DERMAL UPTAKE OF SOLVENTS FROM THE VAPOR-PHASE - AN EXPERIMENTAL-STUDY IN HUMANS

The control of exposure to hazardous substances in the workplace has t raditionally focused on uptake via the inhalation route, Control of sk in uptake has generally been considered for solids and liquids but the potential for uptake from vapours and gases has received relatively l ittle attention. The current work was undertaken to establish a method ology to study the dermal uptake from vapours and to provide new and c omparative information on a range of substance vapours. Groups of huma n volunteers were exposed to a small range of substances either 'whole body' or via the skin only. Substances (xylene, toluene, tetrahydrofu ran [THF], methyl ethyl ketone [MEK] and 1-methoxypropan-2-ol [M2P]) w ere selected on the basis of their predicted dermal uptake from the va pour phase; their industrial use and potential for occupational exposu re; the existence of a health-based occupational exposure limit; the a vailability of an analytical technique(s) for the substance and/or met abolite(s); and as representatives of chemical classes, Exposures were for four hours generally at the level of the UK Occupational Exposure Standard, Uptake was assessed by monitoring of parent or metabolite i n blood, single breath or urine following exposure. Uptake of xylene, toluene and THF vapours via the skin under the conditions of this stud y was estimated to contribute around 1-2% of the body burden received following whole body (including inhalation)exposure. MEK showed more u ptake via the skin, contributing around 3-3.5% of the body burden. Mos t dermal uptake was seen for the glycol ether M2P for which estimates of between 5-10% of whole body exposure body burden were obtained. The results of this and other studies indicate that uptake of vapours acr oss the skin can occur but that for some substances (e.g. xylene, tolu ene, THF) this is likely to contribute little to the body burden. For other substances, such as the glycol ethers, skin uptake from vapours may be an important contributor to total uptake, particularly in situa tions where respiratory protective equipment is used to control inhala tion exposure. Crown Copyright (C) 1998, Published by Elsevier Science Ltd on behalf of BOHS.