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Cross-Sectional Silica Exposure Measurements at Two Zambian Copper Mines of Nkana and Mufulira
University of Michigan, School of Public Health, Department of Environmental Health Sciences, 1420 Washington Heights Ann Arbor, MI 48109-2029, USA
National Institute for Scientific and Industrial Research, International Airport Road, P.O. Box 310158, Lusaka, Zambia
National Institute for Occupational Safety and Health, 4676 Columbia Parkway, MS-R7, Cincinnati, OH 45226, USA
* Author to whom correspondence should be addressed.
Received: 17 September 2007 / Accepted: 30 April 2008 / Published: 30 June 2008
Abstract: We measured the quartz content of 20 bulk settled dust and 200 respirable dust samples in a cross-sectional dust exposure assessment that is part of an epidemiological study to ascertain the risk of nonmalignant respiratory diseases among Zambian copper miners. Dust samples were collected from the copper mines of Mopani Copper Mine plc (Mufulira and Nkana Mines). Analytical measurements employed NIOSH Method 0600 for gravimetric analysis of respirable dust and NIOSH Method 7500 for quartz analysis in bulk and respirable dust samples. The measured quartz content of respirable dust showed that 59% and 26% of Mufulira and Nkana Mine samples, respectively, were above the calculated U.S. Occupational Safety and Health Administration permissible exposure limit. The mean intensities of respirable dust exposure at Mufulira and Nkana were 0.992 mg/m3 (range 0-7.674) and 0.868 mg/m3 (range 0-6.944), respectively while the mean intensities of respirable quartz at Mufulira and Nkana were 0.143 mg/m3 (range 0-1.302) and 0.060 mg/m3 (range 0-0.317), respectively. These results indicate weak dust monitoring at these mines which may increase the risk of nonmalignant disease in many miners. Since Zambian mining regulations do not have crystalline silica exposure limits, these results accord with the recommendation that Zambian mining houses and the government establish crystalline silica analysis laboratory capacity and adopt dust mass concentration occupational exposure limits for more protective dust monitoring of workers.
Keywords: crystalline silica; silicosis; exposure; respirable dust; monitoring; mining
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Hayumbu, P.; Robins, T.G.; Key-Schwartz, R. Cross-Sectional Silica Exposure Measurements at Two Zambian Copper Mines of Nkana and Mufulira. Int. J. Environ. Res. Public Health 2008, 5, 86-90.
Hayumbu P, Robins TG, Key-Schwartz R. Cross-Sectional Silica Exposure Measurements at Two Zambian Copper Mines of Nkana and Mufulira. International Journal of Environmental Research and Public Health. 2008; 5(2):86-90.
Hayumbu, Patrick; Robins, Thomas G.; Key-Schwartz, Rosa. 2008. "Cross-Sectional Silica Exposure Measurements at Two Zambian Copper Mines of Nkana and Mufulira." Int. J. Environ. Res. Public Health 5, no. 2: 86-90.