Diclofenac
Cities measured
87
Detected in
87 / 87
Highest
0.082 μg/L — Cairo
Overview
Diclofenac is a widely used NSAID anti-inflammatory drug considered a persistent pharmaceutical pollutant — it resists conventional biological wastewater treatment (20–40% removal). It was placed on the EU Priority Substances Watch List in 2015.
Health Relevance
Environmentally, diclofenac caused catastrophic vulture population collapses in South Asia in the 1990s–2000s: veterinary diclofenac accumulated in livestock carcasses, causing fatal renal failure in vultures. Over 95% of vulture populations in India, Pakistan, and Nepal were lost within a decade.
Regulatory Limits
Drinking Water Directive 2020/2184
No EU drinking water limit. On EU Watch List since 2015.
Controversy & Contested Science
The South Asian vulture crisis is one of the most dramatic pharmaceutical pollution disasters — 40 million birds lost in 10 years. The cause was identified only in 2004. India banned veterinary diclofenac in 2006, but illegal use continues. Related NSAIDs (ketoprofen, aceclofenac) filled the gap. In Europe, diclofenac is among the pharmaceuticals most frequently detected in rivers, yet no binding limit exists. The regulatory gap reflects the difficulty of simultaneously risk-assessing hundreds of pharmaceuticals — each requiring expensive toxicological and epidemiological evaluation.