Pharmaceuticals found in water-fish-osprey food web
A recent U.S. Geological Survey (USGS) and Baylor University study demonstrated that ospreys (Pandion haliaetus, or commonly, fish eating hawks or eagles) do not carry significant amounts of human pharmaceutical chemicals, though these chemicals are prevalent in water. This finding published in Integrated Environmental Assessment and Management is the first published study that examines the bioaccumulation of pharmaceuticals in the water-fish-osprey food web.
Pharmaceuticals have been finding their way into the environment, primarily through wastewater, urban overflow and even bio-solids applied to agricultural lands. The impact of these accumulated pharmaceuticals on wildlife is unknown. Ospreys occupy the top of the food web. They often nest in highly developed or city areas and eat only fish. Thus they serve as an ideal sentinel for monitoring contaminants limited to a small area.
Rebecca Lazarus and her team at the USGS analysed water samples, collected from 12 sites in the Chesapeake Bay area, and blood samples, from fish and osprey nestlings living along neighbouring waterways. They evaluated the bioaccumulation potential of 113 pharmaceuticals and metabolites, and an artificial sweetener, sucralose in this food web.
They found that the concentrations of pharmaceuticals in water and fish were greatest in places located close to wastewater treatment plants and in highly urbanized areas. However, of the 18 compounds found in water samples, only 7 pharmaceuticals and the artificial sweetener, sucralose were found in fish. Sucralose was the only non-pharmaceutical chemical sampled, and it served as an effective marker for of human activity. Only one compound, diltiazem (very common antihypertensive drug), though present at very low concentration, was detected in significant level in osprey blood plasma, which indicates these compounds are not generally being transferred up the food web. However the threshold level for this drug is still not known in ospreys, and there is no obvious evidence to suggest the adverse effects.
The study was complemented by an exposure model which predicted 15 compounds out of a set of 113 pharmaceuticals having the potential to exceed a human therapeutic dose. This hypothesis deserves further exploration. This type of screening model may be helpful to spot additional compounds that may be detectable in wildlife particularly in high-trophic level species.
For the full article, visit:http://onlinelibrary.wiley.com/doi/10.1002/ieam.1570/abstract
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