PubMed · 2026-06-30
Researchers in South Korea found that estrogen metabolites from sewage treatment plants accumulate in freshwater fish and remain hormonally active, accounting for far more of the measured estrogenic contamination than the well-known estrogens scientists typically test for. Two compounds, epiestriol and 17-epiestriol, were largely overlooked until now.
Well-known estrogens (estrone, E2, estriol, ethinylestradiol) explained only 27% of estrogenic activity in fish muscle and 11% in eggs, leaving the majority of activity unaccounted for.
17-epiestriol, an estrogen breakdown product produced in sediments and transferred to fish, contributed up to 27% of measured estrogenic activity on its own.
A six-step screening workflow identified 14 candidate compounds; 7 of 11 tested were confirmed as newly recognized estrogen receptor agonists, primarily estrogen metabolites and anabolic agents.