Effect ofdietary intake oftrimethylamine on humanmetabolism oftheindustrial catalyst dimethylethylami ne

Objectives-The aim was to studythe effect oftrimethylamine (TMA) on the metabolismof the industrial catalyst dimethylethylamine (DMEA) to ascertainwhetherbiological monitoring of industrial exposure toDMEA iscompromisedandexcretion ofthemalodorous DMEA insweatandurineisincreased by dietary intake ofTMA. Methods-DMEA (0125 mg) and TMA (0/300/600 mg)were givensimultaneously once weeklyforsixweekstofivehealthy volunteers. Plasmawas collected before andone hourafterthedoses, andurine 0-2,2-4,4-6,6-8, and8-24hoursafter the doses.Specimens were analysed by gas chromatography witha nitrogen sensitive detector. Results-Bothamines were readily absorbedfromthegastrointestinal tract and excretedinurinewithin24 hours (DMEA 80%;TMA 86%).Oralintakeof TMA increased theDMEA contentof plasmaand urinedose dependently, although therewere largeindividual differences. Plasmaandurinary TMA concentrations alsoincreased, butnotdose dependently. Moreover, thefindings suggestedthe formationof endogenous TMA, little dealkylation ofDMEA and TMA, andconsiderable first-pass metabolism. Conclusions-Although intakeofTMA reducedN-oxygenation ofDMEA and TMA,total urinary DMEA values (aggregateofDMEA and itsoxideDMEAO excretion) were unaffected. Thus,monitoringoccupational exposure to DMEA byanalysis ofbiological specimens isnot confoundedby dietary intakeofTMA, providedthattotalurinaryDMEA is monitored. Althoughtheincreased urinary and hidrotic excretion ofDMEA may contribute tobodyodourproblems, theywere primarily duetoTMA excretion, whichismuch thegreater. (Occup Environ Med1995;52:478-483)