Oestrogenic activity of a textile industrial wastewater treatment plant effluent evaluated by the E-screen test and MELN gene-reporter luciferase assay

This study quantified the biological oestrogenic activity in the effluent of a textile industrial wastewater treatment plant (IWWTP) in northwestern Italy. Samples of the IWWTP effluent were collected monthly, both before and after tertiary treatment (ozonation). After solid phase extraction, all samples were subjected to two in vitro tests of total estrogenic activity, the human breast cancer cell line (MCF-7 BUS) proliferation assay, or E-screen test, and the luciferase-transfected human breast cancer cell line (MELN) gene-reporter assay, to measure the 17β-oestradiol equivalent quantity (EEQ). In the E-screen test, the mean EEQ values were 2.35±1.68 ng/L pre-ozonation and 0.72±0.58 ng/L post-ozonation; in the MELN gene-reporter luciferase assay, the mean EEQ values were 4.18±3.54 ng/L pre-ozonation and 2.53±2.48 ng/L post-ozonation. These results suggest that the post-ozonation IWWTP effluent had a lower oestrogenic activity (simple paired t-tests, p<0.05). The average reduction of estrogenic activity of IWWTP effluent after ozonation was 67±26% and 52±27% as measured by E-screen test and MELN gene-reporter luciferase assay, respectively. There was a positive and significant correlation between the two tests (Rho S=0.650, p=0.022). This study indicates that the environmental risk is low because oestrogenic substances are deposited into the river via IWWTP at concentrations lower than those at which chronic exposure has been reported to affect the endocrine system of living organisms.