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Joseph J. Mangano MPH MBA, Radiation and Public Health Project, June 7, 2011

Purpose.  This report will present and analyze data on radioactivity levels in the U.S. from the Fukushima nuclear meltdowns, and any changes in health status since this radioactivity entered the U.S. environment and diet.

Background.  On March 11, 2011, a powerful earthquake and tsunami caused the Fukushima nuclear plant, with six reactors, to lose cooling water (from loss of electricity).  Three reactor cores and two waste pools suffered meltdowns.  Explosions caused breaches in containment buildings, and high levels of radioactivity entered the environment.  The radioactive plume moved east, reaching the West Coast on March 17.

Japanese radioactivity in the U.S. is being ingested by Americans through breathing and the food chain.  This phenomenon has occurred previously, such as above-ground nuclear weapons tests and the 1986 Chernobyl meltdown.

This report examines changes in environmental radiation levels in the U.S., along with changes in health status, since the arrival of the plume in March.

EPA System of Measuring Environmental Radiation.  The federal government has monitored levels of environmental radioactivity since 1957, during the time of above-ground nuclear weapons testing.  Originally managed by the U.S. Public Health Service, this task has been assigned to the U.S. Environmental Protection Agency since 1975.

The EPA makes periodic measurements of radioactivity concentrations in air, precipitation, water, and milk.  It operates a system known as RADNET, which includes 124 stations in the continental U.S., Alaska, Hawaii, Saipan, and Guam.

Historical data beginning in 1978 are available on the EPA web site, and earlier data are also available in hard copy format.  After Fukushima, the EPA increased the frequency of their measurements, and on April 5, made 2011 data available in interactive format.  However, on May 3 the Agency reverted to its normal schedule of quarterly measurements, claiming recent samples could detect no radioactivity.

For March and April 2011, the EPA has made available online hundreds of radioactivity measurements (Table 1).  All individual readings can be accessed by visiting www.epa.gov/japan2011/rert/radnet-sampling-data.html#precip.  

Table 1
March-April 2011 EPA Measurements of Radioactivity




Drinking Water

Air (Filter)  

Air (Cartridge)

Number of Sites












Number of Samples












Samples with Detectable Iodine-131












The EPA made measurements of 10 radioactive chemicals only produced in atomic bomb explosions and nuclear reactor operations.  The vast majority of measurements did not detect radiation, and were marked “ND” (not detectable).  The one exception to this general inability to detect radiation was Iodine-131 (I-131).  This chemical has a short half-life (8 days), which means it originated from a current source – most likely a nuclear reactor.  It is not clear why the EPA detects I-131 more easily than other chemicals.

I-131, like all forms of radioactive iodine, attacks the thyroid gland after ingestion.  It can cause cancer and other disorders of the thyroid, which plays a key role in physical and mental development, especially in the fetus and infant.

The greatest number of detectable I-131 samples are in air (cartridge method), air (filter method), and precipitation, with 105, 72, and 77, respectively.  Unfortunately, the air cartridge samples cover 12 sites, only 4 in the continental U.S., limiting a national analysis.  Air filter samples include 13 sites in the continental U.S., just 6 outside California and Florida.  Precipitation has the greatest geographic spread of measurements and will be analyzed as a rough proxy for U.S. levels of radioactivity from Japan.

Patterns of Iodine-131 in Precipitation.  Historical EPA data shows the typical level of I-131 in U.S. precipitation is about 2 picocuries of I-131 per liter of water (pCi/l).  This number was determined by measurements at 9 U.S. sites on May 1-3, 1986, just before the plume from the Chernobyl accident arrived over the nation.  A picocurie is a measure of radioactivity, and is one-trillionth of a curie.

After Fukushima, from March 22-25, samples of I-131 in precipitation at 12 U.S. sites had an average (median) level of 39.6 pCi/l, or about 20 times greater than normal.  This figure was roughly half of 1) the peak level after Chernobyl and 2) after a large above-ground atomic bomb test by China in late September 1976 (Table 2):

Table 2
Historical EPA Measurements of I-131 in Precipitation

Event                           Dates               No. of Sites   No. of Samples   Median I-131
Large Chinese           10/  4/76-                     11                    26                   75.5
Bomb test               11/  2/76

Prior to Chernobyl       5/  1/86-                       7                      9                     2.0
(“normal”)                 5/  3/86

Chernobyl peak          5/14/86-                     36                     45                    99.5

Chernobyl end           5/27/86-                     18                     20                    25.5

Fukushima peak         3/22/11-                     22                     37                    44.5

Concentrations of I-131 in 77 EPA measurements in precipitation with a detectable level varied greatly.  Some were quite small, while others were much greater than normal, approximating or exceeding 100 times the normal concentration.  Table 3 lists the 10 highest individual U.S. levels of I-131 in March and April.

Table 3
Iodine-131 in Precipitation, Highest Levels in U.S., March/April 2011

Location                                  Date                I-131 Level
*   1. Boise ID                       March 22              390
*   2. Boise ID                       March 22              242
     3. Kansas City KS              March 29              200
     4. Salt Lake City UT          March 28              190
     5. Jacksonville FL              March 31              150
*   6. Richmond CA                March 22              138
*   7. Richmond CA                March 22              138
*   8. Olympia WA                 March 24              125
     9. Boston MA                   March 22               92
* 10. Portland OR                  March 25               86.8

* Located in the Pacific Northwest

Of the 10 highest samples, 6 were from stations in the Pacific Northwest, including northern California, Idaho, Oregon, and Washington.  A seventh, Salt Lake City, is not technically part of the Pacific Northwest, but is relatively close to the region.  Thus, it is prudent to conclude that this region received the greatest amount of fallout from Fukushima, and thus any changes in health status that might be linked to the Japanese meltdowns would occur there.

Trends in Infant Deaths in the Pacific Northwest.  The U.S. Centers for Disease Control and Prevention (CDC) has published the Morbidity and Mortality Weekly Report (MMWR) for decades.   Since 1993, each edition of the MMWR includes deaths by age group for each of 122 U.S. cities with a population of over 100,000.  The MMWR is available at http://www.cdc.gov/mmwr/mmwr_wk/wk_cvol.html.

The MMWR report on deaths has certain limits.  It only represents 30% of all U.S. deaths.  It lists deaths by place of occurrence, while final statistics are place of residence.  It also represents deaths by week a report is filed to the local health department, rather than date of death.  Finally, some cities do not submit reports for all weeks.

Despite these limits, patterns of deaths reported in the MMWR are often consistent with final statistics, if a large enough group of cities and/or long enough time period are used.  Final data for 2011 deaths are released in 2013 or 2014, and are only available for full years.  Thus, MMWR data are helpful to make before-and-after comparisons in a year.

One age category used by the MMWR is under age one (infants).  This is the most likely group to detect any link with Japanese fallout.  All humans are affected by radiation exposure, but the fetus and infant are much more susceptible, because of their rapid growth and cell division.  Damaging a fetal or infant cell makes it more likely that the cell with divide into more damaged cells before it can repair itself, as opposed to a slower-dividing adult cell.  Damaging a cell’s DNA code, as radiation does, makes it more likely that a baby will be stillborn, die in infancy, be born prematurely/at low weight, or be born with a birth defect.

There is a precedent for radioactivity linked with higher infant deaths.  On May 5, 1986, fallout from Chernobyl reached the U.S., just 9 days after the meltdown.  EPA measurements of I-131 in U.S. milk showed that from mid-May to late June, average concentrations were 5-6 times greater than in the same period in 1985.  Several years later, a journal article presented official CDC data showing the U.S. infant death rate rose in the four months after Chernobyl compared to a year earlier (+0.43%, compared to a decline of -4.22% for the other 8 months, an excess of 593 deaths).  CDC data confirm the magnitude of this four month “bump” was unprecedented, suggesting Chernobyl fallout may have contributed to higher infant death rates in the summer of 1986 (Table 4).

Table 4
Changes in Infant Death Rates, U.S., 1985-1986

                                    Deaths < 1 Yr             Rate/1000 Births         % Change
Date                            1985    1986                1985    1986                In Rate           
May-August                12788   12800                 9.85     9.90                + 0.43                    
Other 8 Mos.              27242   26091               11.04   10.58                 -  4.22

Note: Chernobyl fallout arrived in the U.S. environment on May 5, 1986.  Excess Deaths = [0.43 – (-4.22) ] x 12,800 = 593.  Source: Gould JM and Sternglass EJ.  Low-level radiation and mortality.  CHEMTECH, Jan. 1989, 18-21.

The MMWR 2011 data show that in the four weeks immediately preceding the arrival of Japanese fallout, an average of 181.5 infant deaths were reported (in 111 cities with full reporting for each week).  For the 10 weeks following, the number increased to 185.6 deaths per week, a 2.3% increase, which is not statistically significant (Table 5).

Table 5
Infant Deaths, 111 U.S. Cities, By Week, 2011

Week Ending              Infant Deaths
2/26/11                        173
3/  5/11                        189
3/12/11                        164
3/19/11                        200
                                                            Number /average 4 weeks       726 (181.5)
3/26/11                        182
4/  2/11                        200
4/  9/11                        187
4/16/11                        154
4/23/11                        167
4/30/11                        190
5/  7/11                        183
5/14/11                        200
5/21/11                        212
5/28/11                        181
                                                            Number /average 10 weeks     1856 (185.6)
% Change in Average                         +2.3%

Note: Includes all 122 U.S. cities in the MMWR, except for those with at least one week missing data (San Francisco, Duluth, Minneapolis, St. Paul, Columbus, Fort Worth, Paterson, New Orleans, Phoenix, Worcester, Tucson).

The MMWR includes 8 cities in the Pacific Northwest, namely Boise ID, Portland OR, Seattle WA, Berkeley CA, Sacramento CA, Santa Cruz CA, San Francisco CA, and San Jose CA.  Weekly reported infant deaths in the four weeks immediately preceding the arrival of Japanese fallout and the 10 weeks following are given in Table 6.

Table 6
Infant Deaths, 8 Pacific Northwest Cities, By Week, 2011

Week               Infant Deaths (Deaths < 1 Year)                                                                   
Ending                Boise   Portland    Seattle    Berk    Sacra     S. Cruz   S. Fran     S. Jose   Total
2/26/11                2           0              3           0        2              0          4          0           11
3/  5/11                0           4              1           0        1              0          0          3            9  
3/12/11                0           1              2           0        2              0          1          2            8
3/19/11                0           0              2           1        2              0          2          2            9

3/26/11                1           2              6           1        2              0          2           2          16
4/  2/11                0           0              3           0        1              1          ---          1           6  
4/  9/11                1           0              0           0        2              1          1           1           6
4/16/11                0           1              2           1        5              0          0           2          11
4/23/11                0           0              4           0        1              0          2           4          11
4/30/11                0           3              5           0        4              0          1           5          18
5/  7/11                1           0              2           1        4              0          3           7          18
5/14/11                2           2              3           0        3              0          2           1          13
5/21/11                2           1              2           2        5              0          1           2          15
5/28/11                0           2              0           0        1              0          3           5          11

  4 Weeks Before Japan Fallout          Total (Average) Weekly Deaths           37 (  9.25)
10 Weeks After Japan Fallout            Total (Average) Weekly Deaths         125 (12.50)
% Change in Average                                                       +35.1%  (p<.09)

Note: No data reported for San Francisco, week ending April 2

The average weekly infant deaths for the 8 cities rose sharply from 9.25 to 12.50, a jump of 35.1%.  Because a large number of deaths are involved (37 and 125 in the two periods), the change approaches statistical significance at p<.09 (p<.05 is significant).

A review of MMWR data shows that the average weekly number of deaths for all other age groups in the Pacific Northwest (and the U.S.) changed little in the periods before and after the arrival of Japanese fallout.

Discussion.  The EPA increased the frequency of monitoring environmental radioactivity in the U.S. after the meltdowns at Fukushima.  The Agency documented higher concentrations in the U.S., especially in late March.  However, most measurements of chemicals other than I-131 did not detect radioactivity, and after observing declining levels, the EPA decided to resume its normal schedule of quarterly measurements.

Despite these limitations, it appears that the Pacific Northwest received the most Japanese fallout in the U.S.  While these levels are much lower than near the Fukushima plant, it is still important to review health status data for unusual patterns.

The MMWR is useful for examining very recent mortality data in cities across the nation.  A comparison of infant deaths during the four weeks prior to the arrival of Japanese fallout and the 10 weeks following showed a 35.1% rise in 8 Pacific Northwest cities.

The data suggest that the following steps be taken to enhance the research:

1. Review independent measures of U.S. radioactivity to confirm EPA data are consistent

2. Review changes in environmental radioactivity and infant deaths in Japan, as high radioactivity levels and rising infant deaths would be expected

3. Continue to monitor infant deaths in the Pacific Northwest and the U.S., using MMWR

4. Request data from state/local health departments on infant health, even if incomplete

Finally, the data should be shared with the appropriate regulators, namely the U.S. Nuclear Regulatory Commission, the EPA, and state radiation protection bureaus.  Information suggesting that relatively low exposures to radiation from nuclear reactors are linked with infant health problems should be part of the regulatory process.



1. Environmental Protection Agency, Office of Radiation Programs.  Environmental Radiation Data.  Montgomery AL: Eastern Environmental Radiation Facility.  Report 8, April 1977 (hard copy reports with radioactivity in precipitation after China bomb test), and Report 46, September 1986 (radioactivity in precipitation after Chernobyl).

2. Environmental Protection Agency.  RadNet, formerly Environmental Radiation Ambient Monitoring System.  http://oaspub.epa.gov/enviro/erams_query.simple_query (radioactivity in air, precipitation, water, and milk, beginning 1978).

3. Environmental Protection Agency. www.epa.gov/japan2011/rert/radnet-sampling-data.html#precip (radioactivity in air, precipitation, water, and milk for March/April 2011).

4.  U.S. Centers for Disease Control and Prevention.  Morbidity and Mortality Weekly Report. http://www.cdc.gov/mmwr/mmwr_wk/wk_cvol.html (weekly deaths by age for 122 U.S. cities).