Off to the beach!
Details about Strontium-90 further below. Five-days old news, but thought I’d mention it anyhow, by way of Korean Global TV news agency ‘Arirang’ (May 10, 2011): http://www.arirang.co.kr/News/News_View.asp?nseq=115777&code=Ne8&category=1
Click on the image to watch or read the news report:
Aren’t we lucky the FDA still refuses to test fish caught off Alaska? (they have not changed their stance their insane announcement in April), or the EPA’s decision to quickly go back to only testing every 3 months in a few isolated spots (see halfway down my May 13 blogpost, here).
Not that the concentrations in the water are a concern on the coast of North America or beyond (they ARE off the coast of Japan), but the effects of bioaccumulation and biomagnification can concentrate these thousands of times.
Bioaccumulation refers to an increase in concentration of a pollutant from the environment to the first organism in a food chain, biomagnification refers to an increase in concentration of a pollutant from one link in the food chain to another (such as plankton to fish, fish to larger fish, larger fish to humans, with the concentrations of radionuclide concentrations increasing with each step, similar to what has been observed for mercury and some pesticides).
Makes me wonder if these bureaucrats live on a planet where water doesn’t move in ocean currents around the world…? Last time I checked the oceans were still liquid… [SOURCE: http://enochthered.wordpress.com/2008/03/17/bioconcentration-and-biomagnification-of-radionuclides-of-biochemically-significant-elements/]
About 8% of the ingested Sr-90 remains in the body after 30 days. About 4% remains after 1 year. Sr-90 is most commonly ingested by eating contaminated foods and water, especially from ground water, milk, and above-ground vegetables exposed to radioactive fallout. It is especially efficient at adhering to soil particles. Children under 1 year of age are especially susceptible to Sr-90.
US EPA Limits of Radioactive Isotopes:
EPA has established a maximum contaminant level of 4 millirem per year for beta particle and photon radioactivity from man-made radionuclide’s in drinking water.
Iodine-131 = 3piC/L (0.11 Bq/L)
Cesium-137 = 200 picocuries per liter (7.41 Bq/L)
Stronium-90 = 8 picocuries per liter. (0.30 Bq/L)
Technetium-99 = 900 picocuries per liter (33.3 Bq/L)
Tritium = 20,000 picocuries per liter (741 Bq/L)
Uranium-238 = 30 µg/L (micrograms/liter)
Iodine-129 = 3 picocuries per liter (0.11 Bq/L)
Milk = 170 Bq/kg (of iodine-131)
*All except Iodine-131 found here: http://www.ecy.wa.gov/programs/nwp/gwcontaminants.htm
Iodine-131 and milk/food max statistic found here:
FDA has set a Derived Intervention Level (DIL) for Iodine-131 of 170 Bq/kg in foods prepared for consumption.
Derived Intervention Levels for consumption or export:
Iodine-131 = 170 Bq/kg
Cesium-137 = 1200 Bq/kg (also Cesium-134)
Plutonium = 2 Bq/kg (includes Plutonium-238 + Plutonium-239 + Americium-241)
Stronium-90 = 160 Bq/kg
Ruthenium-103 &106 = (C3 / 6800) + (C6 / 450) < 1
Bold data sourced from: http://fukushimafaq.wikispaces.com/Radiation+Allowable+Levels
[Edit note: this link above replaced a broken one and outdated data, replacement inserted on Dec 26, 2013; rest remains unchanged.]
Together with caesium isotopes 134Cs, 137Cs, and iodine isotope 131, strontium-90 was among the most important isotopes regarding health impacts after the Chernobyl disaster. The health effects depend on how a particular isotope is taken up in the body, what form the release of its decay energy takes, and what is the residence time of the isotope within the body. Isotopes can decay by releasing alpha, beta or gamma radiation. Alpha radiation is composed of helium nuclei (2 protons and 2 neutrons). These are large and energetic and therefore potentially very damaging), but do not penetrate far. Beta radiation is composed of fast moving electrons, and gamma radiation is composed of photons (light particles). Beta and gamma radiation penetrate to a much greater extent.
The radioactive material of most concern in the initial stages of a nuclear accident is iodine 131, a major fission product which was responsible for the majority of health effects seen so far in the Chernobyl area. Iodine 131 has a half life of only 8 days, so it is of most concern early on. It is taken up by the thyroid gland where it can be retained (especially in young children), greatly raising the risk of thyroid cancer. Other isotopes of concern include Cesium 137, with a half life of 30 years, and strontium 90, with a half life of 29 years. Unlike iodine 131, both of these isotopes stay in a contaminated area for hundreds of years. Cesium 137 is taken up by the body in place of potassium, while strontium 90 is taken up in place of calcium. Cesium accumulates primarily in muscles and organs, while strontium accumulates in bones. At Chernobyl, cesium 137 appears to have represented a much larger health risk than strontium 90. Strontium-90 is a “bone seeker” that exhibits biochemical behavior similar to calcium. After entering the organism, most often by ingestion with contaminated food or water, about 70–80% of the dose gets excreted. Virtually all remaining strontium-90 is deposited in bones and bone marrow, with the remaining 1% remaining in blood and soft tissues. Its presence in bones can cause bone cancer, cancer of nearby tissues, and leukemia. (SOURCE: http://www.bibliotecapleyades.net/ciencia/ciencia_uranium33.htm + Wikipedia)
Not to be confused with the 50-day-half-life radionuclide Strontium-89, which has been detected in Hawaii milk. More on that, as well as the difference between EPA and FDA maximum levels, in this April 27/28, 2011 article: http://blogs.forbes.com/jeffmcmahon/2011/04/27/radioactive-strontium-found-in-hilo-hawaii-milk/