safety; Eds, T. Damstra, S. Barlow, A.
Bergman, R. Kavlock,G. van der Kraak., Global Assessment of the
State-of-the-Science of Endocrine Disruptors. World Health
Organization, 2002, pp. 180. (http://www.ehp.niehs.nih.gov/who/).
2 The U.S. EPA organized in October
2000 in North Carolina a workshop on the low-dose issue, in
which the possibility of observation by standard methods of new
effects of endocrine disruptors at dose levels lower than the
conventional NOEL or NOAEL*. While acknowledging credibility to
both the affirmative and negative reports on low-dose effects of
BPA, the session questioned the reproducibility of the low-dose
effect data, and referred to a report that a long term test
found no effect of diethylstilbestrol (DES) or BPA. The workshop
concluded that the low-dose effects are poorly understood
currently.
*http://nipserver.niehs.nih.gov//htdocs/liaison/FinalRptLowDose.FR.html
3 This is the reason why the
prescriptions for oral contraceptives and estrogen replacements
after menopause need prudence even if patients ask for one.
4 Considering the fact that EPA has
conducted adolescence assays, the effects in adolescence should
have been mentioned in the executive summary. |
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