Skip Navigation
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.


The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Your Environment. Your Health.

New Findings on Deformed Frogs in Minnesota

National Institute of Environmental Health Sciences (NIEHS)

News Release

Archive - New Contact Information

For more information about this archival news release, please contact Christine Flowers, Director, Office of Communications & Public Liaison at (919) 541-3665.
Tuesday, September 30, 1997, 12:00 p.m. EDT
Contact: Tom Hawkins, NIEHS
(919) 541-1402

JOINT NEWS RELEASE BY: Minnesota Pollution Control Agencyand the National Institute of Environmental Health Sciences, NIH

State and federal officials today announced new findings which may provide a significant step toward understanding why so many deformed frogs have turned up in Minnesota and elsewhere in recent years.

At a press conference in St. Paul today, staff of the Minnesota Pollution Control Agency (MPCA) and the National Institutes of Health's National Institute of Environmental Health Sciences (NIEHS) discussed information on a recent study of the water from two wetland sites in Minnesota where high numbers of deformed frogs have been found in the last two years.

The sites, both in the northwestern part of the state, have been studied the past two summers by researches from the MPCA and the University of Minnesota. At one of the sites, researches have at different times in the season found a high proportion of frogs with missing or contorted limbs and other abnormalities.

Water from the two sites was provided to NIEHS scientists from whom the MPCA had requested help with the frogs investigation last winter. Using a lab test called a FETAX assay, an NIEHS laboratory grew the embryos of the Xenopus frog species (African clawed frog) in water from the two sites.

The test, which takes four days to complete, was run multiple times using dilutions of the water from the Minnesota sites ranging from zero to 100 percent. At concentrations above 50 percent, a high percentage of the frog embryos developed in the water showed a wide range of abnormalities, similar to what has been observed in frog larvae in the field in Minnesota since 1995. Moreover, the number of abnormalities increased with the concentration of the water from Minnesota sites. Water from "normal" sites (no deformed frogs found) did not produce harmful effects in the frogs.

According to NIEHS staff, these results strongly indicate that something in the water, at least at these two sites, can cause these abnormalities in the lab. Still unknown is what the harmful agent may be and whether these findings will be seen at other sites where high numbers of deformed frogs have been found.

The FETAX test also gave positive results using both surface water and ground water from the sites, including tap water from private wells used by the closest residence to each site. Residents at the sites have been advised of the findings and have been offered the option for the state to provide them with bottled water as a precaution until more is known.

MPCA Commissioner Peder Larson said, "These findings give us a big piece of the puzzle we've been looking for in regard to the problems with the frogs. It does not provide evidence of a human health link, but it does underline the need to look more closely at what all this may mean for the environment. If the frog investigation was a priority for us before, it's even more so now."

Dr. George Lucier, Director of the Environmental Toxicology Program of the NIEHS, emphasized that NIEHS is working hard with the MPCA to determine the significance of these findings to human health. He said that "we know that something in the water, including groundwater, is extraordinarily potent in malforming frogs, we now need to determine if people are at risk. The causative agent or agents could be chemical contaminants or natural products such as pond plants or algae."

Larson also congratulated the NIEHS for their work, and praised the partnership the two agencies have developed to work on the problem. "This is really a significant finding, and we're extremely grateful for their participation," he said. "Working together with them has helped us do much more than we could have otherwise."

"The NIEHS is widely recognized as the premier toxicology research center in the world with outstanding laboratory resources that a state government could make use of under appropriate circumstances," Kenneth Olden, Ph.D., NIEHS Director said, "So this situation is an ideal opportunity to apply our science to a serious public health concern, in partnership with state government."

Staff of the two agencies discussed plans for further work at the press conference, including collecting more samples from these and other study sites around the state, conducting studies on water from additional sites where significant numbers of deformed frogs have been found, and determining the identity of the causative agent or agents. Of critical importance will be to determine if the water from other sites appears to have the same properties, whether ground water at other sites is similarly affected, and what the human health implications of these findings may be.

to Top