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Seoul Metro to roll out health measures after further blood cancer cases among maintenance staff

Published: 19 Jun. 2025, 14:58 Updated: 19 Jun. 2025, 19:37

A worker dismantles and repairs a subway train at a maintenance depot. [JOONGANG ILBO]

Additional cases of blood cancer have been confirmed among workers responsible for subway train maintenance at Seoul Metro, which operates lines No. 1 through 8. In response, Seoul Metro announced Thursday that it will implement comprehensive measures, including improving the work environment and expanding health screenings.

The Korea National Open University’s Industry-Academic Cooperation Foundation recently released the results of its blood cancer study on the company, according to Seoul Metro on Thursday. Commissioned by Seoul Metro, the foundation conducted a six-month investigation starting in December 2024 into workplace hazards and their potential link to the onset of blood cancer.

The study surveyed 4,438 individuals who were current, former or retired employees in the vehicle maintenance division — those involved in subway car inspections, repairs and upkeep. It found a total of 11 cases of blood cancer, including five new cases in addition to the six previously reported.

Of the five newly identified cases — three leukemia and two lymphoma — two individuals were found to have already passed away. Including two other maintenance workers with blood cancer identified by Seoul Metro last year, the total number of confirmed cases now stands at 13.

The newly identified cases involved workers who for years dismantled subway cars, cleaned them with solvents, repainted them and performed inspection work, including replacing and repairing parts and machinery.

A worker services a subway train at Seoul Metro’s Gunja Train Depot in Seongdong District, eastern Seoul, in August 2024. [YONHAP]

Researchers pointed to benzene exposure as a possible contributing factor. The report noted that although Seoul Metro banned the use of benzene in 2011 after its risks became widely known, “significant benzene exposure likely occurred during cleaning and painting tasks until 2011, and during painting duties until 2022.”

The foundation identified benzene as a substance with a high risk of causing blood cancer. The International Agency for Research on Cancer classifies benzene as a Group 1 carcinogen known to cause blood cancer.

However, it remains unclear whether the incidence of blood cancer among Seoul Metro’s vehicle maintenance workers is statistically higher than in the general population. When researchers compared the blood cancer incidence rate of workers in the vehicle division to that of the general public, they found a standardized incidence ratio of 1.13.

Subway trains await maintenance at Gunja Train Depo in Seongdong District, eastern Seoul, in August 2024. [YONHAP]

Although this suggests a slightly higher rate among vehicle maintenance workers, the researchers concluded that the result could be due to chance and is not scientifically conclusive. The same held true when comparing only non-Hodgkin lymphoma cases.

Meanwhile, Seoul Metro plans to announce a set of comprehensive countermeasures to prevent future cases of blood cancer by July. The company will support medical expenses for those affected and provide assistance with legal and administrative fees for filing workers’ compensation claims. It also plans to conduct biannual blood tests for workers previously exposed to benzene and improve working conditions at train depots.

Translated from the JoongAng Ilbo using generative AI and edited by Korea JoongAng Daily staff.
BY MOON HEE-CHUL [[email protected]]