Proceedings of the 2007 Georgia Basin Puget Sound Research Conference
Session 2E: Seafood Safety and Human Health I
Chair: Joe Gaydos
Human Health Evaluation of Puget Sound Fish
Washington Department of Health conducted a human health evaluation of contaminants in Puget Sound fish. Over 100 contaminants were measured in muscle tissue (without skin) from English sole, four rockfish species, and two salmon species. DOH concluded that two contaminants were of potential public health concern: polychlorinated biphenyls (PCBs) and mercury.
Based on contaminant concentrations in fish and on estimates of consumption by recreational anglers, tribal members, and consumers of fish from the Asian Pacific Islander community, DOH determined that frequent consumers of certain Puget Sound fish may be exposed to contaminants above a level of concern. DOH considered risks, benefits, and data uncertainties when providing meal advice for anglers and other consumers.
No meal restrictions were necessary for English sole (flatfish) from non- or near-urban areas of Puget Sound. DOH recommended one rockfish meal per week unless otherwise noted for urban areas. Puget Sound Chinook had higher levels of PCBs and mercury than coho, resulting in a recommendation of one meal per week. Additionally, those eating Chinook salmon from the Puget Sound winter fishery (blackmouth) were advised to limit consumption to two meals per month. Puget Sound coho salmon were relatively low in contaminants. A list of low contaminant fish, including those from the market, was created to assist consumers in making healthy selections.
A Survey of Cadmium in Pacific Oysters: Spatial Distribution, Influencing Factors and Ways to Minimize Concentrations
Cadmium (Cd) is a toxic trace metal known to bioaccumulate in molluscan shellfish, particularly Pacific oysters (Crassostrea gigas.) Over the past few years, several shipments of Pacific oysters from Puget Sound and Canada have been rejected by Hong Kong for exceeding the 2 µg/g import standard. This study evaluates the spatial distribution of Cd concentrations in Pacific oyster tissue harvested from 31 commercial, recreational and tribal shellfish growing areas located throughout Puget Sound and Washington State coastal estuaries. Findings indicate that a weak spatial trend exists with oyster Cd levels increasing in a northward and seaward direction with the exception of consistently elevated levels along the length of Hood Canal. Cd concentrations from 92 oyster composites ranged from 0.44 to 2.5 µg/g with a state-wide average of 1.24 ± 0.57 µg/g. Seventeen percent of composites exceeded Hong Kong’s 2 µg/g import standard. Factors influencing the spatial distribution of Cd in oysters (water quality, sediment chemistry, seasonality) will be discussed as well as ways to minimize tissue concentrations (site selection, time of harvest, grow-out method, processing technique), having practical implications for growers and harvesters throughout Georgia Basin and Puget Sound.
Assessment of Trace Metals in Tissues of Geoduck Clams from Eastern Puget Sound
The Suquamish Tribe and the Washington State Department of Health recently partnered to assess the concentrations of trace metals (As, Cd, Cr, Pb, and Hg) in the tissues of geoduck clams harvested from the Richmond Beach tract, located between Edmonds and Seattle, Washington in eastern Puget Sound. The purpose of this assessment was to evaluate the human health risks associated with consumption of geoducks from this area of Puget Sound. Evaluating the human health risks associated with contaminants in fish and shellfish tissue requires that samples be processed in a manner consistent with how they would be prepared by consumers. Considering the preparation practices of end consumers, geoduck tissues from 60 geoducks collected from the Richmond Beach tract were segregated into three parts: gut ball (viscera), neck/strap (siphon and mantle), and the outer skin of the siphon. Gut ball and neck/strap tissues from each geoduck were separately analyzed for total As, Cd, Cr, Pb, and Hg. A subset of tissues from the outer skin of siphons was also analyzed. In general, trace metal concentrations were highest in the outer skin, and lowest in the neck/strap. The results from this study have helped to explain inconsistent results among past studies and suggest some important considerations in future studies of geoduck tissues, particularly when the objective is the assessment of human health risks.
Results and Discussion of the Swinomish Health Risk Assessment of Contaminated Seafood
This presentation will summarize the Swinomish Indian Tribal Community’s Bioaccumulative Toxics in Native American Shellfish Project. The project, initiated in 2002, hypothesized that Swinomish people are exposed to low level, bioaccumulative toxics when gathering and consuming local shellfish. Results will be presented from the human health risk assessment of two species of clams, associated sediment, and Dungeness crab, which were tested for heavy metals, organotins, PCBs (both aroclors and the WHO list congeners), chlorinated pesticides, polyaromatic hydrocarbons, and dioxins/-furans. The presentation will also discuss shortcomings of the current risk assessment methodology, data gaps and uncertainties, and provide more culturally appropriate alternatives to remedy some of these faults. Other topics to be touched upon include: the use of traditional harvesting techniques in sampling procedures, and culturally competent mitigation options, outreach and education efforts. The project was funded by U.S. EPA grant #R-829467.
Science, Policy and Practice: Washington’s PBT Chemical Action Plans
There are currently about 80,000 registered chemicals in the US, and 1,500 new chemicals are registered each year. A small class of these chemicals, called “persistent bioaccumulative toxics (PBTs), present a particular problem because:
• PBTs remain in the environment for a long time (Persistent).
• People and animals accumulate PBTs in their bodies (Bioaccumulative).
• PBTs threaten human health and the environment. New information points to risk to children’s healthy development, since some PBTs harm the central nervous system, as well as cause reproductive and other problems (Toxic).
• PBTs readily migrate between our air, land and waterPublic concern is increasing regarding exposures by children to PBTs. Children are more susceptible to PBT exposures since they are still undergoing growth and development of their bodies and brains. Children are closer to the ground and have greater “hand-to-mouth” behaviors. Many PBTs are present in breast milk, which results in additional loading of chemicals during infancy.
Special efforts to bring together the best science, the most meaningful policy and effective public health education practice are required to address the serious problems that PBTs pose. In 2000, the Washington State Department of Ecology (Ecology) drafted the nation’s first PBT reduction strategy. Since that time, Ecology has partnered with the Washington State Department of Health (DOH) to create and implement chemical action plans for Mercury (2003) and PBDEs (2006) and to develop rules for PBTs in Washington. In addition, Ecology has adopted the nation’s first PBT regulation.
Next steps call for Ecology and DOH to develop chemical action plans for lead in 2007, polyaromatic hydrocarbons in 2008 and perfluorooctane sulfonates in 2009. However, a much greater challenge is that current US chemical policy has resulted in:
• a lack of data on chemicals in commerce;
• high burdens for agency action;
• a focus on review of new chemicals without adequate attention to existing chemicals; and
• chemical by chemical approach to chemicals management that is slow and cumbersome.There has also been relatively little attention paid to chemicals in products. Due to these limitations, many efforts to reduce and substitute chemicals are largely voluntary and dependant on the willingness of industry and commerce to participate.
Cryptosporidium and Giardia Species in Marine Wildlife: Do they Present a Risk to Human Health?
Cryptosporidium and Giardia species are protozoal pathogens that infect humans, domestic animals and wildlife. Historically they have been thought of as terrestrial and freshwater pathogens but their infective stages can survive in marine waters for up to a year and be concentrated by filter feeding bivalves. Little is known about the epidemiology of these pathogens in marine ecosystems, especially the role that marine wildlife could play in their transmission. We tested harbor seals, marine-foraging river otters, and hybrid glaucous-winged / western gulls, three common marine wildlife species in the Georgia Basin / Puget Sound, for infection with Cryptosporidium and Giardia species. Giardia cysts were detected in 4% of gull samples (n=78), 19% of river otter samples (n=57), and 43% of seal samples (n=99). Fourteen positive seal samples were amplified by PCR and confirmed as G. lamblia. Three were from one site and were identified as the G. lamblia dog genotype, suggesting transmission to seals from coyotes or domestic dogs. Sequences from the other eleven samples represented a novel G. lamblia genotype. Cryptosporidium sp. oocysts were detected in 7% of river otters sampled but not detected in gulls or seals. The one amplified otter sample was most similar to the ferret genotype of C. parvum. Marine wildlife shed Cryptosporidium and Giardia species in the Puget Sound region but preliminary data failed to identify the genotypes most commonly infecting humans. More work is needed to better understand the zoonotic potential of the wildlife isolates identified and the potential that sewage outflows could be contaminating marine waters with Cryptosporidium and Giardia of human origin.