By: Jung Min-ho

Civic groups criticized police on Monday for using water cannons containing a “lethal” substance to disperse protesters.

In their latest clash with labor activists and families of the Sewol ferry victims, police fired water cannons containing 0.3 percent solution of pelargonic acid vanillylamide (PAVA), a chemical incapacitant, at Gwanghwamun Plaza on Friday.

The Korean Federation of Medical Activist Groups for Health Rights claims overexposure to PAVA can cause serious long-term damage to internal organs and even death.

“Many of the protesters claimed they suffered dizziness, headaches and difficulty in breathing after being exposed to the water,” a group member said. “Some of them even vomited.”

PAVA is known to cause distress to the lungs and airways. Studies show that certain groups are at much greater risk, but there seems to have been no real effort to quantify this risk.

In the U.S., some researchers have found that PAVA and pepper spray could cause fatalities.

The discovery is alarming, given that Korean police have already used more than 500 liters of such water since last month. That is 2.5 times more than the total amount used in 2013.

Police said protesters had turned violent and tried to force their way through barricades. But demonstrators argued that police provoked them by using violent methods.

In fact, experts say the use of violent methods such as pepper spray is likely to make people more aggressive. That suggests that water cannons are more likely to cause violence than to stop it.

Amnesty International on Saturday expressed concern over the government’s excessive use of police force.

On May Day, labor groups denounced government policies they believe will reduce wages, job security and retirement benefits for state employees. They were later joined by supporters of the ferry victims’ families who want a thorough investigation into the sinking.

Ferry victims’ families and civic groups have filed a petition with the United Nations calling for an investigation into what they claimed was brutal suppression of protesters by Korean riot police.

The petition claims police violated people’s rights to hold protests, saying many of them were injured because of police violence.

A total of 304 people, mostly students from one high school, died when the ferry Sewol sank last year. Nine bodies have not been found.

The tragedy shocked and enraged the country as it became clear the tragedy was almost entirely man-made ― the result of an illegal redesign, an overloaded cargo bay, an inexperienced crew and an unhealthy nexus between operators and state regulators.