초록
Objectives: This study was conducted upon a request from a domestic research institute in 2022 to determine the extent to which researchers may be exposed to thallium (Tl) during a research experiment using thallium compounds. Although it is not a hazardous factor subject to workplace environment measurement, thallium is highly harmful to the human body and an occupational exposure limit (OEL) have been established. An exposure assessment of actual researchers was conducted and management measures were presented. Methods: The measurement and analysis method for thallium were performed according to NMAM (NIOSH, Manual of Analytical Methods) 7302. The measurement was performed using a three-piece cassette equipped with a mixed cellulose ester (MCE) membrane filter connected to a high-flow sampling pump with a flexible polyurethane tube. The analysis was performed using an inductively coupled plasma - optical emission spectrometer (ICP-OES). For the evaluation of the time-weighted average, sampling was performed for more than six hours at a flow rate of two L/min, and the sampling flow rate was compensated using a flow compensation device. The average flow rate before and after sampling was used for accurate calculation of the air volume. Conclusions: Although personal exposure assessments for powder injection and growth work were not detected, the area exposure assessment results on the work table evaluated the maximum concentration as 0.0038 mg/m3, confirming the possibility of scattering to the surroundings during work. The personal exposure assessment results for researchers in the post-processing work after interior cleaning of the chamber were evaluated as 0.0110 mg/m3, which exceeded 10% of the occupational exposure limit of 0.1 mg/m3 determined by the Ministry of Employment and Labor. The American Conference of Governmental Industrial Hygienists threshold limit value for thallium is 0.02 mg/m3. When evaluated based on this, the personal exposure concentration in the post-processing work after interior cleaning of the chamber was evaluated to exceed 50% of the occupational exposure limit. It was determined that improvement of the work environment is necessary.
