Biomonitoring of technical grade 1-alkoxy-2-propanol acetates by analysing urinary 2-alkoxypropionic acids

Abstract

Today commercially available 1-alkoxy-2-propanol acetates contain a harmful isomer 2-alkoxy-1-propanol acetates, which makes up less than 20% of the commercial product. This harmful isomer provides a means with which to study the toxicity and exposure to alkoxypropanols. Assessing exposure to technical grade 1-alkoxy-2-propanol acetates through the biological monitoring of urinary 2-alkoxypropionic acids has been found to be the most accurate method. The method developed in this study provides a procedure for the simultaneous urinalysis of methoxyacetic acid (MAA), ethoxyacetic acid (EAA), butoxyacetic acid (BAA), oxalic acid (OA), 2-methoxypropionic acid (2-MPA) and 2-ethoxypropionic acid (2-EPA). This possibility is very valuable in workplaces where workers are exposed simultaneously to different glycol ethers. This study was conducted among 54 silkscreen printers, who gave a urine sample to be analysed using a capillary gas chromatograph for 2-MPA and 2-EPA. The mean urinary concentrations of 2-MPA and 2-EPA were 1.27 (S.D. = 1.60) mmol/mol creatinine (median = 0.53, n = 26) and 1.23 (S.D. = 2.31) mmol/mol creatinine (median = 0.26, n = 39), respectively. The urinary excretion of 2-MPA and 2-EPA immediately after shift was linearly dependent on the preceding technical grade 1-methoxy-2-propanol acetate ( y = 0.16 x + 0.26, n = 26, R 2 = 0.78) and technical grade 1-ethoxy-2-propanol acetate ( y = 2.05 x − 0.09, n = 39, R 2 = 0.68) respective exposure, as measured in the workers' breathing zone. According to the results of this study it is possible to monitor exposure to the technical grade 1-methoxy-2-propanol acetate and technical grade 1-ethoxy-2-propanol acetate through urinalysis of 2-MPA and 2-EPA.