The frequency of malformations is highest in frogs that have recently metamorphosed from tadpoles. Multiple Possible Causes . Specific Causes for Increase not Determined . Contaminants, UV-B radiation and perhaps parasites play roles. Much disagreement and internecine sniping among researchers aggravates the situation.
Chemical contaminants imply human health risks.
The Big Amphibian Conservation Gaps No Amphibian Census Bureau . Trends and status of most amphibians in North America are unknown. Weak Methodology Development . Insufficient Statistical Power . Field study sample sizes are usually too low to statistically detect associations between environmental causal factors and population size.