Screening estrogenic oxidized by-products by combining ER binding and ultrafiltration

Area of Science:

• Environmental Chemistry
• Toxicology
• Endocrinology

Background:

• Endocrine disrupting chemicals (EDCs) such as 17β-estradiol (E2), 17α-ethynylestradiol (EE2), bisphenol A (BPA), and nonylphenol (NP) pose risks to environmental and human health.
• Understanding the transformation products of EDCs during water treatment processes like ozonation and chlorination is crucial for assessing residual risks.

Purpose of the Study:

• To investigate the estrogenic activity of by-products generated from the ozonation and chlorination of four common EDCs.
• To identify and characterize specific chlorinated by-products of BPA and NP with retained estrogenic activity.

Main Methods:

• Oxidation of E2, EE2, BPA, and NP using ozonation and chlorination.
• In vitro estrogenic activity testing using MCF-7 cell proliferation assay.
• Identification of estrogenic by-products using estrogen receptor (ER) binding with ultrafiltration and liquid chromatography-mass spectrometry (LC/MS).

Main Results:

• Chlorination of BPA resulted in by-products with slightly increased estrogenicity compared to BPA.
• Chlorinated nonylphenol retained approximately 10% of its original estrogenic bioactivity.
• Ozonation of all four EDCs and chlorination of E2 and EE2 significantly reduced their estrogenic activities.

Conclusions:

• The study identified specific chlorinated by-products of BPA and NP that retain estrogenic activity.
• Ozonation appears to be an effective method for reducing the estrogenicity of these EDCs.
• Further research is needed to fully understand the environmental and health implications of EDC by-products from chlorination.