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April 1975

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

Author Affiliations

From the Department of Pathology (Neuropathology) (Drs. Spencer and Schaumburg) and the Saul R. Korey Department of Neurology (Dr. Schaumburg), Albert Einstein College of Medicine, The Bronx, NY, and the Health and Safety Laboratory (Drs. Raleigh and Terhaar), Eastman Kodak Co., Rochester, NY.

Arch Neurol. 1975;32(4):219-222. doi:10.1001/archneur.1975.00490460035002

Because of a number of cases of peripheral neuropathy that occurred in factory workers employed in a fabricprinting 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.

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