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Immunotoxic Effects of Silica Exposures in Gold Mining


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This was a study proposed to measure the immunotoxic effects of subterranean Gold Mines in South Africa.

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Immunotoxic Effects of Silica Exposures in Gold Mining

  1. 1. Immunotoxic Effects of Silica Exposure in Gold Miners in South Africa Ahmed Ibrahim Dr. Marc Schenker Environmental Epidemiology December 06, 2007
  2. 2. Importance Background Objective Study Design Evaluation Questions
  3. 3. Importance <ul><li>Mining and infectious disease </li></ul><ul><li>Economic burden </li></ul><ul><li>Public Health </li></ul><ul><li>Environmental Justice </li></ul>
  4. 4. <ul><li>Toxicology Studies </li></ul><ul><li>-silica exposure in rats: activation of TH1 </li></ul><ul><li>increased IgM, IgG, LALN’s </li></ul><ul><li>2. Epidemiological Studies </li></ul><ul><li>Lung Cancer </li></ul><ul><li>COPD </li></ul><ul><li>High risk of infections </li></ul>Background
  5. 5. Objective Does silica exposure cause immunodeficiency in South African gold miners?
  6. 6. <ul><li>Cross Sectional Study </li></ul><ul><li>Addendum </li></ul><ul><li>2. Prospective Cohort Study </li></ul>Study Design
  7. 7. <ul><li>Cross Sectional Study </li></ul><ul><li>Prevalence of immunodeficiency among gold miners </li></ul><ul><li>Sending Surveys to Foreman to recruit miners </li></ul><ul><li>Inclusion Criteria </li></ul><ul><li>Healthy (assessed by onsite physician) male (15-60) </li></ul><ul><li>2. HIV negative </li></ul><ul><li>3. Miner/Nonminer (age, sex, resident matched controls) </li></ul><ul><li>4. Not taking medication </li></ul>
  8. 8. <ul><li>Data Collection (n=500) </li></ul><ul><li>Age </li></ul><ul><li>Disease history (before/after mining job) </li></ul><ul><li>Position in mine (e.g. rock driller) -dose </li></ul><ul><li>Years of service -exposure </li></ul><ul><li>Residence </li></ul><ul><li>Serum sample (WBC)- Readout </li></ul>
  9. 9. <ul><li>5 year observational period </li></ul><ul><li>2. Same groups as cross sectional </li></ul><ul><li>3. Continue to monitor WBC every three months. </li></ul><ul><li>4. Await infection </li></ul><ul><li>5. Compare immune responses to infection </li></ul>2. Prospective Cohort Study
  10. 10. <ul><li>Strengths </li></ul><ul><li>Important question </li></ul><ul><li>Two-tiered approach to save resources </li></ul><ul><li>High translation potential </li></ul><ul><li>Weakness </li></ul><ul><li>No strong evidence for rationale (exploratory) </li></ul><ul><li>May not provide meaningful results (e.g. wrong readout) </li></ul>Design Evaluation
  11. 11. QUESTIONS