Intrinsic Human Elimination Half-Lives of Polychlorinated Biphenyls Derived from the Temporal Evolution of Cross-Sectional Biomonitoring Data from the United Kingdom

Abstract

BackgroundMost empirical estimates of human elimination kinetics for persistent chemicals reflect apparent elimination half-lives that represent the aggregated effect of intrinsic elimination, ongoing exposure, and changes in body weight. However, estimates of intrinsic elimination at background levels are required for risk assessments for the general population.ObjectiveTo estimate intrinsic human elimination half-lives at background levels for nine polychlorinated biphenyl (PCB) congeners, we used a novel approach based on population data.MethodsWe used a population pharmacokinetic model to interpret two sets of congener-specific cross-sectional age–concentration biomonitoring data of PCB concentrations measured in lipid and blood samples that were collected from 229 individuals in 1990 and 2003. Our method is novel because it exploits information about changes in concentration in the human population along two dimensions: age and calendar time.ResultsOur approach extracted information about both elimination kinetics and exposure trends from biomonitoring data. The longest intrinsic human elimination half-lives estimated in this study are 15.5 years for PCB‐170, 14.4 years for PCB‐153, and 11.5 years for PCB‐180.ConclusionsOur results are further evidence that a maximum intrinsic elimination half-life for persistent chemicals such as PCBs exists and is approximately 10–15 years. A clear conceptual distinction between apparent and intrinsic half-lives is required to reduce the uncertainty in elimination half-lives of persistent chemicals. The method presented here estimates intrinsic elimination half-lives and the exposure trends of persistent pollutants using cross-sectional data available from a large and growing number of biomonitoring programs.

Estimation of human body concentrations of DDT from indoor residual spraying for malaria control

“…decrease of exposure (Ritter et al, 2011b). With our assumption of an environmental half-life of 10 years, the decrease of exposure is slower than intrinsic elimination (half-lives of 2.2 and 6.2 years).…”

Assessing infant exposure to persistent organic pollutants via dietary intake in Australia

“…These foods were dairy (Ritter et al 2011) and longevity of products containing PBDEs/PCBs, exposure has continued well past these times.…”

Interpreting PCB levels in breast milk using a physiologically based pharmacokinetic model to reconstruct the dynamic exposure of Italian women

“…The changes of the tissue composition from birth to adulthood and the breast milk during lactation were taken into account leading to age-dependent partition coefficients. 38--44 Values for the intrinsic half-lives were taken from the recent study of Ritter et al 45 No quantitative information was available to assign a value to the placental transfers. The toxicokinetic data of Abraham et al 30 were then used to estimate this parameter.…”

“…This modeling enables an accurate description of the kinetics of PCBs, as blood or serum levels are usually higher in the mother than in the fetus. 30,50 The PBPK model was parameterized with values 45 and data sets 30 that are independent of our biomonitoring data. No inter-individual variability was modeled for the toxicokinetic processes.…”