Forum Sardegna

maurizio feo ha scritto:

Elevated childhood cancer incidence proximate to U.S.
nuclear power plants.
From: Archives of Environmental Health | Date: 2/1/2003 | Author: Chang, Carolyn; Dave, Amie;
Feinberg, Elyssa; Frimer, Marina; Mangano, Joseph J.; Sherman,
Numerous reports document elevated cancer rates among children living near
nuclear facilities in various nations. Little research has examined U.S. rates near the
nation's 103 operating reactors. This study determined that cancer incidence for children
< 10 yr of age who live within 30 mi (48 km) of each of 14 nuclear plants in the eastern
United States (49 counties with a population > 16.8 million) exceeds the national
average. The excess 12.4% risk suggests that 1 in 9 cancers among children who reside
near nuclear reactors is linked to radioactive emissions. If cancer incidence in 5 western
states is used as a baseline, the ratio is closer to 1 in 5. Incidence is particularly elevated
for leukemia. Childhood cancer mortality exceeds the national average in 7 of the 14
study areas.
IONIZING RADIATION poses a significant health risk to fetuses, infants, and children.
Pelvic X-rays delivered to pregnant mothers raise cancer risk during childhood, (1,2) and
increased background radiation is associated with elevated cancer levels among
exposed children. (3-5) Ingestion of fission products is also linked with elevated
childhood cancer levels. Temporal increases in leukemia and other cancers have been
documented among children living near sites where large-scale atomic weapons tests
were conducted in the 1950s and 1960s. (6-9) Thyroid cancer incidence rose sharply
among children living in Belarus (especially the Gomel region) and the Ukraine after the
1986 accident at the Chernobyl plant. (10-12) Elevated thyroid cancer incidence in
children in Belgium and northern England after the Chernobyl accident has also been
reported. (13,14)
Childhood cancer is the most commonly used measure for evaluating health risks for
persons living near nuclear installations. The young are more susceptible to
radionuclides than adults because (a) a given dose is proportionally larger for a fetus or
child than for an adult, (b) the fetus and young child are undergoing rapid cell growth and
division during these life stages, and (c) the child undergoes increasing tissue
differentiation in the maturation process.
Reports on childhood cancer near various nuclear plants in the United Kingdom have
found higher than expected rates. (15-25) Most studies focus on leukemia, a condition
that may be initiated by bone- and bone-marrow-seeking radioisotopes such as
strontium-89 and -90, and barium-140. These fission products are not found in natural
background radiation, but are exclusively byproducts of nuclear weapons explosions and
nuclear reactor operations.
Elevated childhood cancer incidence rates proximate to nuclear facilities have been
reported in Canada, (26) France, (27) Germany, (28) and the former Soviet Union. (29)
Some of these reports conclude that a causal relationship exists between radiation
exposure and childhood cancer risk, whereas others suggest only a statistical
association. Still other reports on childhood cancer near nuclear installations have
shown no risk from proximity to nuclear sites.
There are few studies of childhood cancer rates near nuclear facilities in the United
States--the site of 103 of the world's 435 nuclear power reactors. The nation's 1st
nuclear weapons reactor commenced operation in 1943; the 1st nuclear power reactor
achieved initial criticality in 1957. The studies that have been conducted have been
small in scope, with mixed results. Johnson (30) found an excess of cancer incidence
(25 observed vs. 16 expected) in the period 1969 to 1971 among children 0-14 yr living <
13 mi (21 km) from the Rocky Flats weapons processing facility. Data from Hatch et al.
(31) show that cancer cases in the area < 10 mi (16 km) from the Three Mile Island
complex rose from 34 to 47 cases for children 0-24 yr in the 5 yr after the 1979 accident.
Goldsmith reported excess leukemia mortality for children 0-9 yr in the 4 counties closest
to the Oak Ridge and Hanford nuclear weapons installations in the 1950s and 1960s, but
not in the 1970s. (32) Enstrom (33) found no excess cancer mortality near the San
Onofre plant, but Johnson (34) documented that myeloid leukemia deaths among local
children increased after the plant began operation.
Jablon et al. (35) reported a significant excess of leukemia incidence in children ages 0-
9 yr who lived in 5 counties near 4 nuclear plants in Connecticut and Iowa, but no
excess incidence for other childhood cancers, and no excess childhood leukemia/cancer
deaths. The Jablon report compared cancer incidence near the Connecticut and Iowa
plants with rates for each respective state, and compared cancer mortality with national
rates. Cancer incidence and mortality for children < 10 yr in local counties exceeded
state and national standards for each of the 4 areas. Moreover, the proportion of
excesses for incidence and mortality was very similar (Table 1).
The Surveillance, Epidemiology and End Results (SEER) program of the U.S. Centers
for Disease Control and Prevention collects data on 5 states and 4 metropolitan areas
with established tumor registries, covering about 1/10 of the U.S. population. The SEER
data show that, from 1998 to 2000, cancer incidence in children < 15 yr was 14.83 per
100,000, the highest since SEER was formed in 1973. From 1975 to 2000, cancer rates
in children rose 31.7% for all types of cancers, and 39.6% and 49.6%, respectively, for
leukemia and brain/other nervous system cancers, which make up over half of childhood
malignancies. (36) The increasing trend in childhood cancer incidence has spurred
considerable debate on its etiology; the U.S. Environmental Protection Agency has
suggested that environmental pollutants are 1 potential cause. (37) Since the completion
of the Jablon study, which included data only through 1984, many states have
established cancer registries. Our study uses data from some of those registries to
determine cancer incidence for children < 10 yr who live within 30 mi (48 km) of a
nuclear plant in the eastern United States.