1. Environment & Health Research Unit, South African Medical Research Council, Johannesburg, South Africa
2. Faculty of Health Sciences, School of Public Health, University of the Witwatersrand, Johannesburg, South Africa
3. Faculty of Health Sciences, Environmental Health Department, University of Johannesburg, Johannesburg, South Africa
4. Physical Address: South African Medical Research Council, Health Clinic Building, corner of Beit and Sherwell Streets, Doornfontein, 2028 (Johannesburg), South Africa.
5. Faculty of Humanities, Psychology Department, University of Johannesburg, Johannesburg, South Africa
6. School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa