Finding Something Fishy—

Battelle Examines Chemical Contaminants in Fish and Shellfish for Human Consumption

Human health risk assessments are an important decision-making tool in predicting, forecasting, and determining the consequences of industrial activities on the environment. These assessments evaluate the potential health impacts associated with direct or indirect exposures to site-related contamination. Battelle’s approach begins with a foundation for characterizing the problem, the expertise to perform quality analytical and toxicological tests, and the experience and knowledge to combine these tools into a scientifically based methodology.

Recently, Battelle was asked to provide technical support for the cleanup of contaminated sediment potentially associated with past industrial practices and accidental releases from facilities around San Francisco Bay. Battelle developed a risk-based, regional approach for the management of contaminated sediments that protects, restores, and maintains human and ecological health. These site investigations were technically challenging due to limited data availability and the diverse interests of many stakeholders. To overcome these difficulties, Battelle developed assessment techniques that offer innovative and cost-effective management of contaminated sediments.

A primary concern when evaluating human exposures to sediments is the potential risk associated with the consumption of fish and shellfish from these areas. California state and regional agencies conducted a pilot study in 1994 to provide data on concentrations of chemical contaminants in San Francisco Estuary fish. The study found elevated levels of several chemicals (e.g., PCBs and total mercury) in edible fish tissues, prompting the Office of Environmental Health Hazard Assessment to issue an interim health advisory for human consumption of fish caught in the estuary.

The focus of Battelle’s evaluation is the potential contribution of individual facilities to the overall human health risk posed by fish consumption. Most recreation-ally preferred fish species are highly mobile, therefore, it is difficult to attribute measured tissue concentrations to a specific source because of the prevalence of other chemical sources to the estuary as well as limited data regarding the bioavailability of sediment-associated chemicals.

Battelle developed a proposed approach for evaluating sediments that incorporates potential risks of fish consumption into the remedial investigation/feasibility study decision process while taking into account the factors described above. This approach, developed in conjunction with the regulatory agencies, focuses on two objectives:

1. determine the risk associated with the consumption of shellfish exposed to site-specific sediments to identify areas that should be evaluated in a feasibility study (FS); and
   
2. collect and analyze recreational fish tissue from the vicinity of the site and from other locations throughout the Bay for the purpose of a statistical comparison to determine differences in potential risk.

To achieve the first objective, all bioaccumulative chemicals identified by the U.S. Environmental Protection Agency Region 9 will be evaluated as chemicals of potential concern in shellfish tissue generated from 28-day bioaccumulation tests with site-specific sediments. These data will be used to evaluate the cancer and non-cancer risks associated with the consumption of shellfish from the site. Locations where risks exceed acceptable levels will be included in the FS.

To address the second objective, fish tissue data will be collected to determine whether risks associated with consuming fish from the vicinity of the site are significantly higher than those associated with consuming fish from other Bay locations. The focus of this investigation will be to determine if the concentrations of chemicals in fish near a facility are the same or different from the ambient conditions in the rest of the Bay. Any similarity or difference in the chemical concentrations indicates a parallel similarity or difference in risk. Preliminary evaluations based on existing data indicate that chemical levels in fish from the vicinity of the site are similar to those collected elsewhere in the Bay; however, additional data are required to achieve statistical confidence.

The proposed approach will provide useful information for communicating relative risks to citizens and recreational anglers regarding the potential risks at the site versus other areas in San Francisco Bay.

For more information, contact Don Gunster at (781) 952-5378, gunster@battelle.org.