Affiliation: | 1. Marshfield Clinic Department of Medicine-Pediatrics, Marshfield, Wis;2. Essentia Institute of Rural Health, Duluth, Minn;3. Marshfield Clinic Research Foundation, National Farm Medicine Center, Marshfield, Wis;4. University of Wisconsin School of Medicine and Public Health Department of Pediatrics, Madison, Wis;5. Department of Occupational Medicine, Marshfield Clinic, Marshfield, Wis |