Fish in seas near the Norwegian Arctic city of Tromsoe are getting an unexpectedly strong cocktail of caffeine and painkillers from local sewers, a study has found.
Some samples taken very close to a sewer outlet near a psychiatric hospital also showed measurable amounts of anti-epileptic drugs and anti-depressants.
"We don't know what effect this is having on the environment," said Mr Ole-Anders Braathen, head of department at the Norwegian Institute of Air Research which led the study.
The study showed traces of caffeine from human drinks like coffee and cola at 20-80 nanograms (billionth of a gram) per litre in seas off Tromsoe.
Mr Braathen said the sea water contained measurable traces of ibuprofen, an anti-inflammatory drug often used to treat arthritis.
He said levels of pharmaceutical residues matched those expected for a European city three times the size.