Congener-specific intake fractions for PCDDs/DFs and Co-PCBs: modeling and validation

Area of Science:

• Environmental Chemistry
• Environmental Modeling
• Toxicology

Background:

• Polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDDs/DFs) and coplanar polychlorinated biphenyls (Co-PCBs) are persistent organic pollutants.
• Accurate assessment of environmental intake fractions (iFs) is crucial for understanding pollutant exposure and risk.

Purpose of the Study:

• To calculate and compare model-based and measurement-based intake fractions (iFs) for PCDDs/DFs and Co-PCBs emissions.
• To evaluate the performance of integrated multimedia and food-chain models in predicting environmental concentrations and human exposure.

Main Methods:

• Utilized a level III multimedia model and a food-chain exposure model.
• Compared predicted environmental concentrations (air, water, soil) and food intakes with measured data.
• Calculated measurement-based iFs and compared them with model-based iFs.

Main Results:

• Model accurately predicted air concentrations but underestimated soil and water concentrations for PCDDs/DFs and Co-PCBs, attributed to historical pollution.
• Predicted and observed fish intakes agreed well; meat and milk intakes showed discrepancies for PCDDs/DFs but agreement for Co-PCBs.
• Model modifications improved congener profile predictions, suggesting separate modeling for chickens and consideration of feed production bias.

Conclusions:

• Model-based iFs for air emissions of OCDD and 2378-TCDD were 0.001% and 0.1%, respectively.
• Co-PCBs generally exhibited higher iFs than PCDDs/DFs, underscoring the significance of the fate factor in emission assessments.
• The study validates the integrated modeling approach and identifies areas for refinement in assessing complex environmental pollutant dynamics.