Handbook of Solvents - George Wypych - ChemTech - Ventech!

1410 Kaye H. Kilburn
measured to calculate with duration of exposure, lifetime peak levels, lifetime averages, and
cumulative exposure. Possible relationships of neurobehavioral test scores to these surrogates
for dose were searched by regression analysis. No relationships were found for these
dose surrogates which was disappointing.
TCE dominated the mixture of chlorinated aliphatic solvents in air and water of northeast
Phoenix around two Motorola microchip manufacturing plants that began production
in 1957. Neighbor’s complaints of adverse health effects started amelioration effects in
1983. An underwater TCE solvent plume spread west and south of the plants in the Salt
River aquifer. Test wells showed concentrations of TCE from 50 ppm to 1.4%. Also air dispersal
was important for direct exposure as TCE escaped into the air from the plant. It
drained into dry wells, sewers and into a canal running northwest through the neighborhood.
In 1993, 236 exposed adults were compared to 161 unexposed ones from a town 80 km
northwest across the mountains at a higher elevation. The exposed group showed delayed
blink reflex, faster sway speed, slowed reaction time, impaired color discrimination and reduced
cognitive function and perceptual motor speed and reduced recall. Airway obstruction
was shown by pulmonary function testing. Adverse mood state scores and frequencies
of 32 symptoms were also increased. 4,28
Remedial efforts directed at dumping and ground water had not reduced the effect suggesting
either these were ineffective or impairment was permanent and had developed after
1983. Additional groups of subjects on plume but not in the lawsuit were not different from
clients so there was no client bias. Phoenix residents off the plume had only abnormal slowing
of blink interpreted as due to TCE and abnormal airway obstruction compared to the unexposed
population of Wickenburg, AZ. Airway obstruction was attributed to Phoenix wide
air pollution. Proximity within 1.6 km seemed to increase impairment.
In 1998 retesting of 26 people from original groups showed improvement with faster
blink reflexes but worse airway obstruction that had persisted (ref. 4 and unpublished). The
improvement to normal in blink paralleled that seen in chlorine exposed people 3 years after
exposure and first evaluations that were abnormal. 4 The perceptual motor tests, trail making
A and B and peg placement were improved, as were cognitive function measured as Culture
Fair and verbal recall. We deduced that diminished TCE releases from Motorola after 1993
allowed recovery of cranial nerves V and VII so blink latency decreased, accompanied by
some improvement in vigilance and tracking for the better scores. A possible reversal of effect
is so important that these observations should be verified in other groups.
Workers welding and grinding on jet engines in a repair shop were an unusual way to
focus attention on the Gerber-Wellington aquifer in Oklahoma. 28 Our attention was temporarily
on metals in alloys but when testing of 154 workers showed impaired balance, slowed
choice reaction times and impaired color discrimination compared to 112 unexposed subjects,
the priority became effects on the brain. These worker’s cognitive function, perceptual
motor and recall were all abnormal using the same tests as in Phoenix. We probed for
their exposures after observing these effects and found that these workers had used TCE,
trichloroethane, methanol and Freon FC-113 in metal cleaning. The 112 control subjects
had not worked with solvents or TCE, but many people, both workers and control groups,
lived on and drew well water from the Gerber-Wellington aquifer that is contaminated with
TCE. Mapping the blink reflex latencies in the control group showed the people with normal
blink lived outside the aquifer. The aquifer was TCE contaminated (national priority