TP8 Biomonitoring
A105 & A106
1:20 PM - 4:40 PM, Tuesday
() Modeling Approaches to Improve Seafood Biotoxin Monitoring for Protection of Human Health.
Judd, N1, Griffith, W1, Faustman, E1, 1 University of Washington, Department of Environmental and Occupational Health Sciences, Seattle, WA, USA
ABSTRACT- Exposure to domoic acid produced by harmful algal blooms may lead to a variety of adverse health effects including amnesiac shellfish poisoning. These blooms cause rapid increases in seafood domoic acid concentrations and are difficult to predict, so an appropriately sensitive and frequent monitoring program is critical. To reduce human exposure, Washington State Department of Health (WA DOH) relies on early detection and prevention of consumption of contaminated seafood through beach closures when levels in shellfish exceed 20 ppm. Domoic acid has not historically been a problem in Puget Sound, unlike the WA coast where closures are common and sampling is more frequent during seasonal collection periods. Puget Sound sampling is currently performed biweekly and more frequently if detectable levels are found. In WA DOH samples analyzed through 2001, 9.7% of razor clams from the WA coast and 98.3% of blue mussels from Puget Sound were reported as non-detects. The first domoic acid closure in Puget Sound occurred in September 2003. Collection of shellfish is year round in the heavily populated Puget Sound area, and there is the potential for people to be exposed for several days before a bloom is detected and a closure is issued. Using historical data on domoic acid levels in WA coast shellfish collected by the Olympic Region Harmful Algal Bloom (ORHAB) project, rates of concentration increase due to blooms were estimated. These estimates were used to generate probability based projections of potential exposure to domoic acid under the current Puget Sound sampling regime and with more frequent sampling. The value of more sensitive analysis (better than the current 1 ppm limit of quantitation) for early detection of blooms was also explored. Modeling results indicate 4 or more days of exposure above the closure level may occur with the current monitoring program. Uncertainties about the frequency of blooms and background levels of domoic acid in Puget Sound complicate evaluation of the benefits of more frequent and more sensitive sampling. Supported the Pacific Northwest Center for Human Health and Oceans funded by NIEHS (P50 ES012762) and NSF and the Center for the Study and Improvement of Regulation at Carnegie Mellon University.
Key words: biotoxin, biomonitoring, seafood, risk assessment