An analytical method was developed for the determination of free and conjugated PGME-alpha in urine. The method involves a solid-phase extraction on LC-18 columns and a GC/FID analysis after derivatization with trimethysilylimidazole. The assay was linear (least-squares regression coefficient 0.996), specific, reproducible (intraassay variability 10%, interassay variability 10%), and allowed a high level of PGME recovery (more than 90%). The assay was applied to the analysis of urine samples from three workers who were occupationally exposed to PGME to estimate their exposure. The highest value of PGME concentration in urine was 7.78 mg/l. Air concentrations of PGME ranged between 20 and 40 ppm. A statistically significant correlation was found between measurements of external exposure and PGME in urine. An important fraction of PGME in urine was found to be conjugated.

This study has demonstrated the relatively high pulmonary uptake compared with the dermal uptake. It has also shown the rapid excretion in urine (3.5 h) and in expired air (10 min). With regard to metabolism, this study has established the presence of conjugated PGME in urine.

Objective: The two isomers propylene glycol monomethyl ether [PGME-a (1-methoxy-2-propanol, M2P) and PGME-b (2-methoxy-1-propanol)] have different toxicities due to the different ways they are metabolised. The higher toxicity of PGME-b 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-a 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-a 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 b isomer, and GC analysis has shown that the product used for this human volunteer exposure contained approximately 0.3% of the b isomer. The objective of this study was to determine the levels of 2-MPA in urine after these exposures to 99.7% PGME-a. 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-a vapour and from under the detection limit to 2.10 mg/l for exposure of one hand in PGME-a liquid. 2-MPA concentrations in urine samples from a nonexposed person or from a person exposed to PGME-a vapour at 15 ppm (inhalation and dermal exposure) and also from a person exposed to PGME-a 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.

Identification of potential exposures in Switzerland was carried out. Out of a total of 150,000 products, 2334 were found to contain PGME and most contained between 1% and 10% PGME. There was a great increase in the number of products declared between 1983 and 1991. The principal fields of use were in inks, varnishes and paints.

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