Exposures among Workers at an Indium Tin Oxide Production Facility
1CDC/NIOSH, Morgantown, WV
The National Institute for Occupational Safety and Health (NIOSH), conducted exposure assessments at an indium tin oxide production facility. Tasks identified as strong predictors of full-shift exposure to respirable indium may help inform the design of engineering and administrative controls, and the use of personal protective equipment, which in turn may increase the effectiveness of interventions designed to mitigate occupational exposure to indium.
Situation / Problem:
Indium tin oxide production, use, and reclamation has increased greatly in the last twenty years subsequent to increased global demand for indium tin oxide in flat-panel displays, touch screens, photovoltaics, and optoelectronics. Occupational exposure to indium is associated with pulmonary alveolar proteinosis (PAP), cholesterol ester crystals and granulomas, pulmonary fibrosis, emphysema, and pneumothoraces. Few exposure assessments of personal respirable and inhalable indium have been reported to date. Task-based sampling can be utilized when measuring sufficiently high exposures that exceed the detection limit of an analyte, despite the shorter sampling durations. A cost-effective alternative approach to task-based sampling is to use task diaries in combination with full-shift samples to identify determinants of full-shift exposures.
Full-shift and composite personal samples were collected to assess personal exposure to respirable and inhalable indium. Additionally, NIOSH staff observed workers as they performed their regular job duties and recorded task duration, task location, materials, and use of personal protective equipment in task diaries. All personal air samples were analyzed for indium content (NIOSH Method 7303). Tasks were recorded in task diaries and were recoded into task groups using the Advanced REACH Tool. A linear mixed-effects regression model was used to generate estimates for task groups as determinants of full-shift respirable indium.
Results / Conclusions:
Tasks recorded in task diaries (n=120) were recoded into 48 task groups. Task groups by department as a predictor of full-shift respirable indium were significant for powder transfer and powder fraction. The final model included the following task groups as significant positive determinants of full-shift respirable indium exposure: sanding; powder transfer tasks in reclaim; unload mill; powder transfer tasks in refinery; and material handling (measure, test, and scan ITO tile and cylinder). Our results identified tasks that can be targeted with engineering, administrative, and personal protective equipment controls, thereby increasing the effectiveness of interventions designed to mitigate occupational exposure to indium.
Exposure Assessment Strategies
Acknowledgements and References
List any additional people who worked on the project or provided guidance and support along with details on the role they played in the research. (Please include first name, last name, organization, city, state and country).
Kristin, Cummings, Respiratory Health Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA: organized and oversaw field investigations and helped with interpretation of the results.
Marcia, Stanton, Respiratory Health Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA: participated in the field investigations and helped recode individual tasks into task groups using the Advanced Reach Tool.
Reid, Harvey, Respiratory Health Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA: helped with the data analyses and interpretation.
Aleksandr, Stefaniak Respiratory Health Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA: assisted with the data analyses.
M. Abbas, Virji, Respiratory Health Division, National Institute for Occupational Safety and Health, Morgantown, WV, USA: helped with the study design, data analyses, and interpretation of results.
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