Toluene Fact Sheet

Source of Exposure

Toluene is an important organic solvent used in the production of many household and industrial products. Toluene is similar in nature to benzene and has been substituted in its application. Many industrial grades of toluene contain up to 20% benzene. Toluene is commonly found in solvents for gums, fats, adhesives, petroleum products, and paint products. During the 1960's, toluene became known as a substance of abuse by minors in the sniffing of glue. Because of its accessibility and low cost, it has remained a source of abuse in lower socioeconomic areas. Exposure occurs primarily through the inhalation of vapors and direct contact with the skin.

Symptoms

Acute exposure to toluene will cause depression of the central nervous system. There is evidence that long-term exposure to toluene can cause permanent cerebral impairment. Other recognized adverse health effects include defatting dermatitis, conjuctivitis, keratitis, chemical bronchitis, hepatomegaly, parethesias of extremities, renal damage, and behavioral changes. Toluene does not have the potent hematological toxicity of benzene, but there are isolated reports of bone marrow damage after toluene exposure.

Blood Concentrations

Data shows the average blood concentration in the general population to be approximately 1.0 PPB. (EHS data) The Threshold Limit Value set for toluene in ambient air is 100,000 PPB. Workers exposed to the TLV for two hours produced blood concentrations of 900 PPB (Sato et al, 1975).

Toxic Levels

Toluene has been abused for its narcotic effect on the central nervous system. Blood taken from a group of 7 people arrested for intoxication revealed serum toluene levels as low as 300 PPB (Bonnichsen et al, 1966). Other studies have shown that toluene was detected on the breath of abusers with blood levels of less than 1000 PPB. Studies performed by Santran & Dodson showed electroencephalographic abnormalities in long-term abusers. Post-mortem blood concentrations for toluene levels have been reported in ranges from 10,000 - 80,000 PPB. Individuals who have been sensitized may manifest negative health effects at concentrations well within the ranges considered safe for the average population.

Metabolism

Toluene has a half-life in the body of approximately 7.5 hours. Following an exposure to toluene, approximately 20% of the exposure will be exhaled unmetabolized. The remaining 80% will converted in the body to benzoic acid which is conjugated with glycine or glucuronic acid and excreted in the urine. This will account for over half the original dose in a 24-hour period.

Summary

Classification:   Aromatic Solvent
Population Average:   1.0 PPB (whole blood)
Threshold Limit Value:   900 PPB (whole blood)/100,000 PPB (air)
Onset of Symptoms:   200 PPB (whole blood)
Death:   10,000 PPB (whole blood)
Half-Life:   7.5 hours
LD SO:   (oral-rats) 5,000 mg/kg

References

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Bennett, R.H. and Forman, H.R. , "Hypokalemic periodic paralysis in chronic toluene exposure," Arch.Neurol. 37: 673, 1980.

Bonnichsen, R. , Maehly, A.C. , and Moeller, M. , "Poisoning by volatile compounds. 1. Aromatic hydrocarbons," J.For.Sci. 11: 186-204, 1966.

Boar, J.W. and Hurtig, H.I., "Persistent cerebellar ataxia after exposure to toluene," Ann.Neurol. 2: 440-442, 1977.

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United Nations Environment Programme,, IRPTC Legal File 1983, Vol. II, pp. VII/763, Geneva, Switzerland, International Register of Potentially Toxic Chemicals, 1984.