The
multiple nuclear meltdowns at the Fukushima plants beginning on March
11, 2011, are releasing large amounts of airborne radioactivity that
has spread throughout Japan and to other nations; thus, studies of
contamination and health hazards are merited. In the United States,
Fukushima fallout arrived just six days after the earthquake, tsunami,
and meltdowns. Some samples of radioactivity in precipitation, air,
water, and milk, taken by the U.S. government, showed levels hundreds
of times above normal; however, the small number of samples prohibits
any credible analysis of temporal trends and spatial comparisons. U.S.
health officials report weekly deaths by age in 122 cities, about 25 to
35 percent of the national total. Deaths rose 4.46 percent from 2010 to
2011 in the 14 weeks after the arrival of Japanese
fallout, compared with a 2.34 percent increase in the prior 14 weeks.
The number of infant deaths after Fukushima rose 1.80 percent, compared
with a previous 8.37 percent decrease. Projecting these figures for the
entire United States yields 13,983 total deaths and 822 infant deaths
in excess of the expected. These preliminary data need to be followed
up, especially in the light of similar preliminary U.S. mortality
findings for the four months after Chernobyl fallout arrived in 1986,
which approximated final figures.
We
recently reported on an unusual rise in infant deaths in the
northwestern United States for the 10-week period following the arrival
of the airborne radioactive plume from the meltdowns at the Fukushima
plants in northern Japan. This result suggested that radiation from
Japan may have harmed Americans, thus meriting more research. We noted
in the report that the results were preliminary, and the importance of
updating the analysis as more health status data become available (1).
Shortly
after the report was issued, officials from British Columbia, Canada,
proximate to the northwestern United States, announced that 21
residents had died of sudden infant death syndrome (SIDS) in the first
half of 2011, compared with 16 SIDS deaths in all of the prior year.
Moreover, the number of deaths from SIDS rose from 1 to 10 in the
months of March, April, May, and June 2011, after Fukushima fallout
arrived, compared with the same period in 2010 (2). While
officials could not offer any explanation for the abrupt increase, it
coincides
with our findings in the Pacific Northwest.
Any
comparison of potential effects of radiation exposure must attempt to
examine the dose-response relationship of the exposure of a population.
In the United States, the principal source of dose data (i.e.,
environmental radiation levels) is the U.S. Environmental Protection
Agency (EPA). Health data are the responsibility of the U.S. Centers
for Disease Control and Prevention (CDC), which provides weekly reports
on mortality in 122 U.S. cities. These are
preliminary data, but are the most useful at a date so soon after an
event such as Fukushima.
The
goal of this report is to evaluate any potential changes in U.S.
mortality resulting from exposure to the Fukushima plume, using EPA and
CDC data.
BACKGROUND:
POST-CHERNOBYL HEALTH TRENDS
A
quarter of a century before the Fukushima disasters, the meltdown at
Chernobyl and the presence of environmental fallout presented a similar
challenge for researchers to assess any adverse health effects. The
discussion that began after the April 26, 1986, meltdown is still very
much a current one, with varying estimates. A recent conference
concluded that 9,000 persons worldwide survived with or died from
cancer (3), while a compendium of more than 5,000 research papers put
the excess death toll (from cancer and all other causes) at 985,000 (4).
In
the United States, Chernobyl fallout was detected in the environment
just nine days after the meltdown. Gould and Sternglass (5) used EPA
measurements of environmental radiation post-Chernobyl (6) and found
elevated levels of radioactivity in air, water, and milk. For example,
EPA data indicate that from May 13 to June 23, 1986, U.S. milk had 5.6
and 3.6 times more iodine-131 and cesium-137 than were recorded in
May–June of 1985 (see Appendix Table 1, p. 60). In some
cities, especially those in the harder-hit Pacific Northwest, average
concentrations were as much as 28 times the norms, while some
individual samples were much higher.
Gould
and Sternglass (5) also studied preliminary mortality data, to analyze
any potential impact from fallout. Using a 10 percent sample of all
U.S. death certificates, they found that during the four months after
Chernobyl (May–August1986), total deaths in the United States
rose 6.0 percent over the similar period in 1985 (see Appendix Table 2)
(7; estimated deaths based on a 10% sample of death certificates, minus
the New England states, for which data were incomplete at the time).
Eventually, final
figures showed an increase of 2.3 percent, which exceeded the 0.2
percent decline in the first four months of the year (8). The number
ofe xcess deaths, or the difference between the actual and expected
death totals, is 16,573. To date, the cause of this unusual pattern
remains unknown, and no research testing hypotheses for causes other
than Chernobyl has been published. This difference has a very high
degree of statistical significance; there is a less than 1 in 109
probability that it occurred by random chance. The change in
deaths for infants was also analyzed. Preliminary data showed an
increase of 3.1 percent in U.S. infant deaths in the first four months
after Chernobyl, 1985 versus 1986. The final increase was 0.1 percent,
compared with a 2.3 percent decline in the four months before
Chernobyl. The 1985–1986 differences in infant death rates
were –2.9 percent (January–April) and +0.4 percent
(May–August). These gaps amounted to excess infant deaths of
306 and 424, and differences were significant at p < 0.08 and p
< 0.055. The stillbirth, neonatal, and prenatal mortality
increased in England and Wales within 11 months after
Chernobyl’s initial release (9, 10), and in Germany (11). In
two Ukrainian districts with increased levels of cesium-137 ground
contamination, there was a significant increase in stillbirths (12).
U.S. publications offered evidence that Americans may have
suffered harm from Chernobyl, especially damage to fetuses and infants.
Reports covered elevated levels of various radiation-related disorders,
including newborn hypothyroidism (13), infant leukemia (14), and
thyroid cancer among children (15). Gould and Sternglass (5)
showed that trends using preliminary data were rough approximations of
the final data. Because of the lengthy delay in generating final
statistics—2011 data will probably not be published on the
CDC website until 2014—we believe that analyzing preliminary
health data at this time is a useful exercise that can approximate
final mortality patterns and help guide future research on the effects
of fallout from the Fukushima meltdowns.
METHODS
Environmental Radioactivity
The first component of any analysis of potential adverse health effects
from Fukushima fallout in the United States is the doses received by
humans. After March 17, 2011, when the airborne radioactive plume first
reached the United States, the EPA accelerated its program of sampling
environmental radioactivity. Instead of quarterly measures in
precipitation, milk, water, and air, samples were taken weekly,
sometimes more frequently. Radioisotope levels in late March and early
April tended to be higher than typical levels, but declined in April,
even though Fukushima meltdowns and emissions continued. On May 3, the
EPA announced that it would revert to quarterly measurements.
The number of samples and percentage with detectable radioisotope
levels reported by the EPA in March–April 2011 were far fewer
than those taken and reported in the period after Chernobyl in
May–June 1986. Reporting for some of the principal
radioisotopes is given in Table 1 (16). The number of samples
for which the EPA was able to detect measurable concentrations of
radioactivity is relatively few. Assuming that the EPA attempted to
measure each of the 10 isotopes in air, precipitation, milk, and
drinking water, only 13.3, 6.2, 2.2, and 2.4 percent, respectively,
resulted in detectable levels. Of the 452 samples with
detectable levels, 297 were iodine-131 measurements.
This dataset was much weaker than that reported by the EPA in
May–June 1986, in the aftermath of the Chernobyl meltdown.
For example, the EPA reported 2,304 milk samples in the United States,
with 2,000 (86.8%) reporting a positive number for the three isotopes
barium-140, cesium-137, and iodine-131 (6). After Fukushima, there were
670 measurements of milk for 10 isotopes, with just 2.2 percent
reporting a positive numerical value (16). Clearly, the 2011 EPA
reports cannot be used with confidence for any comprehensive assessment
of temporal trends and spatial patterns of U.S. environmental radiation
levels originating in Japan.
Table 1
The EPA data
cannot be used to assess the amount of time that Fukushima radiation
existed in the U.S. environment, or which areas of the nation received
the highest amount of fallout. Anecdotal samples provide an abridged
set of data. For example, iodine-131 in precipitation reached 242 and
390 picocuries per liter (pCi/L) in Boise, Idaho, on March 22, hundreds
of times greater than the typical value of about 2.0 pCi/L. The next
highest value (200 pCi/L) was
recorded in Kansas City, Kansas, on March 29. The 10 highest values
included diverse locations such as Salt Lake City, Utah (190 pCi/L),
Jacksonville, Florida (150 pCi/L), and Boston, Massachusetts (92
pCi/L). Despite the paucity of data, it appears that radioactivity from
Fukushima reached many, perhaps all, areas of the United States.
Without more specific data, only the United States as a whole can be
used to understand any potential changes in health status.
Health
Status
Vital statistics in the United States, including morbidity and
mortality, are typically not made publicly available until at least two
years after the event occurred. Moreover, vital statistics are publicly
issued only for entire years, not portions of years, as would be needed
to analyze temporal trends before and after the Fukushima meltdowns.
Obtaining data for portions of years would be possible only by making
special requests to state and local health departments
that maintain and collect data.
The CDC produces weekly statistics on U.S. deaths for each of five age
groups and for all ages combined, and for pneumonia/influenza, as part
of the Morbidity and Mortality Weekly Report. The statistics include
122 U.S. cities with populations over 100,000, representing about 25 to
35 percent of the nation’s deaths. The number of
deaths is reported voluntarily by health officers in these cities, and
represents the place of occurrence of death rather than the place of
residence. A death is counted when the death certificate is
filed, not necessarily on the date
of death. Only raw numbers of deaths, and not mortality rates, are
given. In some cities, a week’s total is reported with a
“U” (unavailable), although by 2011 this lack of
reported information occurred only in a small minority of participating
cities.
While the limitations of the CDC weekly mortality statistics should be
understood and considered, so that the data are cautiously interpreted,
these limits should not preclude their use. Each week, about 11,000
total deaths are reported. The experience of mortality patterns found
by Gould and Sternglass (5) using a 10 percent sample of U.S. deaths
that approximated final statistics offers further evidence that the CDC
mortality data can be helpful at this still-early date. In
this report, we analyze changes in U.S. deaths in the period after
Fukushima fallout arrived in North America, compared with a similar
period for 2010.
Total deaths and deaths of infants under one year, who are most
susceptible to the adverse health effects of exposure to radioactivity,
are reported.
As of this
writing, 14 weeks of post-Fukushima data have been reported by the CDC.
All but 3 of the 122 cities in the CDC report submitted actual number
of deaths (vs. “unavailable”) in more than 99
percent of the reporting periods. This 14-week period includes weeks 12
to 25 of 2011 (March 20 to June 25), approaching the four-month period
in which Gould and Sternglass found an unexpectedly large increase in
deaths after Chernobyl. Here, reported deaths are compared with weeks
12 to 25 in 2010 (March 21 to June 26). Any 2010–2011
changes are compared with those for the prior 14-week period (December
12, 2009, to March 20, 2010 vs. December 11, 2010, to March 19, 2011:
weeks 50 to 52 and 1 to 11).
The 2010–2011 comparison of deaths in weeks 12 to 25 included
119 of the 122 cities in the CDC report. Excluded were Fort Worth,
Texas; New Orleans, Louisiana; and Phoenix, Arizona; for these cities,
deaths in more than half of the weeks were reported as
“unavailable.” The completeness of reporting for
both periods exceeded 99 percent. For the earlier 14-week periods, only
104 of the 122 cities that reported death figures more than 99 percent
of
the time were included. For the cities and weeks excluded from the
analysis, see Appendix Table 3.
Statistical significance between the 2010 and 2011 death trends was
calculated by using the difference between two means. The observed
difference was the actual 2010–2011 change for weeks 12 to
25, and the expected difference was the 2010–2011 change for
the preceding 14 weeks. The formula used for calculating statistical
significance is given in Appendix Table 4.
RESULTS
U.S. Total Deaths
During weeks 12 to 25, total deaths in 119 U.S. cities increased from
148,395 (2010) to 155,015 (2011), or 4.46 percent. This was nearly
double the 2.34 percent rise in total deaths (142,006 to 145,324) in
104 cities for the prior 14 weeks, significant at p < 0.000001
(Table 2). This difference between actual and expected changes of +2.12
percentage points (+4.46% – 2.34%) translates to 3,286
“excess” deaths (155,015 × 0.0212)
nationwide. Assuming a total of 2,450,000 U.S. deaths will occur in
2011 (47,115 per week), then 23.5 percent of deaths are reported
(155,015/14 = 11,073, or 23.5% of 47,115). Dividing 3,286 by 23.5
percent yields a projected 13,983 excess U.S. deaths in weeks 12 to 25
of 2011.
After March 19, 2011, total deaths were higher than a year earlier in
11 of the 14 weeks, with a 7.5 percent or greater increase in four of
the weeks. The greatest rise occurred in weeks 12 to 20, with a 5.37
percent increase (96,900 to 102,108). In weeks 21 to 25, the
increase was a considerably lower 2.74 percent (51,495 to 52,907).
Whether this pattern will continue into the future or is temporary is
not yet known.
Table 2
U.S. Infant Deaths
The CDC weekly report provides reported deaths in the 122 participating
cities for each of five age groups (<1, 1–24,
25–44, 45–64, and over 65). Of special interest to
any analysis of potential health risks of environmental toxins are the
fetus and infant, which are at greater risk than older children or
adults. Their immune systems are immature and less likely to fight off
disease; their cells are dividing very rapidly and are less likely than
a damaged adult cell to repair before mitosis. Thus, we examined trends
for deaths of infants under one year
old. The same cities used for total deaths are used here (Table 3).
Infant death numbers are much smaller, accounting for just over 1
percent of total U.S. deaths in recent years.
Between 2010 and 2011, the total number of infant deaths for weeks 12
to 25 rose 1.80 percent (2,674 to 2,722), compared with a 8.37 percent
decline (2,520 to 2,309) in the prior 14-week period. This difference
was highly significant (p < 0.0002). In 8 of 14 weeks after
March 19, 2011, an increase occurred from the year before, compared
with just 4 of 14 weeks in the prior 14-week period. Some weeks had
relatively large increases and decreases, because the smaller number of
infant deaths is subject to greater variability.
The 10.17 percentage point difference between actual and expected
(+1.80% and –8.37%) means that 277 of the 2,722 infant deaths
(2,772 × 0.1017) are “excess.” Assuming
that 30,000 U.S. infant deaths will occur in 2011 (577 per week), this
means that 33.7 percent of deaths are reported (2,722/14 = 194, or
33.7% of 577). Dividing 277 by 33.7 percent yields a projected 822
excess infant deaths in the United States in the 14 weeks after March
19, 2011.
Individual Locations
Another means of analyzing trends in mortality is to study geographic
area. The CDC weekly report can be subdivided into either individual
cities or regions. It is difficult to offer an a priori hypothesis on
areas with the highest expected mortality increases after Fukushima
fallout arrived, since the EPA data on radioactivity levels are
limited. Moreover, voluntary reporting practices in a single city or
area are subject to change over time, potentially skewing trends. The
impact of such changes is less likely to affect patterns in a national
group of 122 cities,
since it is more likely that changes that increase or decrease deaths
would offset each other.
Deaths reported from U.S. cities with the largest populations and
complete reporting in weeks 12 to 25 (2010 and 2011) and from the 14
previous week periods are given in Table 4 (all deaths) and Table 5
(infant deaths). Of the eight most populated cities, Chicago and
Phoenix (3rd and 5th highest population) are omitted due to incomplete
data.
TABLE 3 - 5
For deaths of all
ages, the U.S. 2010–2011 change of +3.56 percent in the 14
weeks after mid-March was well above the +0.19 percent change for the
14-week period before mid-March. This difference between the two
changes of +3.37 percentage points was statistically significant at p
< 0.0001.
DISCUSSION
The
Fukushima meltdowns, and the introduction of radioactivity across the
globe, indicate that accurate measurements are needed on subsequent
changes in environmental radioactivity and in health status. In the
United States, there have been limitations in both measures.
Radioactivity samples in precipitation, air, water, and milk were
sporadically reported by the Environmental Protection Agency. Many
measurements failed to produce detectable levels, and on May 3, 2011,
the agency reverted to its policy of making only quarterly measurements.
Some elevated concentrations were found to be up to several hundred
times the norm soon after the arrival of the Fukushima fallout, but no
meaningful temporal trends and spatial patterns can be discerned from
these data.
Few
aggregate data on health status are available until several years after
a death or specific diagnosis. Immediately after Fukushima, the only
nationwide health status data available in the United States were
weekly deaths by age reported by 122 U.S. cities (about 25% to 35% of
all U.S. deaths), as reported by the Centers for Disease Control and
Prevention. In the 14 weeks after the Fukushima fallout arrived in the
United States, total deaths reported were
4.46 percent above the same period in 2010; in the 14 weeks before
Fukushima, the increase from the prior year was just 2.34 percent. The
gap in changes for infant deaths (+1.80% in the latter 14 weeks,
–8.37% for the earlier 14 weeks) was even larger. Estimated
“excess” deaths for the entire United States were
projected to be 13,983 total deaths and 822 infant deaths.
Patterns
of deaths among persons of all ages strongly reflect patterns among the
elderly, who account for over two-thirds of all deaths. For the older
population, explanations for excess deaths must be considered after
exposure to higher levels of radioactive fallout. If cancer in some
patients becomes active again, it may mean they already have cells
carrying all but one of the three to four requisite mutations to
express cancer. Exposure to radiation (or a toxic chemical) can provide
the one final mutation to reactivate a quiescent tumor (17). Also
vulnerable are those elderly with depressed immune status, made worse
by exposure to radiation.
The
CDC weekly mortality data have limitations. They represent only a 25 to
35 percent sample of all deaths, which may or may not accurately
represent the entire nation. Deaths are reported voluntarily and thus
are subject to variations from city to city and for unusual
circumstances in a week or period (e.g., totals during the Christmas
holiday season appear to be much lower). Weekly totals are sometimes
reported as unavailable and so cannot be used in any analysis.
The
deaths reported are by city of occurrence, whereas all final statistics
are by residence at time of death. Deaths are categorized when the
death certificate is filed, not necessarily the date of death. Finally,
the CDC weekly reports provide raw numbers of deaths, not the more
useful mortality rates, as populations or numbers of births are not
given.
Nonetheless, 25
to 35 percent of the United States is not a small sample, representing
all large cities and many smaller ones in all regions of the nation.
When extended periods are used, the numbers become larger and more
meaningful, because any variations increasing or decreasing death
counts are more likely to balance each other out. The total of 155,015
U.S. deaths in the 14-week period after Fukushima, 2,722 of which are
infant deaths, represents a large database that is meaningful in a
preliminary analysis of potential Fukushima effects. Not to use them
would mean a two- or three-year absence of any health status data,
until final figures are made public.
The statistically significant difference in increased number of
reported deaths (total and infant) for the 14-week period after
Fukushima has an added dimension because of similar findings for the
four months immediately after the Chernobyl meltdown in 1986, using a
10 percent sample of U.S. deaths. The post-Chernobyl increases, based
on preliminary death data, were roughly comparable to the increases
calculated from final death data (see Appendix Table 2).
The preliminary versus final 1985–1986 change for the period
May–August in total deaths was within 3.7 percentage points
(+6.0% vs. +2.3%), and the count of infant deaths was within 3.0
percentage points (+3.1% vs. +0.1%). Thus, it is unlikely that, for
Fukushima, final death counts would show results markedly different
from the finding that more Americans, especially infants, died than
expected in the 14-week period following arrival of the Fukushima
fallout.
The 14-week excess death projections after mid-March 2011 (13,983
total, 822 infant) are relatively similar to actual excesses in
May–August 1986 (16,573 total, 306 infant).
Recent
assessments have suggested that the amount of radioactivity released
from Fukushima equals or exceeds that released from Chernobyl. Given
the continuing emission of radioisotopes from the melted reactors, the
high density of population around the plant, and the close proximity to
food sources, we can expect that morbidity and mortality will be high
in Japan. The relative homogeneity of the Japanese population will
allow for comparison of health consequences for people living in areas
with lesser and greater levels of contamination, as has been done in
areas affected by Chernobyl (4).
Adverse health effects may also be expected in the United States, even
though exposures have been far below those in Japan. Low-dose radiation
exposure, previously assumed to be harmless, has been linked with
elevated disease rates in children born to women who underwent pelvic
X-rays while pregnant (18), Americans exposed to atomic bomb fallout
(19), nuclear plant workers (20), and, for leukemia, children exposed
to very low doses after Chernobyl (21). In addition to physical
diseases is loss of cognitive ability in adolescents following low-dose
ionizing radiation in utero (22).
The human fetus and infant are especially radiosensitive, given their
rapid cell growth and cell division, as well as their small size that
results in a proportionately larger dose. These exposures include
X-ray, alpha, beta, and gammaradiation. Depending on the time of in
utero radiation exposure, the result can be expressed as spontaneous
abortion, premature birth, low birth weight, stillbirth, infant death,
congenital malformations, and brain damage. While this report
concentrates on effects to humans, all life is sensitive to nuclear
radiation exposure, including plants, fungi, insects spiders, birds,
fish, and other animals (23). The best-studied group near Chernobyl
(birds) shows a 50 percent decrease in species richness and a 66
percent drop in abundance in the most contaminated areas, compared with
normal background in the same neighborhood (24).
More importantly, the findings reported here, plus the disease patterns
that developed after Chernobyl, indicate that public health personnel
can anticipate and plan to put in place diagnostic and treatment
procedures. Given the continued high levels of radioactive iodine, it
is predicted that the incidence of thyroid disease, including thyroid
insufficiency in newborns and thyroid cancer in children and adults,
will increase (4, 25).
The health effects of exposure to radioactivity from the Fukushima
meltdowns, both in Japan and around the world, will take a long time to
fully assess. The paucity of data from the U.S. EPA is unfortunate and
will hamper future studies. A quarter of a century after the Chernobyl
disaster, and more than 60 years after the bombings of Hiroshima and
Nagasaki, compilations of health casualties are still being updated. It
is critical that research should proceed with all due
haste, as answers are essential to early diagnosis and treatment for
exposed people, particularly children and the very young.
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