Handbook of Solvents - George Wypych - ChemTech - Ventech!

1412 Kaye H. Kilburn
Levels of toluene were less than 200 ppm for 4 years prior to this study, although above 500
ppm earlier.
The axiom that environmental exposures are “never” to pure chemicals is matched by
another that the mixtures are frequently so complex as to defy description. The few observations
suggest that effects seen from mixtures may be due to one or two specific neurotoxic
agents. Judgment must be exercised to curb bias and accept the most plausible attribution as
the above studies illustrate.
Studies of a population exposed in Louisiana to toluene rich solvents and other chemicals
distilled from a site for 17 years were contrasted to unexposed people living 55 km to
the east. 41 The Combustion site accepted 9 million gallons of used motor oil in 1975-1976
and 3 to 4 million gallons from 177 to 1983. Tons of liquid chemical waste from over 100
chemical factories was consigned to this site including toluene, xylene, styrene and benzene,
many chlorinated aliphatics solvents like TCE and chlorinated aromatics including
PCBs and dibenzofurans. Lead, cadmium, mercury and other metals were present in samples
of sludge in ponds after the site closed in 1983 but they were rich in toluene, benzene
and other aromatics. Modeling based on toluene and benzene and using standard Environmental
Protection Agency assumptions and a windrose showed symmetrical spread eastward.
Excesses of leukemia in school children, cancers and neurobehavioral symptoms in
the about 5,000 neighbors of the site led to neurobehavioral testing for impairment in 131
adult subjects within 2 km of the site and 66 adult controls from voter registration rolls of a
town 50 km east. The exposed group matched controls for age but were 1.4 years less educated.
There were adverse effects from exposures while living within 2 km from the site for 4
to 17 years. 41 that were shown by slowed simple and choice reaction times and abnormal
sway speeds. Cognitive function in Culture Fair and block design was decreased and pegboard
and trail making A and B were diminished, as was recall of stories. Profile of mood
states (POMS) scores were 2.5 fold increased with low vigor and high depression, tension,
confusion, anger and fatigue. Thirty of 32 symptoms inquiring about chest complaints, irritation,
nausea and appetite associated, balance, mood, sleep, memory and limbic brain were
significantly more frequent in exposed people and the other two were rare in both groups.
When differences were adjusted for age, color discrimination and similarities became abnormal
were added and trail making A became normal.
The second study was designed to answer how large an area-population was affected,
was direction important and were abnormalities related to the duration of exposure. 42 I examined
408 subjects selected to fill 3 distances outward to 1.6, 3.2 and 4.8 km in 8 compass
octants, thus 24 sectors. The same tests were given by the same staff and results replicated
the earlier study. Regression analysis of each test against distance showed no significant coefficient
and comparison of inner and other sectors found no differences, thus there was no
evidence of a diminished effect from distance. There were no effects of direction. A possible
lessening of effect for durations of exposure of less the 3 years was seen only for peg
placement and trail making B scores. Distance, direction and duration as surrogates for exposure
did not influence impairment as measured.
We concluded that the periphery of effect was beyond 4.8 km meaning a health impact
area larger than 75 km 2 . There was no gradient of effect from the distilling plant outward
suggesting airborne spread and mixing had produced even dosing from a large “cloud”. 4
Peoples migration inside the exposure zone did not influence effects. Bias of examiners