Health Effects of the Alkylbenzenes. I. Toluene

Abstract

The alkylbenzenes, toluene being the most common example, represent a class of six-membered ring aromatic compounds that have a variety of alkyl groups attached. These chemicals are liquids with relatively low boiling points and are used primarily as solvents or as starting materials in the synthesis of other chemicals and drugs. They are also integral components of gasoline, distillate fuels and other petroleum products. These substituted aromatics are economically important in the chemical, petroleum, pharmaceutical, polymer, paint and dye industries. Alkylbenzenes such as toluene, xylene, ethylbenzene, styrene and cumene are toxicologically important since they are produced, used or disposed of in the largest quantities and therefore might pose significant and potential health risks to man and the environment. In general, the toxicity of alkylbenzenes has been found to be relatively low. Also, for the most part, human and environmental risks are low; however, there may be a few operations where the potential for high exposure could exist. These exposures are minimized by workplace controls or personal protective equipment. Furthermore, health risks for humans are minimized by guidelines for maximum allowable exposure concentrations which have been established for the workplace. This present paper reviews the toxicology and disposition of toluene in animals and humans.

Mortality of workers employed in shoe manufacturing.

“…Experimental studies suggest that tolu en e is associated with skin ca ncer, leukemia, and hematosarcomas in rats and mice (4)(5). However, these effects may have been due to the presence of benzene as an impur ity (6).…”

Developmental Neurotoxicity of Toluene: in vivo and in vitro Effects on Astroglial Cells

“…Toluene (methylbenzene) is an aromatic hydrocarbon commonly used as a starting material in the manufacture of a variety of organic compounds, and as a solvent or thinner in numerous industrial products including paints, lacquers, enamel, varnish, glue, gums, fat and resins [Low et al, 1988]. In 1994, production of toluene in the United States was estimated at more than three million tons [Greenberg, 1997].…”

Reproductive and Developmental Toxicity of Toluene: A Review

“…Consumer exposure may occur through the use of toluene-containing products such as gasoline, cosmetics, rubbercement, nail polish, stain removers, paintbrush cleaners, fabric dyes, inks, adhesives, and cigarette smoke (4). In addition, the practice of intentional inhalation exposure for narcotic effects may produce prolonged exposures to greater than 500 ppm, the level at which narcotic effects have been reported (9). The current permissible exposure limit (PEL) for toluene in air established by the U.S. Occupational Safety and Health Administration (OSHA) and by the California Division of Occupational Safety and Health is 100 ppm (375 mg/m3).…”

“…Tolueneismetabolizedprimarily in the liver by pathways that are similar in humans and in other mammalian species. Thehalf-lifeofeliminationoftoluene from blood in humans is approximately 3.4hr, comparedto 1 hr in rats and mice (9).…”

“…Toluene in the environment is rapidly biodegraded and does not tend to bioaccumulate. Absorption, Metabolism, and Toxicity of Toluene During prolonged inhalation exposures to toluene, 75 to 80% ofthe inhaleddoseis initially absorbed, droppingtoapproximately 50% absorption2to3 hrlater (9). Between4and 18% oftoluene is expired unchangedthrough the lungs, and < 1% is excreted unchanged in the urine (9,11).…”