Handbook of Solvents - George Wypych - ChemTech - Ventech!

1320 Tilman Hahn, Konrad Botzenhart, Fritz Schweinsberg
Allergic potential of solvent products depends on the typical solvent structure. For example,
in glycol ethers their allergic potential is proportional to the charge of interacting
molecules. 59
Allergic effects can also be associated with other skin conditions caused by solvents
such as irritations. Multiple areas of skin damage, including solvent allergies, can change
the skin structure and provoke severe skin disease. 60
In addition to other substances (pesticides, food additives, dust, smoke, etc.), allergic
effects of solvents are discussed as an initial cause of MCS. 61
Organic solvents are associated with human autoimmune diseases, but defined
pathomechanisms of these solvents have not yet been detected (role of solvents in the initiation
or progression of autoimmune diseases). 62
20.1.2.4 Toxic effects of solvents on other organisms
In addition to humans, microorganisms animals and plants are also exposed to solvents. The
interaction between organisms and solvents are often specific. For example, the reactions
elicited by certain solvents depend on the species and abilities of the particular organism affected.
Hydrophobic organic solvents, in particular, are toxic to living organisms, primarily
because they disrupt cell membrane structure and mechanisms. Some living organisms especially
certain bacterial species, are able to adapt to these solvents by invoking mechanisms
such as accelerating repair processes (through changes in the rate of phospholipid
biosynthesis), reduction of the diffusion rate of the solvent and active reduction of the
intracellular concentration of the solvent. More information and examples are shown in
Chapter 14.4.2.
20.1.2.5 Carcinogenicity
The term carcinogenicity is used for toxicants that are able to induce malignant neoplasms.
Carcinogens can be effective at different stages of the carcinogenic process, e. g., initiation,
promotion and progression. They may interact with other noxes and thereby enhance tumor
development. Interactive carcinogenesis can be described as co- and syn-carcinogenesis. A
co-carcinogen is defined as a non-carcinogenic compound that is able to enhance tumor development
induced by a given carcinogen. In syn-carcinogenesis two or more carcinogens,
each occurring in small amounts that are usually not sufficient to induce a tumor in a specific
target organ, may interact to lead to tumor formation in that organ.
As with all carcinogens the carcinogenic potency of solvents has been assessed by
short-term in vitro tests, e. g., Ames assay, by long-term tumor induction experiments in animals
and - especially important for the evaluation of the carcinogenic action in humans -
prospective and retrospective epidemiological studies, for solvent exposure mainly in work
places.
From this data it is generally not possible to evaluate the carcinogenic action of solvent
mixtures, which occur in the majority of exposure situations. It is also important to note, that
for a number of reasons, e. g., very long latency period of tumor generation, accumulation of
single hits in the target cells, significance of repair mechanisms it is not possible to define
TLVs for carcinogens.
In accordance with the evidence available, different classes for chemical carcinogens
have been developed by health authority organizations. 1,2,34-36 Examples of the classification
of carcinogenic solvents are presented in Table 20.1.3.