Predictive modelling of steroid oestrogens in sewage effluent and rivers demonstrates the potential for endocrine disruptive effects in wild fish populations in South Australia

Endocrine disruption in wild fish has been well characterised in the UK where it has been linked to sewage treatment works (STW) effluent containing the steroid oestrogens: 17β-oestradiol (E2), oestrone (E1) and 17α-ethinylestradiol (EE2). In Australia, they have been detected in effluents at concentrations similar to those found in the UK and there is some evidence of endocrine disruptive effects in fish downstream of STW’s (Batty and Lim, 1999). This study is the first to use predictive modelling to assess the concentrations of steroid oestrogens in South Australian STW effluents and the Onkaparinga River as a preliminary risk assessment for wild fish populations. The predicted concentrations in STW effluents and the receiving rivers in South Australia were comparable to those in the UK and when the models were modified to project scenarios under climate change and population growth for 2050, there was generally an increase in the average concentrations in both countries. Under both present day and future scenarios, effluent discharge on the Onkaparinga River in South Australia is projected to cause concentrations of steroid oestrogens in receiving waters exceeding the 1ng/L combined EEQ PNEC, suggesting that without sufficient mitigation there is a risk of endocrine disruptive effects occurring in wild fish populations.