Add to ORKGI am grateful to the Almighty God for providing me with an opportunity to complete my studies. I would like to thank my supervisor Professor JD Donaldson for his guidance and support throughout the research. I also give my deepest thanks to Dr P. Barnard for his environmental chemistry skills, guidance, patience and encouragement over this research and the maintenance of a lively and friendly atmosphere. My sincere thanks are expressed to Mr B. Wheals and Dr D. Dick for their contribution in the development of this work and to Mr S. A Mirhassani for help in interpretation statistical results. Special thanks go to my wife for her patience on staying with me over my research. It is most important to thank from the Ministry of Health and Medic...