eo
reported by Park, et al, the beagle dog with the smallest
lung burden,
i.e.,
0.2 uCi,
developed lung cancer.°"
The
highest Durden in Tabie V is comparable to the lowest
beagle exposure;
the
lowest exposure in Table V,
the
19
cases with lung burdens in the 0.024 uCi range are only an
order of magnitude less than the lowest beagle exposure.
We would suggest that tnis is potentially a serious situation.
As of this time, none of these individuals has developed
lung cancer.””
However,
it is only 9 years Since the exposure
and there is good reason to sugcest that the
latent period
(the time between exposure and the development of cancer)
is much loncer than this.”
In the beagle dog experiments,
the lowest lung burden was associated with a latent period
of 11 years.
The latent period may be longer in man and
particularly at these
cases involved.
4
;
lower dosacaes and
the small number of
Therefore, while these exposed individuals
will be expected to supply pertinent data relative to this
hot particle cancer risk over the next
10
to 20 years,
these exposures give us no information at this time that would
warrant modifying the risk per particle or the critical
particle activity.
64/ Park, J.F., et al, Health Physics, Op. cit. p. 805.
65/
Richmond, Chet, Op.
cit.,
p.
320.