Assessment of Potential Cancer Risk from Consumption of PCBs Bioaccumulated in Fish and Shellfish

Area of Science:

• Environmental toxicology
• Chemical risk assessment
• Ecotoxicology

Background:

• Polychlorinated biphenyls (PCBs) are persistent organic pollutants found in aquatic environments.
• Human exposure to PCBs can occur through the consumption of contaminated fish and shellfish.
• Assessing the cancer risk associated with PCB ingestion is crucial for public health.

Purpose of the Study:

• To evaluate the potential cancer risk to adults from ingesting PCBs in fish and shellfish.
• To model PCB bioaccumulation in aquatic animals using equilibrium partitioning.
• To investigate the influence of various factors on PCB cancer risk estimates.

Main Methods:

• Utilized an equilibrium partitioning model for PCB bioaccumulation in aquatic organisms.
• Assessed the impact of PCB hydrophobicity, food-chain sources, environmental degradation, and biotransformation on cancer risk.
• Compared risk assessments using toxic equivalency factors for specific congeners versus PCB mixtures.

Main Results:

• Cancer risk increased exponentially with PCB hydrophobicity.
• Food-chain sources were necessary to elevate cancer risk above 10(-6).
• Environmental degradation and biotransformation significantly reduced estimated cancer risk, even at slow rates.

Conclusions:

• Deviations from conventional risk assessment assumptions (e.g., steady-state, negligible degradation/biotransformation) significantly impact PCB cancer risk estimates.
• Factors like environmental degradation and metabolic processes in aquatic animals are critical for accurate risk assessment.
• Risk assessment for specific PCB congeners may differ substantially from assessments of PCB mixtures.