Airway Inflammation Among Workers in the Silicon Carbide Processing Industry

Exposure to noxious gases and particles is associated with an increased prevalence of respiratory and cardiovascular diseases. Thus, investigation of possible airway inflammation and/or systemic inflammation in workers exposed to high levels of dust is important. Silicon Carbide (SiC) Processing Inc. provides cutting fluid (slurry) for the production of solar cells and is at present the largest provider of slurry to the solar industry worldwide. In the production process, the recyclable materials (SiC), polyethylene glycol (PEG)) of the used slurry are recovered. The airborne exposure consists mainly of SiC (dust particles) and evaporation from the recycling of PEG. High levels of dust have been measured and, seventeen per cent of the measurements in the processing hall were equal to or higher than the Norwegian occupational exposure limit. Thus, assessment of possible systemic and airway effects of this exposure is of interest. A prospective design will be applied and the effects studied by means of registration of respiratory symptoms, spirometry, nitric oxide (NO) in exhaled air, induced sputum and blood sampling over a 3 year period. Exposed subjects will also be compare with non- or low exposed subjects (administrative/office workers). Efforts will be made to include all eligible subjects and to avoid drop-outs. If early signs of airway or systemic inflammation in workers or in cells are demonstrated in the study, it will be necessary to implement measures to reduce the exposure levels.

The primary aim of the present study of workers exposed to Silicon Carbide dust in the workplace is to determine whether this exposure is associated with inflammatory changes in the lungs.

The secondary aims are: - to examine possible changes in systemic inflammatory markers and - to examine changes in lung function among Silicon Carbide processing workers during a period of 3 years. Possible changes in lung function will be monitored by spirometry and gas diffusion measurements (study A). Airway inflammatory responses and changes in circulating inflammatory markers will be assessed by examination of the induced sputum samples and blood samples every 6th month in a subgroup of workers (study B).