1. Department of Environmental Health Sciences; University of Michigan School of Public Health; Ann Arbor Michigan
2. Diagnostic Medicine, Claremont; Cape Town South Africa
3. Faculty of Health Sciences, School of Public Health and Family Medicine; University of Cape Town; Cape Town South Africa
4. Department of Radiology; Charlotte Maxeke Johannesburg Academic Hospital; Parktown Johannesburg South Africa
5. Faculty of Health Sciences; University of the Witwatersrand; Johannesburg South Africa
6. Medical Bureau of Occupational Diseases; Braamfontein Johannesburg South Africa
7. Dr SK Matseke Memorial Private Hospital; Diepkloof Soweto South Africa
8. Department of Radiology; University of Wisconsin School of Medicine and Public Health; Madison Wisconsin
9. Department of Environmental Health, Pulmonary Medicine; Department of Internal Medicine; University of Cincinnati; Cincinnati Ohio