Why are amphibians particularly sensitive to environmental contaminants?

Question

also, what structures allow frogs to move in water and on land?

Answer 1

Amphibians are sensitive to pollutants because they have a moist skin that allows diffusion of water and air across and into their body easily.  In this way, dissolved pollutants can also easily cross their skin.

What structures allow frogs to move in water and on land?  Their webbed feet, I guess.

Answer 2

Amphibians are particulary sensitive to environmental contaminants because their eggs can only develop in a limited pH range. Amphibians lay their eggs in water and if the water has been exposed to a contaminant raising or lowering the pH the eggs will not survive. Many times ecologists look to amphibians and birds as a warning of pollution in an ecosystem.

Answer 3

because pollutants affect their ability to reproduce and cause mutations that are passed on to their offspring.  just a guess but they tend to move around on their legs, not their wings