OCCURRENCE AND LEVELS OF THE ENDOCRINE DISRUPTOR BISPHENOL-A IN OSE, OWENA AND ALA RIVERS, ONDO STATE.

Abstract

Endocrine-disrupting compounds (EDC) are of great concern with regards to their potential effects on humans and aquatic life. This study investigated the occurrence and levels of an EDC, bisphenol-A (BPA), in water and sediments of Ose, Owena and Ala rivers in Southwestern Nigeria. Water and corresponding sediment samples were obtained from 5 locations on each river, with successive locations separated by a distance of about 1 km. Physico-chemical characteristics of the water and sediment samples were determined, and extraction of BPA from water (liquid-liquid extraction) and sediment (centrifugation) was carried out with dichloromethane and a 2:1 mixture of dichloromethane/n-hexane, respectively. The extracts were derivatized with Sigma Sil-A and analysed with gas chromatography - mass spectrometry (GC-MS) instrument. BPA was detected in all the samples, at values ranging from 0.41-5.19 µg/L in water and 0.64-10.6 µg/kg in sediments. For the majority (87%) of all the sampling points on the Rivers, BPA concentrations in the sediment samples were higher than that in the corresponding water samples. Detection of BPA in the rivers revealed an exposure route of humans and cattle to BPA in the studied locations. Concentrations of BPA in the River waters showed a strong association with chemical oxygen demand (COD) values, while no association was obtained between BPA concentrations in sediments and the physico-chemical properties of the sediments.