355.
In a companion paper [M29] the specific causes of death contributing to
the excess risk of mortality in radiologists were examined.
In the 1920-1929
cohort the radiology specialists, in addition to the previously-noted cancer
mortality [M28], showed also the highest death rate for diabetes, cardiovascular-renal diseases, stroke, hypertension and suicide.
After this early period
radiologists ranged highest among other comparison groups only for cancer mortality.
The excess of leukaemia observed in the
disappeared.
1920-939 cohorts subsequently
During the same period, however, lymphoma mortality, particularly
multiple myeloma, increased significantly in radiologists entering their
profession in 1930-1949.
Except for this latter finding, which was discussed
in relation to possible effects of radiation on the immune system, the data reported confirmed and extended previous observations.
The authors were aware of
the peculiarity of their findings, since American radiologists are the only human population where life-shortening effects of radiation, over and above those
related to an excess tumour induction, has been observed.
They specifically
commented on this point and reaffirmed the validity of their observations. They
also added [M28] that it may be premature to state conclusively that such an effect has disappeared in the 1940-1949 cohort, since relatively few persons in
this cohort (193 out of 1011) had passed through the ages when mortality is
higher: examination of an additional 5-10 years period might be required to
determine whether such an effect has been reduced through a decrease of the
occupational exposure.
356.
Very recently Polednak et al.
[P4] reported on the mortality of a group
of women employed in the dial-—painting industry in the United States.
A cohort
of 634 subjects working in this industry during 1915-1929 was traced from employment lists.
Mortality in these subjects was compared on the basis of death
certificates with the general mortality rate of American white females.
An in-
creased death rate was observed in comparison with the expected rate in the ex-
posed population (240 cases versus 188.5 expected).
357.
Bone cancer (22 causes versus 0.3), cancer of non-specified sites (18
versus 2.6), cancer of the colon (10 versus 5) diseases of the blood and haemopoietic organs (4 against 1) and external causes (31 against 101) were also
increased, as compared to the general population.
Mortality from selected
causes was also examined as a function of the year of first exposure, time
period of observation and age at first exposure.
The mortality ratios from
all causes and all cancers in women exposed after
1925 were lower than in women