But the studies did not evaluate exposure to chemicals during maintenance work, blackouts, gas leaks or other incidents when the level of toxic gas goes up sharply, the judges said. The court ordered the Korea Workers' Compensations & Welfare Service, a government agency, to pay compensation to Kim's family.
Claims for compensation for injuries and disease linked to the workplace are decided by the agency, which levies companies to fund its payouts. The agency had previously denied compensation to Kim's family who appealed to the Seoul court.
The latest ruling is the second case in South Korea in which a court recognized a link between leukemia and working conditions at Samsung memory chip factories.
In 2011, a court said the deaths of two Samsung workers from leukemia were associated with their work at the company and ordered the government agency to pay compensation to their families. The agency appealed and the case is pending.
Kim worked at Samsung's chip factory in Giheung between 1999 and 2004 on "Line 2", which was one of the three oldest chip manufacturing lines at Samsung. The two other workers who died of leukemia and won compensation from the government agency worked on these three lines, all of which were built during the 1980s.
Lee Jong-ran, an attorney who helps tech industry workers, said most leukemia deaths of Samsung worker were among employees who worked at the old lines. They were shut and renovated after 2006.
The judges said there was a "high probability" that benzene, formaldehyde or other leukemia-causing materials were contained in the chemicals Kim used, or created during the manufacturing process.
But it said it was not possible to further determine Kim's exposure to carcinogens partly because Samsung hadn't cooperated.
"Samsung Electronics, which did not preserve information of chemical materials used during Kim's work and did not disclose some data citing trade secrets, is partly a cause," the ruling said.
Samsung was not a defendant in Kim's case.
"While the court's decision appears to have been based on probability, as a party that was not a part of the proceedings, we feel that it would be inappropriate for us to comment on the matter," Samsung said in a statement. "Regardless, Samsung's top priority has always been ensuring the health and safety of every person we employ."