CANBERRA, Oct. 24 (Xinhua) -- The South Australian capital, Adelaide, has recorded the highest methamphetamine use of all the cities in the world tested via wastewater samples.
Adelaide, Canberra and Toowoomba were the three Australian cities out of 120 worldwide to have their sewage monitored in the study of 60 million people between 2011 and 2017.
The results, published in the journal "Addiction" on Wednesday, were part of the largest wastewater-based study undertaken in the world.
In 2017, Adelaide's wastewater revealed between 507 and 659 mg of methamphetamine -- or "ice" per 1,000 people each day, compared with between 270 and 331 mg in Canberra and Toowoomba.
The only foreign city to come close was Seattle, with 418 mg on average over the three years of the city's tested wastewater. It was the only U.S. city to be part of the study, which mainly focused on Europe.
Researchers from 41 international institutions, including the University of South Australia and University of Queensland, mapped the use of amphetamine, methamphetamine, ecstasy and cocaine.
The highest cocaine levels were in the British cities of London and Bristol, Amsterdam in the Netherlands, Antwerp in Belgium, Zurich, Geneva and St. Gallen in Switzerland.
Amphetamine use was highest in Belgium and the Netherlands, which was also the highest for ecstasy, also known as MDMA.
The study's authors found the wastewater results generally matched with other methods of estimating drug use, such as surveys and seizures by authorities.
They found wastewater testing "provides updated and objective estimates of drug use and allows identifying and highlighting new trends and specific profiles of use much earlier" than other indicators.
University of South Australia research associate Richard Bade was one of the lead authors of the study.
Bade told the Australian Broadcasting Corporation (ABC) on Thursday that methamphetamine use was linked to several health conditions, including mental disorders, elevated heart rates and domestic violence.
"It's important we determine the scale of the illicit drug market so that countries can work out the best way to tackle a 100 billion dollars industry, which is contributing to the global burden of disease and affecting the economic development of many countries," he told the ABC.
He said the study did not necessarily find that Adelaide was the world leader in methamphetamine use because many countries and cities were not involved in the study. "To put into a bit of context, the study was from 2017 and in fact since that time methamphetamine use in South Australia has actually been on the decrease," Bade said.