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