Toxicity Profiles

RAGs A Format for Nitrobenzene - CAS Number 98953

Nitrobenzene is an oily yellow liquid with an almond-like odor. It is an industrial chemical mostly produced (98%) in the United States to manufacture a chemical called aniline. The major use of aniline is in the manufacture of polyurethanes. Nitrobenzene is also used to produce lubricating oils such as those used in motors and machinery. A small amount of nitrobenzene is used in the manufacture of dyes, drugs, pesticides, and synthetic rubber.

Nitrobenzene is absorbed by humans through oral, inhalation, or dermal exposure. A small amount of nitrobenzene may cause mild irritation if it contacts the skin or eyes directly. Repeated exposures to a high concentration of nitrobenzene can result in methemoglobinemia, a condition in which the blood’s ability to carry oxygen is reduced. This condition may turn the skin a bluish color and may cause nausea, vomiting, and shortness of breath. Effects such as headache, irritability, dizziness, weakness, and drowsiness may also occur. There is also some evidence that breathing high concentrations of nitrobenzene may damage the liver. Animal studies have reported effects on the blood and liver from exposure to nitrobenzene.

Under the Guidelines for Carcinogen Risk Assessment, nitrobenzene is classified as "likely to be carcinogenic to humans" by any route of exposure. In animals, breathing nitrobenzene resulted in an increase in liver, thyroid, and kidney tumors.

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

Noncarcinogenic Health Effects
  • The Oral Chronic Reference Dose is 2.00E-03 (mg/kg-day).
  • The Oral Chronic Reference Dose has a modifying factor of 1.
  • The Oral Chronic Reference Dose has an uncertainty factor of 10000.
  • The Oral Chronic Reference Dose is based on the NTP study from 1993.
  • The Oral Chronic Reference Dose study target organ is not identified.
  • The Oral Chronic Reference Dose study critical effect is increased methemoglobin levels.
  • The overall confidence in the Oral Chronic Reference Dose is medium.

  • The Inhalation Chronic Reference Concentration is 9.00E-03 (mg/m3).
  • The Inhalation Chronic Reference Concentration has a modifying factor of 1.
  • The Inhalation Chronic Reference Concentration has an uncertainty factor of 30.
  • The Inhalation Chronic Reference Concentration is based on the CIT study from 1993.
  • The Inhalation Chronic Reference Concentration study target organ is not identified.
  • The Inhalation Chronic Reference Concentration study critical effect bronchiolization of the alveoli and olfactory degeneration .

Carcinogenic Health Effects
  • The Inhalation Unit Risk is 4.00E-05 (ug/m3)-1.
  • The Inhalation Unit Risk is based on the CIIT rat study from 1993.
  • The Inhalation Unit Risk study tumor type is liver hepatocellular adenomas or carcinomas, kidney tubular adenomas or carcinomas, thyroid follicular cell adenomas or carcinomas.