1.   But at least in some areas, scientists report on Thursday, evidence shows the frog deformities are being caused not by toxins but by parasitic worms.

2.   In Minnesota, where there have been the greatest concerns about frog deformities and water quality, Dr. Helgen said there remains no clear-cut cause.

3.   Pollutants may be the root cause if it turns out that frog deformities are in fact becoming more common, as many experts suspect.

4.   Unfortunately, almost any theory on frog deformities will be tough to prove.

5.   At the conference last month in Shenandoah National Park, scientists ranging from molecular biologists to herpetologists examined theories that link the frog deformities to chemicals or parasites.

6.   SCI-US-DEFORMED FROGS Parasitic worms cause frog deformities.

7.   Gernes said the scientific community is skeptical of a report by California biologist Charles Dailey blaming the frog deformities on snake parasites.