The U.S. Environmental Protection Agency announced on Tuesday that trace amounts of radiation from Japanese nuclear reactors continue to be found in West Coast monitors.
Results from RadNet filters in San Francisco, Anaheim, Riverside, and Seattle show three new types of radioactive isotopes previously unreported to the public. They include Cesium-137, Tellurium-132, Iodine-132, and Iodine-131. High exposure to some of these isotopes is dangerous to human health.
Cesium-137 is a known carcinogen and is a byproduct of nuclear fission with a half life of 30 years, making it one of the more long-lasting isotopes released. Tellurium-132 was responsible for a large part of the dose that impacted Chernobyl workers in the first week, while Iodine was thought to be the cause of a spike in thyroid cancers among children living near the Russian reactor. Iodine-131 is considered dangerous at low doses, which causes mutations, than high doses, which kills cells, and is therefore used in medical treatment to aggressively attack cancer cells.
Late Friday, the EPA announced that Xenon-137 had been found at a Sacramento monitoring site, the agency’s first public announcement that radioactive material from the Japanese nuclear incidents was reaching U.S. shores.
The agency has been careful to stress that the levels of the radioactive isotopes detected do not present cause for concern. But up until the latest press release, the EPA has not provided any data to back up its claims. Tuesday’s press release gave the results in picocuries per meter cubed, a standard of measurement that the U.S. government uses to estimate the portion of radioactivity in all the atoms that make up cubic meter of air space (a picocurie is one-trillionth of a curie).
A single person carries about 120,000 picocuries of radioactivity in our bodies quite naturally from the surrounding environment. The levels the EPA announced for San Francisco were 0.0013 picocuries/meter^3 of Cesium-137, 0.0075 of Tellurium, 0.0066 of Iodine-132, and 0.068 of Iodine-131.
The press release states:
“In a typical day, Americans receive doses of radiation from natural sources like rocks, bricks and the sun that are about 100,000 times higher than what we have detected coming from Japan. For example, the levels we’re seeing coming from Japan are 100,000 times lower than what you get from taking a roundtrip international flight.”
Updated information on San Francisco levels can be found here, while data for the rest of the West Coast and Hawaii is available here.