ST. PAUL, Minn. -- A once polite scientific investigation into what may be causing deformed frogs around the nation is turning rancorous, with researchers accusing colleagues of making rushed and unnecessarily alarming announcement
"I'm saddened by this," said Gil Veith, associate director of the Environmental Protection Agency's National Effects Laboratory. "Now federal scientists are going to look like idiots. Even the ones who are ultimately proven right.
The contentiousness of the research also illustrates how difficult it can be to determine whether effects on wildlife are from artificial or natural factors, and what their implications may be for human health.
Since frogs with extra legs and other deformities were first discovered in Minnesota in 1995, frogs with similar abnormalities have been reported in more than a dozen states, setting off a flurry of concern and research.
On Sept. 30, officials from the National Institute of Environmental Health Sciences and the Minnesota Pollution Control Agency announced that samples of Minnesota surface and ground water -- including well water -- had produced abnormalities in laboratory frogs. The researchers emphasized that they did not know what compound in the water may have caused the developmental defects or how it may have contributed to deformities in wild frogs. They also said the human health risks posed by well contamination were unknown. But residents with affected wells were offered bottled water as a precaution.
The announcement infuriated other scientists familiar with the experimental procedure used, a "bioassay" in which embryos of the African clawed frog, a commonly used lab animal, were exposed to Minnesota water samples for 96 hours then microscopically examined for irregularities in head and gut development.
"They're looking at a totally aquatic species from Africa with a very different physiology. And they're looking at it after four days of development, before it even has legs," said Andrew Blaustein, a zoologist at Oregon State University. "In my opinion the press conference was alarmist and very premature."
Researchers at the EPA's Mid-Continent Ecology lab in Duluth duplicated the experiments -- and came to a radically different interpretation of the results.
"The NIEHS acted irresponsibly in a rush for headlines," said the EPA's Veith. "They overlooked some very basic rules for running bioassays. They're not experienced with aquatic species. The Duluth lab is, and the results from Duluth are as clear as you can get."
According to the EPA's scientists, the abnormalities produced in the NIEHS lab resulted from a benign ion imbalance in the water samples. When several ordinary salts were added to the water at levels recommended for rearing African clawed frogs, embryos grew normally. Such imbalances are common in Minnesota water and are known to interfere with bioassays. They also can increase the toxicity of contaminants in water and therefore cannot be ruled out as contributing to deformities in native frogs. But EPA scientists say NIEHS and MPCA had no reason to alarm the public over possible human health risks.
"Results don't mean anything if they aren't interpreted properly," said Joe Tietge, a research biologist in the EPA's Duluth lab who conducted the parallel experiments. "Anybody with a tropical fish aquarium knows that if you fill it with tap water it will kill the fish. That doesn't mean your tap water isn't safe to drink."
Tietge stressed that the EPA's results are so far confined to a single site, a lake in central Minnesota that has produced profoundly abnormal frogs for the past three years.
Jim Burkhart, the NIEHS scientist who is coordinating the investigation with MPCA, said he was unhappy about making the public announcement before his agency had fully interpreted data from assays at about 50 sites currently under investigation. "We had no intention of going public until we were further along," said Burkhart. "But the MPCA insisted, and we had to respect their call even though we didn't have all the answers."
Judy Helgen, a research scientist who manages the MPCA's frog investigation, confirmed that the decision to go public was theirs -- and that they would make the same call today. The MPCA's concern, she said, was that news of their findings was already beginning to leak and that deliveries of bottled water to homes near wetlands with deformed frogs would lead to a public panic.
"We felt that as a public agency we needed to let people know exactly where our research was at," said Helgen. "As scientists, none of us wanted to go public. We're already doing too much of this work in the public eye."
George Lucier, director of the environmental toxicology program at NIEHS, said well water at the site both agencies are looking at has normal ion levels, and yet it also produced abnormalities.
Burkhart also maintains that NIEHS never claimed to have found a toxicant in the water. And he said the assays in question were only one of many tests his agency has spent about $600,000 on thus far. He said he was happy to learn that EPA had duplicated their assay results but distressed by the conclusions EPA has arrived at after testing only a single site.
"We're still seeking the truth," said Burkhart. "I'd be loath to make any kind of generalization based on one sample."
Burkhart said the site looked at by EPA has many properties that do not seem to apply at other locations under investigation. And a longer experiment, in which African Clawed Frogs exposed to water from that same site are being grown out through limb development, is underway, he said.
But he also conceded that NIEHS still has insufficient data to support its preliminary finding of a "concordance" between positive assay results and deformed frogs, apart from the evidence from a handful of sites originally reported. That possible concordance is the only link between lab results and deformities in the field.
"In science, spurious correlations happen all the time," said the EPA's Tietge. "It's one of the weakest forms of evidence to support a hypothesis."
Tietge said he will present more evidence from his work on deformed frogs at a scientific meeting in San Francisco later this month. Experiments last summer have effectively ruled out the insecticide methoprene as a cause of deformities, he said.
But another prime suspect -- ultraviolet radiation in sunlight -- will get a boost from the first duplication in the lab of certain abnormalities seen in the field. In Tietge's experiments using leopard frogs, a native species that has been widely afflicted with deformities in the wild, exposure to UV alone induced hind-limb abnormalities.
But whatever role UV may play, said Tietge, it is not likely to be the whole answer. "There's no silver bullet," he said. "It's not going to turn out to be just one thing."