Electrophysiological studies of shoemakers exposed to sub-TLV levels of n-hexane

Abstract

Background and objectives: Exposure to n-hexane, a neurotoxic solvent, has been associated with sensorimotor polyneuropathy, both in occupationally exposed workers and in glue-sniffing addicts. The present study was carried out to ascertain whether exposure to sub-TLV levels of n-hexane was associated with electrophysiological abnormalities and to determine if these possible abnormalities have any correlations with parameters such as the biological exposure index (BEI) of this neurotoxic chemical, workers' TWA exposure to n-hexane and/or duration of employment.

Materials and methods: Twenty-seven asymptomatic male workers from 6 shoemaking workshops were studied and compared with a group of 20 age- and sex-matched normal controls with no history of exposure to any neurotoxic agent. They underwent physical examinations as well as conventional needle electromyographic examinations and sensory and motor nerve conduction studies of upper and lower extremities. The TWA exposure to n-hexane and urinary concentration of free 2,5-hexanedione were also determined. Data were analyzed using version 16.0 of the SPSS/PC statistical package.

Results: The TWA exposure to n-hexane was estimated to be 83.2 mg/m(3). Electrophysiological studies showed that the amplitudes of sensory nerve action potential (SAP) for median and sural nerves were significantly lower in exposed subjects than in unexposed normal controls. Additionally, a significant correlation was found between these decreases and the urinary concentration of free 2,5-hexanedione.

Conclusion: The significant decrements in SAP amplitudes for the median and sural nerves may be considered as appropriate indicators for early detection of n-hexane-induced peripheral neuropathy in asymptomatic workers with current exposure to sub-TLV levels of n-hexane.