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- 37 -

reported by Park, et al, the beagle dog with the smallest
lung burden, i.e., 0.2 uCi, developed lung cancer.°'

The

highest burden in Table 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 this is potentially a serious situation.
As of this time, none of these individuals has Geveloped
lung cancer.°>

However, it is only 9 years since the exocsure

anc there is gooc reason to Sugeest that the latent period
sposure and the cevelcoment of cancer)

tp

{tne time between

is much longer tran this.

In the beagle dog exzserinents,

}

4

The

t

of ll vears.

fu
rt

che lowest lung Durden was associated witn a latent perisdé
ent period may be longer in man and

particularly at these lower dosages and the small number of
cases

involved.

Therefore,

while these

exposed individuals

will be expected to supply pertinent data relative to this
hot oarticle cancer risk over the next 10 to 20 vears,
these exposures cive us no information at this

‘time that would

warrant modifying the risk per particle or the critical
garticls activity.

S1/

Park, J.F.,

et

al, Health Physics, On. cit. p. 803.

43/

Richmond, Crst, On. cit.,
A,

on.

320-

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