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. 1993 Jul;50(7):586–597. doi: 10.1136/oem.50.7.586

Mortality among workers in the diatomaceous earth industry.

H Checkoway 1, N J Heyer 1, P A Demers 1, N E Breslow 1
PMCID: PMC1035494  PMID: 8343419

Abstract

A cohort mortality study was conducted among workers from two plants in the diatomaceous earth mining and processing industry in California. Diatomaceous earth consists of the skeletal remains of diatoms. Exposure to amorphous (non-crystalline) and crystalline silica in the form of quartz results from open pit mining and exposure to crystalline silica (principally cristobalite) occurs in the processing of the material. Lung cancer and non-malignant respiratory diseases have been the health outcomes of greatest concern. The main study cohort included 2570 white men (533 Hispanic and 2017 non-Hispanic workers) who were employed for at least 12 months cumulative service in the industry and who had worked for at least one day during the follow up period, 1942-87. Vital status was ascertained for 91% of the cohort and death certificate information was retrieved for 591 of 628 (94%) identified deaths. The all causes combined standardised mortality ratio (SMR) was slightly increased (SMR = 1.12; 628 observed) compared with rates among US white males. The principal contributors to this excess were increased risks from lung cancer (SMR = 1.43; 59 observed) and non-malignant respiratory disease (NMRD) excluding infectious diseases and pneumonia (SMR = 2.59; 56 observed). The excess of lung cancer persisted when local county rates were used for comparison (SMR = 1.59). Internal rate comparisons by Poisson regression analysis were conducted to assess potential dose-response relations for lung cancer and NMRDs. Mortality trends were examined in relation to duration of employment in dust exposed jobs and with respect to an index of cumulative exposure to crystalline silica. The crystalline silica index was a semiquantitative measure that combined information on duration of exposure, differences in exposure intensity between jobs and calendar periods, the crystalline content of the various product mixes, and the use of respiratory protection devices. Increasing gradients of risk were detected for lung cancer and NMRD with both exposure indices. The relative risk trends for lung cancer and NMRD with crystalline silica exposure lagged 15 years were respectively: 1.00, 1.19, 1.37, and 2.74, and 1.00, 1.13, 1.58, and 2.71. Based on a review of available but limited data on cigarette smoking in the cohort and from application of indirect methods for assessing confounding variables, it seems unlikely that smoking habits could account for all of the association between exposure to dust and lung cancer. The intense and poorly controlled dust exposures encountered before the 1950s were probably the most aetiologically significant contributors to risks from lung cancer and NMRDs. The absence of an excess of lung cancer among workers hired since 1960, and the finding of no deaths attributed to pneumoconiosis as an underlying cause of death among workers hired since 1950 indicate that exposure reductions in the industry during the past 40 years have been successful in reducing excess risks to workers. Further mortality follow up of the cohort and the analysis of radiographic data will be needed to determine conclusively the long term patterns of disease risks in this industry.

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Selected References

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  1. Acquavella J. F., Donaleski D., Hanis N. M. An analysis of mortality follow-up through the National Death Index for a cohort of refinery and petrochemical workers. Am J Ind Med. 1986;9(2):181–187. doi: 10.1002/ajim.4700090209. [DOI] [PubMed] [Google Scholar]
  2. Amandus H. E., Shy C., Wing S., Blair A., Heineman E. F. Silicosis and lung cancer in North Carolina dusty trades workers. Am J Ind Med. 1991;20(1):57–70. doi: 10.1002/ajim.4700200106. [DOI] [PubMed] [Google Scholar]
  3. Amandus H., Costello J. Silicosis and lung cancer in U.S. metal miners. Arch Environ Health. 1991 Mar-Apr;46(2):82–89. doi: 10.1080/00039896.1991.9937433. [DOI] [PubMed] [Google Scholar]
  4. Arellano M. G., Petersen G. R., Petitti D. B., Smith R. E. The California Automated Mortality Linkage System (CAMLIS). Am J Public Health. 1984 Dec;74(12):1324–1330. doi: 10.2105/ajph.74.12.1324. [DOI] [PMC free article] [PubMed] [Google Scholar]
  5. Beskow R. Silicosis in diatomaceous earth factory workers in Sweden. Scand J Respir Dis. 1978 Aug;59(4):216–221. [PubMed] [Google Scholar]
  6. CALDWELL D. M. The coalescent lesion of diatomaceous earth pneumoconiosis. Am Rev Tuberc. 1958 Apr;77(4):644–661. doi: 10.1164/artpd.1958.77.4.644. [DOI] [PubMed] [Google Scholar]
  7. Carta P., Cocco P. L., Casula D. Mortality from lung cancer among Sardinian patients with silicosis. Br J Ind Med. 1991 Feb;48(2):122–129. doi: 10.1136/oem.48.2.122. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Checkoway H., Pearce N., Hickey J. L., Dement J. M. Latency analysis in occupational epidemiology. Arch Environ Health. 1990 Mar-Apr;45(2):95–100. doi: 10.1080/00039896.1990.9935932. [DOI] [PubMed] [Google Scholar]
  9. Checkoway H., Waldman G. T. Assessing the possible extent of confounding in occupational case-referent studies. Scand J Work Environ Health. 1985 Apr;11(2):131–133. doi: 10.5271/sjweh.2243. [DOI] [PubMed] [Google Scholar]
  10. Chen S. Y., Hayes R. B., Liang S. R., Li Q. G., Stewart P. A., Blair A. Mortality experience of haematite mine workers in China. Br J Ind Med. 1990 Mar;47(3):175–181. doi: 10.1136/oem.47.3.175. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Cooper W. C., Jacobson G. A 21-year radiographic follow-up of workers in the diatomite industry. J Occup Med. 1977 Aug;19(8):563–566. [PubMed] [Google Scholar]
  12. Cooper W. C., Sargent E. N. A 26-year radiographic follow-up of workers in a diatomite mine and mill. J Occup Med. 1984 Jun;26(6):456–460. doi: 10.1097/00043764-198406000-00019. [DOI] [PubMed] [Google Scholar]
  13. Costello J., Graham W. G. Vermont granite workers' mortality study. Am J Ind Med. 1988;13(4):483–497. doi: 10.1002/ajim.4700130408. [DOI] [PubMed] [Google Scholar]
  14. Finkelstein M., Liss G. M., Krammer F., Kusiak R. A. Mortality among workers receiving compensation awards for silicosis in Ontario 1940-85. Br J Ind Med. 1987 Sep;44(9):588–594. doi: 10.1136/oem.44.9.588. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Fletcher A. C., Ades A. Lung cancer mortality in a cohort of English foundry workers. Scand J Work Environ Health. 1984 Feb;10(1):7–16. doi: 10.5271/sjweh.2361. [DOI] [PubMed] [Google Scholar]
  16. Goldsmith D. F., Guidotti T. L., Johnston D. R. Does occupational exposure to silica cause lung cancer? Am J Ind Med. 1982;3(4):423–440. doi: 10.1002/ajim.4700030408. [DOI] [PubMed] [Google Scholar]
  17. Guénel P., Højberg G., Lynge E. Cancer incidence among Danish stone workers. Scand J Work Environ Health. 1989 Aug;15(4):265–270. doi: 10.5271/sjweh.1853. [DOI] [PubMed] [Google Scholar]
  18. Harris J. E. Cigarette smoking among successive birth cohorts of men and women in the United States during 1900-80. J Natl Cancer Inst. 1983 Sep;71(3):473–479. [PubMed] [Google Scholar]
  19. Heppleston A. G. Silica, pneumoconiosis, and carcinoma of the lung. Am J Ind Med. 1985;7(4):285–294. doi: 10.1002/ajim.4700070404. [DOI] [PubMed] [Google Scholar]
  20. Hodgson J. T., Jones R. D. Mortality of a cohort of tin miners 1941-86. Br J Ind Med. 1990 Oct;47(10):665–676. doi: 10.1136/oem.47.10.665. [DOI] [PMC free article] [PubMed] [Google Scholar]
  21. Infante-Rivard C., Armstrong B., Petitclerc M., Cloutier L. G., Theriault G. Lung cancer mortality and silicosis in Québec, 1938-85. Lancet. 1989 Dec 23;2(8678-8679):1504–1507. doi: 10.1016/s0140-6736(89)92943-7. [DOI] [PubMed] [Google Scholar]
  22. Legge R. T., Rosencrantz E. Observations and Studies on Silicosis by Diatomaceous Silica. Am J Public Health Nations Health. 1932 Oct;22(10):1055–1060. doi: 10.2105/ajph.22.10.1055. [DOI] [PMC free article] [PubMed] [Google Scholar]
  23. McDonald J. C. Silica, silicosis, and lung cancer. Br J Ind Med. 1989 May;46(5):289–291. doi: 10.1136/oem.46.5.289. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. McMichael A. J. Standardized mortality ratios and the "healthy worker effect": Scratching beneath the surface. J Occup Med. 1976 Mar;18(3):165–168. doi: 10.1097/00043764-197603000-00009. [DOI] [PubMed] [Google Scholar]
  25. Mehnert W. H., Staneczek W., Möhner M., Konetzke G., Müller W., Ahlendorf W., Beck B., Winkelmann R., Simonato L. A mortality study of a cohort of slate quarry workers in the German Democratic Republic. IARC Sci Publ. 1990;(97):55–64. [PubMed] [Google Scholar]
  26. Merlo F., Costantini M., Reggiardo G., Ceppi M., Puntoni R. Lung cancer risk among refractory brick workers exposed to crystalline silica: a retrospective cohort study. Epidemiology. 1991 Jul;2(4):299–305. doi: 10.1097/00001648-199107000-00012. [DOI] [PubMed] [Google Scholar]
  27. Miettinen O. S. Components of the crude risk ratio. Am J Epidemiol. 1972 Aug;96(2):168–172. doi: 10.1093/oxfordjournals.aje.a121443. [DOI] [PubMed] [Google Scholar]
  28. Ng T. P., Ng Y. L., Lee H. S., Chia K. S., Ong H. Y. A study of silica nephrotoxicity in exposed silicotic and non-silicotic workers. Br J Ind Med. 1992 Jan;49(1):35–37. doi: 10.1136/oem.49.1.35. [DOI] [PMC free article] [PubMed] [Google Scholar]
  29. Puntoni R., Goldsmith D. F., Valerio F., Vercelli M., Bonassi S., Di Giorgio F., Ceppi M., Stagnaro E., Filiberti R., Santi L. A cohort study of workers employed in a refractory brick plant. Tumori. 1988 Feb 29;74(1):27–33. doi: 10.1177/030089168807400105. [DOI] [PubMed] [Google Scholar]
  30. SMART R. H., ANDERSON W. M. Pneumoconiosis due to diatomaceous earth; clinical and x-ray aspects. Ind Med Surg. 1952 Nov;21(11):509–518. [PubMed] [Google Scholar]
  31. Samet J. M., Wiggins C. L., Key C. R., Becker T. M. Mortality from lung cancer and chronic obstructive pulmonary disease in New Mexico, 1958-82. Am J Public Health. 1988 Sep;78(9):1182–1186. doi: 10.2105/ajph.78.9.1182. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Savitz D. A. Changes in Spanish surname cancer rates relative to other whites, Denver area, 1969-71 to 1979-81. Am J Public Health. 1986 Oct;76(10):1210–1215. doi: 10.2105/ajph.76.10.1210. [DOI] [PMC free article] [PubMed] [Google Scholar]
  33. Sherson D., Svane O., Lynge E. Cancer incidence among foundry workers in Denmark. Arch Environ Health. 1991 Mar-Apr;46(2):75–81. doi: 10.1080/00039896.1991.9937432. [DOI] [PubMed] [Google Scholar]
  34. Sorahan T., Cooke M. A. Cancer mortality in a cohort of United Kingdom steel foundry workers: 1946-85. Br J Ind Med. 1989 Feb;46(2):74–81. doi: 10.1136/oem.46.2.74. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Steenland K., Beaumont J., Halperin W. Methods of control for smoking in occupational cohort mortality studies. Scand J Work Environ Health. 1984 Jun;10(3):143–149. doi: 10.5271/sjweh.2349. [DOI] [PubMed] [Google Scholar]
  36. Steenland K., Beaumont J., Spaeth S., Brown D., Okun A., Jurcenko L., Ryan B., Phillips S., Roscoe R., Stayner L. New developments in the Life Table Analysis System of the National Institute for Occupational Safety and Health. J Occup Med. 1990 Nov;32(11):1091–1098. doi: 10.1097/00043764-199011000-00008. [DOI] [PubMed] [Google Scholar]
  37. Westerholm P., Ahlmark A., Maasing R., Segelberg I. Silicosis and risk of lung cancer or lung tuberculosis: a cohort study. Environ Res. 1986 Oct;41(1):339–350. doi: 10.1016/s0013-9351(86)80195-5. [DOI] [PubMed] [Google Scholar]

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