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HEALTH HAZARDS OF SOLVENTS
by Michael McCann, PhD, CIH
In general, solvents are one of the most underrated hazards in art. They are used for a million purposes: to dissolve and mix with oils, resins, varnishes, inks; to remove paint, varnish, lacquers; to clean brushes, tools, silk screens and even hands. As a result, artists are continually being exposed to solvents.
Almost all organic solvents are poisonous if swallowed or inhaled in sufficient quantity, and most cause dermatitis after sufficient skin contact. High concentrations of most solvents can cause narcosis (dizziness, nausea, fatigue, loss of coordination, coma, and the like). This can increase the chances for mistakes and accidents. As mentioned earlier, long-term exposure to high concentrations of many solvents can cause brain damage. In particular, aromatic hydrocarbons, aliphatic hydrocarbons and chlorinated hydrocarbons appear to be implicated. Some solvents - for example,benzene (benzol) and carbon tetrachloride - are so toxic that they shouldn't be used. Other solvents - for example, acetone and ethanol (ethyl or grain alcohol)- are reasonably safe.
Solvents fall into several classes with similar properties. If one member of a class of solvents is toxic, usually another safer member can be chosen.
ALCOHOLS are generally anaesthetics and irritants of the eyes and upper respiratory tract. In high concentrations, methanol (wood or methyl alcohol) can cause dizziness, intoxication, blurred vision and possible liver and kidney damage. If swallowed, it can cause blindness and even death. Ethanol, available as denatured alcohol containing some methanol, is a safer solvent. Amyl alcohol acts as on the nervous system causing dizziness, nausea, vomiting and double vision. Uses: shellac thinner, paint and varnish remover, lacquer thinners, etc.
AROMATIC HYDROCARBONS are among the most dangerous solvents. They may be absorbed through the skin, although their major hazard is by inhalation. In general they are strong narcotics . The most dangerous is benzene (benzol), which causes chronic poisoning from the cumulative effect of exposure to small amounts. Its effects are destruction of bone marrow, leading to a loss of red and white blood cells,and sometimes leukemia. Toluene (toluol) doesn't have the long term chronic effects of benzene on the bone marrow, but may cause liver and kidney damage. Its immediate effects can be more severe then those of benzene if a person is exposed to a high enough concentration. Toluene may also cause adverse reproductive effects. With proper ventilation, however, toluene is a suggested replacement for benzene. Xylene (xylol) is similar to toluene. Styrene is more toxic than toluene or xylene and may cause respiratory irritation, narcosis, liver, kidney and possibly nerve damage. Uses: resin solvent, paint and varnish remover, flourescent dye solvent, common silk screen wash-up, lacquer thinners, aerosol spray cans, etc.
CHLORINATED HYDROCARBONS, like aromatic hydrocarbons, are very hazardous. Some have been used as anaesthetics in the past, but were found to be too toxic. All of them dissolve the fatty layer of the skin and can cause dermatitis. They also cause liover and kidney damage. The drinking of alcohol after exposure to many chlorinated hydrocarbons can make people very sick. One of the most toxic chlorinated hydrocarbons is carbon tetrachloride and it shouldn't be used. It can be absorbed through the skin and exposure to small amounts can cause severe liver and kidney damage. Exposure to larger amounts can cause unconsciousness and death, especially if alcoholic beverages are ingested. Other toxic chlorinated hydrocarbons include tetracloroethane (acetylene tetrachloride), chloroform, ethylene dichloride, perchloroethylene and trichloroethylene. The last four solvents have been shown to cause liver cancer in mice. Methyl chloroform (1,1,1-trichloroethane) appears to be less toxic than other chlorinated hydrocarbons at low concentrations, but has caused many fatalities when inhaled at high concentrations (for example, "glue sniffing" or working in enclosed spaces). Methylene chloride (dichloromethane) is highly volatile and high concentrations may cause narcosis, lung irritation, pulmonary edema, and is a probable human carcinogen. Methylene chloride also decomposes in the body to form carbon monoxide and inhalation of large amounts has resulted in fatal heart attacks. People with heart problems and smokers are particularly at high risk. Although most of the chlorinated hydrocarbons are not flammable, they may decompose in the presence of ultraviolet light or excess heat (e.g., a lit cigarette) to form the poison gas phosgene. In general try to replace chlorinated hydrocarbons with less toxic solvents. Uses: wax, oil, resin, grease and plastics solvent, paint strippers.
ALIPHATIC HYDROCARBONS, also called petroleum distillates, tend to be less toxic than most other solvents. They have a mild narcotic effect and can cause lung irritation in large amounts. If ingested, they may cause pulmonary edema (chemical pneumonia) and possible death due to aspiration into the lungs. Petroleum distillates are also skin irritants. n-Hexane, one of the most volatile petroleum distillates, may cause peripheral neuropathy - nerve inflammation and possible paralysis of arms and legs - from chronic inhalation of large amounts. These symptoms will disappear after a couple of years, but sometimes, with very high exposures, permanent damage to the central nervous system can result. Hexane is found in "extremely flammable" rubber cements and their thinners, in some aerosol spray adhesives and other aerosol spray products,and in low-boiling naphtha (petroleum ether). In recent years, hexane has been replaced by the less toxic heptane in many products. Other petroleum distillates in increasing order of boiling point are gasoline, benzine (VM&P Naphtha), mineral spirits (odorless paint thinner, turpentine substitutes, white spirits) and kerosene. Normal mineral spirits has about 15-20% aromatic hydrocarbons. Odorless mineral spirits and turpenoid have these more toxic aromatic hydrocarbons removed, and are recommended as substitutes for regular mineral spirits and turpentine. Uses: paint thinners, rubber cement thinners, silk screen poster inks, clean-up solvent, and similar products.
ESTERS are eye, nose and throat irritants and have anesthetic effects. Most common acetates are not skin irritants or sensitizers. Ethyl acetate is the least toxic, followed by methyl and amyl acetates. They have good odor warning properties. Uses: lacquer, resin and plastics solvent.
GLYCOL ETHERS AND THEIR ACETATES recently have been found to be much more toxic than previously thought. Methyl cellosolve (ethylene glycol monomethyl ether) and butyl cellosolve (ethylene glycol monobutyl ether) were known to cause anemia and kidney damage. Cellosolve (ethylene glycol monoethyl ether) and its acetate were considered less toxic. Animal and human studies, however, show that cellosolve, methyl cellosolve, and their acetates can cause birth defects, miscarriages, testicular atrophy and sterility at low levels. All glycol ethers need study to determine if they also cause adverse reproductive effects. Uses: photoresists, color photography, lacquer thinners, paints,aerosol sprays.
KETONES cause narcosis and irritation to the eyes and upper respiratory tract in high concentrations. Their odor warning properties are a good indication of the degree of exposure. They also cause defatting of the skin upon prolonged exposure, resulting in dry, scaly, cracked skin. Acetone is one of the safest solvents (except for its high flammability) and does not seem to have any lasting effects. Methyl ethyl ketone (MEK) is more toxic than acetone. Methyl butyl ketone may cause peripheral neuropathy similar to that caused by n-hexane. Methyl ethyl ketone acts synergistically with both n-hexane and methyl butyl ketone to cause neuropathy at levels that neither would by themselves. Other highly toxic ketones include cyclohexanone and isophorone. Uses: Solvents for lacquers, oils, waxes, plastics, vinyl silk screen inks, and so forth.
Another common solvent, TURPENTINE, is a common oil paint and varnish thinner. Turpentines from many sources are skin irritants and sensitizers for many people, and can be absorbed through the skin. Their vapors are irritating to the eyes, nose and throat upon prolonged exposure, and some turpentines may cause severe kidney damage. Resulting symptoms includeheadaches, gastritis, anxiety and mental confusion. Turpentine is highly poisonous by ingestion, with one tablespoon possibly being fatal to a child.
CITRUS SOLVENTS (d-limonene) have been touted as non-toxic. they are definitely less hazardous by ingestion than most other solvents, although they have a citrus-like odor that has caused children to drink them when they have been carelessly left around. They can still make a child sick, but are less likely to cuase fatalities. there have been some rpeorts of skin, eye and respiratory irritation from their use. - excerpted from Health Hazards Manual for Artists, 4th ed., Lyons and Burford, New York NY (1994). (c) copyright Michael McCann 1994