Handbook of Solvents - George Wypych - ChemTech - Ventech!

1326 Jenni A Ogden
20.2 COGNITIVE AND PSYCHOSOCIAL OUTCOME OF CHRONIC
OCCUPATIONAL SOLVENT NEUROTOXICITY
Jenni A Ogden
Department of Psychology, University of Auckland, Auckland, New Zealand
20.2.1 INTRODUCTION
Many organic solvents used in industry are neurotoxic, and may lead to a range of largely irreversible
cognitive and psychological or psychiatric impairments in workers who are exposed
over long periods of time, or who have had a peak exposure (an episode in which they
were briefly exposed to a larger than normal level of solvent). The most vulnerable workers
are those who work in the spray painting, boat building, printing, textile, plastic, agricultural
and pharmaceutical industries. Often self-employed workers or those in small businesses
are more at risk because the safety measures they take are not as closely monitored,
and peer pressure to use safety equipment even when it is unwieldy, restrictive or expensive,
is unlikely to be as strong as in large workshops. In addition they may be less well educated
regarding the neurotoxic effects of the solvents they work with. The great majority of workers
diagnosed with OSN are men, presumably because men make up the bulk of the
workforce in trades and industries that use neurotoxic solvents.
The chronic, and often slow and insidious effects of occupational solvent
neurotoxicity (OSN) include psychological and psychiatric symptoms, impairments in cognitive
functioning, and negative psychosocial consequences. The Scandinavian countries
are the research leaders in this field, and in recent years health professionals and industries
in the United States and other major industrialized countries have become increasingly
aware of the debilitating symptoms that can affect workers exposed to neurotoxins over a
long time. 1 There have been allegations that OSN is often over-diagnosed by health professionals
who are zealous believers, and that a significant number of workers who complain
of OSN symptoms are malingering in the hope of obtaining financial compensation. 2 While
these allegations almost certainly have some credibility, especially in countries such as the
USA, where civil litigation has resulted in large settlements and the existence of OSN is
now enshrined in legal precedent, 2 there is ample evidence that the OSN syndrome does exist
and is a major health problem for workers in industries that utilize neurotoxic solvents. A
number of research studies establishing the existence of OSN have been conducted in countries
where there is only limited, if any, financial gain to be made from diagnosing OSN, including
Hong Kong 3 and New Zealand. 4
One of the primary difficulties researchers and health professionals face when trying
to ensure that the symptoms they are observing are indeed the result of OSN, lies in the fact
that the neurological damage resulting from chronic neurotoxin exposure tends to be diffuse,
or may, for example, involve a neurotransmitter imbalance. It is therefore unlikely to
be evident on a Computerized Tomograph (CT) or Magnetic Resonance Image (MRI) of the
brain. A neurological examination is rarely helpful, 5 and in many cases the psychological
and cognitive impairments are the only clear indicators of neurotoxicity. A
neuropsychological assessment which utilizes a range of tests to assess cognitive abilities
including attention, concentration, psychomotor speed, memory and visuospatial skills,
along with a psychological interview or questionnaire assessing depression, irritability, mo-