Meike Ruenz, Katharina Goerke, Tamara Bakuradze, Klaus Abraham, Alfonso Lampen, Gerhard Eisenbrand, Elke Richling

• Scope This study investigates a potential correlation between the intake of heat-processed food and the excretion of the acrolein (AC) biomarkers N-acetyl-S-(3-hydroxypropyl)-l-cysteine (HPMA) and N-acetyl-S-(carboxyethyl)-l-cysteine (CEMA) based on two human studies. Methods and Results Human exposure to AC is monitored using the AC-related mercapturic acids HPMA and CEMA in the urine of a) non-smoking volunteers under defined living conditions and b) of non-smoking volunteers on unrestricted or vegan diet under free living conditions. Free living volunteers in part show markedly enhanced urinary excretions of HPMA and CEMA. The intake of heat-processed food does not influence AC-related biomarker excretion. Incidentally enhanced urinary exposure biomarker levels appear to suggest AC exposure possibly from open fire, barbecuing, or tobacco smoke. However, kinetics of urinary biomarkers related to tobacco and other potential smoke exposure, do not correlate with those observed for HPMA and CEMA. Conclusion This study is the first to convincingly show a sustained and substantial background exposure to AC in non-smoking humans, clearly independent from uptake of heat-processed foods. The data strongly point to endogenous AC generation by pathways of mammalian and/or microbial metabolism as yet not taken into consideration.