 |
| @ 0.1,1.0,10 x label rate; credit: Brühl et al |
A
new study published in
Scientific Reports found commonly used agricultural chemicals kill frogs when used at recommended dosages. Scientists associated with the University of Koblenz-Landau tested seven commonly used pesticides on European common frogs
(Rana temporaria) and found all of them were potentially lethal to frogs. Two fungicides, "Headline" and "Captan Omya" were particularly lethal
[chart], killing all of the test subjects at recommended application levels. Amphibians of all types, especially frogs, are in decline world wide . One third of the world's amphibians are currently threatened by extinction. Scientists believe 130 amphibians have gone extinct in the last thirty years. The study warns that continuous use of agricultural chemicals for more than a century could be partly responsible for vanishing amphibians. Habitat loss, climate change and disease pose the largest threats to their survival. Terrestrial exposure to chemicals has a more dramatic effect on frogs compared to aquatic exposure when frogs are in their tadpole stage. "Headline", the brand name for pyraclostrobin, killed all test subjects in one hour at its labeled dosage, but all the chemicals killed at mortality rates from 20% to 100%. Pyraclostrobin is used on 90 different crops around the world. Chemical giant BASF refused to accept the test results calling the study a "laboratory worst case scenario". Lead scientist Carsten A. Brühl said there is good evidence that frogs are in fields where chemicals are applied and sometimes applied multiple times. Up to 50% of a breeding population could be directly exposed to lethal chemicals. Depending on interception rates by plants is misleading. Even when dosages were cut by 90% 3 of the 7 chemicals were still lethal to frogs. The scientist encouraged BASF to provide researchers with interception rates in order to identify toxic risk to amphibians. Amphibians are distinct from mammals and birds because their skin is permeable allowing them to breath underwater, so chemical testing protocols for birds and mammals is not applicable. Recently European chemical testing procedures have been
criticized as too simplistic. Testing on amphibians is not currently required by EU regulations.
