Evidence of gross contamination of surface water from Jukskei River, South Africa with hexabromocyclododecane (HBCDD) and tetrabromobisphenol A (TBBPA) flame retardants

Brominated flame retardants (BFRs) such as polybrominated diphenyl ethers (PBDEs), hexabromocyclododecane (HBCDD) and tetrabromobisphenol A (TBBPA) are important industrial chemicals that have been widely employed for fire retardation purposes in different applications. HBCDD, for instance, consists of three major diastereoisomers, namely: α, β and γ, and it is primarily used as additive flame retardant in extruded and expanded polystyrene that is commonly used for thermal insulation in buildings, and sometimes in upholstery textiles [1]. On the other hand, TBBPA is often used either as a reactive or additive flame retardants in polymeric materials during manufacturing processes. Its major area of application is in the electronic circuit boards of electrical and electronic appliances. Regardless of their areas of application, both HBCDD and TBBPA may be released from treated products, thus resulting in the widespread contamination of the environment. Because of its environmental persistence, toxicity, bioaccumulation potential and its propensity to undergo long-range atmospheric transport, like pentaand octa-BDE commercial formulations, the HBCDD technical formulation has been globally restricted. Among the legacy BFRs, only TBBPA and decaBDE technical formulations are still being produced and used. In South Africa, there are no information on the production and usage of these BFRs. It is, however, assumed that imported raw materials for local industries and other imported items containing these chemicals are the only means through which these chemicals get into the country [2, 3]. With the growing economic instability within the Southern African region, more immigrants are constantly migrating to South Africa for economic opportunities. The resultant effects of these migration trend include exertion of high pressure on limited infrastructural facilities and the generation of large quantities of waste streams. These problems are particularly exacerbated in informal settlements which are characterized with old-fashioned consumer products such as furniture, carpets, electronic and electrical appliances, which are suspected to contain these chemicals. In particular, the establishment of these informal settlements along the banks of inland rivers within the city is contributing to the declining quality of these freshwater systems because obsolete items and other waste materials are often dumped along the banks of the rivers. It therefore becomes imperative to investigate the potential impacts of these activities with respect to the release of BFRs along the catchment of these inland rivers. The location of the Jukskei River and its direction of flow provide unique opportunity to assess the impacts of associated activities in informal settlements situated along its banks on its water quality. Besides the contamination of the river by the influx of greywater from the informal settlements, the river also serves as a major conveyance of urban run-off and discharged effluents. During the periods of high precipitation, which coincides with the summer season, large quantities of debris are often transported into the river channel via urban run-off from the adjacent informal settlements. Under these circumstances, it becomes necessary to characterize the surface water of the impacted river during periods of low and high precipitations so that the contributions of the identified sources can be evaluated. For hydrophobic substances such as HBCDD and TBBPA, their presence in surface water at relatively high concentrations may be indicative of fresh release from local sources. Given their strong affinity to solids, these chemicals are expected to significantly accumulate in bottom sediment in aquatic systems. Since previous studies were specifically focused on the assessment of PBDEs concentrations in the investigated river [4, 5], we aimed to assess the degree of contamination of surface water from the Jukskei River with respect to the levels of both HBCDD and TBBPA with a view to identify the potential hotspots of these contaminants along the watercourse of the river.