Handbook of Solvents - George Wypych - ChemTech - Ventech!

1252 Pentti Kalliokoski, Kai Savolainen
shortly considered. Exposure data presented originate mainly from literature; however,
some unpublished data obtained from the Finnish Institute of Occupational Health (FIOH)
has been added to indicate the order of magnitude of current exposure levels in industrialized
countries (data cover the years 1994-1996).
Exposure to organic solvents should be avoided mainly due to the risk of neurotoxic
effects. Acute effects are narcotic resembling those caused by the use of alcohol. Those appear,
for example, as a decrease in reaction time and impairment in psychological performance.
Chronic neurotoxic effects are often called as the organic psychosyndrome (OPS)
including memory disturbances, excessive tiredness, personality changes, irritability and
affect lability. Intellectual reduction may occur but it seems that development of real dementia
would require simultaneously heavy consumption of alcohol. 1 Increased risk of
sleep apnoea has been observed among men exposed occupationally to organic solvents. 2
Exposure to toluene, xylene, and styrene has been found to contribute to the development of
noise-induced hearing loss. This interaction has been suggested to be due to neurotoxic injuries
caused by solvents in the cochlea. 3
Long-term exposure to carbon disulfide and n-hexane may result in peripheral neuropathy.
It should be noted that n-heptane and n-octane have not been shown to cause the type
of peripheral neuropathy (numbness, weakness, and pain in extremities) associated with
n-hexane. 4 Otherwise than the other alkanes, n-hexane is metabolized to a reactive, toxic
compound (2,5-hexanedione). 5
Organic solvents are generally skin irritants. Repeated or prolonged contact may cause
erythema and dryness of the skin. Defatting may lead to cracked skin. Many solvents also
readily absorb through the skin (see 18.4.2). Reactive solvents, such as styrene and
vinyltoluene, may cause contact dermatitis. 6 The annual incidence of occupational diseases
caused by organic solvents was 20.6 cases/10,000 exposed workers in Finland in the
1980’s. More than half of the cases (64%) were dermatoses. 7
Benzene is a well-known human carcinogen. An association with exposure to benzene
and leukemia was detected already in 1920’s. 8 There is some evidence that exposure to
other organic solvents may constitute a carcinogenic risk. The International Agency for Research
on Cancer (IARC) has concluded that there is sufficient evidence for the carcinogenicity
of painters’ occupational exposure. 9 Epidemiological studies conducted among dry
cleaning and metal degreasing workers suggest an increased cancer risk due to exposure to
chlorinated solvents. 10 The carcinogenicity of aromatic solvents (styrene, toluene, and
xylene) has been investigated in many large epidemiological studies. Although the results
have been inconclusive, certain site-specific associations (e.g., for lymphohematopoietic
tissues) have appeared in some of the studies. 11 Only styrene has shown to have some
genotoxic activity in animal studies. 9
18.4.2 EXPOSURE ASSESSMENT
Inhalation is usually clearly the most important route for occupational exposure to solvents.
Organic solvents also enter the body through the skin. 12 For some solvents, especially for
alkoxyalcohols (glycol ethers) and their acetates, this is even the main route of absorption.
Even the skin uptake of vapor can be significant for these compounds. 13 Dermal absorption
of vapors is, however, usually negligible and contact with liquid is required. Increased
workload and heat enhance both inhalation and dermal absorption. 14 Skin contamination
may also lead to oral uptake due to eating and smoking but this is of minor importance for
volatile solvents.