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