Validation of a methodology for modelling PCDD and PCDF intake via the foodchain

The US EPA foodchain exposure methodology has been assessed, linking background concentrations of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in the atmosphere with eventual intake of these chemicals by humans via the foodchain. The methodology is assessed against background environmental concentrations of View the MathML source and the background daily adult intake of View the MathML source in the UK diet comprising meats, vegetables, dairy produce, fish and miscellaneous food groups. The environmental fate and transport of View the MathML source is estimated for each of the seventeen, 2,3,7,8-positional View the MathML source isomers individually from the atmospheric burden in the atmosphere and into the environmental medium or food product of interest. The model predicts View the MathML source deposition rate and soil concentration to within ± 50% of the measured I-TEQ values. For grass, the model underpredicts View the MathML source concentrations but the lack of a reliable and coherent data set precludes further investigation as to the likely causes. The model performs well on food products, with the exception of potatoes (underpredicts by a factor of 20) and ‘other’ vegetables (underpredicts by a factor of 3). The total modelled View the MathML source intake via the diet is 61 pg I-TEQ day−1 as opposed to the measured intakes of 69 pg I-TEQ day−1 (excluding plant foods) and 81 pg day−1 (including data for plant foods measured in a previous survey, and not representative of contemporary exposures). The major contributor to total View the MathML source intake is via milk and milk products, accounting for about 40% of the daily dietary intake. ‘Hidden’ fats and oils account for 35% of the View the MathML source intake, followed by the ingestion meat and meat products (12%). As a group, vegetables do not appear to contribute significantly to the total adult background intake of View the MathML source via the diet.