Propylene glycol monomethyl ether occupational exposure (PGME). 4. Analysis of 2-methoxypropionic acid in urine.

Objective. The two isomers propylene glycol monomethyl ether [PGME-α (1-methoxy-2-propanol, M2P) and PGME-β (2-methoxy-1-propanol)] have different toxicities due to the different ways they are metabolised. The higher toxicity of PGME-β has been attributed to the formation of 2-methoxypropionic acid (2-MPA) as a metabolite of primary alcohol. Six healthy male volunteers were exposed to PGME-α vapour (15, 50 and 95 ppm) with and without respiratory protection for 6 h, including a 30-min break. They were also exposed to PGME-α liquid (10% or 30% in water), via one hand, for 30 min or 1 h. Commercial products of M2P always contain a small quantity of the β isomer, and GC analysis has shown that the product used for this human volunteer exposure contained approximately 0.3% of the β isomer. The objective of this study was to determine the levels of 2-MPA in urine after these exposures to 99.7% PGME-α. Method. An analytical method developed by Laitinen [6] was used for the determination of 2-MPA in the urine of exposed volunteers. Results. End exposure levels of 2-MPA were found to reach from 1.19 to 3.29 mg/l for inhalation and dermal exposure to PGME-α vapour and from under the detection limit to 2.10 mg/l for exposure of one hand in PGME-α liquid. 2-MPA concentrations in urine samples from a non-exposed person or from a person exposed to PGME-α vapour at 15 ppm (inhalation and dermal exposure) and also from a person exposed to PGME-α vapour up to 95 ppm with respiratory protection (dermal-only exposure) all varied from under the detection limit to 0.30 mg/l and are then not significant. [ABSTRACT FROM AUTHOR]