Toxicity Profiles

RAGs A Format for Toluene - CAS Number 108883

Toluene is a colorless organic liquid with a sweet pungent odor. Toluene is isolated by distillation of reformed or pyrolized petroleum and coal tar; however, most of the toluene produced remains as a benzene-toluene-xylene (BTX) mixture for use in gasoline. The primary use of isolated toluene is in the production of benzene and for backblending into gasoline to increase octane ratings. Toluene is also used as raw material in the production of benzyl chloride, benzoic acid, phenol, cresols, vinyl toluene, and TNT; as a solvent for paints and coatings; and in adhesives, inks, and pharmaceuticals.

In humans and animals, the primary effect associated with inhalation exposure to toluene is central nervous system (CNS) depression. Short-term exposure of humans to 100-1500 ppm has elicited CNS effects such as fatigue, confusion, incoordination, and impairments in reaction time, perception, motor control and function. Exposure to concentrations ranging from 10,000-30,000 ppm has resulted in narcosis and deaths. Equivocal evidence shows that exposure to toluene in utero causes an increased risk of CNS abnormalities and developmental delay in humans.

No studies on human exposure to toluene and carcinogenicity are available. An increased incidence of hemolymphoreticular neoplasms was reported in rats exposed to 500 mg/kg of toluene by gavage for 2 years; however, results from two long-term inhalation studies indicate that toluene is not carcinogenic at concentrations up to 1200 ppm. Based on U.S. Environmental Protection Agency (EPA) guidelines, toluene was assigned to weight-of-evidence group D, not classifiable as to human carcinogenicity.

The following is a presentation of the toxicity information associated with Toluene.

• The Oral Chronic Reference Dose is 8.00E-02 (mg/kg-day).
• The Oral Chronic Reference Dose has a modifying factor of 1.
• The Oral Chronic Reference Dose has an uncertainty factor of 3000.
• The Oral Chronic Reference Dose is based on the NTP study from 1990.
• The Oral Chronic Reference Dose study target organ is kidney.
• The Oral Chronic Reference Dose study critical effect is increased kidney weight.
• The overall confidence in the Oral Chronic Reference Dose is medium.

• The Inhalation Chronic Reference Concentration is 5.00E+00 (mg/m³).
• The Inhalation Chronic Reference Concentration has a modifying factor of 1.
• The Inhalation Chronic Reference Concentration has an uncertainty factor of 10.
• The Inhalation Chronic Reference Concentration is based on the Foo et al. study from 1990 and multiple others.
• The Inhalation Chronic Reference Concentration study critical effect is neurological effects.
• The overall confidence in the Inhalation Chronic Reference Concentration is high.

• The Dermal Chronic Reference Dose is 6.40E-02 (mg/kg-day).
• The Dermal Chronic Reference Dose is based on a gastrointestinal absorption factor of 0.8000.

• The Inhalation Chronic Reference Dose is calculated to be 1.43E+00 (mg/kg-day).