Japan’s radioactive seafood problem

Given the dose factors of 10-25 nSv/Bq (*), even in the most pessimistic case (highest contamination & dose factor), you'd need to eat more than 4...

Given the dose factors of 10-25 nSv/Bq (*), even in the most pessimistic case (highest contamination & dose factor), you'd need to eat more than 400 kg of the stuff in one year to reach the (very conservative) 1 mSv limit. That's quite a lot of seafood, even by Japanese standards! Over such a large amount of food, you're going to expect (from your results) max. around 20 Bq/kg, so the "safe limit" is now 2 tons... Come on!

(*)
http://www.fda.gov/Food/FoodSafety/FoodContaminantsAdulteration/ChemicalContaminants/Radionuclides/ucm078341.htm
http://www.irsn.fr/EN/Research/publications-documentation/radionuclides-sheets/Documents/CS137SAN.pdf

Hi Zamm, unfortunately it's not a simple as that. Any exposure heightens the risk of developing cancer, ingestion of radiation is more harmful than ex...

Hi Zamm, unfortunately it's not a simple as that. Any exposure heightens the risk of developing cancer, ingestion of radiation is more harmful than external environmental exposure, and seafood is just one of the many exposure risks faced by the public. As there is not enough contamination monitoring (environmental and food) happening, there is no reliable way of determining cumulative exposure risks for the public, and without labelling showing food contamination levels, there is no way for the public to make informed decisions about the food they eat.

Dear GregM,

Sieverts is a biological unit that already takes into account the internal/external difference, through the 'dose conversion factors'. These are obviously different for each element (average residence time in the body & radiation type) and exposure (external irradiation / inhalation / ingestion), which yields ca. 13 (adult) and 25 (infant) nSv/Bq for ingested Cs-137. If one assumes a rather high 50 kg/year ingestion of seafood at 20 Bq/kg for an adult, you get 13 µSv, which roughly corresponds to typ. 2-3 h of long-distance flying and to ca. 0.5% of a typical 2.5 mSv natural dose. So why should one label such food when you don't see radiation warnings on your airplane ticket?
Likewise, you don't label the water you drink, the food you eat, the natural gas you use for indoor cooking or the construction materials you use to build your home, all potentially larger natural sources of radiation than 'contaminated' Japanese seafood - you simply set conservative "no worry" limits.
Finally, your data vs. your previous results shows this already very low contamination is falling quite fast owing to dilution. If at all, people should worry more about contaminated farmland, which, according to Tchernobyl experience, can be a real long-term problem if no remediation is done.

Exposure data (1 pCi = 0.037 Bq, flight: 1 Gy ≈ 1 Sv):
http://www.physics.isu.edu/radinf/natural.htm
http://www.hpa.org.uk/webc/HPAwebFile/HPAweb_C/1194947389360

Your previous (August) results:
http://www.greenpeace.org/japan/Global/japan/pdf/110809GP_MarineResearch_Data.pdf

Allowed in Japan: 500 Bequerel per Kg. Dangerous to health: 20 Bequerel per Kg. Cesium directly harms the hearts of our children: http://chernoby...

Allowed in Japan: 500 Bequerel per Kg. Dangerous to health: 20 Bequerel per Kg. Cesium directly harms the hearts of our children: http://chernobyl-today.org/images/stories/Bandajevski_2001_Radiocaesium_and_heart.pdf
Cesium-137 in relatively small doses (20-30 Bq/kg); a breach of the regulatory processes in the body: PAGE 2 – 3:http://chernobyl-today.org/images/stories/BANDAJEVSKI_UNSCEAR_-_REUTERS_Sept_22nd_2010_Eng_V2.pdf

internal becomes radiation 8,760hrs/year. you can't walk away from exposure when it's inside of you, and there is no eliminating all contaminants once inside your body!

When the Chernobyl disaster happened we were living in Germany and were told to avoid anything over 10 Bequerel/kg if possible. It seems t me that co...

When the Chernobyl disaster happened we were living in Germany and were told to avoid anything over 10 Bequerel/kg if possible. It seems t me that countries just raise the limits to suit the disaster. That is not public protection! It was acknowledged that any amount of radiation, no matter how small, can pass through a cell and damage its DNA sufficiently to turn it into a cancer cell. Damaged DNA replicates itself and causes increasing problems down through the generations. Radioactivity accumulates and concentrates over time in the environment, the food chain and of course, in our bodies. We cannot do anything about natural background radiation, but the best way to protect our health is to avoid adding any man-made radiation source wherever possible.

You can't focus on seafood intake only and pretend everything else is not contaminated. To get an idea, you need to consider what happens if all t...

You can't focus on seafood intake only and pretend everything else is not contaminated. To get an idea, you need to consider what happens if all the food you eat is contaminated like seafood: in this case 400 kg/year is an underestimation.
Also, greenpeace reports up to 80 Bq/kg for Cs, but how about other isotopes? Furthermore, some of the isotopes will never leave your body after they get into it, so your internal expodure increases every year.