A recent abstract published in Geophysical Research Abstracts indicates that Iodine-131 and radiocesium levels in Hawaii were NOT NEGLIGIBLE:
Geophysical Research Abstracts Vol. 18, EGU2016-10453, 2016 EGU General Assembly 2016 © Author(s) 2016. CC Attribution 3.0 License. Quantifying Atmospheric Fallout of Fukushima-derived Radioactive Isotopes in the Hawaiian Islands http://meetingorganizer.copernicus.org/EGU2016/EGU2016-10453.pdf
Trista McKenzie (1) and Henrietta Dulai (2) (1) Geology and Geophysics, University of Hawaii at Manoa, Honolulu, United States (firstname.lastname@example.org), (2) Geology and Geophysics, University of Hawaii at Manoa, Honolulu, United States (email@example.com)What risks to the food supply and the environment are posed by Cesium-137 levels up to 69.9 Bq/m2 and Iodine-131 levels up up to 445.8 Bq/m2?
We found that Fukushima-derived cesium was present in both mushrooms and soil and the soil inventories ranged 2.2-60.9 Bq/m2 for Cs-137 and 16.1-445.8 Bq/m^2 for I131. Additionally, we found that Fukushima-derived cesium inventories in soils were correlated with precipitation gradients.
What other radionuclides were present and not measured? For example, how much Iodine-133 was present? How much Strontium-89? Were these isotopes measured at all?
What were total contamination levels for all radionuclides desposited?
None of those questions are answered as readers are assured that levels were below depositions from atmospheric testing.
However, radioisotopes in soil no doubt concentrated in plants and animals living in contaminated arenas. In 1962, Harold Knapp described how radioiodine from a single deposition in pasture-land bioaccumulates and biomagnifies, producing substantial and injurious radiation doses for children consuming milk:
S. Kirsch (2004) ‘Harold Knapp and the Geography of Normal Controversy: Radioiodine in the Historical Environment’, Osiris, 19, 167-181.What levels of iodine-131 were found in cows' milk in those areas measuring up to 445.8 Bq/m2?
I cannot answer these questions but I find the selective and delayed news coverage disturbing.
Below find a background discussion of EPA and FDA intervention levels derived from a very instructive article written by Jeff McMahon in 2011. Please note that the EPA is using a different measurement (picocuries) than the FDA (becquerels):
Jeff McMahon’s April 14, 2011 blogpost “Why Does FDA Tolerate More Radiation Than EPA?” for Forbes Magazine provides an instructive comparison of variability in protective guidelines across the EPA and FDA during the Fukushima crisis.[i] McMahon observes that the EPA’s protective standards for radioiodine and radiocesium in drinking water are much lower than the FDA’s protective standards for these radionuclides:
EPA does not allow drinking water to contain more than 3 picoCuries per liter of Iodine-131 and 200 pCi/l of Cesium-137.
FDA allows up to 4,700 picoCuries of Iodine-131 in a liter of milk and up to 33,000 picoCuries of Cesium-137.
McMahon explains the discrepancy as stemming from each agency’s temporal timeline: the “EPA assumes long-term exposure over 70 years. FDA assumes you’re encountering the radiation all at once.” McMahon also notes:
The EPA’s level is calculated so that in a population of one million people, the radiation will result in no more than one additional cancer fatality.
The FDA standard, on the other hand, accepts two extra cancer fatalities in a population of 10,000.
Indeed, the FDA’s Specific Derived Intervention levels illustrate tolerance for relatively high levels of radionuclides in food:
The specific Derived Intervention Levels are here: http://www.fda.gov/downloads/newsevents/publichealthfocus/ucm250779.pdf
The specific “FDA derived intervention level or criterion for each radionuclide group” are as follows “for all components of the diet” for Strontium 90, Iodine 131 and Plutonium 238 and 239
Sr-90 160 Bq/kg
I-131 170 Bq/kg
Cs-134 + 137 1200 Bq/kg
Pu-238 + Pus 239 + Am 241 is 2 Bq/kg
These guidelines state that the “alternate units for milk” in picocuries per liter are the following:
Cs-134 + Cs-137 33,000
The FDA treats each radionuclilde independently when creating derived intervention levels:
The DIL for each radionuclide group is applied independently (see discussion in Appendix D). Each DIL applies to the sum of the concentrations of the radionuclides in the group at the time of measurement…
From this model we can presume that drinking daily levels of milk containing 4399 picocuries per liter in Strontium-90, 4699 picocuries per liter in Iodine-131 and 32,999 picocuries per liter constitutes an acceptable level of risk for the FDA.
[i] Jeff McMahon (2011, April 14) “Why Does FDA Tolerate More Radiation Than EPA? Forbes Magazine, http://www.forbes.com/sites/jeffmcmahon/2011/04/14/why-does-fda-tolerate-more-radiation-than-epa/