1. Department of Family and Community Medicine, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
2. Center for Worker Health, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
3. Department of Family and Community Medicine, Meharry Medical College, Nashville, Tennessee, USA
4. Department of Biostatistical Science, Division of Public Health Sciences, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA
5. Department of Radiology, Wake Forest School of Medicine, Winston-Salem, North Carolina, USA