Published in Scientific Reports Nature May 15, 2014 -
A massive amount of radioactive materials has been released into the environment by the Fukushima Dai-ichi Nuclear Power Plant accident, but its biological impacts have rarely been examined. Here, we have quantitatively evaluated the relationship between the dose of ingested radioactive cesium and mortality and abnormality rates using the pale grass blue butterfly, Zizeeria maha. When larvae from Okinawa, which is likely the least polluted locality in Japan, were fed leaves collected from polluted localities, mortality and abnormality rates increased sharply at low doses in response to the ingested cesium dose. This dose-response relationship was best fitted by power function models, which indicated that the half lethal and abnormal doses were 1.9 and 0.76 Bq per larva, corresponding to 54,000 and 22,000 Bq per kilogram body weight, respectively. Both the retention of radioactive cesium in a pupa relative to the ingested dose throughout the larval stage and the accumulation of radioactive cesium in a pupa relative to the activity concentration in a diet were highest at the lowest level of cesium ingested. We conclude that the risk of ingesting a polluted diet is realistic, at least for this butterfly, and likely for certain other organisms living in the polluted area.[Diarist's emphasis]
Note that the LD50 level - the amount of internal contamination with cesium that will kill half [50%] of the test population of butterfly larvae - is just under 2 becquerels [disintegrations per second]. Also note that bioaccumulation of cesium in the larvae was highest at the lowest level of ingestion - this means that uptake of cesium, a potassium mimic in biological tissues, was highest in caterpillars consuming the least contaminated leaves. The implications of that do seem a bit alarming.
A previous field study had documented a decrease in the abundance of insects - particularly butterflies - in the contaminated region, while another documented a high incidence of morphological abnormality (mutations) in gall-forming aphids. This study quantifies physiological effects on a prevalent butterfly species in the polluted area, even to documenting how much cesium in the diet it takes to reach a 50% lethality level, and a 50% abnormality rate. The researchers conducted controlled experiments in the lab to reach their conclusions. From the Discussion section of the publication -
The relevance of our results to humans remains undetermined and will remain so because of the impossibility of controlled experiments [of this type] in humans. However, it should be noted that we sampled contaminated leaves from Fukushima City, which many people inhabit as though nothing had happened, and from Hirono Town, which some people returned to inhabit. Moreover, our results are consistent with the previous human results after the Chernobyl accident, in which infant mortality increased sharply in West Germany and in the United States. Gould and Sternglass (1989) speculated that the increased infant mortality rate immediately after the Chernobyl accident may have been caused by the ingestion of radioactive iodine. Although they used a logarithmic model rather than a power function model to fit their dose-response relationship, both models share a sharp non-linear increase at low doses. Implications of the half lethal and abnormal doses we obtained in the present study will impact future discussions on the effects of radioactive exposure on other organisms, including humans.[Diarist's emphasis]
In view of the heavy-handed push by pro-nuclear lobbyists, governmental lapdogs, vested industry interests and 'experts' from various academic and/or scientific disciplines to diminish or dismiss altogether public concerns about environmental contamination from the Daiichi disaster, this confirmation of dangers to biological life forms from chronic low-level exposures to radioactive contamination should help to remind people that such dangers did not magically disappear just because Fukushima made it perfectly clear that multiple meltdowns, exploding reactor plants and burning spent fuel pools can happen in the real world.
Meanwhile, back at the plant...
Record high radiation in seawater off Fukushima plant
[May 17, 2014]
Radiation has spiked to all-time highs at five monitoring points in waters adjacent to the crippled Fukushima No. 1 power station, plant operator Tokyo Electric Power Co. said Friday.[Diarist's emphasis]
The measurements follow similar highs detected in groundwater at the plant. Officials of Tepco, as the utility is known, said the cause of the seawater spike is unknown.
"Unknown," eh? Hardly. Tepco reported tritium readings from the in-port sampling stations at levels that went as high as 1,900 Bq per liter, along with 840 Bq/L of strontium-90. Which is known to cause bone cancer and is considered 100 times more dangerous than cesium. We have heard from various scientists monitoring the Pacific for cesium that strontium is not considered an issue because it is produced at only 50% the rate that cesium is produced by nuclear reactors. But the biological damage factor renders such assurances moot.
At two monitoring sites outside the port tritium levels were reported to be 8.7 and 4.3 Bq/L (the second site is 3 kilometers from the facility). Strontium levels were not reported for these sites, but at the ratio noted in the in-harbor measurements, strontium levels would exceed normal regulatory limits.
At any rate, Tepco ran out of temporary storage tank space to store contaminated groundwater awhile back, and is now setting up "a bypass system to prevent further buildup." This involves, in the utility's own words, simply letting the water leak into the Pacific as-is.
The utility also plans to start releasing the built-up tank water to the ocean by Wednesday of this week. These releases, we are informed, will be diluted so as not to exceed legal limits. What they might be diluting it with to achieve such low levels is not specified, but it can't be the grossly contaminated groundwater they're going to be "simply" pumping straight into the ocean.
All of these figures and assurances from Tepco and METI should be taken with a sizeable grain of salt, given that 'official' release figures from both the utility and the Japanese government have been so regularly found to be low by several factors of ten that it's entirely reasonable to multiply by 10 or 100 routinely, and sometimes by 100.
Bottom line here is that there's really nothing that Japan can or will do - even with the help of the entire nuclear world - to stop the constant releases of deadly radionuclides from their destroyed reactors at Fukushima. The best anyone could hope for was that airborne releases and new fission product releases would diminish over the first year or two, and they did. Once the corium flows reached the leaky groundwater flooded basements/earth, waterborne releases became the primary concern. They have been attempting for nearly two and a half years to minimize those, but have now reached the limits of their delaying tactics and the bulk must be released to the Pacific. These will continue essentially forever, and be most dangerous to organic life for several hundred years. What might be doable to diminish that damage is not what anybody has seriously suggested BE done, and not what anybody's going to do. Over the centuries and millennia to come the bulk of nuclear garbage produced at Daiichi will get out, the webs of life on planet earth will have to live (and/or die) with it.
How many more Fukushimas will humanity have to suffer before putting an end to this Worse-than-Sith technology? Which we all know by now is 'good' for only two things: 1. Mass Death & Destruction, and 2. Boiling Water (plus Mass Death & Destruction).