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Tuberculosis and silica exposure in South African gold miners.
Occup Environ Med 2006; 63(3):187-92OE

Abstract

AIMS

To examine the effect of silica exposure, in the absence of silicosis, on the prevalence of pulmonary tuberculosis (PTB), which is epidemic among South African gold miners.

METHODS

Cross-sectional study of 520 gold miners over 37 years of age. Length of service, and cumulative and average dust and quartz exposure indices were derived for each miner. Chest radiographs were read for PTB by two NIOSH "B" readers. PTB was defined as a self-reported history of PTB or PTB on chest radiograph. Logistic regression was used to adjust for age, smoking, and silicosis. PTB effects of different exposure metrics for silica, scaled on their interquartile range (IQR), were compared.

RESULTS

Means (ranges) were: age 46.7 (37.1-59.9) years; length of service 21.8 (6.3-34.5) years; average intensity of respirable quartz 0.053 (0-0.095) mg/m3. PTB prevalence was 19.4% (95% CI 16.0 to 22.8) on history alone, and 35.2% (95% CI 31.1 to 39.3) on history or on chest radiograph. Length of service was poorly predictive of PTB, while all exposure indices which included dust or quartz yielded prevalence odds ratios (PORs) of approximately 1.4 (95% CI approximately 1.1 to 1.8) for changes of one interquartile range in exposure. Controlling for silicosis--by adjustment or restriction--did not modify these results. Drillers and winch operators had the highest PTB prevalences and the highest dust and silica exposures.

CONCLUSION

Older in-service gold miners in South Africa have a high prevalence of PTB, which is significantly associated with dust and silica exposure, even in the absence of silicosis. Limitations include a survivor workforce and the use of cumulative exposures based on current exposures. Dust control is an important component in control of the PTB epidemic in South African gold mines.

Authors+Show Affiliations

School of Public Health and Family Medicine, University of Cape Town, Cape Town, South Africa. jim@cormack.uct.ac.zaNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

16497860

Citation

teWaternaude, J M., et al. "Tuberculosis and Silica Exposure in South African Gold Miners." Occupational and Environmental Medicine, vol. 63, no. 3, 2006, pp. 187-92.
teWaternaude JM, Ehrlich RI, Churchyard GJ, et al. Tuberculosis and silica exposure in South African gold miners. Occup Environ Med. 2006;63(3):187-92.
teWaternaude, J. M., Ehrlich, R. I., Churchyard, G. J., Pemba, L., Dekker, K., Vermeis, M., ... Myers, J. E. (2006). Tuberculosis and silica exposure in South African gold miners. Occupational and Environmental Medicine, 63(3), pp. 187-92.
teWaternaude JM, et al. Tuberculosis and Silica Exposure in South African Gold Miners. Occup Environ Med. 2006;63(3):187-92. PubMed PMID: 16497860.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Tuberculosis and silica exposure in South African gold miners. AU - teWaternaude,J M, AU - Ehrlich,R I, AU - Churchyard,G J, AU - Pemba,L, AU - Dekker,K, AU - Vermeis,M, AU - White,N W, AU - Thompson,M L, AU - Myers,J E, PY - 2006/2/25/pubmed PY - 2006/4/1/medline PY - 2006/2/25/entrez SP - 187 EP - 92 JF - Occupational and environmental medicine JO - Occup Environ Med VL - 63 IS - 3 N2 - AIMS: To examine the effect of silica exposure, in the absence of silicosis, on the prevalence of pulmonary tuberculosis (PTB), which is epidemic among South African gold miners. METHODS: Cross-sectional study of 520 gold miners over 37 years of age. Length of service, and cumulative and average dust and quartz exposure indices were derived for each miner. Chest radiographs were read for PTB by two NIOSH "B" readers. PTB was defined as a self-reported history of PTB or PTB on chest radiograph. Logistic regression was used to adjust for age, smoking, and silicosis. PTB effects of different exposure metrics for silica, scaled on their interquartile range (IQR), were compared. RESULTS: Means (ranges) were: age 46.7 (37.1-59.9) years; length of service 21.8 (6.3-34.5) years; average intensity of respirable quartz 0.053 (0-0.095) mg/m3. PTB prevalence was 19.4% (95% CI 16.0 to 22.8) on history alone, and 35.2% (95% CI 31.1 to 39.3) on history or on chest radiograph. Length of service was poorly predictive of PTB, while all exposure indices which included dust or quartz yielded prevalence odds ratios (PORs) of approximately 1.4 (95% CI approximately 1.1 to 1.8) for changes of one interquartile range in exposure. Controlling for silicosis--by adjustment or restriction--did not modify these results. Drillers and winch operators had the highest PTB prevalences and the highest dust and silica exposures. CONCLUSION: Older in-service gold miners in South Africa have a high prevalence of PTB, which is significantly associated with dust and silica exposure, even in the absence of silicosis. Limitations include a survivor workforce and the use of cumulative exposures based on current exposures. Dust control is an important component in control of the PTB epidemic in South African gold mines. SN - 1470-7926 UR - https://www.unboundmedicine.com/medline/citation/16497860/Tuberculosis_and_silica_exposure_in_South_African_gold_miners_ L2 - http://oem.bmj.com/cgi/pmidlookup?view=long&pmid=16497860 DB - PRIME DP - Unbound Medicine ER -