BRATTLEBORO – A Connecticut River fish caught four miles upstream from the Vermont Yankee nuclear reactor this winter tested positive for low levels of strontium-90, a highly dangerous radioactive isotope recently confirmed in soil outside the plant.

But the Department of Health said Monday that the fish's strontium-90 was not related to this winter's radioactive leak at Vermont Yankee, and state officials attributed the strontium to atmospheric testing in the 1960s and the Chernobyl nuclear disaster 20 years ago, which spread radioactive fallout even as far away as Vermont.

The department said the fish posed no health or safety problem, and said that most fish in Vermont and New England would have similar levels of radioactivity.

William Irwin, radiological health chief for the Health Department, said that the fish was caught on Feb. 10, four miles north of Vermont Yankee as part of the testing done in the wake of the tritium leak at the plant, which was first disclosed publicly on Jan. 7.

Tests have shown the radioactive leaks, originally described as a tritium leak, actually released at least six different radioactive materials – cobalt-60, cesium-137, manganese, zinc, tritium and now strontium-90.

Irwin said the fish tested at 58.8 picocuries per kilogram for strontium-90. He said the fish's bones had a higher level of strontium-90 than its flesh, which he said was nonetheless safe to eat, since 43.3 picocuries per kilogram is considerable minimal detectable levels.

"Even if in edible portions, there is no expected, measurable health risk from the consumption of fish contaminated from these extremely low, fallout-derived quantities of strontium-90," Irwin said. Irwin said he didn't know what kind of fish it was, nor how big or old it was. He said that the environmental samplers are supposed to catch yellow and white perch, largemouth, smallmouth and rock bass, northern pike or chain pickerel. The fish was caught in Hunt's Meadow in Brattleboro, he said. Arnie Gundersen, a nuclear engineer who is a member of the Legislature's Public Oversight Panel, said he hoped the state would do samples of "hundreds of fish" rather than a handful, to get more data on the possible strontium-90 connection.

But Gundersen said he had his doubts about Irwin's explanation of the source of the fish's radioactivity, noting that if the fish picked up its radioactivity from atmospheric tests and Chernobyl, it would have also tested positive for cesium-137.

Gundersen called strontium-90 "the worst" of the radioisotopes found to have leaked out of Vermont Yankee, noting it is water soluble and bone-seeking.

"I would check a hell of a lot more fish," said Gundersen. "It raises a lot of concerns."

Irwin said that the fish was caught quite a distance, more than four miles, from Vermont Yankee, which he said was further proof that the fish strontium-90 didn't come from the plant.

And Irwin said that a fish caught immediately in the vicinity of the plant in the so-called Vernon pool, tested below "detectable levels," but he said that the state planned on doing much more testing on fish, noting these were the first tests on fish looking for strontium-90.

David Deen, the river steward for the Connecticut River Watershed Council, said that fish carry trace amounts of pollutants, particularly mercury.

Deen, a Westminster fishing guide and member of the Vermont Legislature, said that he would be very interested to see more fish tested for the nuclear fission byproduct.

Deen said four miles was insignificant to any species of fish, noting he had seen studies of the Battenkill that brown trout have moved 16 miles.

"It doesn't matter what the species is, a walleye or a bass or perch, it could have been in the Vernon pool and easily end up four miles north," he said.

"This is the legacy of the '50s and '60s, until above-ground testing was discontinued. It's like mercury levels, emissions are going down, but the mercury in our fish is still high, all the consumption warnings are still in place. There is a serious lag time," said Deen.

"I want to see what the levels are and what the background levels are in other tests," said Deen.

David Lochbaum, a nuclear engineer with the Union of Concerned Scientists, said that strontium-90 poses a greater public health hazard than tritium.

"The limit for tritium in drinking water is 20,000 picocuries per liter. For strontium-90, the drinking water limit is far lower, something like 6 picocuries per liter," Lochbaum wrote in an e-mail.

The Department of Health routinely tests many environmental factors, including fish, around Vermont Yankee, for possible radioactivity.

Irwin said that most fish in Vermont – and New England for that matter – would have some strontium-90 in their bones because of atmospheric testing of nuclear weapons and the Chernobyl nuclear disaster.

He said that the department didn't have extensive data on strontium in fish because it had never done the testing before, but the contaminated fish was free of any other radioactive isotopes, which he said proved that its radioactive contamination was not due to the Vernon reactor, which is located on the banks of the Connecticut River.

Late Friday afternoon, Entergy Nuclear released test data that showed that strontium-90 had been found in soil that is also contaminated with other radioactive isotopes as a result of a leak at Vermont Yankee. The plant had had the results for about a week, but released the information at about 5:30 p.m. on Friday.

Entergy Nuclear spokesman Larry Smith said he was unaware of the contaminated fish, and said he would be unable to get answers from Entergy staff about its fish testing protocol until today since the reactor was coming back on line.

susan.smallheer@rutlandherald.com