Handbook of Solvents - George Wypych - ChemTech - Ventech!

1414 Kaye H. Kilburn
Air sampling was not permitted, concentrations of styrene are unknown and contributions
of other chemicals to this exposure cannot be excluded. However, exposures to formaldehyde
and phenol are unlikely as these workers did not “lay-up” fiberglass resin.
Inhalation of sprayed styrene is the most attribution for the neurobehavioral impairments.
The impairment exceeded that found in a review of boat building and other studies but tests
were more sensitive and the styrene levels may have been higher. We encourage more
neurobehavioral evaluations of styrene spraying workers using such sensitive tests.
Polychlorinated biphenyls (PCBs), the ultimate (poly)chlorinated solvents are 2
membered ring compounds that when heated to 270 o produce dibenzofurans (DBFs) that
are 1,000 or more times as neurotoxic. 53 Initial evaluations were of a few PCB exposed individuals
and 14 firemen exposed to DBFs who showed severe impairment measured after a
medical schools power plant transformers cooked and exploded. Most of the firemen could
not pass the physical, balance and truck driving requirements to return to duty and were retired
on disability. 4,54
A community study explores effects of environmental exposures. PCBs were used as
pump lubricants in natural gas pipelines running north from Texas and Louisiana from 1950
to the middle 1970’s. One pumping station was at Lobelville, TN and at least 16 other US
communities had them. 4 Ninety-eight adult village dwellers were compared to 58 unexposed
subjects from 80 km east or 35 km north. The exposed people were the most abnormal
group I have studied. They had abnormal simple and choice reaction times, balance, hearing,
grip strength and the visual function of color discrimination, contract sensitivity and
visual field performance. The cognitive functions of Culture Fair, digit symbol were abnormal
as were vocabulary, information, picture completion and similarities. Story recall was
diminished and peg placement and trail making A and B and fingertip number writing errors
were decreased. Other possible associations were ruled out and there were no other causes
of impairment. This exposure had caused the most severe neurobehavioral impairment for
these people that I have observed. 4 It exceeded that from distilling chemical waste rich in toluene,
from TCE and from other solvents.
n-hexane by inhalational or through the skin causes peripheral nerves to die-back.
Glue sniffing exposure frequently combines n-hexane and toluene. Twenty-five percent of
workers using glue in shoes and leather goods with n-hexane, 40 to 99.5% had symptomatic
polyneuropathy, slowed nerve conduction and neurological signs. 55 Abnormal findings increased
with age and durations of exposure and were accompanied by lower limb weakness
and pain, abnormal sensations (parenthesis) in the hands and muscles spasm. In another
shoe plant exposure group upper extremity nerve conduction was slowed, frequently after 5
years of exposure. 56 Sensormotor distal neuropathy characterized 98 of 654 workers in the
Italian shoe industry, 47 had decreased motor conduction velocity with headache, insomnia,
nausea and vomiting irritability and epigastric pain. 57 Most workers improved when removed
from exposure. 56 In Japan beginning in 1964 several studies found polyneuropathy
in polyethylene laminating printers 58 and makers of sandals and slippers. 59 A major metabolite
of n-hexane and of methyl butyl ketone is 2,5-hexanedione that is more neurotoxic than
these precursors causing swelling of nerve axons and accumulations of neurofilaments in
mid-portions of peripheral nerves. 60 Methyl ethyl ketone studied in workers lengthened
choice reaction time and motor nerve conduction and decreased vibration sensation signs of
neuropathy. These effects were also seen in glue sniffers. 2