Radiation levels detected in Washington state from Japan’s tsunami-slammed Fukushima nuclear plant are fading, state and local health officials said this week.
In tests conducted in Washington state, officials said the measurable amount of radioactive Iodine-131 in sampled air specimens taken in Olympia peaked on March 18, and peaked in rainwater samples one week later.
Officials with the state Department of Health said trace levels of radiation found in Washington were “minuscule.” A very low trace level of I-131 was detected in an air sample from a Seattle-area monitor on March 20, but levels have sharply declined in recent tests.
State health officials also began testing rainwater after I-131 was detected in air samples. Officials said low levels detected in Seattle-area rainwater have steadily declined, and tests have confirmed there is not a health threat in the water.
Testing began after the earthquake-tsunami disaster last month in Japan, and the single “venting” of the containment vessels at the Fukushima plant on March 12. Experts said the half-life of radioactive iodine is eight days, so the amount of radiation from the venting at the Japanese nuclear plant will be undetectable in approximately 80 days, which would be by May 31.
No other releases are believed to have occurred that would lead to more contamination reaching the U.S., according to health officials.
Officials said detected levels of I-131 were a fraction of a percentage point of the level that would pose a public health concern for “a single point in time exposure” (that standard considers that the risk of drinking two liters of water daily for 70 years would increase the risk of cancer by one person in 1 million).
Dr. Roger Case, health officer for Island County, also noted the vast majority of Island County residents get their drinking water from wells or community and municipal water systems — none of which have been affected by the release of radiation in Japan.
The U.S. Environmental Protection Agency recently reported minuscule levels of radioactive iodine in one milk sample from the Spokane area, and a sample from the Tacoma area showed no detectable iodine.
