Effects of salinity pH and temperature on the Octanol-water partition co-efficient of Bisphenol A

Bisphenol A (BPA) has been widely used as an industrial plasticizer and is considered an endocrine disrupting chemical (EDC). BPA can be released into the aquatic environment and magnify in the food chain, resulting in human exposure. To understand and predict the environmental fate and toxicity in the aquatic environment, the octanol-water partition coefficient (Kow) was determined at various salinity, pH and temperatures using the OECD guideline 107 shake flask method. With increasing salinity the log Kow of BPA at 25˚C increased from 3.44 to 3.55. The log Kow also changed at different pH, it decreased at pH > pKa, at pH between 6 and 8 a small increase (from 3.39 – 3.47) was observed which was then followed by a decrease at pH 10 (to 2.99). Increasing temperatures (between 25°C and 45°C) affect log Kow leading to decreased log Kow values (3.42 to 3.18). The log Kow for the natural seawater (salinity 29 psu and pH 8) was also determined at 3.52. The experimental and the default values were input into the prediction program EPI Suite™, which was used to assess environmental fate and toxicity of BPA. Using the experimental values enables a more accurate model for site specific samples can be defined. The model using the experimental Kow values of natural seawater indicated higher bioaccumulation and higher sediment adsorption but slightly lower aquatic toxicity than the default values. These findings imply that BPA in the marine environment is more bioaccumulative therefore has a greater biomagnification potential in fish species, particularly benthic feeders. This may adversely impact on human health and prove detrimental to humans that consume these marine species compared to similar species from a freshwater environment.