Polychlorinated biphenyls (PCBs) in the UK population: estimated intake, exposure and body burden

Abstract

This paper presents a detailed congener-specific estimate of PCB exposure to the UK population. The average sigma PCB intake (i.e. the sum of IUPAC congeners No. 28, 44, 52, 61/74, 66, 99, 101, 105, 110, 118, 138, 151, 153, 156, 170, 180, 183, 187, 189, 194/205, 201, 202, 206 and 209) for the contemporary UK population was estimated to be 0.53 micrograms/person/day. Food consumption accounted for 97% of the sigma PCB exposure, with fish, milk and dairy products, vegetables and meat and animal fat accounting for 32, 24, 24 and 15%, respectively. The congener pattern for different food products varied, with vegetables playing a major part in the intake of lower chlorinated compounds, whilst fatty foods such as fish, dairy products and meat, were of greater importance for the intake of higher chlorinated compounds. Theoretical body burdens and body fat concentrations of selected PCB congeners were derived for the UK population, based on the estimated contemporary human daily intake of PCBs and a number of assumptions. PCB body burdens and adipose tissue concentrations were generally predicted to increase with age. However, adipose concentrations increased at a slower rate in the older population, due to a dilution effect caused by the increase in body fat weight with age. These theoretical estimates were then compared with measured values for adipose tissue from the Welsh population. Theoretical body burdens and adipose tissue concentrations (not accounting for any metabolic losses) were below the actual values measured for the contemporary Welsh population by between a factor of 2.5 and 4. This discrepancy becomes greater when metabolic losses are included, and probably occurs because present day exposure to PCBs through foodstuffs is likely to be lower than in the past. The lower chlorinated congener No. 28 is more readily removed from the body and is predicted to reach an equilibrium concentration in humans. In contrast, the higher chlorinated No. 153 was predicted to accumulate in the body throughout life. The effect of PCB transfer via breast milk is shown to be important in lowering the body burden of the mother (by approximately 20% over 3 months) and substantially increasing that in the offspring.