Hexahydrophthalic acid in urine as an index of exposure to hexahydrophthalic anhydride

Post-shift and next-morning urine was sampled from workers exposed to hexahydrophtalic anhydride (HHPA), an epoxy hardener, sensitising at low exposure levels. Exposure levels of HHPA in air (gas chromatography, GC) in the range of 30-270 micrograms/m3 corresponded to urinary concentrations of 0.9-2.8 mumol hexahydrophthalic acid (HHP acid; GC-mass spectrometry)/mmol creatinine. In the morning samples the concentrations were less than 0.04-0.3 mumol HHP acid/mmol creatinine. In unexposed controls, the level was less than 0.1 mumol/mmol creatinine. A correlation was found between the time-weighted levels of HHPA in air and HHP acid in the post-shift urine (rs = 0.93; P less than 0.023), indicating that the determination of HHP acid in urine is suitable for biologic monitoring of HHPA exposure.