Health Risks of Ionizing Radiation: - Clark University

preconception doses between 2.5 and 10 mSv
(OR 2.8, 1.0-7.6), although this was not part of a
detectable dose-response trend (Doyle et al. 2000).
In one result that almost certainly has a lot to do
with chance, LNHL risk appeared 8 times higher
with paternal preconception exposure to less than
0.1 mSv in the UK case-control study (RR 8.17,
1.18 - ∞) based on 6 cases and 0 controls in that
dose range (Draper et al. 1997). These findings are
remarkable but they are also persistent; most of
the exposed workers in these studies had received
officially reported doses of less than 100 mSv before
conception of their children 11 .
Studies of the children of atomic bomb survivors
have not produced significant findings, occasionally
leading to claims that there is no transgenerational
effect in this cohort. It may be the case, however,
that this cohort cannot provide sufficient evidence
to make claims in either direction. Based on the
information reviewed in this chapter it seems
reasonable to consider that the exposure of the
father in the months leading up to conception may
be the critical exposure for transgenerational effects.
If this is the case then we should look carefully at
the atomic bomb survivor data. Yoshimoto (1990)
reported that there were 17 childhood leukemia cases
Preconception Exposures 123
(diagnosed at age 100 mSv; Roman et al. (1999) give a RR of 7.7 for doses ≥ 10 mSv in the 6 months before conception;
and according to the dose-response coefficient (RR)of 1.6 per 100 mSv (Dickinson and Parker 2002a) a mean
dose of 435 mSv would give a RR of (1.6 4.35 = 7.7). If the exposed cohort of 31,150 individuals is restricted to the
2% that were conceived within 6 months of the bombing and further restricted by the assumption that half of the
exposed parents were men then we are left with 312 individuals. In this case we should expect 0.17 spontaneous
cases of childhood leukemia and, according to the risk estimates mentioned above, about 1 case of radiation-induced
leukemia. Given the random nature of carcinogenesis it would be virtually impossible to recognize this effect in this
cohort.