Status of brominated flame retardants, polychlorinated biphenyls, and polycyclic aromatic hydrocarbons in air and indoor dust in AFRICA: A review

摘要

While many African countries are signatories of the United Nations’ Environment Programme (UNEP) Stockholm Convention aimed at eradication or reduction of persistent organic pollutants (POPs) in the environment, many such countries have limited financial and technical capacities to either combat the effects of POPs or effect their removal from the environment. Amongst those chemicals listed as POPs under the Stockholm Convention are polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and hexabromocyclododecane (HBCDD). Also of concern are polycyclic aromatic hydrocarbons (PAH), which are listed under the UN Economic Commission for Europe (UN-ECE)’s protocol on long range transboundary air pollution (LRTAP). This review examines the state of knowledge pertaining to concentration levels and trends of these contaminants in air (both indoor and outdoor) and indoor dust in Africa. Despite there being no known manufacture of PBDEs or HBCDD in Africa, concentrations in air of these contaminants in Africa are comparable to those in continents where the chemicals were initially produced and known to be widely used. Insufficient data were available to discern any temporal trend in concentrations of the target contaminants. However, the evidence highlights sources of PCBs, PBDEs, and HBCDD in Africa to include obsolete electrical and electronic equipment and informal handling and treatment of electronic waste. Elevated concentrations of PAHs in air and in indoor dust are evident. Concentrations of PAHs in indoor dust can be significantly influenced by outdoor sources, particularly vehicular emissions leading to higher concentrations in urban settings. With the current and projected increase in African urbanisation and demand for consumer goods, there is substantial potential for concentrations of PBDEs, HBCDD, PCBs, and PAHs to rise in the near future. There is therefore a need for long-term monitoring of concentrations of these chemicals in air and indoor dust at a range of locations across the African continent. This should be designed to assess spatial trends and human exposure via inhalation and incidental dust ingestion, as well as facilitating elucidation of temporal trends of POPs in Africa and evaluation of the impacts of measures to reduce concentrations.