All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Loren Hopkins reports an honorarium from Baylor College of Medicine for speaking at a conference. Lauren B. Stadler reports institutional support from the National Science Foundation to purchase laboratory equipment and from the Houston Health Department. Katherine Ensor reports institutional support from the Houston Health Department for analysis of samples, unpaid presidency of the American Statistical Association, and unpaid membership on the Institute of Pure and Applied Mathematics Board of Trustees. John J. Dennehy reports institutional support from the New York City Department of Environmental Protection and research reagents from Qiagen, Inc. Davida S. Smyth reports support from the City University of New York and the Department of Environmental Protection, and support from the National Science Foundation outside the current work. Monica Trujillo reports contract support from the New York City Department of Environmental Protection. Devon A. Gregory reports a grant from the National Institutes of Health (NIH). Marc C. Johnson reports a grant from NIH. Allison Wheeler reports support from the Colorado Department of Public Health and Environment. Bradley J. White reports paid employment by Verily Life Sciences, and stock ownership in Verily Life Sciences as part of compensation. Marlene K. Wolfe reports consulting fees from Verily Life Sciences. No other potential conflicts of interest were disclosed.