Improving the risk assessment of lipophilic persistent environmental chemicals in breast milk

Abstract

Lipophilic persistent environmental chemicals (LPECs) have the potential to accumulate within a woman's body lipids over the course of many years prior to pregnancy, to partition into human milk, and to transfer to infants upon breastfeeding. As a result of this accumulation and partitioning, a breastfeeding infant's intake of these LPECs may be much greater than his/her mother's average daily exposure. Because the developmental period sets the stage for lifelong health, it is important to be able to accurately assess chemical exposures in early life. In many cases, current human health risk assessment methods do not account for differences between maternal and infant exposures to LPECs or for lifestage-specific effects of exposure to these chemicals. Because of their persistence and accumulation in body lipids and partitioning into breast milk, LPECs present unique challenges for each component of the human health risk assessment process, including hazard identification, dose–response assessment, and exposure assessment. Specific biological modeling approaches are available to support both dose–response and exposure assessment for lactational exposures to LPECs. Yet, lack of data limits the application of these approaches. The goal of this review is to outline the available approaches and to identify key issues that, if addressed, could improve efforts to apply these approaches to risk assessment of lactational exposure to these chemicals.

Keywords:

• children
• exposure
• PBT chemicals
• persistent organic pollutants
• POPs
• research needs
• risk assessment
• uncertainty

Acknowledgements

Appreciation is expressed to Rebecca Dzubow, Susan Makris, Lyle Burgoon, and John Vandenberg (U.S. EPA) for providing a thorough review of the draft manuscript, to Audrey Turley (ICF International) for workshop planning, facilitation, and support, to Penny Kellar and Whitney Kihlstrom (ICF International) for technical editing and workshop support, to Kristen Fedak (ICF International) for research, technical writing, and workshop support, to Susan Knadle (California Environmental Protection Agency), Wilfried Karmaus (University of South Carolina), Walter Rogan and Paul Foster (National Institute of Environmental Health Sciences) for workshop participation, and to Anu Mudipalli and Sheppard Martin (U.S. EPA) for review of workshop briefing materials.

Declaration of interest

The employment affiliation of the authors is shown on the cover page. The following authors were participants in a multidisciplinary workshop that served as the basis for this review paper: MAV, SAA, JSL, MHD, SH, MPL, MTP, DGF, YMT, SKS, CW, JCS, JLC, WGF, BMF, RSHY, JBB, HAE, SEF, JES, and RT. Some workshop participants chose not to participate as authors in the development of this review. Those individuals are acknowledged in the preceding section. The workshop was co-chaired by GML and EDM. ICF International organized the workshop under contract from the U.S. EPA (Contract No. EP-C-09-009, Work Assignments 2-62, 3-62, and 4-62). Workshop organization functions performed by ICF International included the independent identification and selection of workshop participants. ICF International is a for-profit firm providing professional services and technology solutions to clients in the following markets: energy, environment, and infrastructure; health, social programs, and consumer/financial; and public safety and defense. ICF International provides these services to both government and private sector clients. This research was also supported [in part] by the Intramural Research Program of the National Institutes of Health (NIH), National Institute of Environmental Health Sciences (NIEHS). The following workshop participants received support for travel and/or lodging: MAV, SAA, JSL, MHD, SH, MTP, DGF, SKS, WGF, BMF, RSHY, and JBB. MAV, SH, SKS, JLC, WGF, BMF, RSHY, JBB, and JSL received an honorarium for their participation in the workshop. LaKind Associates is a private consulting firm specializing in strategic risk management, assessment of human exposures and health risks, biomonitoring, state-of-the-science reviews, and environmental regulatory review; LaKind Associates consults to governmental and private sectors. The Hamner Institutes for Health Sciences is a nonprofit research institute with a primary focus on drug and chemical safety, including the development of methods to improve human health risk assessment. This paper has been reviewed in accordance with the peer and administrative review policies of the U.S. EPA, Food and Drug Administration (FDA), NIEHS, and Agency for Toxic Substances and Disease Registry (ATSDR) and approved for publication. The views expressed in this report are those of the authors and do not necessarily reflect the opinions and/or policies of the U.S. EPA, FDA, NIEHS or ATSDR. The remaining authors are all employees of either state governments or various academic institutions. Many of the academic scientists participating in the workshop and authoring this paper have received financial support for their research programs from the U.S. EPA and/or the NIH. All authors have sole responsibility as individual scientists for the writing and content of this review. The views, conclusions and recommendations are not necessarily those of their employers.