South Korea‘s nuclear commission ruled on Tuesday that some of the mattresses manufactured by Daijin Bed Co. contain radioactive material above the standard and ordered a recall.

The radioactive levels, including for radon, of seven Daijin mattresses were up to 9.3 times above the national tolerance standard, the Nuclear Safety and Security Commission said.

Radon is a radioactive, colorless and odorless gas occurring naturally as an indirect decay product of uranium or thorium. It is considered a health hazard due to its radioactivity, and exposure to radioactive gas can cause lung cancer.

The finding comes just five days after the commission initially ruled that the seven Daijin models, produced in 2016, contained safe levels of radon.

The new finding concluded that the annual radiation dose of the models tested came to 1.94 millisievert (mSv), outside of the safety standard for processed products of 1 mSv per year.

“The level of radioactive exposure is expected to be different depending on each person’s life pattern and environment,” the commission said in a press release. “Consumers should immediately stop using the models before the product recovery is completely carried out.”

It admitted that its initial examination was careless as the harmful substances were found in sponges inside an inner layer of the Daijin mattresses.

“In the first examination, we looked into the inner layers of the mattress only,” said an official from the commission. “But now we knew that the radioactive materials were detected at the sponges as well.”

Meanwhile, over 600 consumers have joined the move to file a suit against the company as of Monday.

A local law firm representing the consumers said the number is expected to rise following the announcement from the nuclear commission, adding that it is also reviewing whether to file a suit against the government. (Yonhap)