Biotransformation of acrylates. Excretion of mercapturic acids and changes in urinary carboxylic acid profile in rat dosed with ethyl and 1-butyl acrylate.

1. The excretion of urinary metabolites was studied in rat dosed intraperitoneally with ethyl acrylate and 1-butyl acrylate. 2. Physiological carboxylic acids, namely, 3-hydroxypropanoic acid, lactic acid and acetic acid were determined by hplc and may be derived from the xenobiotic acrylates. 3. A significant increase in the amounts of 3-hydroxypropanoic acid and acetic acid excreted within 24 h after dosing was found in both the ethyl acrylate and 1-butyl acrylate-exposed rats. 4. A slight increase in the excretion of lactic acid (p < 0.10) was also found in animals exposed to ethyl and 1-butyl acrylates. 5. Two mercapturic acids, N-acetyl-S-(2-carboxyethyl)cysteine and the corresponding N-acetyl-S-[(2-alkoxycarbonyl)ethyl]cysteine were formed from both acrylate esters and were determined by glc. For ethyl acrylate the conversion to mercapturic acids amounted to 11% of the administered dose, whereas for 1-butyl acrylate the corresponding conjugates decreased from 3.6% to 0.5 mmol/kg to 1.6% at 3.0 mmol/kg. 6. Mercapturic acids appear to be potential biological markers of exposure to acrylate esters. However, more sensitive methods would be required for their determination than those available at present.