Quantitative monitoring and statistical modeling of dermal and inhalation exposure to monomeric and polymeric 1,6-hexamethylene diisocyanate during automotive spray-painting Public Deposited

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Last Modified
  • March 22, 2019
Creator
  • Fent, Kenneth W.
    • Affiliation: Gillings School of Global Public Health, Department of Environmental Sciences and Engineering
Abstract
  • Dermal and inhalation exposures to both the monomeric and polymeric forms of 1,6-hexamethylene diisocyanate (HDI) are associated with respiratory sensitization and occupational asthma. However, limited research has been performed on the evaluation of dermal and inhalation exposure to individual monomeric and polymeric HDI in the automotive refinishing industry due to the lack of specific and sensitive analytical methods and measurement techniques. The objective of this research was to develop methodology to quantify dermal and inhalation exposure to HDI and its oligomers (uretidone, biuret, and isocyanurate), to use this methodology to obtain detailed exposure profiles for 47 automotive painters in North Carolina and Washington State, and to use linear mixed modeling to identify the primary determinants of analyte-specific breathing-zone concentrations (BZCs) and dermal concentrations. A highly sensitive and specific liquid chromatography/mass spectrometry method capable of quantifying monomeric and polymeric HDI in air, tape-stripped skin, and paint samples was developed and validated in the occupational setting. Isocyanurate represented the predominant species (i.e., > 90%) of the HDI-based polyisocyanates in sampled paint, air, and skin. The tape-strip sampling methodology that we used had superior collection efficiency and specificity compared to other methods in the literature, while our air measurements of HDI and isocyanurate depended on the type of sampler (i.e., one- or two-stage) used to monitor the breathing-zone. The primary determinants of BZC and dermal concentration were unique to each analyte. As expected, for each of the measured polyisocyanate species, paint concentration was a significant predictor of BZC, and the product of BZC and paint time was a significant predictor of dermal concentration. The models developed in this study provided us with a better understanding of the processes leading to dermal and inhalation exposure to monomeric and polymeric HDI. This understanding was used to identify and quantitatively characterize control interventions for reducing polyisocyanate exposures for the ultimate goal of protecting automotive spray-painters from potential adverse health effects, such as occupational asthma.
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  • In Copyright
Advisor
  • Nylander-French, Leena A.
Degree granting institution
  • University of North Carolina at Chapel Hill
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