-
143 -
change at all and remained between 46 and 47 years.
The mean age at death of
radiologists was 55.8 years in 1934-1939; 59.3 years in 1940-1949; 64.5 years
in 1950-1959 and 70.1 years from 1960.
The rate of this increase was higher
than that of the general male population, so that from 1960 on the two curves
expressing the increase in the average age at death versus time crossed with
each other.
The life-shortening observed in preceding years could not be
attributed to any one cause in particular, such as leukaemia, but was the
aggregate of shorter life-spans associated with many causes of death.
Leukaemia
had a higher risk (about 5 times) among radiologists than among the male population at large, but it occurred rarely and only after a number of years of
occupational exposure.
It was more common in radiologists after 40 years of
age, but more common before 40 in the general population.
excessive incidence of leukaemia in radiologists decreased.
In recent years the
From the above
findings Warren and Lombard concluded that radiation protection measures had
been effective in providing adequate safeguards for the radiology specialists.
351.
Miller and Jablon [M27] searched for late radiation effects among men
trained as radiology technicians in the United States Army during the Second
World War.
The mortality experience of this group of people (6560 persons in
total) was compared over the period 1946-1963 with that of other groups trained
by the Army as pharmacy (1522 persons) or medical laboratory technologists (5304
persons).
It was difficult to ascertain the radiation dose but it was concluded
from ancillary evidence, in the absence of more complete records, that they received substantially greater radiation that did patients exposed to x rays for
diagnosis.
Causes of death were investigated and in only 1 out of 16 possible
comparisons between exposed and non-exposed groups there was a statistically significant difference of any interest in the present context.
It referred to an
excess of tumours of the respiratory tract which was elevated among radiologists:
however, the difference between expected and observed values was due in part to
the low mortality rate from this cause of death in the control samples.
No sig-
nificant excess of leukaemia was found among the radiographers, but in a study
of this size a two- to three-fold increase in the risk of leukaemia could have
gone undetected.
352.
No information on life-span-shortening was reported as such.
There was yet another report from Japan on the mortality and causes of
death of radiology technicians during the period 1966-1972 [K19].
Among these
technicians affiliated to the Japanese professional association there were dur-
ing the above-mentioned period 134 deaths, a number much lower than expected,
age