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Study of lung cancer due to airborne lead in the US

Study of lung cancer due to airborne lead in the US. Lead is a heavy metal found in the air Historically lead came motor vehicles. After phase out of leaded gasoline, a major source is now lead smelters People are exposed to lead by breathing, and it accumulates in the blood

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Study of lung cancer due to airborne lead in the US

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  1. Study of lung cancer due to airborne lead in the US • Lead is a heavy metal found in the air • Historically lead came motor vehicles. After phase out of leaded gasoline, a major source is now lead smelters • People are exposed to lead by breathing, and it accumulates in the blood • Health impacts are particularly a concern for children, and they include: damaged organs, nervous system, lower IQ, etc • Question: What is the health impact of airborne lead on lung cancer?

  2. Some standards and statistics • National Standard for airborne lead • Quarterly average < 1.5 mg/m3 • OSHA standard for blood lead • Concentration in blood < 25mg/100ml • National health statistics for lung cancer • 1999 lung cancer incidence rate = 55 (per 100,000) • 1999 lung cancer incidence = 150,000

  3. Model-based health impact assessment f(PbA) E[PbA] of lung cancer due to exposure to lead Spatiotemporal monitoring BME spatiotemporal mapping Exposure assessment, PbA(s,t) Stochastic Toxicokinetics modelling Log PbB=a+b log PbA Dose assessment, PbB(s,t) Epidemiological research /biostatistics D= dt PbB(t) SIR=1+(1/ h -1)(1-exp-3D/Ds) H=(SIR-1)h Health effect assessment, H(s,t) Demographics, population p(s,t) L=Hp Population impact assessment, L(s,t) Uncertainty evaluation

  4. Exposure to airborne lead in the US BME median estimate of airborne lead concentration (mg/m3)

  5. Toxicokinetic lead model Log(PbB)=1.9652+0.2356 log PbA (Lai et al., JIAOEH, 1997)

  6. Dose of lead in the blood due to exposure to airborne lead BME median estimate of blood lead concentration (mg/100ml)

  7. Dose of lead in the blood due to exposure to airborne lead BME 16% quantile of blood lead concentration (mg/100ml) We expect people had at least this amount in the blood with only a 16% chance of being wrong

  8. Epidemiology study for lung cancer Cumulative lead dose in relation to Standardized Incidence Rate (SIR) of lung cancer (Lundstrom et al., SJWEH, 1997)

  9. Dose / Health response model Proposed model of health effect: D= dt PbB(t) SIR=1+(1/ h -1)(1-exp-3D/Ds) H=(SIR-1)h • D = cumulated dose • = expected lung cancer incidence rate • Ds = saturation (lethal) dose

  10. Lung cancer incidence rate due to exposure to airborne lead BME median estimate of lung cancer incidence rate (per 100,000) due to exposure to airborne lead from 1984 till year t)

  11. Lung cancer incidence density due to exposure to airborne lead BME median estimate of lung cancer incidence density (per sqmi) due to exposure to airborne lead from 1984 till year t)

  12. Exposure to airborne lead in the US

  13. Dose of lead in the blood due to exposure to airborne lead

  14. Lung cancer incidence rate due to exposure to airborne lead

  15. Total incidence of lung cancer due to exposure to airborne lead

  16. Toxicokinetic sensitivity analysis Lead model 2: Log(PbB)=a’+0. 6 log PbA

  17. Toxicokinetic sensitivity analysis Total incidence of lung cancer due to exposure to airborne lead using toxicokinetic models 1 and 2

  18. Conclusion for airborne lead study • Model-based exposure mapping and health impact assessment provides a framework to assess the impact of airborne lead pollution on lung cancer in the US • The framework allows for an uncertainty evaluation • The analysis estimates a total incidence of 32,500+/-2,000 cases of lung cancer due to exposure from 1984 to 2000. • A sensitivity analysis shows that extrapolation of toxicokinetic models to low dose is a critical • Future work should consider stochastic toxicokinetic modelling

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