The effect of silica dust on ventilatory function of foundry workers

Abstract

In order to study the exposure level of silica dust and the effects of silica dust on ventilatory function, respirable dust samples were collected with personal air samplers by means of NIOSH method 0500 in selected foundry operations, and ventilatory function tests were performed on 209 male foundry workers and 239 male control subjects. The average quartz concentrations of respirable dust were the highest in melting (0.079 mg/m3) and followed by molding (0.051 mg/m3), finishing (0.041 mg/m3) and coremaking (0.023 mg/m3) in descending order. No significant differences in mean values for all ventilatory indices expressed as a percentage of the predicted value were demonstrated between smokers and nonsmokers in foundry workers and control subjects. Mean values for all ventilatory indices except FVC in foundry workers were significantly lower than those in control subjects. Mean values for FEV1%, MMF, FEF25, FEF50 and FEF75 expressed as a percentage of the predicted value tended to decrease with increasing cumulative dust exposure. In foundry workers, proportions of workers with low MMF, FEF50 and FEF75 were noticeably higher than those for other indices, and were significantly increased with increasing cumulative dust exposure. With the above considerations in mind, it suggested that increasing exposure to silica dust be associated with progressive deterioration in ventilatory function of an obstructive nature and that MMF, FEF50 and FEF75 be sensitive indices in the detection of early obstructive changes in air flow of workers exposed to silica dust.