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Exposure Assessment-2
O5D.4 Exposure profiles of workers in indium-tin oxide powder manufacturing, target manufacturing and recycling factories in taiwan
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  1. Yuan-Ting Hsu1,
  2. Ting-Yao Su3,
  3. Hui-Yi Liao1,
  4. Yu-Chieh Kuo4,
  5. Saou-Hsing Liou1
  1. 1National Institute of Environmental Health Sciences, National Health Research Institutes, Miaoli County, Taiwan
  2. 2Graduate Institute of Life Sciences, National Defense Medical Center, Taipei City, Taiwan
  3. 3Division of Occupational Hazards Assessment, Institute of Labor, Occupational Safety and Health, Ministry of Labor, New Taipei City, Taiwan
  4. 4Department of Environmental and Occupational Health, National Cheng Kung University, Tainan City, Taiwan

Abstract

We aimed to investigate indium exposure profiles and the relationship between ambient exposure and internal dose of indium among workers with different job characteristics in order to improve the work environment and protect workers from overexposure.

We recruited 329 workers from indium-tin oxide (ITO) powder and target manufacturing and recycling factories. The workers were categorized into six groups, as powder, ITO target, bonding, processing, recycling process and administration department as reference group. Field and personal air sampling were performed to monitor indium concentrations of work environments and breathing zones of workers. Cumulative exposure were evaluated by respirable dust concentrations in personal sampling, exposure duration and work duration. Plasma indium (P-In), urine indium (U-In) and U-In adjusted for creatinine (U-In/creatinine) were used as internal dose.

One-fourth of air indium concentrations of ITO manufacturing and recycling factories were exceeded permissible exposure limit (PEL) in Taiwan. Thirty-six percent of workers in this study exposed to unacceptable airborne concentration of indium. Over one-fifth of workers had P-In higher than Japanese biological exposure index (BEI) of 3 µg/L. After adjusting for potential confounders, significant positive were found between indium cumulative exposure and P-In (β=0.56, p<0.001), U-In (β=0.38, p<0.001), and U-In/creatinine (β=0.34, p<0.001) in bonding process. A significant positive were found between indium cumulative exposure and P-In (β=0.53, p=0.003), U-In (β=0.39, p=0.047) and U-In/creatinine (β=0.34, p=0.01) in processing process.

We suggest that U-In was an useful biomarker to assess indium exposure of indium manufacturing workers. The distribution and elimination of indium differed by its chemical form, which lead to characterization of the chemical form of indium is important for biomonitoring. Notably, although workers were exposed to indium below PEL, P-In still exceeded Japanese BEI. An appropriate exposure index need to be specified.

https://doi.org/10.1136/OEM-2019-EPI.130

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