Experiences with the dermal assessment of VOCs Jeroen ... · PDF file GC-FID analysis...

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Transcript of Experiences with the dermal assessment of VOCs Jeroen ... · PDF file GC-FID analysis...

  • How to measure dermal exposure? Experiences with the dermal assessment of VOCs

    Jeroen Vanoirbeek

    Centre for Environment and Health

  • Dermal exposure

    • Prevention was/is mainly focused on airborne exposure

    • Occupational disease did not decrease

  • • Inhalation: o traditionally perceived as the most

    important exposure pathway

     Considered during basic risk assessment

     Occupational Exposure Limits (OELs) available

     Sampling and validated analytical methods

    developed

     Respiratory protection: validated based on

    statistical analysis of monitoring data

     Control methods

    • Dermal: o (often) perceived as a secondary

    exposure pathway or even

    completely ignored

     Considered during basic risk assessment

     OELs not available

     No validated analytical methods

     Controls = only reliance on PPE

     No validation

    Inhalation vs. dermal exposure

  • Bureau of Labor Statistics (BLS) Data, 2010

    • 13 million workers in the US are potentially exposed to chemicals that can

    be absorbed through the skin

    • Largest category of non-fatal occupational illness;~16% of all non-fatal

    occupational illness.

    • Does not include estimates of systemic diseases associated with skin disorders.

  • Skin exposure to chemicals in the workplace is a significant problem in the US. Both the number of cases

    and the rate of skin disease in the US exceeds recordable respiratory illnesses. In 2010, 34,400 recordable

    skin diseases were reported by the Bureau of Labor Statistics (BLS) at a rate of 3.4 injuries per 10,000

    employees, compared to 19,300 respiratory illnesses with a rate of 1.9 illnesses per 10,000 employees.

    Most chemicals are readily absorbed through the skin and can cause other health effects and/or contribute to

    the dose absorbed by inhalation of the chemical from the air. Many studies indicate that absorption of

    chemicals through the skin can occur without being noticed by the worker. In many cases, skin is a more

    significant route of exposure than the lung. This is particularly true for non-volatile chemicals which are

    relatively toxic and which remain on work surfaces for long periods of time. The number of occupational

    illnesses caused by skin absorption of chemicals is not known. However, it is argued that an estimated

    60,000 deaths and 860,000 occupational illnesses per year in the US attributed to occupational exposure, a

    relatively small percentage caused by skin exposure would represent a significant health risk.

    https://www.osha.gov/SLTC/dermalexposure/

    Official awareness (OSHA)

  • Skin exposure to chemicals in the workplace is a significant problem in the US. Both the number of cases

    and the rate of skin disease in the US exceeds recordable respiratory illnesses. In 2010, 34,400 recordable

    skin diseases were reported by the Bureau of Labor Statistics (BLS) at a rate of 3.4 injuries per 10,000

    employees, compared to 19,300 respiratory illnesses with a rate of 1.9 illnesses per 10,000 employees.

    Most chemicals are readily absorbed through the skin and can cause other health effects and/or contribute to

    the dose absorbed by inhalation of the chemical from the air. Many studies indicate that absorption of

    chemicals through the skin can occur without being noticed by the worker. In many cases, skin is a more

    significant route of exposure than the lung. This is particularly true for non-volatile chemicals which are

    relatively toxic and which remain on work surfaces for long periods of time. The number of occupational

    illnesses caused by skin absorption of chemicals is not known. However, it is argued that an estimated

    60,000 deaths and 860,000 occupational illnesses per year in the US attributed to occupational exposure, a

    relatively small percentage caused by skin exposure would represent a significant health risk.

    https://www.osha.gov/SLTC/dermalexposure/

    Official awareness (OSHA)

  • Official awareness (WHO)

  • WHO recommendations

  • WHO recommendations

  • Currently, study designs used to estimate dermal exposure

    are mainly oriented to practical issues. There is no method

    applicable for all circumstances, nor can a guide be

    provided to aid in the selection of a proper method for

    specific circumstances. To overcome the current gaps in

    knowledge, comparative studies are needed. These should

    help to compare the usefulness of the methods, to derive

    harmonized protocols and, finally, to improve our

    understanding of the underlying processes and

    determinants of dermal exposure

    WHO conclusion

  • Schneider et al. (1999)

    established a multi-

    compartment conceptual model

    Modeling dermal exposure

  • Methods to assess dermal exposure

    • Indirect methods o Surface sampling methods (non-human)

    o Biomonitoring

  • Surface sampling methods (non-human)

    Indirect methods

  • Indirect methods Human Biomonitoring

    Urine

    Blood

    “Classical” matrices

    Hair

    “Alternative” matrix

  • Methods to assess dermal exposure

    • Indirect methods o Surface sampling methods (non-human)

    o Biomonitoring

    • Direct methods - in situ techniques (e.g. video imaging) o Removal techniques

    o Interception techniques

  • In situ techniques

    Video imaging

    Rajan B. (2008) Controlling skin exposure to chemicals and wet-work. West Midlands, UK: RMS Publishing

    The pixels intensity correlate with the

    amount of mass deposited on the skin

  • Removal techniques

    Wiping

    Tape stripping Washing

  • Interception techniques

    Patch method Glove method

    Whole body method

    Behroozy A, 2013, IJOEM

  • WHO, 2014

  • Studies with active charcoal patches

    • Van Wendel de Joode B et al., 2005

    o Measured parameters: benzene and toluene

    • passive air monitoring (mg/m³) and dermal patches (wrist of hand; (µg/cm²x8h) and urinary

    S-phenylmercapturic acid (SPMA)

    o Cohort: petrochemical plant (n = 35)

    o Results

    • Both benzene and toluene could be measured in the air (far below MAK) and on patches

    • Benzene : contribution of dermal exposure to internal dose were limited

    • Substancial differences between jobs

    • Some jobs more contribution of dermal exposure

    o Conclusions

    • More studies necessary, preferentially with higher exposure to solvents

    • The design of the charcoal pads need to be improved to limit direct contact and splashes

  • Studies with active charcoal patches

    • Vermeulen R et al., 2006

    o Measured parameters: benzene and toluene

    • passive air monitoring and dermal patches (palm of hand and abdomen; µg/cm²x1h) and

    unmetabolized urinary benzene (Ubz) and toluene (Utol)

    o Cohort: shoe factory (70 subjects, 113 observations on multiple days)

    o Results

    • Air concentrations very low (far below MAK)

    • Concentrations on patches were barely measurable

    • Only when performing gluing tasks

    • Some abdominal exposure was found for toluene, but no correlation between hand and abdomen patch

    o Conclusions

    • Active charcoal patches are a useful technique to quantitatively assess dermal exposure

    • Dermal exposure to benzene and toluene in shoe manufacturing factory is rare

  • Our experience

    • Develop a suitable method for quantitative evaluation of dermal exposure to different VOCs using dermal patches

    • Apply quantitative dermal risk assessment in an industrial setting, along with air sampling and biomonitoring

  • Selection of the monitoring tool

    • Permea-Tec Patch (SKC inc)

    • Can we use this qualitative indicative patch and perform quantitative assessments of dermal exposure?

    Active charcoal on patch Qualitative colorimetric evaluation

    of solvents presence

  • Introduction

    • Permea-TecTM patches (SKC Inc.)

    • Desorption/recovery Efficiency

    o “Phase Equilibrium method”

    o 180 VOCs, divided over 10 standard solutions

    DE (%) = peak area + patch

    peak area - patch X 100

  • Hypothesis

    • Method development based on existing VOC air method:

    o Non-polar compounds (e.g. toluene, m-, p- and o-xylene) :

    • DE nearly quantitative (approaches 100 %), conc. independent

    o Polar compounds (e.g. acetone) :

    • DE not quantitative, conc. dependent (Dubinin isotherm)

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