Toward ecosystem-based sediment quality guidelines for polychlorinated biphenyls (PCBs).

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Marine Biology

Background:

• Polychlorinated biphenyls (PCBs) are persistent organic pollutants with potential ecological and human health risks.
• Existing Sediment Quality Guidelines (SQGs) in Canada and British Columbia aim to protect aquatic ecosystems from PCB contamination.
• The effectiveness of current SQGs in safeguarding wildlife and human consumers requires thorough investigation.

Purpose of the Study:

• To evaluate the adequacy of current SQGs for PCBs in protecting ecosystems and human health.
• To assess PCB concentrations in various biota and sediments off the Pacific coast of British Columbia.
• To develop a revised methodology for establishing PCB SQGs that ensures ecological and human safety.

Main Methods:

• Measurement and compilation of PCB congener concentrations in sediments, bivalves, crustaceans, fish, and marine mammals.
• Calculation of species- and location-specific Biota-Sediment Accumulation Factors (BSAFs).
• Estimation of potential PCB concentrations in wildlife under SQG-equivalent sediment PCB levels.

Main Results:

• Sediment PCB concentrations were mostly below the SQG, but tissue concentrations in fish and shellfish often exceeded wildlife consumption guidelines.
• PCB levels in marine mammals surpassed toxicity reference concentrations.
• Estimated PCB concentrations in wildlife, assuming sediment levels at SQGs, exceeded both wildlife and human consumption guidelines, and marine mammal toxicity thresholds.

Conclusions:

• Current SQGs for PCBs in British Columbia are insufficient for protecting wildlife and human health.
• A new methodology for developing PCB SQGs is proposed, considering ecological diversity and specific population needs (e.g., First Nations).
• The proposed methodology offers a framework for creating more effective SQGs for PCBs and other bioaccumulative substances.