State health officials are testing large rainwater catchment systems this week on the Big Island, Maui and Kauai for radiation from Japan’s nuclear release, but re-emphasized that radiation in milk, rainwater and likely in locally grown produce remains minute.

Lynn Nakasone, administrator of the Health Department’s Environmental Health Services Division, said produce will not be tested, as other officials noted there is concern about creating a health scare and hurting local farmers.

"I know people are thinking, ‘Oh, a little bit (of radiation) here, a little bit there (adds up),’ " Nakasone said. "But think of it as calories. What if milk had 0.000004 calories and produce had 0.000003 calories and so on? So you add up all these little calories, but then you probably won’t get to even one calorie.

"(The radiation from Japan) is kind of like that. We’re talking about so minute amounts. Even if you took all the cumulative doses for everything, you are still way below any kind of action level and it’s not a health risk at all."

Nakasone spoke about Hawaii’s radiation levels yesterday during and after an "informational briefing" held by state Sen. Josh Green, chairman of the Senate Health Committee and a Big Island physician.

Green said a "profound" number of people have been asking about the radiation issue in Hawaii.

Two U.S. Food and Drug Administration officials from Maryland also participated via phone, and one, John Verbeten, said there is no concern about seafood caught across the Pacific and served in Hawaii.

"It’s a big ocean," Verbeten said, adding that radiation released from Japan’s Fukushima reactors will dissipate to a great extent.

However, all milk and milk products, vegetables and fruits produced from the four Japanese prefectures of Fukushima, Ibaraki, Tochigi and Gunma are being detained upon entry in the U.S. and are not being allowed to enter the food supply unless shown to be free from radionuclide contamination, the FDA said on its website.

Particulates with radiation are carried on the wind, fall in rain and gather in surface water and on food crops and grass eaten by dairy cows.

Testing showed that milk collected on April 4 from a dairy in Hilo had 43 pico­curies per liter for cesium-134 and 137 combined, and 18 picocuries for iodine-131. Another sample was taken by the U.S. Environmental Protection Agency Wednesday and the results are expected back later this week, Nakasone said.

The FDA’s "derived intervention level" — the point at which steps would be taken to safeguard the public — is 33,000 picocuries for the combined cesium isotopes and 4,700 picocuries for iodine-131. At those levels the sale of affected milk could be stopped.

Nakasone said yesterday that combining the three isotopes, it would be necessary to drink 1,000 liters of milk with the trace radiation amounts, or 4,000 cups, to get the equivalent of a less than 4-millirem dental X-ray.

The average person is exposed to about 620 millirems of radiation a year. According to the American Nuclear Society, a chest X-ray is 10 millirems and a six-hour flight in a jetliner results in an exposure of 3 millirems.

Health experts in Hawaii said 35,000 millirems is the lowest exposure of ionizing radiation that could lead to mild changes in the blood.

The Health Department said on its website that the highest radiation air sample reading in Hawaii from the Japanese nuclear crisis was from iodine-131 at a level of 1.4 picocuries per cubic meter on March 20.

"Minuscule" amounts of iodine-132, cesium-134 and -137, and tellurium-132 also were detected, but have since dropped to undetectable amounts, the department said.

Rainwater catchment testing at big collection systems was conducted yesterday and is expected to take place today at two locations on Hawaii island, one on Maui and one on Kauai, officials said.

The EPA’s "maximum contaminant level" for radiation in water is 3 picocuries per liter, which supposes a 70-year consumption of two liters per day at that level and translates to about 700 picocuries per liter a year, or about 4 millirems of radiation, health officials said.

Jeff Eckerd, acting program manager of the department’s indoor and radiological health branch, said that duration is not expected to be seen with the radiation decreasing in Hawaii.

Additionally, a lot of surface water catchment systems can have millions of gallons and water previously added to the system and can dilute even further small amounts of radiation, Eckerd said. Rainwater in Hawaii previously was found to have 2 picocuries per liter.

Eckerd said "it’s still a very serious situation in Japan," but what we’re seeing now in Hawaii "is the (radiation) levels in the air are dropping, so we should see some levels in water and other areas also decreasing significantly over time."