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Explore the difficulties faced in assessing exposure to diesel soot and its health effects. Learn about the mechanisms, fine dust, carbon, and future developments in this field.
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Challenges in exposure assessment to Diesel soot M.P. Guillemin Institute of Occupational Health Sciences Lausanne - Switzerland
Michel Guillemin • Director of the Institute of Occupational Health Sciences in Lausanne, Switzerland • Chemist and occupational hygienist most interested by the exposure assessment strategies • Committed to the development of our knowledge in the area of complex mixtures and not well specified hazards
Outline Introduction What is Diesel exhaust ? Health effects Mechanisms Exposure assessment Fine dust Carbon Further developments Conclusion
What is diesel exhaust ? • Gas phase • Usual gases found after the burning of fuels • Particulate phase • A core of « elemental carbon » coated with organic compounds and inorganic compounds
Effect on the workers’ lung Acute and temporary effects irritation chest tightness wheeze Chronic effects alteration of the lung function response of the immune system inflammation reaction cancer
Health effects Animal
Mechanisms of action - pneumoconiosis Risk of pneumoconiosis in relation to cumulative exposure 90 80 Quartz 70 60 50 Risk (%) 40 30 Coal 20 PVC 10 0 0 20 40 60 80 100 120 Exposure (mg/m3 years)
Mechanisms of action - clearance Clearance half-time for ultrafine particles and other dusts 1000 Ultrafine TiO 2 800 Diesel 600 Quartz Clearance half-time (days) 400 PVC 200 TiO 2 0 0 5 10 15 20 3 Dust concentration [mg/m ]
Health effects Pooled relative risk estimates and heterogeneity-adjusted 95% confidence intervals Bus workers Truck drivers Equipment operators Railroad workers 0.5 0.75 1 1.25 1.5 1.75 2
Diesel exhaust-induced carcinogenesis Particle Macrophage Inflammation Cell injury Cell proliferation Hyperplasia Fibrosis Cytokines Growth factors Proteases Nongenotoxic Pathway
Diesel exhaust-induced carcinogenesis Malignant tumor Initiated cell Activation of protooncogenes Inactivation of tumor supressor genes Promotion Organic Chemicals Preneoplastic lesion Detoxification Excretion Progression Activation Initiation DNA Adducts Mutations DNA Repair Genotoxic Pathway
First attempts in measuring exposure • Gases and «total dust» • Respirable particles • Respirable particles and nicotine • Total carbon
Potential Surrogate of Diesel Exhaust Particulates • Elemental carbon • Small particles counting • Particles identification and counting • Dinitro-Polynuclear Aromatic Hydrocarbons • ...
Conclusions • Real Occupational Health problem • Potential problem in Public Health • Need of a multidisciplinary approach • Political awareness and financial support