A new study assessed the dangers linked with pharmaceutical contaminants in water in the United Kingdom, where scientists found cocaine still present even after water went through a thorough process of purification.

Tap water was inspected at four different areas and it showed a metabolized form of cocaine, an illegal drug, which appears to have already passed through a human body. Such a drug is called benzoylecgonine, a form generated once cocaine has already been processed by a human body. The Drinking Water Inspectorate found it at all four sites.

Public Health England assessed the risk of the pharmaceuticals found in Britain's water supply and reported that the amount of cocaine was at about a quarter of what appeared prior the treatment. Four nanograms of the drug per liter is unlikely represent any danger to the public, the agency said.

"Intakes of the compounds detected in drinking water are many orders of magnitude lower than levels of therapeutic doses. Estimated exposures for most of the detected compounds are at least thousands of times below doses seen to produce adverse effects in animals and hundreds of thousands below human therapeutic doses," the report said.

The benzoylecgonine levels were so low that the amount did not pose a danger to health, but this finding is an indication of how prevalent cocaine use in the UK has become. Steve Rolls, of the drug-policy think tank Transform, said Britain has almost the highest level of cocaine use in the western part of Europe. Because use is going up, the drug is becoming cheaper.

Aside from benzoylecgonine, the inspectors found other drugs in the water. Traces of a drug for epilepsy treatment, carbamazepine, and the pain-killer ibuprofen were also found. Inspectors also found the drinking water it contained high amounts of caffeine as well.

The United Nations Office on Drugs and Crime says that one in 20 teenagers aged 16 to 24 in Britain have already tried cocaine. The number of patients in cocaine addiction treatment in the United Kingdom increased from 10,770 in 2006-2007 to 12,592 in 2007-2008. It estimates almost 700,000 people from 16 to 59 years old take the illegal drug each year. St. George's University in London reported in February that cocaine was the cause of death for 115 British people in 2012. Other drug-related causes killed 1,700 people in the same year.