RADIATION: RADIOACTIVE ISOTOPES IN DRINKING WATER AND FOOD

 Facts and Information about Radiation Exposure The Energy Collective,

Willem Post   19 March 2011“……Airborne radioactive isotopes from the Chernobyl and Fukushima Nuclear Power Plant fires were spread by the weather and have entered the soil, water, and the fauna and flora. The isotopes are most harmful if they enter the human body through inhalation, ingestion or open wounds.

The isotopes of greatest concern for drinking water and food (including seafood and kelp) are:

tritium: half-life 12.3 years, 0.018 MeV beta emitter, does not collect in body, is eliminated with urine.*

strontium-90: half-life 29 years, 0.546 MeV gamma-ray emitter, collects in bones and teeth

iodine-131: half-life 8.1 days, 0.4 MeV beta and 0.4 MeV gamma-ray emitter, collects in thyroid

cesium-137: half-life 30.2 years, 0.3 MeV beta and 0.66 MeV gamma-ray emitter, collects in fleshy tissue, such as kidneys

radium-226: half-life 1,620 years, 4.9 MeV alpha emitter, collects in bones, liver, breast; a major source is flyash from coal plants

** Tritium has a biological half-life of about 10 days due to taking in and eliminating of water. The radiation fraction in the body of an ingested dose = biological half-life/isotope half-life = 10 days/ (365 days/yr x 12.3 years) = 0.0022. Tritium is a least dangerous isotope.

Grazing cows concentrate iodine-131 in their milk, causing milk consumers, such as infants, to be excessively exposed, and concentrate cesium-137 in their flesh. Pregnant women, nursing mothers, fetuses and young children face the greatest danger from iodine-131, because it accumulates in the thyroid.

Children are at much higher risk than adults because they are growing, and their thyroid glands are more active and in need of iodine. The gland is smaller in children than in adults, so a given dose of iodine-131 will deliver a higher dose of radiation to a child’s thyroid and potentially do more harm.

According to the Centers for Disease Control and Prevention, if an adult and a newborn ingest the same dose of radioactive iodine, the thyroid dose will be 16 times higher to a newborn than to an adult; for a less than 1-year-old, eight times the adult dose; for a 5-year-old, four times the adult dose.

Pregnant women take up more iodine-131 in the thyroid, especially in the first trimester. The iodine crosses the placenta and reaches the fetus; its thyroid takes up more iodine as pregnancy progresses. During the first week after birth a baby’s thyroid activity increases up to fourfold and stays at that level for a few days, so newborns are especially vulnerable.

Potassium iodide can protect the thyroid by saturating it with normal iodine. People in Japan have been advised to take it.

 

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