immunotoxic effects of silica exposures in gold mining
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Immunotoxic Effects of Silica Exposure in Gold Miners in South Africa
Ahmed Ibrahim Dr. Marc Schenker
Environmental EpidemiologyDecember 06, 2007
Importance
Background
Objective
Study Design
Evaluation
Questions
Importance
1.Mining and infectious disease
2.Economic burden
3.Public Health
4.Environmental Justice
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
Objective
Does silica exposure cause immunodeficiency in
South African gold miners?
1.Cross Sectional Study
Addendum
2. Prospective Cohort Study
Study Design
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
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
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
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
QUESTIONS
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