Long-Term Exposure to Silica Dust and Risk of Total and Cause-Specific Mortality in Chinese Workers: A Cohort Study

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Background:
Human exposure to silica dust is very common in both working and living environments. However, the potential long-term health effects have not been well established across different exposure situations.

Methods and Findings:
We studied 74,040 workers who worked at 29 metal mines and pottery factories in China for 1 y or more between January 1, 1960, and December 31, 1974, with follow-up until December 31, 2003 (median follow-up of 33 y). We estimated the cumulative silica dust exposure (CDE) for each worker by linking work history to a job–exposure matrix. We calculated standardized mortality ratios for underlying causes of death based on Chinese national mortality rates. Hazard ratios (HRs) for selected causes of death associated with CDE were estimated using the Cox proportional hazards model. The population attributable risks were estimated based on the prevalence of workers with silica dust exposure and HRs. The number of deaths attributable to silica dust exposure among Chinese workers was then calculated using the population attributable risk and the national mortality rate. We observed 19,516 deaths during 2,306,428 person-years of follow-up. Mortality from all causes was higher among workers exposed to silica dust than among non-exposed workers (993 versus 551 per 100,000 person-years). We observed significant positive exposure–response relationships between CDE (measured in milligrams/cubic meter–years, i.e., the sum of silica dust concentrations multiplied by the years of silica exposure) and mortality from all causes (HR 1.026, 95% confidence interval 1.023–1.029), respiratory diseases (1.069, 1.064–1.074), respiratory tuberculosis (1.065, 1.059–1.071), and cardiovascular disease (1.031, 1.025–1.036). Significantly elevated standardized mortality ratios were observed for all causes (1.06, 95% confidence interval 1.01–1.11), ischemic heart disease (1.65, 1.35–1.99), and pneumoconiosis (11.01, 7.67–14.95) among workers exposed to respirable silica concentrations equal to or lower than 0.1 mg/m³. After adjustment for potential confounders, including smoking, silica dust exposure accounted for 15.2% of all deaths in this study. We estimated that 4.2% of deaths (231,104 cases) among Chinese workers were attributable to silica dust exposure. The limitations of this study included a lack of data on dietary patterns and leisure time physical activity, possible underestimation of silica dust exposure for individuals who worked at the mines/factories before 1950, and a small number of deaths (4.3%) where the cause of death was based on oral reports from relatives.

Conclusions:
Long-term silica dust exposure was associated with substantially increased mortality among Chinese workers. The increased risk was observed not only for deaths due to respiratory diseases and lung cancer, but also for deaths due to cardiovascular disease.

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Vyšlo v časopise: Long-Term Exposure to Silica Dust and Risk of Total and Cause-Specific Mortality in Chinese Workers: A Cohort Study. PLoS Med 9(4): e32767. doi:10.1371/journal.pmed.1001206
Kategorie: Research Article
prolekare.web.journal.doi_sk: https://doi.org/10.1371/journal.pmed.1001206

Souhrn

Zdroje

1. Ministry of Health of the People's Republic of China 2009 [Chinese annual health statistical report in 2009.] Beijing Ministry of Health of the People's Republic of China

2. World Health Organization Global Occupational Health Network 2007 Elimination of silicosis. GOHNET Newsletter 12 Geneva World Health Organization Global Occupational Health Network

3. US National Institute for Occupational Safety and Health 2002 Health effects of occupational exposure to respirable crystalline silica Washington District of Columbia) US Department of Health and Human Services

4. KauppinenTToikkanenJPedersenDYoungRKogevinasM 1998 Occupational exposure to carcinogens in the European Union in 1990–93 Carex International Information System on Occupational Exposure to Carcinogens. Helsinki: Finnish Institute of Occupational Health

5. SchenkerMBPinkertonKEMitchellDVallyathanVElvine-KreisB 2009 Pneumoconiosis from agricultural dust exposure among young California farmworkers. Environ Health Perspect 117 988 994

6. MerchantJA 1986 Occupational respiratory diseases Washington (District of Columbia) US Department of Health and Human Services

7. OxmanADMuirDCShannonHSStockSRHnizdoE 1993 Occupational dust exposure and chronic obstructive pulmonary disease. A systematic overview of the evidence. Am Rev Respir Dis 148 38 48

8. CalvertGMRiceFLBoianoJMSheehyJWSandersonWT 2003 Occupational silica exposure and risk of various diseases: an analysis using death certificates from 27 states of the United States. Occup Environ Med 60 122 129

9. BrownTPRushtonL 2005 Mortality in the UK industrial silica sand industry: 1. assessment of exposure to respirable crystalline silica. Occup Environ Med 62 442 445

10. SteenlandK 2005 One agent, many diseases: exposure-response data and comparative risks of different outcomes following silica exposure. Am J Ind Med 48 16 23

11. PopeCAIIIEzzatiMDockeryDW 2009 Fine-particulate air pollution and life expectancy in the United States. N Engl J Med 360 376 386

12. SamoliEPengRRamsayTPipikouMTouloumiG 2008 Acute effects of ambient particulate matter on mortality in Europe and North America: results from the APHENA study. Environ Health Perspect 116 1480 1486

13. LadenFSchwartzJSpeizerFEDockeryDW 2006 Reduction in fine particulate air pollution and mortality: extended follow-up of the Harvard Six Cities study. Am J Respir Crit Care Med 173 667 672

14. BrookRDFranklinBCascioWHongYHowardG 2004 Air pollution and cardiovascular disease: a statement for healthcare professionals from the Expert Panel on Population and Prevention Science of the American Heart Association. Circulation 109 2655 2671

15. DominiciFPengRDBellMLPhamLMcDermottA 2006 Fine particulate air pollution and hospital admission for cardiovascular and respiratory diseases. JAMA 295 1127 1134

16. ChenWZhuangZAttfieldMDChenBTGaoP 2001 Exposure to silica and silicosis among tin miners in China: exposure-response analyses and risk assessment. Occup Environ Med 58 31 37

17. ZhuangZHearlFJOdencrantzJChenWChenBT 2001 Estimating historical respirable crystalline silica exposures for Chinese pottery workers and iron/copper, tin, and tungsten miners. Ann Occup Hyg 45 631 642

18. DosemeciMChenJQHearlFChenRGMcCawleyM 1993 Estimating historical exposure to silica among mine and pottery workers in the People's Republic of China. Am J Ind Med 24 55 66

19. WuZHearlFPengKMcCawleyMChenA 1992 Current occupational exposures in Chinese iron and copper mines. Appl Occup Environ Hyg 7 735 743

20. ThurstonSWEisenEASchwartzJ 2002 Smoothing in survival models: an application to workers exposed to metalworking fluids. Epidemiology 13 685 692

21. RothmanKJBoiceJDAustinH 1982 Epidemiologic analysis with a programmable calculator, 2nd edition Boston Epidemiology Resources

22. ChenWYangJChenJBruchJ 2006 Exposures to silica mixed dust and cohort mortality study in tin mines: exposure-response analysis and risk assessment of lung cancer. Am J Ind Med 49 67 76

23. World Health Organization 2002 The world health report 2002—reducing risks, promoting healthy life Geneva World Health Organization

24. BirkTMundtKAGuldnerKParsonsWLuippoldRS 2009 Mortality in the German porcelain industry 1985–2005: first results of an epidemiological cohort study. J Occup Environ Med 51 373 385

25. ArndtVRothenbacherDDanielUZschenderleinBSchuberthS 2004 All-cause and cause specific mortality in a cohort of 20 000 construction workers; results from a 10 year follow up. Occup Environ Med 61 419 425

26. HodgsonJTJonesRD 1990 Mortality of a cohort of tin miners 1941–86. Br J Ind Med 47 665 676

27. McDonaldADMcDonaldJCRandoRJHughesJMWeillH 2001 Cohort mortality study of North American industrial sand workers. I. Mortality from lung cancer, silicosis and other causes. Ann Occup Hyg 45 193 199

28. MeijersJMSwaenGMSlangenJJ 1996 Mortality and lung cancer in ceramic workers in The Netherlands: preliminary results. Am J Ind Med 30 26 30

29. CheckowayHHeyerNJSeixasNSWelpEADemersPA 1997 Dose-response associations of silica with nonmalignant respiratory disease and lung cancer mortality in the diatomaceous earth industry. Am J Epidemiol 145 680 688

30. BellMLEbisuKPengRDWalkerJSametJM 2008 Seasonal and regional short-term effects of fine particles on hospital admissions in 202 US counties, 1999–2005. Am J Epidemiol 168 1301 1310

31. ItoKMathesRRossZNadasAThurstonG 2011 Fine particulate matter constituents associated with cardiovascular hospitalizations and mortality in New York City. Environ Health Perspect 119 467 473

32. WyndhamCHBezuidenhoutBNGreenacreMJSluis-CremerGK 1986 Mortality of middle aged white South African gold miners. Br J Ind Med 43 677 684

33. WeinerJBarlowLSjogrenB 2007 Ischemic heart disease mortality among miners and other potentially silica-exposed workers. Am J Ind Med 50 403 408

34. NemmarAHoetPHVanquickenborneBDinsdaleDThomeerM 2002 Passage of inhaled particles into the blood circulation in humans. Circulation 105 411 414

35. VinzentsPSMollerPSorensenMKnudsenLEHertelO 2005 Personal exposure to ultrafine particles and oxidative DNA damage. Environ Health Perspect 113 1485 1490

36. KellyFJ 2003 Oxidative stress: its role in air pollution and adverse health effects. Occup Environ Med 60 612 616

37. StaynerLSteenlandKDosemeciMHertz-PicciottoI 2003 Attenuation of exposure-response curves in occupational cohort studies at high exposure levels. Scand J Work Environ Health 29 317 324