Nitrate
Cities measured
87
Detected in
87 / 87
Elevated / alert
2
EU limit
50 mg/L
Highest
32 mg/L — Accra
Overview
Nitrate is the most widespread agricultural contaminant in European groundwater, entering water from fertilisers, manure, and sewage. Stockholm's tap water (from Lake Mälaren) is relatively protected from agricultural runoff and has low nitrate concentrations.
Health Relevance
In infants under six months, nitrite (converted from ingested nitrate) can bind haemoglobin, reducing oxygen transport — 'blue baby syndrome' (methemoglobinaemia). In adults, nitrate is a precursor to carcinogenic N-nitrosamines.
Regulatory Limits
Drinking Water Directive 2020/2184
50 mg/L (EU Directive and WHO).
Controversy & Contested Science
The 50 mg/L EU limit was set in the 1970s based on infant methemoglobinaemia data — not designed to address long-term cancer risk. A 2018 IARC Monograph classified ingested nitrate as Group 2A (probably carcinogenic) under conditions enabling endogenous nitrosation. Danish and Finnish cohort studies have found elevated colorectal cancer risk at nitrate exposures well below the EU limit, including at 3.87 mg/L/day. Industry groups representing fertiliser manufacturers have lobbied extensively against tightening the limit. An EU EFSA reassessment is ongoing.