title: Quantification and statistical modeling--part II: dermal concentrations of monomeric and polymeric 1,6-hexamethylene diisocyanate.
abstract: We conducted a quantitative dermal and inhalation exposure assessment of monomeric and polymeric 1,6-hexamethylene diisocyanates (HDI) in 47 automotive spray painters from North Carolina and Washington State. We report here the use of linear mixed modeling (LMM) to identify the primary determinants of dermal exposure. Dermal concentrations of HDI, uretidone, biuret, and isocyanurate were significantly higher in 15 painters who did not wear coveralls or gloves (N = 51 paint tasks) than in 32 painters who did wear coveralls and gloves (N = 192 paint tasks) during spray painting. Regardless of whether protective clothing was worn, isocyanurate was the predominant species measured in the skin [geometric mean (GM) = 33.8 ng mm(-3)], with a 95% detection rate. Other polyisocyanates (GM < or = 0.17 ng mm(-3)) were detected in skin during <23% of the paint tasks. According to marginal R(2) statistics, mixed models generated in this study described no <36% of the variability in dermal concentrations of the different polyisocyanates measured in painters who did not wear protective clothing. These models also described 55% of the variability in dermal concentrations of isocyanurate measured in all painters (N = 288 paint tasks). The product of analyte-specific breathing-zone concentration (BZC) and paint time was the most significant variable in all the models. Through LMM, a better understanding of the exposure pathways governing individual polyisocyanate exposures may be achieved. In particular, we were able to establish a link between BZC and dermal concentration, which may be useful for exposure reconstruction and quantitatively characterizing the protective effect of coveralls and gloves. This information can be used to reduce dermal exposures and better protect automotive spray painters from potential adverse health effects.
authors.affiliation: Department of Environmental Sciences and Engineering, Gillings School of Global Public Health, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA.
authors.forename: Kenneth W
authors.initials: KW
authors.lastname: Fent
authors.forename: Linda G
authors.initials: LG
authors.lastname: Trelles Gaines
authors.forename: Jennifer M
authors.initials: JM
authors.lastname: Thomasen
authors.forename: Sheila L
authors.initials: SL
authors.lastname: Flack
authors.forename: Kai
authors.initials: K
authors.lastname: Ding
authors.forename: Amy H
authors.initials: AH
authors.lastname: Herring
authors.forename: Stephen G
authors.initials: SG
authors.lastname: Whittaker
authors.forename: Leena A
authors.initials: LA
authors.lastname: Nylander-French
mesh_terms: D000395:Air Pollutants, Occupational / Q000032:analysis*; D003485:Cyanates / Q000032:analysis*; D005374:Filtration / Q000295:instrumentation; D006801:Humans; D017953:Isocyanates; D009657:North Carolina; D016273:Occupational Exposure / Q000032:analysis*; D010150:Paint; D011481:Protective Clothing / Q000706:statistics & numerical data; D018570:Risk Assessment; D012867:Skin / Q000737:chemistry*; D012869:Skin Absorption; D014227:Triazines / Q000032:analysis; D014861:Washington
chemical_list: D000395:Air Pollutants, Occupational; D003485:Cyanates; D017953:Isocyanates; D014227:Triazines; C509473:isocyanuric acid; C015262:1,6-hexamethylene diisocyanate