1. a Department of Chemical Technology , University of Johannesburg , P.O. Box 17011 Doornfontein 2028, Johannesburg , South Africa
2. b Food, Environment and Health Research Group , Faculty of Health Sciences, University of Johannesburg , P.O. Box 17011, Doornfontein 2028 , Johannesburg , South Africa
3. c Water and Health Research Unit, Faculty of Health Sciences , University of Johannesburg , P.O. Box 17011, Doornfontein 2028 , Johannesburg , South Africa