Medications Leak from Manure to the Environment

“Veterinary medications are released into the environment via grazing cattle and manure spreading on fields, but very little is known about the effects on wildlife,” says Dr Gunnar Carlsson.

Dr Gunnar Carlsson is participating in a project aiming to clarify the occurrence and effects of losses of veterinary medications to the Swedish freshwater environment.

Disturbed development of zebrafish embryos
Dr Gunnar Carlsson has studied how the embryonic development of the zebrafish is affected by fifteen commonly used anti-parasite drugs and anti-bacterial drugs (antibiotics). The zebrafish is an ideal model organism for fish. It reproduces successfully and rapidly in the laboratory setting, the embryonic development is only a few days long. Apart from malformed embryos, Dr Gunnar Carlsson has observed embryos, which look normal and healthy, but show a variety of physiological malfunctions.

“Some embryos display less frequent body movements or no movements at all. Other embryos hatch later, or have an increased or decreased heart beat rate. Embryos exposed to Flumetrin, an anti-parasite drug, are shaking,” says Dr Gunnar Carlsson.

Only trace amounts in freshwater
In parallel with the laboratory experiments on zebrafish, scientists at the Department of Aquatic Sciences and Assessment have analysed surface water and groundwater from areas close to large livestock in southern and western parts of Sweden.

“So far they've found only very low concentrations of veterinary medications in the analysed water samples. Therefore, it seems highly unlikely that wildlife is exposed to the same high concentrations of drugs as our zebrafish embryos in the lab,” says Dr Gunnar Carlsson.

Next, the scientists plan to study the combined effects of veterinary medications on zebrafish embryonic development.