Lung risks increase even with lawful exposure levels
In a timely study on the insidious reach of silica, Swedish researchers have found a significantly high level of chronic lung disease in metal foundry workers exposed to silica dust, even at levels well below government exposure limits.
The findings coincide with the commencement of more stringent silica-related safety regulations for multiple industries in Victoria.
The Swedish study, led by Örebro University's Department of Occupational and Environmental Medicine, looked at patterns of lung disease among a cohort of 1,752 foundry workers, with a particular focus on those exposed to respirable silica dust.
The study cross-referenced the levels of exposure recorded in workplace testing, with the number of years worked. This allowed a quantitative analysis of exposure over a 17-year period to assess the incidence of disease.
The results showed significantly increased incidence of various chronic obstructive lung diseases (COPDs) for all exposure groups as well as increased silicosis risk in higher exposure groups.
The higher incidence of disease occurred at exposure levels well below the current Swedish occupational exposure limit of 0.1mg per cubic metre of air, and even below the threshold that currently applies in most Australian jurisdictions, of 0.05mg per cubic metre.
The researchers say the results showed statistically increased morbidity for respiratory diseases of silica-exposed Swedish foundry workers, particularly at exposure levels well below the current Swedish exposure limit.
The morbidity of COPD and silicosis was significantly increased in the high exposure group in the study, which was still less than the current Swedish exposure threshold of 0.1mg per cubic metre.