Comparing predicted estrogen concentrations with measurements in US waters

Area of Science:

• Environmental Chemistry
• Ecotoxicology
• Water Quality Assessment

Background:

• Steroidal estrogens, including estrone (E1), beta-estradiol (E2), estriol (E3), and ethinyl estradiol (EE2), are commonly found in the aquatic environment.
• Municipal wastewater is a significant source of these endocrine-disrupting compounds.
• Understanding exposure levels is crucial for assessing ecological and human health risks.

Purpose of the Study:

• To model and investigate the range of steroidal estrogen exposure rates in US aquatic environments.
• To compare model predictions with published measured concentrations of estrogens.
• To evaluate potential risks to human and aquatic life from estrogenic compounds.

Main Methods:

• Developed a model to simulate estrogen introduction from municipal wastewater treatment plants across the US.
• Assumed conservative conditions, including no degradation or in-stream dilution.
• Compared model predictions against existing published measured concentrations of E1, E2, E3, and EE2.

Main Results:

• Model predictions generally aligned with most measured estrogen concentrations.
• Certain measurements of beta-estradiol (E2) and ethinyl estradiol (EE2) exceeded model predictions, even under conservative assumptions.
• Fish exposure to E1, E2, and EE2 was found to sometimes substantially exceed chronic no-effect levels, while human exposure remained low.

Conclusions:

• While human exposure to steroidal estrogens from wastewater is generally low, aquatic organisms, particularly fish, face significant risks.
• Elevated concentrations of E2 and EE2 suggest potential underestimation by current models or specific localized sources.
• Further investigation into estrogenic compound fate and transport in aquatic systems is warranted to protect ecological health.