Silicosis epidemiology and demographics
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Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]
Overview
Epidemiology and Demographics
- Workers in a broad range of industries are exposed to crystalline silica. Up to 200,000 miners and 1.7 million non-mining workers in the United States have experienced significant occupational exposure to inhaled silica.[1]
- African Americans have a two to seven times higher rate of developing silicosis compared with white workers with the same dust exposure [2]
- Several epidemics of silicosis have been reported worldwide, including the United States. The worst epidemic of silicosis occurred in 1930-1931, during the construction of Gauley Bridge tunnel in West Virginia (also known as hawks nest tunnel disaster ), more than 400 of the estimated 2000 men who drilled rocks died of silicosis, and almost all the survivors developed silicosis.
- It is estimated that there were between 3600 and 7300 cases per year of silicosis in the United States between 1987 and 1996 [12]. During that decade, nearly 3000 deaths were attributed to silicosis in the United States [13]. The overall mortality attributable to silicosis has decreased substantially in the United States over the past 30 years, largely because of improved workplace protection [14,15]. More recently, in 1996, silicosis was reported in 60 of 1072 workers in an automotive factory. The risk of developing the disease increased as the number of years of exposure increased. Among workers who were employed for more than 30 years, 12% developed silicosis.
From 1968 to 2002, silicosis was recorded as an underlying or contributing cause of death on 16,305 death certificates; of these, 15,944 (98 percent) deaths occurred in men [14].
During 1999–2013, a total of 2,065 decedents had silicosis listed as the underlying or as a contributing cause of death (1,122 [54.3%] decedents had silicosis listed as the underlying cause of death) . The annual number of silicosis deaths declined 40% from 185 in 1999 to 111 in 2013 (p-value for trend <0.001), but the decline appears to have leveled off during 2010–2013. The lowest number of silicosis deaths (88) occurred in 2011. Higher numbers of deaths occurred in 2012 (103) and 2013 (111), but remained within the 95% confidence interval predicted by the first-order autoregressive linear regression model used to evaluate trends for 1999–2013. Among all silicosis deaths, 47 (2.3%) decedents were aged 15–44 years; of these, 34 (72.3%) had silicosis coded as the underlying cause of death (Table). The annual number of silicosis deaths in persons aged 15–44 years varied and was 4, 0, and 8 in 2011, 2012, and 2013, respectively.
Race
- African Americans have a two to seven times higher rate of developing silicosis compared with white workers with the same dust exposure [2]
Age
- No precise information regarding age is available, usually seen at an older age as the disease progress over decades of exposure.
Sex
- Silicosis predominantly affects male workers, reflecting the occupations at risk.
- China has the most patients with silicosis, with more than 500,000 cases recorded between 1991 and 1995, and 6000 new cases and more than 24,000 deaths reported annually.
- In Vietnam the cumulative number of diagnosed cases has now reached 9,000. They constitute 90% of all cases of occupationally compensated diseases. Some 18% of workers engaged in surface coal mining, quarrying, foundry and metallurgy have been found to have silicosis.
- In India, a prevalence of 55% was found in one group of workers, many of them very young, engaged in the quarrying of shale sedimentary rock and subsequent work in small, poorly ventilated sheds. Studies on silicotic pencil workers in Central India demonstrated high mortality rates; the mean age at death was 35 years and the mean duration of the exposure was 12 years.
- In Brazil, in the state of Minas Gerais alone more than 4,500 workers have been diagnosed with silicosis.The state of Rio de Janeiro banned sandblasting after workers were found to have silicosis.
In the USA, it is estimated that more than one million workers are occupationally exposed to free crystalline silica dusts (more than 100 000 of these workers are sandblasters), of whom some 59 000 will eventually develop silicosis. It is reported that each year in the USA about 300 people die from it, but the true number is not known. Abrasive blasting with silica sand, often used to prepare surfaces for painting, has been associated with exposures 200 times greater than the level recommended by the US National Institute for Occupational Safety and Health. This agency recommended that silica sand be prohibited as an abrasive blasting agent.
- In 1988-1994 Quebec, Canada, 40 newly diagnosed workers were compensated
- The Colombian Government estimates that 1.8 million workers in the country are at risk of developing the disease.
Recently, silicosis in Turkish denim sandblasters was detected as a new cause of silicosis due to recurring, poor working conditions. Silicosis is seen in horses associated with inspiration of dust from certain cristobalite-containing soils in California.
Silicosis is an occupational hazard to mining, sandblasting, quarry, ceramics and foundry workers, as well as grinders, stonecutters and those continually exposed to silica dust.
Protective measures such as respirators have brought a steady decline in death rates due to silicosis in Western countries. Unfortunately, this is not true of less developed countries where work conditions are poor and respiratory equipment is seldom used. For instance, life expectancy for silver miners in Potosí, Bolivia is around 40 years due to silicosis.
References
- ↑ Rosenman KD, Reilly MJ, Kalinowski DJ, Watt FC (1997). "Silicosis in the 1990s". Chest. 111 (3): 779–86. PMID 9118719.
- ↑ 2.0 2.1 Cohen RA, Patel A, Green FH (2008). "Lung disease caused by exposure to coal mine and silica dust". Semin Respir Crit Care Med. 29 (6): 651–61. doi:10.1055/s-0028-1101275. PMID 19221963.