TOXIC EFFECTS OF SOLVENT EXPOSURE

G. Wypych (ed.) Handbook of Solvents (-l-Solvent Database on CD-ROM), ChemTec Publishing, Toronto, and Wiliam Andrews Publishing, New York, 2001 Chapter 20 (p. 1315ff.) Toxic Effects of Solvent Exposure. [132] D. J. De Renzo (ed.) Solvents Safety Handbook, Noyes, Park Ridge/USA, 1986. [133] R. V. Golovnaya and T. A. Misharina Thermodynamic Treatment of the Polarity and the Selectivity of Sorbents in Gas Chromatography, Usp. Khim. 49, 171 (1980) Russ. 

It is evident that many solvents present considerable health hazards and hence have been subject to restriction through regulation. Even when using solvents of low toxicity, their odor may be undesirable in both the working environment and in the area around manufacturing facilities. The common modes of entry of these volatile substances in the body are inhalation, skin contact and ingestion. The toxic effects of solvents depend on the amount of solvent and the exposure time, based on which degree of toxicity is represented, as follows. 

To decrease the effect of solvent exposure, substitute hazardous solvents with less toxic or hazardous solvents whenever possible. 

SAN resins themselves appear to pose few health problems in that they have been approved by the EDA for beverage botde use (149). The main concern is that of toxic residuals, eg, acrylonitrile, styrene, or other polymerization components such as emulsifiers, stabilizers, or solvents. Each component must be treated individually for toxic effects and safe exposure level. 

The effects of occupational exposure to lindane have been investigated extensively (96—100). These studies indicated that occupational exposure to lindane resulted in increased body burdens of this chemical however, toxic effects associated with these exposures were minimal and no central nervous system disorders were observed. This is in contrast to the polyneuropathies that are often observed after exposure to other haloorganic solvents. 

In animal studies acetone has been found to potentiate the toxicity of other solvents by altering their metabolism through induction of microsomal enzymes, particularly cytochrome P-450. Reported effects include enhancement of the ethanol-induced loss of righting reflex in mice by reduction of the elimination rate of ethanol increased hepatotoxicity of compounds such as carbon tetrachloride and trichloroethylene in the rat potentiation of acrylonitrile toxicity by altering the rate at which it is metabolized to cyanide and potentiation of the neurotoxicity of -hexane by altering the toxicokinetics of its 2,4-hexane-dione metabolite.Because occupationally exposed workers are most often exposed to a mixmre of solvents, use of the rule of additivity may underestimate the effect of combined exposures. ... 

Benzene is widely used for its solvent properties and as an intermediate in the synthesis of other chemicals. The 1999-2000 recommended threshold limit values are given in Table 57-1. The acute toxic effect of benzene is depression of the central nervous system. Exposure to 7500 ppm for 30 minutes can be fatal. Exposure to concentrations larger than 3000 ppm may cause euphoria, nausea, locomotor problems, and coma vertigo, drowsiness, headache, and nausea may occur at concentrations ranging from 250 to 500 ppm. No specific treatment exists for the acute toxic effect of benzene. 

Toxic effects of chemicals can range from mild and reversible (e.g., headache from inhaling petroleum naphtha vapors that disappears with fresh air) to serious and irreversible (e.g., liver or kidney damage from excessive exposures to chlorinated solvents). Toxic effects from chemical exposure depend on the severity of the exposures. Greater exposure and repeated exposure generally lead to more severe effects. 

Apart from the effects of acute exposure, lower level, chronic exposure can also have toxic effects. For example, it is argued that solvent disease includes impairment of memory and coordination, and changes in personality, but this is a contentious issue. Effects on organs hke the liver and kidney certainly do result from both acute and chronic exposure to certain solvents, for example carbon tetrachloride, which was used in dry cleaning but has now been replaced. 

Finally, another halogenated solvent that causes toxic effects after acute exposure is dichloromethane or methylene chloride. It is used for degreasing engines and metalwork, and is the main constituent of paint stripper. If it is used in confined, enclosed spaces, such as rooms without adequate ventilation, it can lead to serious, unexpected toxic effects. As the solvent is breathed in by the worker it becomes localized in body fat. Later the... 

Apart from the acute toxic effects of high concentrations of the more volatile solvents, there are health hazards from the long-term (chronic) exposure to low levels of solvents. Reproductive effects that are associated with chronic exposure to some solvents used in laboratories are shown in Table 11.8. Evidence from animal studies suggests there are reproductive hazards from handling other solvents. Eor example ... 

The literature on the toxicity of benzene in humans is extensive. The acute effects of benzene exposure generally differ markedly from the chronic effects. Acute exposure to high doses of benzene in air (at concentrations in excess of 3000 ppm) causes symptoms typical of organic solvent intoxication. Symptoms may progress from excitation, euphoria, headache, and vertigo, in mild cases, to central nervous system depression, confusion, seizures, coma, and death from respiratory failure in severe cases. The rate of recovery depends on the initial exposure time and concentration, but, following severe intoxication, the symptoms may persist for weeks. 

Only a very few studies have documented the toxic effects of chemical mixtures on the musculoskeletal system. Almost all of these studies address the effects of tobacco smoking and organic solvent exposure. The following studies are illustrative of those reported. 

Escalona E, Yanes L, Feo O, et al Neurobehavioral evaluation of Venezuelan workers exposed to organic solvent mixtures. AmJInd Med 27 15-27, 1995 Eskenazi B, Gaylord L, Bracken MB, et al In utero exposure to organic solvents and human neurodevelopment. Dev Med Child Neurol 30 492-501, 1988 Feldman RG, Ratner MH, Ptak T Chronic toxic encephalopathy in a painter exposed to mixed solvents. Environ Health Perspect 107 417 22,1999 Fidler AT, Baker EL, Letz RE Neurobehavioural effects of occupational exposure to organic solvents among construction painters. British Journal of Industrial Medicine 44 292-308, 1987... 

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