17β-Estradiol (E2)
Cities measured
87
Detected in
87 / 87
Highest
0.0032 μg/L — Ho Chi Minh City
Overview
17β-Estradiol is the primary natural female sex hormone, excreted by all humans and livestock. It enters water bodies via urine and faeces. It is a potent endocrine-disrupting compound (EDC) at very low concentrations.
Health Relevance
E2 causes feminisation of fish — intersex fish (oviducts in male roach) — at concentrations as low as 1 ng/L in rivers. This has been documented across the UK, Europe, and the US. The contribution of E2 in drinking water to declining human sperm counts and rising reproductive cancers is epidemiologically debated.
Regulatory Limits
Drinking Water Directive 2020/2184
No EU drinking water limit. WHO guideline under review.
Controversy & Contested Science
Between 1973 and 2011, average sperm counts in Western men declined by 50–60% (Levine et al., Human Reproduction Update, 2017). Endocrine disrupting chemicals including E2 in water are proposed as a contributing cause. The 'feminisation of nature' hypothesis argues widespread EDC exposure is an unacknowledged reproductive health crisis. Industry groups dispute the sperm count data and causation. The EU's endocrine disruptor regulatory framework (Regulation 1107/2009; REACH) is among the world's most precautionary for EDCs, but pharmaceutical estrogens remain outside its scope.