gulf dream calibration/validation
DESCRIPTION
A presentation given at X2012 as part of a session of the GuLF study.TRANSCRIPT
WORKING FOR A HEALTHY FUTURE
INSTITUTE OF OCCUPATIONAL MEDICINE . Edinburgh . UK www.iom-world.org
Calibration of the DREAM model for the dermal exposure assessment ofworkers in the GuLF STUDY
John W Cherrie1, Melanie Gorman Ng1, Anne Sleeuwenhoek1, Mark Stenzel2, Richard Kwok3, Berna van Wendel de Joode4, Patricia Stewart5
1 Institute of Occupational Medicine, Centre for Human Exposure Science (CHES)2 Exposure Assessment Applications, LLC3 National Institute of Environmental Health Sciences4 Universidad Nacional de Costa Rica5 Stewart Exposure Assessments, LLC
WORKING FOR A HEALTHY FUTURE
INSTITUTE OF OCCUPATIONAL MEDICINE . Edinburgh . UK www.iom-world.org
Calibration of the DREAM model for the dermal exposure assessment ofworkers in the GuLF STUDY
John W Cherrie1, Melanie Gorman Ng1, Anne Sleeuwenhoek1, Mark Stenzel2, Richard Kwok3, Berna van Wendel de Joode4, Patricia Stewart5
1 Institute of Occupational Medicine, Centre for Human Exposure Science (CHES)2 Exposure Assessment Applications, LLC3 National Institute of Environmental Health Sciences4 Universidad Nacional de Costa Rica5 Stewart Exposure Assessments, LLC
3
Summary…
• Original studies to validate DREAM• GuLF DREAM• Two examples using the adapted model• Preliminary data to help validate the
adapted model
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Original DREAM studies…
• Fully described in initial paper, implemented in Microsoft Access
• The accuracy was assessed by comparing DREAM assessments with measured exposure • Hands and other body parts• Variety of measurement methods, removal and
interception samplers• Six different situations/agents
• Spearman correlation coefficients for individual observations ranged from 0.19 to 0.82
van Wendel de Joode B, Vermeulen R, van Hemmen JJ, et al. Accuracy of a semiquantitative method for Dermal Exposure Assessment (DREAM). Occup Environ Med 2005;62:623–32.
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GuLF DREAM
Emission Deposition
Transfer
Clothing
Body surface factor
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GuLF DREAM
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Boom deployment, near shore…
• Deployed by small vessels • Oil was present on the water• Occasionally had to anchor
the boom• could result in the oil or oily
water contacting hands.
• Hands, forearms, and trouser legs probably got wet with water at times
DREAM
0.04 DU
GuLF DREAM
0.54 GDU
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Boom retrieval, near shore…
• Retrieved by vessels or boats of all sizes, but on small boats mainly manual work
• Significant opportunity for contact of hands, arms, legs and torso with oil and oily water
• Wore safety glasses, abrasion- resistant work gloves (e.g. (leather), rubber boots, and a high-visibility garment
DREAM
0.8 DU
GuLF DREAM
20 GDU
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Validation and calibration
• Validate and calibrate revised model against measurement data
• Have identified sources of dermal exposure measurement data with contextual information that can be used to make DREAM assessments• IOM (heavy fuel oil)• Herrick et al (asphalt)• Soutar et al (biocides)• Hines et al (pesticides)• Stewart et al (pesticides)• Van Wendel de Joode et al (Original DREAM data)
Oil and tar
Dispersants
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Biocide spraying…
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Heavy fuel oil…
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Discussion…
• There are no dermal exposure data for the GuLF study!
• Updated model provides a promising basis for exposure reconstruction
• Some weaknesses in current model…• Evaporation and wind speed• Contaminated clothing• Water and washing• Sticky liquids!
• Validation problematic because of limited data