Researchers in South Korea found an 'astonishingly large amount of Viagra' in wastewater near nightlife hot spots in Seoul

• Researchers found unexpectedly high levels of erectile-dysfunction drugs in wastewater in Seoul.
• Levels were three to four times those found in Brussels and two to five times those in Copenhagen.
• Use of erectile-dysfunction drugs appeared to spike on weekends and in nightlife hot spots.

Researchers found abnormally high concentrations of Viagra and other erectile-dysfunction drugs in the wastewater in Seoul, South Korea, according to a study published in Scientific Reports earlier this month.

The use of such drugs appeared to spike on weekends and in nightlife hot spots, the study found. Researchers estimated use was 31% higher in nightlife areas than in other parts of the city. The levels of the drug sildenafil - more commonly known by the brand name Viagra - detected in Seoul's wastewater were roughly three to four times those found in Brussels and two to five times those in Copenhagen, researchers said.

The levels of the erectile-dysfunction drugs were so high that the sewage-treatments plants were unable to properly filter them out of the wastewater, researchers said in the study.

"The point is that existing sewage facilities are not suitable to filter out drugs consumed by humans and an astonishingly large amount of Viagra was detected in wastewater," Kim Hyunook, a professor at the University of Seoul's environmental engineering school who was one of the authors of the study, told the South China Morning Post.

The researchers analyzed water samples from two sewage-treatment plants in Seoul to measure the concentration of chemicals called phosphodiesterase-5 inhibitors, or PDE-5i, such as sildenafil, tadalafil, and vardenafil, which are prescribed mainly to treat erectile dysfunction. Researchers said the high concentrations of PDE-5i found in the wastewater could mean "relatively large amounts" of PDE-5i were consumed without a legal prescription.

The researchers did not specify during which time period they conducted the study, but the final report was submitted last May. Kim did not immediately respond to a request for comment for this story.

South Korea's Viagra market grew from $33 million to $45 million from 2012 to 2019, according to the study. In addition to Viagra, which is made by Pfizer, South Korea has more than 50 other erectile-dysfunction drugs on the market that are produced by domestic pharmaceutical companies, the Korea Biomedical Review reported in 2017.

South Korea has a rapidly aging population, which the secretary-general of the Organization for Economic Cooperation and Development last year called the country's biggest challenge.

A 2015 report from Grand View Research estimated that the market for erectile-dysfunction drugs would be worth $3.2 billion by 2022.