EFFECT OF DIETARY-INTAKE OF TRIMETHYLAMINE ON HUMAN METABOLISM OF THEINDUSTRIAL CATALYST DIMETHYLETHYLAMINE

Objectives-The aim was to study the effect of trimethylamine (TMA) on the metabolism of the industrial catalyst dimethylethylamine (DMEA) to ascertain whether biological monitoring of industrial exposure to DME A is compromised and excretion of the malodorous DMEA in sweat and uri ne is increased by dietary intake of TMA. Methods-DMEA (0/25mg) and TM A (0/300/600 mg) were given simultaneously once weekly for six weeks t o five healthy volunteers. Plasma was collected before and one hour af ter the doses, and urine 0-2, 2-4, 4-6, 6-8, and 8-24 hours after the doses. Specimens were analysed by gas chromatography with a nitrogen s ensitive detector. Results-Both amines were readily absorbed from the gastrointestinal tract and excreted in urine within 24 hours (DMEA 80% ; TMA 86%). Oral intake of TMA increased the DMEA content of plasma an d urine dose dependently, although there were large individual differe nces. Plasma and urinary TMA concentrations also increased, but not do se dependently. Moreover, the findings suggested the formation of endo genous TMA, Little dealkylation of DMEA and TMA, and considerable firs t-pass metabolism. Conclusions-Although intake of TMA reduced N-oxygen ation of DMEA and TMA, total urinary DMEA values (aggregate of DMEA an d its oxide DMEAO excretion) were unaffected. Thus, monitoring occupat ional exposure to DMEA by analysis of biological specimens is not conf ounded by dietary intake of TMA, provided that total urinary DMEA is m onitored. Although the increased urinary and hidrotic excretion of DME A may contribute to body odour problems, they were primarily due to TM A excretion, which is much the greater.