Metabolites of 2‐ and 3‐Monochloropropanediol (2‐ and 3‐MCPD) in Humans: Urinary Excretion of 2‐Chlorohydracrylic Acid and 3‐Chlorolactic Acid after Controlled Exposure to a Single High Dose of Fatty Acid Esters of 2‐ and 3‐MCPD
Nick Bergau, Zhiyong Zhao, Klaus Abraham, Bernhard H. Monien
Abstract
Scope Fatty acid esters of 2‐monochloropropane‐1,3‐diol (2‐MCPD) and 3‐monochloropropane‐1,2‐diol (3‐MCPD) are formed during the deodorization of vegetable oils. After lipase‐catalyzed hydrolysis in the intestine, 2‐ and 3‐MCPD are absorbed, but their ensuing human metabolism is unknown. Methods and results The compounds 2‐chlorohydracrylic acid (2‐ClHA) and 3‐chlorolactic acid (3‐ClLA) resulting from oxidative metabolism of 2‐MCPD and 3‐MCPD, respectively, are identified and quantified in human urine samples. An exposure study with 12 adults is conducted to determine the urinary excretion of 2‐ClHA and 3‐ClLA. The participants eat 12 g of hazelnut oil containing 24.2 mg kg −1 2‐MCPD and 54.5 mg kg −1 3‐MCPD in the form of fatty acid esters. Average daily amounts of “background” excretion before the exposure are 69 nmol 2‐ClHA and 3.0 nmol 3‐ClLA. The additional mean excretion due to the uptake of the hazelnut oil amounts to 893 nmol 2‐ClHA (34.0% of the 2‐MCPD dose) and 16.4 nmol 3‐ClLA (0.28% of the 3‐MPCD dose). Conclusions The products of oxidative metabolism of 2‐ and 3‐MCPD, 2‐ClHA, and 3‐ClLA, are described for the first time in humans. Due to the lack of specificity, the metabolites may not be used as exposure biomarkers to low doses of bound 2‐ and 3‐MCPD, respectively.