Handbook of Solvents - George Wypych - ChemTech - Ventech!

20.9 Toxicity of environmental solvent exposure for brain, lung and heart 1413
was unlikely. Was the control group suitable? Their average measurements and the distribution
were like three other groups in different parts of the country. The possibility of confounding
exposures was considered from two sites that were beyond 4.8 km and to the
south. Unfortunately, the resources were unavailable to extend testing beyond 4.8 km to
find the rim of Combustion’s effect on people and detect effects of other nearby sites.
Xylene is a solvent for paints, lacquers and adhesives and is a component of gasoline.
In human volunteers in exposure chambers xylene at 70 ppm for 2 hours had no effect on reaction
time or recall memory but levels of 100 to 400 ppm for 2 hours impaired body balance,
memory span, critical flicker fusion and cause eye irritation. 43-45 Alcohol and
1,1,1-trichloroethane had adverse effects on balance that show synergism with xylene. 46 and
increased the latencies for visual and auditory evoked potentials. 47 Occupational studies
have focused on psychiatric symptoms in photogravure workers who also showed headache,
nausea, vomiting and dizziness. 48 Only one study showed impairment for recall memory
attributed to xylene but workers were also exposed to formaldehyde. 49
Xylene toxicity has received less study than that of toluene, but appears considerable
less which supports attributed the neurotoxicity to toluene of mixtures of xylene, benzene
and toluene with straight chain hydrocarbons such as gasoline.
Styrene’s major use is in reinforced fiberglass plastics in constructing boats and bathtubs
and showers and in styrene-butadiene rubber. 2 Small amounts are used in polystyrene
foam cups and packing materials. Styrene inhalation increased locomotion activity in rats
and grip strength at the highest 700 to 1,400 ppm concentrations. 2 Studies of workers
showed hearing loss (increased high frequency hearing thresholds at 16 kHz). 50 Color discrimination
is also reduced. 51 Other observers found abnormal hearing and by
posturography-larger sway areas and poor rotary visual suppression-inhibition or
vestibulatory nystagmus. 52 In 25 studies of workers 2 some showed slowing of reaction time,
poor performance on block design, short-term memory, EEG abnormalities and neuropathy.
These relatively mild effects made me predict less than the severe impairment than observed
in 4 women from a factory making styrene-fiberglass shower-bathtubs. Two sprayed
styrene and the other 2 who had developed skin and airway symptoms on initial exposure
did lay-up and assembly. Five weeks after her first exposure one woman became lightheaded
and dizzy, felt hot and her vision blacked out. On testing reaction times were slow,
sway speed was increased. Problem solving was impaired as was verbal recall and POMS
scores were elevated. She left work stopping exposure. Ten days later, on a trip to the mountains
4,000 feet above sea level she collapsed and became unconscious. Retesting showed
constricted visual fields and worse performance of the above tests. Testing on the second
woman who had developed asthma showed multiple blind spots in her visual fields, diminished
problem solving ability, grip strength, excessive fingertip writing errors and failure to
recall stories after 30 minutes. A third woman also had asthma and severe airway obstruction
showed abnormal balance with eyes open and closed, diminished hearing, bilaterally
constricted visual fields and decreased vibration sense.
The fourth woman had a skin rash and red welts that had kept her away from direct
contact with epoxy and styrene. She had abnormal color discrimination, decreased vibration
sensation, a blind spot in the retina of the left eye and decreased recall of stories. She was the
least impaired although her POMS score and symptom frequencies were increased.