Nervous System Degeneration Produced by the Industrial Solvent Methyl n-Butyl Ketone

Abstract

Because of a number of cases of peripheral neuropathy that occurred in factory workers employed in a fabric-printing plant in 1973, chronic inhalation experiments have been conducted using the printing-ink solvents methyl n-butyl ketone (MBK) and methyl iso-butyl ketone (MIBK). After four months of intermittent respiratory exposure to 1,300 parts per million (ppm) MBK, all six rats tested developed severe symmetric weakness in the hindlimbs. Morphological studies showed massive focal axonal enlargements containing abnormally large numbers of neurofilaments and dying-back axonal degeneration in peripheral and central nerve fibers. Six rats similarly exposed for five months to 1,500 ppm of MIBK showed minimal distal axonal change, but remained neurologically intact. The principal conclusion of this study is that MBK is a neurotoxin in rats.

Computerized Posturography with Sway Frequency Analysis: Application in Occupational and Environmental Health.

“…The observation that the vestibulocerebellar sway is affected by n-hexane is compatible with the data in rats that histopathological changes (distal axonal swelling and degeneration) were caused by n-hexane in the vermis 36,37) , which contains the vestibulocerebellum (lower vermis). Similarly, the observation of the increase in the less than the estimated level in the present study-i.e.…”

“…Furthermore, our study suggested that the possibility that xylene can inhibit the effect of n-hexane on postural balance, i.e. the vestibulocerebellar type of sway was inversely related to MHA, denying adverse effect xylene, which has been known as a neurotoxic substance 37,[45][46][47] . This coincides with the observation that n-hexane-induced slowing of peripheral 31,36,37) .…”

“…the vestibulocerebellar type of sway was inversely related to MHA, denying adverse effect xylene, which has been known as a neurotoxic substance 37,[45][46][47] . This coincides with the observation that n-hexane-induced slowing of peripheral 31,36,37) . There is an evidence that subclinical neuropathy occurs in workers exposed to Industrial Health 2002, 40, [14][15][16][17][18][19][20][21][22] nerve conduction and prolongation of latencies of visual evoked potentials are inhibited by xylene in rats 48) .…”

Clinical neurological findings among car painters exposed to a mixture of organic solvents.

“…Peripheral neuropathy has recently been studied extensively in typical work environments (1,5,7,14), in "sniffers" (8,17,18,23), and in experimental animals (21,27,29,30). In such studies the causes of neuropathy have been n-hexane (14,27,33), trichloroethylene (7), and methyl butyl ketone (1,21,29,31). For "sniffers" the etiologic agents have often been referred to only as "volatile hydrocarbons" (22,32).…”

Proposed Occupational Exposure Limits for Non-Carcinogenic Hanford Waste Tank Vapor Chemicals

“…In the case of 2-hexanone, there is very robust toxicity information particularly as it relates to neurotoxicity. Subchronic inhalation exposure to 2-hexanone at concentrations ranging from 200 ppm to 1600 ppm is associated with the observance of peripheral neuropathy in chickens, rats, cats, and monkeys (Abou-Donia et al 1985;Mendell et al 1974;Spencer et al 1975;Duckett et al 1974). Johnson et al (1979) reported that rats and monkeys that inhaled 100 ppm of 2-hexanone for 9 months developed abnormal neurophysiologic indicators, and this exposure was equivalent to a daily 8-hour TWA of 75 ppm.…”