TABLE 7.3 Peripheral Neuropathy and Solvent Exposure

Reference

Exposed Population

Nonexposed Population

Health Outcomes or Test Type

Solvent

Adjustment

Results

Limitations

Buiatti et al., 1978

Italy

Italian shoe leather workers, perhaps 340; exclusion of workers with history of contact with neurotoxic compounds other than solvents [n not given]

“Normal subjects examined in the neurological department during neurological screening of the normal population” [n not given]

Objective signs of PNS involvement (muscle tone, tendon reflexes, muscle wasting, sensory disorders), subjective symptoms; EMG; maximal motor-conduction velocity, abnormal if lower than 5% fiducial limits in normal population; no detail of when tests were performed relative to last exposure or under what conditions

Mixture of solvents in glues; no details of timing of exposure

Age only

“Polyneuropathic” vs normal; prevalence of polyneuropathy higher in exposed (29% vs 17%; p<0.05); polyneuropathy more frequent with age: 38% over age 40, 18% younger (p<0.005); association between age, maximal motor-conduction velocity in exposed and nonexposed; correlation found between duration of exposure, MCV (r=−0.21; no p value given)

Unclear how many subjects included; study included n-hexane, solvent not sent to Gulf War and a known cause of peripheral neuropathy

Fagius and Gronqvist, 1978

Sweden

42 plastic-coated sheet production workers at steelworks

42 workers in other sections of steelworks

Clinical examination; questionnaire with information on history, exposure, tobacco, alcohol, symptoms (muscle cramping, pain in arms or legs, pins and needles, numbness, reduced sensation, loss of muscle power, diminished muscle volume); vibration sense; MCV, SCV, laboratory tests

Variety of organic solvents; methyl isobutyl ketone, methyl ethyl ketone; duration of employment 6 months–8 years; individual exposure mapped through estimation of mean daily exposure, each subject given exposure coefficient (product of duration in years and mean exposure in minutes per day)

Exposed, referents matched on age, sex, duration of employment

No overt polyneuropathy; one case of possible polyneuropathy in exposed as defined by symptoms; MCV, two cases of suspected polyneuropathy; two reference subjects had high vibration perception; reference subjects showed longer terminal latency in median nerve when all subjects were assessed and when only those with high exposure in preceding 6 months considered. Vibration perception worse in total group of exposed subjects but not retained when only higher exposure considered; considering only exposure in preceding 6 months, higher vibration threshold of forefinger of exposed than of referents (p<0.05), of styloid process of right radius

Authors conclude “some evidence that exposure to organic solvents has a noxious effect on the peripheral nerve function, but the evidence is weak and no definite conclusions can be drawn”



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