Preliminary assessment of oestrogenic activity in water sources in Rietvlei Nature Reserve, Gauteng, South Africa

Abstract

A preliminary assessment was made of oestrogenic activity in water sources in the Rietvlei Nature Reserve, from which water is supplied to the metropolitan area of Pretoria. Single samples were extracted from seven sites using a solid phase C18 cartridge and the extracts assessed for oestrogenic activity using the Recombinant Yeast Screen bio-assay. Estradiol equivalents ranged from 0.31–2.1 ng l⁻¹, which are comparable to those reported for rivers near Paris (1.0–32 ng l⁻¹) and for environmental water in Korea (0.5 pg l⁻¹ and 7.4 ng l⁻¹). The oestrogenic activity found in Rietvlei water samples is supported by a report of intersex in catfish, Clarias gariepinus, in the reserve. Further studies are required to determine whether this phenomenon is consistent, to determine the chemical(s) responsible for this activity and to characterise the potential effects on human, aquatic, and wildlife health in the area.