Funding for this research was provided by:
National Center for Research Resources (UL1RR024979, KO1HL080966)
National Institute of Environmental Health Sciences (P30 ES005605)
National Institute of Allergy and Infectious Diseases (NO1-AI-30040-01)
Center for Health Effects of Environmental Contamination Seed Grants (FY 2010)
Received: 21 October 2017
Accepted: 5 March 2018
First Online: 10 March 2018
Ethics approval and consent to participate
: The sample collection was approved by the Institutional Review Board at the University of Iowa (IRB# 200607708). Voluntary participants signed an informed consent before enrollment.
: This study does not contain individual person’s data.
: The authors have no competing financial interests to disclose.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.