Silicosis remains major cause of illness, death worldwide
MedWire News: Exposure to silica in industry remains a major cause of illness and death worldwide, particularly in developing countries, suggest results from two papers.
Writing in PLoS Medicine, Weihong Chen (Huazhong University of Science and Technology, Wuhan, Hubei, China) and colleagues report the results of a long-term follow-up study of 74,040 metal mine and pottery factory workers with regular exposure to silica.
The workers were followed up from January 1960 to December 2003 for silica dust exposure and associated mortality.
All-cause mortality was higher in workers exposed to silica dust than in those who were not, at 993 versus 551 deaths per 100,000 person-years.
Notably, the team found that those exposed to 0.1 mg/m3 or less of silica dust, the exposure limit set by the US Occupational Safety and Health Administration, had significantly increased risk for death from all causes, ischemic heart disease, and pneumoconiosis compared with no exposure.
Following adjustment for confounders such as smoking, Chen and team estimated that 15.2% of deaths over the study period could be attributed to silica dust exposure.
"Findings from this study have important public health implications for improving occupational safety among those exposed to silica dust in China and around the world," say the authors.
In a seminar paper published in The Lancet, Chi Chiu Leung (Centre for Health Protection, Department of Health, Hong Kong, China) and colleagues agree that silica exposure is still a major problem, with the greatest number of silicosis cases and deaths per year reported in China (6000 new cases and 24,000 deaths annually).
They say that improvements have taken place in developed countries such as the USA following the introduction of dust control and respirators for workers with a reduction in age-adjusted death from silicosis from 8.9 per million workers in 1968 to 0.7 per million in 2004. But add that deaths in young adults (15-44 years) have not fallen since 1995.
The authors call for improvements in environmental controls and safety practices to reduce the risk for silicosis in industry workers, especially as no curative treatments currently exist.
"Besides education about symptoms of silicosis, regular medical assessment might detect adverse health effects in exposed workers before disease reaches an advanced stage," write Leung and team.
"No universal standard exists for the frequency of such assessment because the decision may be affected by past and present respirable silica concentrations, dust particulate characteristics, and economic conditions."
They conclude: "Further efforts are needed for recognition and control of silica hazards, especially in developing countries."
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By Helen Albert