| 1,6-hexamethylene diisocyanate (HDI) is used throughout the automotive repair industry and is a commonly reported cause of occupational asthma in industrialized populations. However, the exact pathological mechanism remains uncertain. Biomarkers from HDI exposure can fill important knowledge gaps between exposure, susceptibility, and the rise of immunological reactions and sensitization leading to asthma. Use of biomarkers in HDI exposure assessment has been limited due to the lack of specific and sensitive analytical methods for their measurement. The objective of this research was to develop and apply quantitative methods for the analysis of novel blood and urinary biomarkers stemming from exposure to HDI monomer to be utilized in HDI exposure assessment studies. To achieve this, we monitored dermal and inhalation exposure to HDI monomer and collected blood and urine from 46 automotive painters. Analytical methods were developed and utilized to quantify 1,6-hexamethylene diamine (HDA) in plasma and hemoglobin and to quantify N-acetyl-1,6-hexamethylene diamine (monoacetyl-HDA) and N,N'-diacetyl-1,6-hexamethylene diamine (diacetyl-HDA) in urine and hemoglobin. Strong associations between cumulative exposure to HDI monomer (dermal or inhalation) and plasma HDA or HDA-hemoglobin adducts were observed (p ≤ 0.10). The significant workplace determinants of plasma HDA levels were paint booth type and coveralls (p ≤ 0.10). These biomarkers may be used in HDI exposure assessment to evaluate workplace controls for reducing exposures and, thus, prevent adverse health effects among workers. |
