Health Risks of Ionizing Radiation: - Clark University

Figure 5-5. A nuclear test conducted as part of Operation
Crossroads off Bikini atoll in the Marshall Islands in 1946
((http://www.astrosurf.com/lombry/quantique-bombesatomiques-pic.htm).
in any five-year period. The authors also make the
important caveat that “…errors in dose estimation
have almost certainly led to underestimation of risk
in our study” (Gilbert et al. 1998, p. 1659).
5.4 South Pacific testing
South Pacific Islanders have suffered greater
exposures than downwinders in the U.S. or
Kazakhstan but in much smaller populations. The
most intensely exposed Marshall Islanders have
shown clear increases in thyroid nodules (Howard
et al. 1997). 13 Two studies have correlated distance
with thyroid nodules for all Marshall Islanders,
predictably indicating that proximity to the tests
increased the exposure to 131 I and therefore the risk
of developing thyroid nodules (Hamilton et al. 1987,
Takahashi et al. 1997). A study of French Polynesia
residents exposed to fallout from French nuclear
tests (1966-74) found that the subjects had thyroid
cancer rates 2-3 times greater than those in Maoris
or Hawaiians, but this was true for people exposed
as adults as well as those exposed as children,
indicating that the difference may not be due to
radiation exposures (de Vathaire et al. 2000).
5.5 Health effects in Scandinavia
Nuclear Weapons Testing 63
We should mention two studies dealing with leukemia
and thyroid cancer in Scandinavia; doses received
by these populations are unclear but researchers
have attempted, as in some of the studies mentioned
above, to correlate disease patterns with probable
peak fallout years. Darby et al. (1992) looked at
leukemia rates in Nordic countries and compared
them with global fallout exposure trends in England,
assuming that the time patterns of exposure should
be similar. No relationships were found. Lund
and Galanti (1999) compared the 1951-1962 birth
cohort in Sweden and Norway to the birth cohort of
1963-70; they were looking for a relationship with
arctic testing at Novaya Zemlya, where major tests
occurred from 1957-1962. They found a significant
increase in thyroid cancers diagnosed before age
14 (RR 1.7; 1.0-3.0) and there was also a nonsignificant
increase in thyroid cancers for the 1947-
1950 cohort relative to the 1963-70 cohort (these
people would have been 7-15 years old during
peak fallout exposures). These authors also made
estimates of thyroid dose based on measurements
of radioactivity in Norwegian milk; the maximum
calculated dose was 1.8 cGy for people born in 1957
and 1958.
5.6 Discussion
In summary, the studies of atomic veterans, cohorts
with average gamma doses of less than 10 mSv, have
consistently found increases in leukemia. Increases
in other related diseases such as multiple myeloma
and polycythemia vera have been observed as well.
Children downwind of the test sites in Nevada and
Kazakhstan have also shown evidence of an increase
in leukemia and thyroid cancer. These results
are discussed in comparison with other sources
of exposure in the leukemia and thyroid disease
sections of this report.
The studies discussed above address exposures
to local fallout, meaning fallout that was generated
13 Of 67 Rongelap Islanders exposed to fallout from the Bravo test (190 rads of external radiation), 24 developed
thyroid nodules by 1990. 26 out of 167 exposed residents of Utirik (11 rads) developed nodules (Howard et al.
1997).