gulf dream calibration/validation

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