Toluene

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Latest Edit: Iva Lloyd, ND 2014-02-17 (EDT)

Toluene is one of many toxic environmental chemicals. Toluene is produced from petroleum refining. The main source of toluene is by inhalation of vapors.

Sources

  • Automotive and aircraft emissions, poor emission-control devices on older vehicles, poor maintenance practices, high-density traffic locales, gasoline filling stations, refineries, tobacco smoke. The amount of toluene in a single cigarette may vary from 80 to 100 micrograms (ug).
  • Blended into gasoline as a component to increase octane number.
  • Two thirds of its use as a solvent carrier in paints, inks, thinners, coatings, adhesives, degreasers, pharmaceutical products.
  • Household: aerosols, spray paint cans, glues, varnishes, shellac, rust preventatives, solvent-based sanitizing agents and germicides, etc.
  • Industry: paint, printing and leather finishing-industry, rubber-coating industry, shoemakers
  • Foods: containing sodium benzoate additive.

Health Impact

  • Depression or excitatory effect on the central nervous system- euphoria followed by disorientation, tremulousness, mood lability, tinnitus, diplopia, hallucinations, dysarthria, ataxia, convulsions, coma.
  • Irritation (eyes, nose, throat), dizziness, taste and olfactory fatigue.
  • Drowsiness, headache, impaired cognitive and motor function, insomnia, anorexia.
  • Solvent abuse through "sniffing" toluene-containing products may lead to gross disorientation, neurological impairment, and death.

Metabolism

  • Metabolized in the liver by cytochrome P-450 dependent multifunction oxidase enzymes which are conjugated principally with glycine, and excreted in the urine as hippuric acid. Smaller amounts can also be conjugated with glucuronic acid. Minor amounts generally undergo hydroxylation to cresols, which are excreted in the urine as sulfate, or glucuronide conjugates.
  • Under conditions of chronic exposure, significant uptake of toluene into lipid-rich tissues (adipose, CNS) may occur. Effects are reversible on cessation of exposure, but are increasingly severe and persistent with increasing concentration and/or duration of exposure.
  • Toluene interferes with the biotransformation of other compounds such as benzene, xylene, and styrene in the liver.
  • Grandjean P, Landrigan PJ. Developmental neurotoxicity of industrial chemicals. Lancet;2006 Dec 16;368(9553):2167-78. PMID: 17174709.