Relating Laboratory and Field Bioaccumulation: Importance of Abiotic and Biotic Parameters, and Use of Trophic Magnification Factors
Lawrence Burkhard, US EPA National Health and Environmental Effects Research Laboratory
Back in November, 2009, in the days leading up to the 30th SETAC North America meeting, SETAC’s Bioaccumulation Advisory Group (BSAG) joined forces with the ILSI Health and Environmental Sciences Institute (HESI) and the United States Environmental Protection Agency (US EPA) to host a workshop in New Orleans on comparing laboratory and field measures of bioaccumulation.
Laboratory studies have investigated different organisms under controlled conditions, varying both abiotic (e.g., pH, salinity, food quantity and quality, contaminant properties) and biotic (e.g., habitat, feeding mode, trophic transport) factors that affect bioaccumulation. Consequently, we have a good understanding of the factors controlling bioaccumulation of organic contaminants in the laboratory. However, experience has led to the generally held belief that laboratory-derived bioaccumulation estimates do not translate easily―or perhaps not at all―to field data.
This was the problem addressed at the 2009 New Orleans workshop and it is a key problem in ecological and human health risk assessment. Laboratory-derived bioaccumulation predictions, particularly for hydrophobic organic contaminants, often play an important role in site-specific remediation decisions, so it’s important that those predictions be accurate. More broadly, we all want to prevent the next generation of “DDT-like” chemicals from reaching unacceptable concentrations in fish, shellfish, birds, mammals, and humans, so it is important that we understand the physical, chemical, biological and ecological processes governing environmental bioaccumulation.
This was the context for the New Orleans workshop, which turned out to be very productive. Since then, workshop participants have reported out to the SETAC community both in Seville, at the 20th SETAC Europe meeting, and in Portland at the 31st SETAC North America meeting. A series of papers from the New Orleans workshop were recently submitted for publication in a future issue of Integrated Environmental Assessment and Management. A summary of the Seville session was published in the 30 September 2010 Globe.
The Portland session focused on understanding and improving the relationships between laboratory and field bioaccumulation measurements. These papers were well received and generated much discussion. The papers presented an approach using fugacity ratios to compare laboratory and field bioaccumulation endpoints, the results from a modeling effort describing the key factors influencing variability in both laboratory and field measurements, and the use and measurement of trophic magnification factors (TMFs) in assessing bioaccumulation potential. Another paper that generated much discussion was presented by Dr. David Walters where the focus of the presentation was on why TMFs differ across ecosystems and if these differences could be accounted for by proper scaling of the data from each ecosystem.
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