Re: Antw: Pregnant policies in Europe? -Reply

[Ccja@aol.com]

Maybe it wouldn't hurt to quote ICRP 60, here.
3.4.4. Effects of antenatal exposure
(90) the effects on the conceptus of exposure to radiation depend on the time
of exposure relative to conception. When the number of cells on the conceptus
is small and their nature is not yet specialized, the effect of damage to
these cells is most likely to take the form of a failure to implant or of an
undetectable death of the conceptus. It is thought that any cellular damage
at this stage is much more likely to cause the death of the conceptus than to
result in stochastic effects expressed in the live-born. Exposure of the
embryo in the first three weeks following conception is not likely to result
in deterministic or stochstic effects in the liveborn child, despite the fact
that the central nervous system ant the heart are beginning to develop in the
third week. During the rest of the period of major organogenesis,
conventionally taken to be from the start of the third week after conception,
malformations may be caused in the organ under development at the time of
exposure. These effects are deterministic in character with a threshold in
man, estimated from animal experiments, to be about 0.1 Gy.

Paragraphs 91-93 go on to say that the nominal fatality probability
coefficient for stochastic effects leading to cancer in the live-born is
likely no more than a few times that for the whole population (caveat emptor:
the data are poor). They further assign a coefficient of 30 IQ points/Sv to
doses in the fetus for the 8-15 week interval; with a smaller one for 16-25
weeks. I thus stand corrected.

Chris Alston