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A short presentation about the dermal conceptual model published by Schneider and co-workers.
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WORKING FOR A HEALTHY FUTURE
INSTITUTE OF OCCUPATIONAL MEDICINE . Edinburgh . UK www.iom-world.org
A conceptual model of dermal exposure
John Cherrie
…acknowledging the contribution of Schneider, Vermeulen, Brouwer, Kromhout and Fogh
Summary...
• Why do we need a conceptual model of dermal exposure?
• From source to exposure: the compartments• The mass transport processes• Uptake• Some implications for measurement
2AIHce2010
Why do we need a model?
• Present methods for dermal exposure monitoring are:• pragmatic• non-standard
• Contextual information generally not collected
• Relevance of other measurements not clear
3AIHce2010
What is the model?
Surface contamination layer Air compartment
Clothing outer layer
Skin contamination layer
Source
Clothing inner layer
4AIHce2010
Environmental compartments…
Surface contamination layer Air compartment
Source
Personal Barrier
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Personal compartments…
Clothing outer layer
Skin contamination layer
Clothing inner layer
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Personal Barrier
Stratum Corneum Barrier
Clothing Barrier
Emission processes...
Source
Personal Barrier
7AIHce2010
Deposition and Losses
Surface contamination layer Air compartment
8AIHce2010
Transfer...
Surface contamination layer
Clothing outer layer
Skin contamination layer
Clothing inner layer
9AIHce2010
Penetration and Permeation...
Clothing outer layer
Clothing inner layer
Clothing Barrier
10AIHce2010
Redistribution...
Surface contamination layer Air compartment
Clothing outer layer
Skin contamination layer
11AIHce2010
Personal Barrier
Stratum Corneum Barrier
Uptake...
Uptake by diffusion… concentration, area exposed, mass and duration are important
Skin contamination layer
Stratum Corneum Barrier
12AIHce2010
Measurement implications...
• Measurement of compartment mass and mass transfer are different
• Mass transfer should be measured under standard conditions
• Particles are less likely to be taken up than liquids
• We should measure both the mass on skin and uptake
13AIHce2010
