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Extended follow-up of lung cancer and non-malignant respiratory disease mortality among California diatomaceous earth workers
  1. Kenneth A Mundt1,
  2. Paolo Boffetta2
  1. 1Ramboll Environ US Corporation, Amherst, Massachusetts, USA
  2. 2Tisch Cancer Institute and Institute for Translational Epidemiology, Mount Sinai School of Medicine, New York, New York, USA
  1. Correspondence to Dr Kenneth A Mundt, Ramboll Environ US Corporation, 28 Amity Street, Suite 2A, Amherst, MA 01002, USA; kmundt{at}

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The updated analysis on mortality among 2343 California diatomaceous earth (DE) workers provides useful information and occupational crystalline silica on health.1

Previously followed through 1992,2 the mortality of this cohort was updated through 2011. Results most relevant to crystalline silica exposure are summarised below (table 1).

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Table 1

Summary of key findings from the updated California diatomaceous earth workers study, by follow-up period

The deficit of lung cancer mortality in the update period appears to ‘balance out’ the earlier excess. For chronic obstructive pulmonary disease and pneumoconiosis, earlier increased mortality was not sustained.

Cox proportional hazards analyses controlling for other factors, but not smoking (unknown for half the workers), demonstrated that the earlier excesses of lung cancer and respiratory diseases were concentrated in the highest exposure groups. For lung cancer, only the highest exposure category (>5.6 mg/m3-years), lagged by 15 years, produced a statistically significant hazards ratio (HR) (2.2, 95% CI 1.07 to 4.5). HRs …

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  • Contributors KAM and PB contributed to the conception of the work, the critique of the Gallagher et al manuscript, the drafting and revising of the letter to the editor for important intellectual content, and the final approval of the version to be submitted for publication.

  • Funding This work was supported by the International Diatomite Producers Association (IDPA).

  • Competing interests IDPA retained KAM and PB to review the updated study on workers at one of their member’s facilities.

  • Provenance and peer review Not commissioned; internally peer reviewed.

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