Quantitative plasma biomarker analysis in HDI exposure assessment

Area of Science:

• Occupational Health and Safety
• Analytical Chemistry
• Toxicology

Background:

• Monitoring occupational exposure to diisocyanates like 1,6-hexamethylene diisocyanate (HDI) is crucial for worker health.
• Quantifying biological markers can provide insights into exposure levels and the effectiveness of control measures.
• 1,6-hexamethylene diamine (HDA) is a metabolite of HDI, making it a potential biomarker for exposure.

Purpose of the Study:

• To quantify 1,6-hexamethylene diamine (HDA) levels in the plasma of spray painters exposed to HDI-containing paints.
• To investigate the relationship between plasma HDA levels and both inhalation and dermal exposure to HDI monomer.
• To evaluate the effectiveness of workplace controls, such as ventilation systems, in reducing exposure.

Main Methods:

• Collected hydrolyzed plasma samples from 46 spray painters over multiple visits.
• Quantified HDA using gas chromatography after derivatization to heptafluorobutyryl derivatives.
• Correlated plasma HDA concentrations with measured inhalation and dermal HDI exposure, considering different time lags.

Main Results:

• HDA was detected in 76% of plasma samples, with concentrations ranging from <0.02 to 0.92 µg/L.
• Plasma HDA levels showed a stronger correlation with HDI exposure occurring 20-60 days prior to blood collection compared to same-day exposure.
• Workers using downdraft-ventilated booths had significantly lower plasma HDA levels, indicating improved exposure control.

Conclusions:

• Plasma HDA concentration serves as a valuable biomarker for cumulative inhalation and dermal exposure to HDI.
• This biomarker can be used to assess the effectiveness of occupational exposure controls in real-world settings.
• Workplace ventilation, specifically downdraft booths, significantly reduces HDI exposure and subsequent HDA levels in workers.