pesticide linked to frog deformities
COULD plant pesticide be the factor which has been causing
frogs around the United States and Canada to become deformed?
Scientists have so far narrowed the causes of deformities
to either a tiny, aquatic parasite or wetland contamination
from chemicals that might threaten other life forms, including
Now, research suggests that for at least some outbreaks,
both factors could be involved and acting in concert.
The findings come from Dr Joseph Kiesecker of Pennsylvania
State University, the same researcher who last year linked
amphibian declines in the western United States to global
Dr Kiesecker tested whether agricultural pesticides
- a prime suspect in malformation - make developing frogs
more susceptible to infection by a parasite known as a
The parasite, which uses frogs as 'intermediate hosts'
in a complex life cycle, causes leg deformities in developing
tadpoles by tunnelling under their skin and becoming encysted,
usually at the base of their growing hind legs.
Dr Kiesecker thinks pesticides amplify the process significantly
by weakening the frogs' immune systems and making them
less able to resist parasitic infections.
Another scientist, Dr David Gardiner of the University
of California, said: 'If it's true that commonly used
pesticides compromise the immune system of a vertebrate
organism, which is what these findings suggest, then we're
looking at a much bigger problem than deformed frogs.'
Further studies are necessary to determine whether the
problem would affect the human food chain, he added.