Exposure assessment and health surveillance in compound semiconductor production

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1. Exposure assessment by working environment and personal exposure sampling : In a gallium arsenide wafers manufacturing plant, arsenic and gallium concentrations of area and personal samples were measured. Processes were Liquid Encapsulated Czochralski (LEC), ingot slicing, wafer lapping, wafer polishing, and Metal Organic Vapor Phase Epitaxy. Arsenic/gallium concentrations in most processes were extremely low. However, exposure levels to elemental arsenic of the LEC cleaning workers were relatively high. The ingot slicing workers could be exposed to high concentrations of gallium arsenide.2. Exposure assessment by biological monitoring : Biological monitoring of arsenic exposure in gallium arsenide wafer manufacturers was performed by chemical species determination of arsenic in urine and hair. It was suggested that urinary inorganic arsenic concentrations of the ingot slicing workers elevated.3. Health surveillance : Hematological, biochemical and immunological tests and determination of urinary porphyrin metabolites (coproporphyrins) were performed to assess the health status of the workers. There were no exposure-related change.4. Conclusion : The LEC cleaning and the ingot slicing processes were relatively high exposure levels to elemental arsenic and gallium arsenide. However, the health status of the workers could keep good if the proper control technology was used.