aOccupational Medicine Division and Centre for Environmental & Occupational Health Research, School of Public Health, University of Cape Town

bDepartment of Environmental and Occupational Studies, Faculty of Applied Sciences, Cape Peninsula University of Technology (CPUT), Cape Town, South Africa

cDepartment of Community Health, Faculty of Medicine, Eduardo Mondlane University, Maputo, Mozambique

Correspondence to Mohamed F. Jeebhay, Occupational Medicine Division and Centre for Environmental & Occupational Health Research, School of Public Health, University of Cape Town, Room 4, 45, Fourth Level, Falmouth Building, Anzio Road, Observatory 7925, South Africa. Tel: +27 21 4066309; fax: +27 21 4066459; e-mail: [email protected]