Hematopoietic carcinogen assessment in bulk chemical products and air samples: focus on benzene exposure among subway maintenance workers

AIMS: Multiple cases of hematopoietic cancer have been reported among subway maintenance workers (MWs) at a company in Korea employing about 3,400 people, prompting a need to examine the relationship between HC and maintenance job characteristics. This study aimed to identify and assess the presence and levels of hematopoietic carcinogens, including benzene, in chemical products and workplace air within subway maintenance process and to provide scientific evidence to support forthcoming epidemiological investigations of HC. METHODS: A total of 169 chemical products used in cleaning, painting, and inspection processes were collected and analyzed using gas chromatography-mass spectrometry (GC-MS) in selected ion monitoring (SIM) mode. Air samples were collected during maintenance tasks and analyzed using GC-MS in SIM mode. Target substances included benzene, trichloroethylene, dichloromethane (DCM), styrene, and tetrachloroethylene. RESULTS: Benzene and DCM at concentrations ≥0.1% were detected in 12.4% of the 169 chemical products analyzed, including three products containing benzene and 18 containing DCM at this level. Airborne concentrations of benzene and DCM were detected in over 50% of the samples collected from painting (n=26) and cleaning operations (n=39), but all were below Occupational Exposure Limits. CONCLUSIONS: The findings provide quantitative and qualitative characterization of current exposure conditions and may support the reconstruction of potential past exposure scenarios to hematopoietic carcinogens among subway MWs, thereby informing subsequent epidemiological investigations.