Handbook of Solvents - George Wypych - ChemTech - Ventech!

20.2 Cognitive and psychosocial outcome 1327
tivation and fatigue, thus plays a major role in diagnosing chronic OSN. 6 The World Health
Organization (WHO) and the Nordic and New Zealand Governments all require that a
neuropsychological assessment be used in the diagnosis of solvent neurotoxicity. 7-9
Many victims of OSN do not realize that their chronic fatigue, irritability, poor memory
and other problems may be associated with the solvents in their workplace, and by the
time they seek help from their doctor, psychologist or marriage guidance counsellor, the
OSN symptoms are likely to be compounded and masked by other work and relationship
problems (themselves possibly a consequence of the OSN symptoms). 6 Identification of
OSN as the primary cause of the problems is therefore even more difficult, and proving
cause and effect usually impossible. That OSN is a significant cause of the person’s problems,
can, however, often be established beyond reasonable doubt, provided that some
guidelines are followed. The individual must clearly have been exposed to neurotoxins over
a long period (usually set, rather arbitrarily, at 10 years or more of occupational exposure),
or have suffered a peak exposure. Other major contributors to neurological impairment
should be excluded (e.g., significant traumatic brain injury, or alcohol addiction), there
should be no evidence of malingering, and the pattern of cognitive impairments and psychological
symptoms should be typical of OSN.
20.2.2 ACUTE SYMPTOMS OF SOLVENT NEUROTOXICITY
Neurotoxic solvent exposure can result in some workers experiencing nausea, vomiting,
loss of appetite, severe headaches, confusion, light-headedness and dermatitis. The solvent
may be detectable on their breath and skin for hours and even days after they have left the
solvent environment. Most of these symptoms resolve when they stop working with solvents
but return when they come into contact with solvents again. Workers who suffer these
acute symptoms do not necessarily go on to develop the chronic syndrome of OSN, perhaps
in many cases because they are so disabled by the acute symptoms they stop working before
irreversible damage occurs. Some workers who suffer acute symptoms do remain in the
work environment, sometimes because of financial necessity, or because they do not realize
the solvents are the cause of their problems. 10 Some workers who develop a chronic OSN
syndrome have suffered from acute symptoms, but others have not. The reason for these individual
differences is not clear.
20.2.3 CATEGORIZATION OF OSN
The 1985 International Solvent Workshop 11 proposed three types of OSN, as follows:
• Type 1 OSN: Characterized by subjective complaints of fatigue, irritability,
depression and episodes of anxiety. No cognitive impairments are demonstrable on
neuropsychological testing, and the psychological symptoms resolve on removal
from the solvents. This is also known as the organic affective syndrome, or the
neurasthenic syndrome.
• Type 2 OSN: A more severe and chronic form than Type 1 in which many of the
symptoms and cognitive impairments are thought to be irreversible when the worker
is removed from the solvent environment. It is also known as mild toxic
encephalopathy. Type 2 has been divided further into two sub-types based on
psychological symptoms (Type 2A) and cognitive impairments (Type 2B). Type 2A
sufferers have a range of symptoms which may include sustained personality and
mood disturbances, fatigue, poor impulse control and poor motivation. Type 2B
symptoms include poor concentration, impairments of new verbal and visual