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Meghan O'Grady Milbrath,¹ Yvan Wenger,¹ Chiung-Wen Chang,¹ Claude Emond,² David Garabrant,¹ Brenda W. Gillespie,³ and Olivier Jolliet¹

¹Department of Environmental Health Sciences, University of Michigan School of Public Health, Ann Arbor, Michigan, USA; ²Department of Environmental and Occupational Health, Faculty of Medicine, University of Montreal, Montreal, Quebec, Canada; ³Department of Biostatistics, University of Michigan School of Public Health, Ann Arbor, Michigan, USA

Abstract
Objective: In this study we reviewed the half-life data in the literature for the 29 dioxin, furan, and polychlorinated biphenyl congeners named in the World Health Organization toxic equivalency factor scheme, with the aim of providing a reference value for the half-life of each congener in the human body and a method of half-life estimation that accounts for an individual's personal characteristics.

Data Sources and extraction: We compared data from > 30 studies containing congener-specific elimination rates. Half-life data were extracted and compiled into a summary table. We then created a subset of these data based on defined exclusionary criteria.

Data synthesis: We defined values for each congener that approximate the half-life in an infant and in an adult. A linear interpolation of these values was used to examine the relationship between half-life and age, percent body fat, and absolute body fat. We developed predictive equations based on these relationships and adjustments for individual characteristics.

Conclusions: The half-life of dioxins in the body can be predicted using a linear relationship with age adjusted for body fat, smoking, and breast-feeding. Data suggest an alternative method based on a linear relationship between half-life and total body fat, but this approach requires further testing and validation with individual measurements.

Key words: elimination rate, half-life, pharmacokinetics, polychlorinated biphenyls, polychlorinated dibenzofurans, polychlorinated dibenzo-p-dioxins. Environ Health Perspect 117:417–425 (2009) . doi:10.1289/ehp.11781 available via http://dx.doi.org/ [Online 3 October 2008]

Address correspondence to M.O. Milbrath, Department of Environmental Health Sciences, Room 6529, 1420 Washington Heights, Ann Arbor, MI 48109-2029 USA. Telephone: (734) 647-0394. Fax: (734) 763-8095. E-mail: meghanom@umich.edu.

Supplemental Material is available online at http://www.ehponline.org/members/2008/11781/suppl.pdf

We thank L. Birnbaum, R. Hites, P. Boffetta, and M.H. Sweeney for their guidance as members of our Scientific Advisory Board, and R. Kimbrough for her assistance.

Financial support for this study came from the Dow Chemical Company through an unrestricted grant to the University of Michigan.

This research was supported by an unrestricted grant from the Dow Chemical Company. D.G. has previously received research grant support, been a consultant to, and served as an expert witness in litigation on behalf of the Dow Chemical Company.

Received 9 June 2008 ; accepted 3 October 2008.