Free crystalline silicon dioxide, or silica, is one of the most common minerals worldwide. It is used to manufacture many items, including glass, bottles, ceramics, but it is also a common additive in the production of foods where it is primarily used as a flow agent in powdered foods or to absorb water. Inhalation of silica dust is associated with developing various diseases including silicosis, a chronic inflammation and scarring of the lungs that damages lung function, lung cancer, tuberculosis, as well as other diseases of the airway.
A seminar, published in The Lancet, calls for an immediate combined effort to recognize and control global silica hazards, in view of the fact that silicosis, an incurable and potentially fatal lung disease, is still a major cause of illness and death worldwide. The paper asks for better environmental controls and safety practices, in order to decrease the risk for people from developing this preventable disease, particularly in developing countries.
Leading author, Dr. Chi Chiu Leung, from the Department of Health in Hong Kong, China explains that silicosis is still a major occupational health concern in both developing, as well as developed countries regardless of decades of prevention efforts, in view of workers being exposed to respirable silica dust in various industries and occupations, for instance, in mining, construction, sandblasting, dental laboratories, and production of pottery and ceramics.
The highest prevalence of silicosis patients is in China, with 500,000 estimated cases of silicosis diagnosed between 1991 and 1995, with 6,000 new diagnosed incidents and over 24,000 deaths reported each year.
Although age-adjusted silicosis-related deaths in developed countries like the U.S. steadily decreased from 8.9 per million in 1968 to 0.7 per million in 2004, through the introduction of protective measures, such as dust control and the use of respirators, the number of silicosis deaths in young adults, aged between 15-44 years, has not fallen since 1995. These deaths are probably the outcome of intense and recent exposures.
In the last 10 years, smaller companies and mines in developing countries have also reported outbreaks of silicosis. These were mainly due to poor observance with regard to health and safety and insufficient protective measures.
According to the authors, companies should be subject to introduce periodic monitoring of silica dust to improve safety at the workplace in all industries that work with silica, saying:
“[Current] enforced or suggested permissible exposure limits for respirable silica were chosen according to the desired level of protection and available methods of dust control and monitoring of technologies, and they vary…in different countries…and have not been confirmed as fully protective by epidemiology studies.”
However, it will take a combined effort to improve preventive measures between workers and through the surveillance of worker health to avoid or control silica exposure at source and transmission.
The authors conclude:
“Besides education about symptoms of silicosis, regular medical assessment might detect adverse health effects in exposed workers before disease reaches an advanced stage. 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.”
Written By Petra Rattue