A series of doping scandals is again exposing the dark side of professional sports in the country. This should raise alarm bells because pro sports are getting bigger and bigger, making them more vulnerable to corrupt practices.

There were three doping cases last week alone, including one involving pro baseball player Choi Jin-haeng of the Hanwha Eagles. Choi tested positive for stanozolol, an anabolic steroid banned by the World Anti-Doping Agency, and the 29-year-old outfielder was banned for 30 games. The Eagles were also fined 20 million won ($18,000).

The Korea Baseball Organization’s decision came only two days after the governing body of women’s pro volleyball suspended Kwak Yoo-hwa of Heungkuk Life for six games for a similar doping violation. The third case involved footballer Kang Soo-il of Jeju United, who was suspended for 15 matches after a drug test.

It is not that rare for Korean sports figures to be hit by doping scandals ― most recently Olympic swimming star Park Tae-hwan shocked the nation last year when he failed a drug test for using a banned substance ― but it was the first time that there were three reports on doping cases in a single week.

KBO officials quoted Choi as saying he had taken a dietary supplement on a friend’s advice, but he didn’t know it contained a banned substance. Kwak reportedly said that she took some dietary pills, and Kang said that he only used a mustache-growing ointment. Both insisted that they did not have any intention of using banned substances.

Many athletes ― amateurs and professionals alike ― insist that they did not have any knowledge of banned substances when they are caught out by doping tests. Perhaps this could be true of some or all of the three cases.

This poses a greater problem. The test on Kang turned up methyl testosterone, a type of steroid. Stanozolol, which led to suspension of Choi, can help athletes build muscle mass, boost acceleration and recover fast from fatigue. That an ointment can contain a type of steroid means that Korean athletes should get more education about using drugs.

The latest cases should awaken the pro sports governing bodies, clubs and athletes to the importance of avoiding the use of banned drugs. Regulations and education must be strengthened to keep illegal, harmful drugs out of sports.