Bioaccumulation of persistent organic pollutants and their trophic transfer through the food web: human health risks to the rural communities reliant on fish from South Africa's largest floodplain

Abstract

The Phongolo River Floodplain (PRF) is South Africa's largest floodplain, unique in being the only large floodplain able to sustain permanent waters throughout the dry season (Kyle, 2002). This highly productive region contains around 90 floodplain associated pans which are rich in biodiversity and is known to be of high ecological and socio-economic importance (Dube et al., 2017). The floodplain is surrounded by informal settlements and rural communities which are reliant on these aquatic resources, not only for domestic use or agricultural purposes such as watering livestock and subsistence farming, but also for subsistence fisheries as a source of protein (Coetzee et al., 2015). A recent study by Coetzee et al. (2015) indicated that several fish species in the study area are important sources of protein within artisanal fishery practices. Contamination due to the introduction of pesticides into aquatic ecosystems is of great concern, as many banned (World Health Organisation (WHO, 2002)) organochlorine pesticides (OCPs) are persistent in the environment and this is reflected by the fact that although many OCPs are no longer used, they still remain present in many, if not all aquatic ecosystems (Gerber et al., 2016). Implementation of effective long term management plans rely directly on fully understanding chemical compounds as well as their risks to both ecosystems and humans, where these aspects can be assessed using; (1) stable isotopes and trophic magnification factors (TMF's) and (2) human health risk assessments via exposure through consumption (Verhaert et al., 2013, Verhaert et al., 2017).