Background information

Where did this problem start?

In August 1995, students from the New Country School in Le Sueur, Minnesota, found large numbers of deformed frogs in a wetland they were studying near Henderson, Minnesota. They found many frogs with deformed, missing or extra legs, as well as deformed eyes or other parts.

Before the end of that season, similar frogs had turned up elsewhere in the Minnesota River Valley.

Minnesota's deformed frogs became big news. Researchers agreed they'd never seen anything like this. Everyone wondered what could be causing these unusual defects, and scientists started investigating.

Looking for deformed frogsBut then it got worse. In the summer of 1996, deformed frogs were reported all over the state. By the end of the year, the MPCA had gotten more than 175 reports of deformed frogs, in two-thirds of Minnesota's counties. Late that summer, we began hearing that deformed frogs were being found in other states as well, even in other countries.

Why are we concerned about the deformed frogs?

Frog populations around the world have showed increasing signs of stress in recent years. Some species have disappeared, and others are no longer found where they used to be. An increase in deformities may be a sign that something is wrong.

Scientists are concerned about what's happening to the frogs, because the health of frogs is closely linked to the health of the environment. Frogs are sensitive to pollution, because they live at the meeting of two environments -- land and water -- and they can easily absorb pollutants through their skin.

Just as miners used canaries in the mines to alert them to poisonous gases, frogs may alert us to problems in our environment.

Do we know what's causing it?

Not yet, but at a press conference in St. Paul on September 30, 1997, 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.

frog with malformed rear legThe sites, both in the northwestern part of the state, were studied by researchers from the MPCA and the University of Minnesota. At one of the sites, researchers, at different times in the season, found a high proportion of frogs with missing or contorted limbs and other abnormalities.

Water from 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.

Questions regarding this latest information may be referred to Ralph Pribble, MPCA, 651- 296-7792; Tom Hawkins, NIEHS, 919-541-1402 or Sandy Lange, NIEHS, 919-541-0530.

What is the MPCA doing?

As of July 2001, the MPCA is no longer working on the malformed frog problem in Minnesota. The Minnesota Legislature did not provide any funding for this research for the upcoming fiscal year, from July 1, 2001 through June 30, 2002.

From 1998 to 2000, the Minnesota Governor and Legislature gave the MPCA special funding to study the frogs. This enabled the MPCA to hire much-needed staff for the project, who regularly visited several study sites around the state to sample the water and sediments and collect frogs for analysis.

Taking samplesIn the past, MPCA staff also worked with a network of researchers who are studying Minnesota's abnormal frogs. These include experts from the University of Minnesota and several researchers elsewhere in the country who are looking at Minnesota frogs. These scientists are examining the frogs' genetic material and looking at their tissues and skeletal systems for evidence of chemical contamination and parasites.

In addition, the MPCA had partnered with federal agencies that were investigating the problem on a national scale, including the National Institute of Environmental Health, the National Wildlife Health Center, and the U.S. Environmental Protection Agency. These partners provided analytical services for water, sediment and frog tissues. Some of this research is continuing even though the MPCA is no longer involved.

What can I do?

You can monitor the frogs in your area by participating in a frog and toad survey through:

Observe and record any abnormalities carefully, but please leave the frogs where you find them.

You can help protect the frogs and our environment by reducing the amount of harmful chemicals that you use and dispose of. If you'd like more information on how to do this, visit SEEK, Minnesota's environmental education website.