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Silica flour exposures in Ontario
American Industrial Hygiene Association Journal
|April 1, 1978
Summary
A study of 16 silicosis cases linked to silica flour exposure in Ontario proposes a new occupational exposure limit. The research established a conversion for dust counts to respirable mass, suggesting a threshold limit value of 0.05 mg/m3.
Area of Science:
- Occupational Health
- Industrial Hygiene
- Pulmonary Medicine
Background:
- Silicosis is a serious lung disease caused by inhaling silica dust.
- Previous occupational exposure limits may not adequately protect workers from silica flour exposure.
- Ontario plants reported 16 cases of silicosis linked to silica flour.
Purpose of the Study:
- To investigate the relationship between dust counts and respirable mass concentrations for silica flour.
- To propose a revised Threshold Limit Value (TLV) for silica flour based on experimental data.
- To inform occupational health guidelines for silica flour handling.
Main Methods:
- Collected dust count data (mppcf) over 37 years from four Ontario plants.
- Developed an experimental relationship to convert dust counts to respirable mass concentrations (mg/m3).
- Analyzed case data of 16 silicosis patients with documented silica flour exposure.
Main Results:
- Established a conversion factor between mppcf and mg/m3 for silica flour dust.
- Identified a correlation between exposure levels and silicosis development in reported cases.
- Calculated a proposed TLV of 0.05 mg/m3 for silica flour.
Conclusions:
- The proposed TLV of 0.05 mg/m3 is recommended for silica flour to prevent silicosis.
- The established conversion method allows for better assessment of airborne silica flour exposure.
- Further monitoring and adherence to revised limits are crucial for worker protection.
