The Interplay Between Environmental Chemical Exposures and Obesity: Proceedings of a Workshop (2016)

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1 Introduction1 On March 2 and 3, 2015, the National Academies of Sciences, Engineering, and Medicine’s Roundtable on Environmental Health Sciences, Research, and Medicine held a workshop to explore the role that chemical exposures may play in the development of obesity. The obesity epidemic that has gripped the United States and much of the developed world for the past several decades has proved remarkably resistant to the various approaches tried by clinicians and public health officials to fight it. This raises the possibility that, in addition to the continued exploration of consumer understanding and behavior, new approaches that go beyond the standard focus on energy intake and expenditure may also be needed to combat the multifactorial problem of obesity. The workshop statement of task is provided in Box 1-1. The speakers at the workshop discussed evidence from both studies with animal models and human epidemiological studies that exposure to environmental chemicals is linked both to weight gain and to glucose tolerance, insulin sensitivity, inflammation, and other aspects of the metabolic syndrome. In addition to conventional environmental chemical exposures, the planning committee for this workshop included one panel to discuss the potential role of other exposures, including sugar, artificial sweeteners, and antibiotics, in aiding or causing obesity. The speakers also examined possible biological pathways and mechanisms underlying the potential linkages. 1 The planning committee’s role was limited to planning the workshop, and this Proceedings of a Workshop has been prepared by the workshop rapporteur as a factual summary of what occurred at the workshop. Statements, recom- mendations, and opinions expressed are those of individual presenters and participants and are not necessarily endorsed or verified by the National Academies of Sciences, Engineering, and Medicine, and they should not be construed as reflecting any group consensus. 1 

2 ENVIRONMENTAL CHEMICAL EXPOSURES AND OBESITY BOX 1-1 Statement of Task An ad hoc committee will plan and conduct a public workshop featuring presentations and discussions to outline current scientific understanding of the effect of environmental chemical exposures on the development of obesity and of potential preventive interventions. The committee will identify specific topics to be addressed, develop the agenda, select and invite speakers and other participants, and moderate the discussions. An individually authored summary of the presentations and discussions at the workshop will be prepared by a designated rapporteur in accordance with institutional guidelines. After hearing about the present state of the science of environmental exposures and obesity, the speakers discussed future research needs and offered suggestions for policies that could reduce the health and human costs of the current epidemic of obesity. The workshop did not focus broadly on public health interventions to treat or prevent obesity. The workshop audience, which took part in the discussions, included both attendees at the workshop, which was held at the National Institute of Environmental Health Sciences in Research Triangle Park, North Carolina, and also people who watched via a webcast and who were able to submit questions to the speakers through the workshop’s website. This workshop, The Interplay Between Environmental Exposures and Obesity, was one in a series of workshops focused on current and emerging environmental issues and their impacts on human health. These workshops are sponsored by the Roundtable on Environmental Health Sciences, Research, and Medicine. The Roundtable was established in 1998 to provide a mechanism for parties from academic programs, consumer interest groups, government agencies, and industry to convene and discuss sensitive and difficult environmental public health issues. The purpose is to share perspectives and foster rigorous dialogue but not to provide recommendations. The following is a summary and synthesis of the presentations and discussions that took place during the 2 days of the workshop. When reading this Proceedings of a Workshop, it is important to keep in mind that the opinions expressed and any recommendations made are those of the individual speakers themselves and do not represent the position of the Academies. Indeed, the purpose of the Roundtable is to provide a mechanism for interested parties in environmental health to meet and discuss sensitive and difficult environmental issues in a neutral setting. The 

INTRODUCTION 3 Roundtable fosters dialogue about these issues, but it does not provide recommendations or even try to find a consensus on these issues. ORGANIZATION OF THIS PROCEEDINGS OF A WORKSHOP The organization of this Proceedings of a Workshop follows the structure of the workshop’s proceedings. Chapter 2 describes the presentations and discussions during Session 1 of the workshop that focused on framing the issue of obesity from both the public health and the environmental health perspectives. Chapter 3 summarizes the presentations and discussions during Session 2 of the workshop, which explored the role of chemical exposures and obesity over the life span. Chapter 4 covers presentations on the biological pathways and environmental influences as well as the subsequent discussions that occurred in the workshop’s third session. Chapter 5 summarizes the presentations and discussions from Session 4 of the workshop on emerging evidence on other exposures that may play a role in the development of obesity. Chapter 6 includes the presentations and discussions from the workshop’s fifth session discussing future research needs. Finally, Chapter 7 recaps the discussions from the workshop’s final session, Session 6, which covered potential policy solutions to obesity discussed at the workshop. The workshop agenda is found in Appendix A, and biographical sketches of the workshop speakers are included in Appendix B.