Trace amounts of leukemia-linked carcinogens were found in semiconductor-producing factories of Samsung Electronics Co. and other chipmakers, a governmental authority said Monday.

“We found that cancer-causing substances are present inside the chip factories,” said Park Jung-sun, head of the state-run Korea Occupational Safety and Health Research Institute, announcing the results of its three-year study of potential cancer risks at chip-manufacturing lines.

The study, conducted between 2009 and 2011 on chip lines of Samsung, Hynix Semiconductor and Fairchild Semiconductor, confirmed the presence of benzene, formaldehyde and radiation at levels way below what is considered harmful. The three have been linked to leukemia.

It is the first time that the presence of carcinogens, long claimed by civic groups and some employees, was confirmed by an authoritative study. The same institute didn’t find any traces of the agents in two previous studies in 2007 and 2008.

There have been public health concerns over workplace safety at Samsung, the world’s No. 1 maker of computer memory chips, after some of its employees died of leukemia and other cancers while or after working at its chip manufacturing lines.

The company, however, has insisted that their deaths were not work-related. A local court last year ruled that some of the cancers the workers contracted could be classified as “industrial accidents.”

“The study says materials are present in levels that are not harmful to humans. But we will strengthen monitoring of workplace safety as it is a matter related to health and safety of our workers,” Samsung said.

According to the study released Monday, benzene was found in 0.00038 ppm and 0.00990 ppm in two different chip-making lines ― both below the permitted 1 ppm. Exposure to such low levels poses no health risks over the lifetime of a worker who works eight hours per day at the plant, the study said.

However, arsenic, a known carcinogen linked to lung cancer, was present above the permitted level, it said.

By Lee Sun-young (milaya@heraldcorp.com)