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Judy S. LaKind,^1,2,3 Cheston M. Berlin Jr.,² Andreas Sjödin,⁴ Wayman Turner,⁴ Richard Y. Wang,⁴ Larry L. Needham,⁴ Ian M. Paul,² Jennifer L. Stokes,² Daniel Q. Naiman,⁵ and Donald G. Patterson Jr.^4,6

¹LaKind Associates, LLC, Catonsville, Maryland, USA; ²Department of Pediatrics, Milton S. Hershey Medical Center, Penn State College of Medicine, Hershey, Pennsylvania, USA; ³Department of Epidemiology and Preventive Medicine, University of Maryland School of Medicine, Baltimore, Maryland, USA; ⁴Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, Georgia, USA; ⁵Department of Applied Mathematics and Statistics, The Johns Hopkins University, Baltimore, Maryland, USA; ⁶EnviroSolutions Consulting, Inc., Jasper, Georgia, USA

Abstract
Background: Conventional wisdom regarding exposures to persistent organic chemicals via breast-feeding assumes that concentrations decline over the course of lactation and that the mother’s body burden reflects her cumulative lifetime exposure. Two important implications stemming from these lines of thought are, first, that assessments of early childhood exposures should incorporate decreasing breast milk concentrations over lactation ; and, second, that there is little a breast-feeding mother can do to reduce her infant’s exposures via breast-feeding because of the cumulative nature of these chemicals.

Objectives: We examined rates of elimination and milk/serum partition coefficients for several groups of persistent organic chemicals.

Methods: We collected simultaneous milk and blood samples of 10 women at two times postpartum and additional milk samples without matching blood samples.

Results: Contrary to earlier research, we found that lipid-adjusted concentrations of polybrominated diphenyl ethers, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and furans, and organochlorine pesticides in serum and milk do not consistently decrease during lactation and can increase for some women. Published research has also suggested an approximate 1:1 milk/serum relationship (lipid adjusted) on a population basis for 2,3,7,8-tetrachlorodibenzo-p-dioxin ; however, our results suggest a more complex relationship for persistent, lipophilic chemicals with the milk/serum relationship dependent on chemical class.

Conclusions: Decreases in concentration of lipophilic chemicals on a lipid-adjusted basis during lactation should no longer be assumed. Thus, the concept of pumping and discarding early milk as means of reducing infant exposure is not supported. The hypothesis that persistent lipophilic chemicals, on a lipid-adjusted basis, have consistent concentrations across matrices is likely too simplistic.

Key words: blood, breast milk, depuration, dioxins, elimination kinetics, infant exposure, partitioning, PBDEs, PCBs, pesticides. Environ Health Perspect 117:1625–1631 (2009) . doi:10.1289/ehp.0900876 available via http://dx.doi.org/ [Online 15 June 2009]

Address correspondence to J.S. LaKind, LaKind Associates, LLC, 106 Oakdale Avenue, Catonsville, MD 21228 USA. Telephone/fax: (410) 788-8639. E-mail: lakindassoc@comcast.net

Supplemental Material is available online (doi:10.1289/ehp.0900876.S1 via http://dx.doi.org/) .

The authors are grateful to the mothers for their participation in the study. We would also like to thank C. Dodson (Centers for Disease Control and Prevention) ; S. LaTournous (Hershey Medical Center) ; and A. Covaci, who kindly shared with us data from his study.

Partial support for this research was provided by the Research Foundation for Health and Environmental Effects (RFHEE) , Arlington, VA.

The findings and conclusions in this paper are those of the authors and do not necessarily represent the views of RFHEE or the official position of the Centers for Disease Control and Prevention. Mention of trade names or commercial products does not constitute endorsement or recommendation for use. RFHEE was not involved in the design, collection, management, analysis, or interpretation of the data or in the preparation or approval of the manuscript.

J.S.L. consults to both industry and government and received support from RFHEE for this study. D.G.P. is a consultant for Axys Analytical Solutions, Fluid Management Systems, Inc., and Trium Environmental Solutions. The other authors declare they have no competing financial interests.

Received 8 April 2009 ; accepted 15 June 2009.