Handbook of Solvents - George Wypych - ChemTech - Ventech!

1328 Jenni A Ogden
learning and memory, psychomotor slowing, and in more severe cases, executive
(or frontal-lobe) impairments. These can include impoverished verbal fluency,
difficulties with abstract thinking, and impairments in the ability to make plans and
organize tasks logically. These cognitive symptoms must be demonstrable on
neuropsychological tests following a solvent-free period. There is some research
which indicates that this separation of Type 2 OSN into psychological and cognitive
impairment profiles is largely unrealistic, as most workers with Type 2 OSN have
symptoms of both types. 10,12 Type 2 OSN is the primary focus of this section given
its largely irreversible nature and its frequency in the workplace.
• Type 3 OSN: This is the most severe form of OSN and signals an irreversible
dementia with severe impairment across most cognitive and emotional domains. It
is also known as severe toxic encephalopathy, and is fortunately rare in occupational
situations. It is more likely to occur in long-term recreational solvent abusers.
20.2.4 ASSESSMENT OF OSN
There have been a few studies reporting specific symptoms caused by a specific solvent.
The widely used industrial solvent trichloroethylene (TCE), has, for example, been reported
to result in severe agitated depression, sometimes accompanied by violent behaviors towards
self and others. 13 Toluene and TCE can cause peripheral neuropathy, and TCE can
damage the trigeminal or fifth cranial nerve, resulting in a loss of sensation to the face,
mouth and teeth. 1 It is, however, rare to be able to pinpoint a specific solvent as the cause of
specific cognitive or psychological symptoms, and most research on occupational solvent
neurotoxicity has been carried out on workers exposed to a mixture of solvents. A core
neuropsychological battery has been developed by the WHO/Nordic Council, 8 and most
other formal and informal batteries developed for the assessment of OSN include a similar
range of tests, as these are the tests most sensitive to the common neuropsychological impairments
of OSN. 9,14,15,16 Specific tests used in these batteries will not be listed here, as
neuropsychologists qualified to administer, score, and interpret these tests can find specialist
information in texts written on OSN assessment. 1
The assessment of OSN may be initiated if a worker receives a poor score on a screening
workplace questionnaire designed to assess the frequency of self-reported problems
such as irritability and poor memory. 12 In other cases the worker comes to the attention of a
health professional because of interpersonal or memory problems which concern the
worker, family, or work colleagues. In New Zealand, in 1993 the Occupational Safety and
Health Service (OSH) of the Government Department of Labour, established a panel of experts
to develop national guidelines for the diagnosis of OSN. 4,9 Workers who are diagnosed
as suffering from OSN are registered as part of the Notifiable Occupational Disease System.
Other panels provide a similar function for other occupational diseases such as asthma and
asbestos-related disorders. Following is a description of the procedures for diagnosing OSN
that the New Zealand panel has developed and tested since 1993. 4,9
Individuals, industries, industrial health workers, or general practitioners can notify a
possible case of OSN to the panel. Occupational hygienists then attempt to measure the
types and levels of solvents the worker has been potentially exposed to throughout his or her
working life. This is easier if the worker is currently in the solvent environment, but estimates
only can be made of solvent levels in previous workplaces, and of the workplace and
worker’s appropriate use of protective equipment over the years. If there is reason to suspect
that the worker has been exposed to neurotoxic solvents for 10 years or more, or has suf-