The Absorption, metabolism and excretion of furfural in man

Summary

In a series of experiments volunteers were exposed to known concentrations of furfural vapour for a period of 8 hours. Inspired and expired air was analysed and pulmonary retention determined: its mean value of 77.9 % is considerably high and is not related to the level or duration of exposure. Furthermore, analysis of expired air showed that after termination of exposure only a very small proportion (less than 1 %) of the retained furfural is eliminated by the lung.

The chief metabolite of furfural in man is furoylglycine, the side metabolite is 2-furanacryluric acid. No free furoic acid was found in freshly excreted urine of exposed persons (in contrast to experimental animals). The course of metabolite excretion indicates that furfural is metabolised very rapidly; its biological half-life is about 2 – 2,5 hours.

In suitably designed experiments it was proved that during stay in a contaminated atmosphere furfural enters the organism not only by way of respiration but also percutaneously. The amount absorbed by the skin corresponds to about 20 –30 % of the dose retained in the lungs; it is rather variable and dependent on microclimatic conditions; it increases with rising temperature and relative humidity of air.

The magnitude of resorption during contact of the skin with liquid furfural was studied and found to be rather serious from the view point of industrial hygiene. At a 15 minute contamination of one hand (up to the wrist) approximately the same amount of furfural is absorbed as would be retained at an 8-hour (or 4-hour) inspiration of air in a concentration equalling MAC values (Soviet norm 10 mg/m³, American norm 20 Mg/M3).