RE: fetal exposure - threshold effects

["Karam, Andrew" <Andrew_Karam@URMC.Rochester.edu>]

Dear Chris,

Thanks for your response.  I had not known that teratogenic effects were
necessarily deterministic.  Knowing this helps to explain that particular
threshold. Does this mean that teratogenic effects are caused by a different
mechanism than damage to a cell's DNA, which I understand to be a stochastic
phenomenon?

Sincerely,

Andy

Andrew Karam, CHP              (716) 275-1473 (voice)
Radiation Safety Officer          (716) 275-3781 (office)
University of Rochester           (716) 256-0365 (fax)
601 Elmwood Ave. Box HPH   Rochester, NY  14642

Andrew_Karam@URMC.Rochester.edu
http://Intranet.urmc.rochester.edu/RadiationSafety

... the fetal effects
discussed, teratogenetic ones, are exactly those for which one might
reasonably expect to see sigmoidal dose-response curves and "practical
thresholds," because they appear to be deterministic (i.e., nonstochastic).
The LNT model/hypothesis is for stochastic effects, e.g., the induction of
cancer. 
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