whole working life.
Not all of this life-shortening may be accounted for by
leukaemia and cancer induction, and other non-neoplastic conditions contriputed to it.
There is no way to derive from the data, since there is no know-
ledge of dose, an approximate value of the life-shortening per unit dose.
There is unanimity in the conclusion that the induction of neoplastic conditions, accompanied or not by life-shortening, has disappeared in more recent
years, presumably after the adoption of radiation protection measures.
380.
States.
True shortening of life has only been seen in the series from the United
Reasons to justify the absence of life-shortening among British radio-
logists have indeed been given and the absence of effect could be accounted for
by objective reasons and on methodological grounds.
It has been pointed out
that with samples of the order of 1000 persons prevalence rations of the order
of 2 to 3 for leukaemia and life-shortening effects of the order of 5 to 6
years can hardly be resolved.
It should also be realized that induction of neo-
plasia is not necessarily linked to life-shortening.
Within the large limits
of variation cited above excess mortality ratio of 1.5 to 2.0 could be compensated by a lower rate of death from other causes, leaving the death ratio from
all causes unchanged with respect to controls [S42].
381.
In spite of the small samples size (about 1200 persons) the data on the
mortality experience of dial painters convincingly showed that the only causes
of death significantly contributing to the life-span-shortening in these women
are bone sarcoma and carcinoma of the head sinuses, tumours known to be specific
226
228
.
:
.
risks for
Ra and
Ra exposure.
To the precision possible with such sample
size, therefore, non-specific mortality was not seen, in spite of the known presence of non-stochastic injury in these subjects, for example, in the bone. On
the other hand, exposure under these conditions was localized and not extended
to the whole body.
382.
The experience on the radiology technologists, both from Japan and from
the United States, is considerably more limited (and therefore much less signi-
ficant) than that on radiology specialists.
appear in contrast with the latter.
However, on the whole, it does not
Here again, induction of leukaemia and of
some forms of cancer induction were often seen [K17, K18, M27, K191;
case life~shortening was reported [K18], but not in others.
in one