Waste streams as current sources of persistent organic pollutants and organophosphate esters in Africa - a critical review

Per- and polyfluoroalkyl substances, chlorinated paraffins, brominated flame retardants, polychlorinated biphenyls and mirex are regulated under the United Nations Environment Programme’s (UNEP’s) Stockholm Convention on Persistent Organic Pollutants (POPs) intended for the eradication of hazardous contaminants in the environment. There is also a major concern for organophosphate esters and specific alternative or novel brominated flame retardants. To date, no evidence exists that major producers of these chemicals occur on the African continent. They are understood to find their way into African environments through the import of commercial products, in particular products with second-hand value and short lifespans, which may enter waste streams in a relatively shorter period. To further understand the current levels of these selected contaminants in African waste streams, existing documents capturing various African waste stream compartments for the above outlined targeted contaminants were gathered from an exhaustive literature review. Key factors influencing the transfer of contaminants from waste or elevated concentrations of contaminants in African waste streams are associated with the nature and/or sources of contaminants, volume of contaminants or waste in relation to the capacity of treatment plants/landfills, condition or age of treatment plants/landfill geomembrane liner, model adopted for contaminants removal and treatment procedures for collected sludges or leachates. Evidence from the selected studies indicates substantial POP contamination in African landfills and dumpsites, wastewater effluents/sludge and human/biological samples around dumpsites and landfills. Unfortunately, the continent has inadequate infrastructural capacity to adequately handle POP in the waste streams. This review provides recommendations and suggestions for future studies.