What is the role of xylene in the etiology of toxic neuropathy?

Updated: Dec 06, 2017
  • Author: Jonathan S Rutchik, MD, MPH, FACOEM; Chief Editor: Tarakad S Ramachandran, MBBS, MBA, MPH, FAAN, FACP, FAHA, FRCP, FRCPC, FRS, LRCP, MRCP, MRCS  more...
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Answer

Xylene often is a component of paints and other industrial processes (see Table 3 for other uses of xylene). A literature search using Medline uncovered 11 epidemiologic studies of painters or other subjects with occupational exposure to organic solvents, including xylene, that found positive associations between exposure and PNS dysfunction. Two studies reported that vibration sensation was significantly less acute in 102 painters than in 102 age- and sex-matched controls. Four studies utilized quantitative sensory test (QST) methods.

In 1991, Bleecker found a correlation between increasing exposure dose and elevated vibration sensation thresholds in 187 workers from 2 paint-manufacturing plants. [33] A second study noted higher vibration thresholds in 80 exposed painters than in controls. [34] Demers et al noted statistically significant differences in vibrotactile measurements by QST of upper and lower extremities between 28 painters and 20 nonexposed controls. [35] In 1989, Bove et al compared 93 painters to a nonexposed control population of 105 construction workers. [36] Subjects were tested by 2 QST devices, a vibrometer and a temperature sensitivity tester. Painters had significantly higher temperature sensation thresholds, and exposure intensity and cumulative exposure over the past month and year were associated positively with vibration thresholds.

In 1989, Padilla et al performed an important animal study in which axonal transport was noted to be decreased by 30-50% in the rat optic nerve system immediately and 13 hours after inhalation exposure to xylene. Exposure was subacute; 800 and 1600 ppm for 6 hours/day, 5 days a week for 8 days led to these abnormalities. The authors concluded that the decreased supply of cellular materials to the axon and nerve-ending regions could initiate the neuronal malfunction reported in solvent-exposed animals and humans. [37] As axonal transport is a process common to all nerves, any perturbation in these processes may disrupt the structure and functional integrity of the neuron. This mechanism has been used to explain both the CNS and PNS toxicity from organic solvents.

Seven men aged 17-22 years developed severe distal symmetrical polyneuropathy after repeatedly inhaling a commercially available brand of lacquer thinner that was composed predominantly of xylene. All 7 were disabled permanently with motor weakness. One man died, 3 remained wheelchair bound, and 3 could walk but demonstrated varying degrees of weakness. Pathologic specimens revealed evidence of peripheral neuropathy.


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