1. Faculty of Medicine, School of Public Health, University of Kinshasa (UNIKIN), Kinshasa I, Democratic Republic of the Congo;
2. Department F.-A, Forel for Environmental and Aquatic Sciences and Institute of Environmental Sciences, Earth and Environmental Science Section, Faculty of Science, University of Geneva, Geneva 4, Switzerland;
3. Croisement Route de Matadi et Avenue de la Libération, Quartier Binza/UPN, National Pedagogic University (UPN), Kinshasa, Democratic Republic of the Congo;
4. Earth and Environmental Section, University of Geneva, Geneva, Switzerland;
5. Department of Chemistry, Faculty of Sciences, University of Kinshasa (UNIKIN), Kinshasa XI, Democratic Republic of the Congo