1. Department of Pharmacology, Faculty of Health Sciences, University of Pretoria , Pretoria , South Africa
2. Toxicology Section, National Institute for Occupational Health, National Health Laboratory Service , Johannesburg , South Africa
3. Molecular Medicine and Haematology, School of Pathology, University of Witwatersrand , Johannesburg , South Africa
4. Water Research Group, Unit for Environmental Sciences and Management, North-West University , Potchefstroom , South Africa