Handbook of Solvents - George Wypych - ChemTech - Ventech!

20.9 Toxicity of environmental solvent exposure for brain, lung and heart 1407
Tests Part of brain measured
Vocabulary long-term memory, frontal lobes
Information, picture completion & similarities long-term memory, frontal lobes
Pegboard performance optic cortex to motor cortex
Trail making A&B (eye-hand coordination)
Fingertip number writing parietal lobe, sensory area of pre-Rolandic fissure
Profile of mood states limbic system for emotional memory
The effects of ethyl alcohol are familiar to most people so I will start with this best
studied of mind altering solvents. Measurements of alcoholic patients in the mid-twentieth
century at New York’s Bellevue Hospital helped David Wechsler formulate his adult intelligence
scale, 11 tests that measure attention, problem solving, concept juggling and memory
including vocabulary. 5 Many other tests were devised to estimate intelligence, how the
mind works as defined by AR Luria and others. 6 Ward Halstead assembled and created
function tests to measure the effects of traumatic damage to the brain by wartime missiles
and by neurosurgery, prefrontal lobotomy. 7 Application of these tests, by Reitan, 8 helped
differentiate the organic brain disorders from schizophrenia and other mental illnesses.
Thus the starting place for testing became brain diseases recognized by the neurologist using
simple bedside qualitative tests. The tests were not used to detect impairment before it
was clinically recognized. The first steps were Benjamin Franklin’s recollections of his own
brain poisoning by lead while he was a printer and Lewis Carroll’s mad hatter, from mercury
used in felting beaver hair. The next steps were taken in Nordic countries in the
1960’s. 9
Carbon disulfide was the first solvent studied and had adverse effects observed by
Delpech in 1863. Neuropsychiatric abnormalities were described 13 years later by
Eulenberg in workers in the rubber and viscose rayon industries. 2 A Finnish psychologist,
Helen Hanninen tested 100 carbon disulfide exposed workers in 1970, 50 were poisoned, 50
exposed and compared them to 50 unexposed. 10 She found intelligence, tasks of attention,
motor skill vigilance and memory were impaired in clinically poisoned and exposed men
compared to unexposed. Digit symbol substitution from the Wechsler’s scale 5 showed the
most effect of exposure. Additional studies of spray painters in the 1970’s and compared to
computer augmented tomography (CT) scans of the brain and function tests. Symptomatic
painters after 20 years or more of exposure had brain atrophy associated with impairment.
11-14
The key to progress in this field was sensitive tests to measure brain function, Table
20.9.3. Fortunately, the Finnish, Danish and Swedish occupational-environmental health
centers units included cooperative neurologists, neurophysiologists and psychologists who
did not defend disciplines to limit activities. The obvious reality that the nervous system
regulates and controls many essential functions helped select measurements to assess vision,
hearing, vibration, odor perception, balance, reaction time including automatic responses
that are measured as blink reflex latency, 15,16 heart rate variation 17 and peripheral
nerve conduction and Hoffmann’s (H) reflex. 18 Tests must be sensitive and reliable, easily
understood and economical of time, taking 3 to 4 hours with rest periods.