Posted by: barn owl | February 14, 2008

More on Environmental Contaminants in Pacific NW Osprey Eggs
The good news from the two previous papers (in my earlier post that was not picked up by the BPR3 aggregator…bummer!) was that the organochlorine pesticide, PCB, PCDD, and PCDF contaminant levels declined in sample eggs collected from Ospreys breeding along the Columbia and Willamette Rivers. Some bad news, however, comes with this report, on herbicide and fungicide contaminant levels in Osprey eggs from the Puget Sound area.

As mentioned in the previous post, the Osprey is a sentinel species for persistent and bioaccumulative organic pollutants (POPs), and research has traditionally focused on the “legacy” organochlorine (OC) pesticides, such as DDTs and chlordanes. The study by Chu and colleagues (2007) instead focuses on levels of current-use chlorophenoxy acid agricultural herbicides (e.g. DCPA) and their degradation products, thought to have bioaccumulation potential in fish, which comprise over 90% of the Osprey’s diet. Levels of pyrethroid insecticides (e.g. cypermethrin, deltamethrin, permethrin) were also examined, as was the current-use broad spectrum fungicide chlorothalonil. Sample Osprey eggs were collected from 11 nests in the Duwamish-Green River area, and from 4 nests in the Everett Bay area, in Washington state, and two different analytical methods were used to detect acidic herbicides and insecticides in egg homogenates.

Although the herbicide DCPA proved to be difficult to measure by standard methods in the Osprey eggs, another compound, diMe-TCP, which is a structural isomer of DCPA, was present in all 15 samples. This latter compound is not a contaminant of DCPA, and its presence is somewhat of a mystery, since it is not an industrial product, and has no known commercial source. The concentrations of diMe-TCP were higher in eggs from the Everett Harbor study area. DiMe-TCP may be a metabolite of tetrachlorylphthalic anhydride (TCPA), a flame retardant and epoxy resin curing agent that acts as a respiratory tract sensitizer. Chlorothalonil was also detectable in a few eggs from Duwamish and Everett Harbor study areas.

The authors demonstrated that gas chromatography/mass spectrometry is an effective method for measuring levels of DCPA and its isomers, in the context of avian egg samples. They suggest that this report is the first documenting diMe-TCP in environmental samples. Importantly, the Chu et al. (2007) paper indicates that DCPA and diMe-TCP can be bioaccumulated in an aquatic food web, and that these compounds are transferred from Osprey mother to egg.

CHU, S., HENNY, C., KAISER, J., DROUILLARD, K., HAFFNER, G., LETCHER, R. (2007). Dacthal and chlorophenoxy herbicides and chlorothalonil fungicide in eggs of osprey (Pandion haliaetus) from the Duwamish–Lake Washington–Puget Sound area of Washington state, USA. Environmental Pollution, 145(1), 374-381. DOI: 10.1016/j.envpol.2005.12.058


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