Jump to main content or area navigation.

Contact Us

Technology Transfer Network - Air Toxics Web Site

1,2-Diphenylhydrazine

122-66-7

Hazard Summary-Created in April 1992; Revised in January 2000

    1,2-Diphenylhydrazine was used in the past to produce benzidine-based dyes.  Currently, the only use for it in the United States is in the production of anti-inflammatory drugs.  Limited information is available on the health effects of 1,2-diphenylhydrazine.  No information is available on the acute (short-term), chronic (long-term), reproductive, developmental, or carcinogenic effects of 1,2-diphenylhydrazine in humans.  In a National Cancer Institute (NCI) study, liver tumors were observed in both sexes of rats and female mice exposed to 1,2-diphenylhydrazine in their diet. EPA has classified 1,2-diphenylhydrazine as a Group B2, probable human carcinogen.

Please Note: The main sources of information for this fact sheet are EPA's Integrated Risk Information System (IRIS), which contains information on the carcinogenic effects of 1,2-diphenylhydrazine including the unit cancer risk for inhalation exposure, and the Agency for Toxic Substances and Disease Registry's (ATSDR's) Toxicological Profile for 1,2-Diphenylhydrazine.

Uses

  • 1,2-Diphenylhydrazine is no longer produced in the United States. (1)
  • 1,2-Diphenylhydrazine is used as a starting material in the production of benzidine.  Benzidine was used in the past to manufacture benzidine-based dyes which are no longer used in the United States, but may still be used in other countries. (1)
  • 1,2-Diphenylhydrazine is used in the production of anti-inflammatory drugs. (1)

Sources and Potential Exposure

  • Human exposure to 1,2-diphenylhydrazine appears to be primarily occupational; however, the number of workers potentially exposed has declined because dye manufacturers in the United States no longer produce benzidine-based dyes. (1)

Assessing Personal Exposure

  • There is no test currently available to determine whether or not exposure to 1,2-diphenylhydrazine has occurred. (1)

Health Hazard Information

Acute Effects:
  • No information is available on the acute effects of 1,2-diphenylhydrazine in humans or animals.
Chronic Effects (Noncancer):
  • No information is available on the chronic effects of 1,2-diphenylhydrazine in humans.  No inhalation data are available in animals.
  • Degenerative alterations in the liver and depressed weight gain have been observed in rats and mice chronically exposed to 1,2-diphenylhydrazine in their diet. (1,2,4)
  • Intestinal hemorrhage in mice and stomach hyperkeratosis and acanthosis in rats has been observed when the rodents were chronically exposed to 1,2-diphenylhydrazine in their diet. (1,2,4)
  • Chronic oral administration of 1,2-diphenylhydrazine produced interstitial inflammation of the lungs in rats. (1)
  • EPA has not established a Reference Concentration (RfC) or a Reference Dose (RfD) for 1,2-diphenylhydrazine. (3)
Reproductive/Developmental Effects:
  • No information is available on the reproductive or developmental effects of 1,2-diphenylhydrazine in humans.
  • In one study, no effects on reproductive organs were found in rats and mice exposed via ingestion. (1)
Cancer Risk:
  • No information is available on the carcinogenic effects of 1,2-diphenylhydrazine in humans.
  • In an NCI study, hepatocellular carcinomas were observed in both sexes of rats and female mice exposed to 1,2-diphenylhydrazine in their diet; mammary adenocarcinomas were also observed in female rats. (3,4)
  • EPA has classified 1,2-diphenylhydrazine as a Group B2, probable human carcinogen. (3)
  • EPA uses mathematical models, based on human and animal studies, to estimate the probability of a person developing cancer from breathing air containing a specified concentration of a chemical. EPA calculated an inhalation unit risk estimate of 2.2 × 10-4 (µg/m3)-1. EPA estimates that, if an individual were to continuously breathe air containing 1,2-diphenylhydrazine at an average of 0.005 µg/m3 (0.000005 mg/m3) over his or her entire lifetime, that person would theoretically have no more than a one-in-a-million increased chance of developing cancer as a direct result of breathing air containing this chemical. Similarly, EPA estimates that breathing air containing 0.05 µg/m3 (0.00005 mg/m3) would result in not greater than a one-in-a-hundred thousand increased chance of developing cancer, and air containing 0.5 µg/m3 (0.0005 mg/m3) would result in not greater than a one-in-ten thousand increased chance of developing cancer. For a detailed discussion of confidence in the potency estimates, please see IRIS. (3)
  • EPA has calculated an oral cancer slope factor of 0.8 (mg/kg/d)-1. (3)

Physical Properties

  • The chemical formula for 1,2-diphenylhydrazine is C12H12N2, and its molecular weight is 184.24 g/mol. (1)
  • 1,2-Diphenylhydrazine occurs as a white crystalline solid that dissolves only slightly in water. (1)
  • The odor threshold for 1,2-diphenylhydrazine has not been established. (1)
  • The vapor pressure for 1,2-diphenylhydrazine is 2.6 × 10-5 mm Hg at 25 °C, and its log octanol/water partition coefficient (log Kow) is 2.94. (1)
Note: There are very few health numbers or regulatory/advisory numbers for 1,2-diphenylhydrazine; thus, a graph has not been prepared for this compound. The health information cited in this fact sheet was obtained in December 1999.

Conversion Factors (only for the gaseous form):
To convert concentrations in air (at 25 °C) from ppm to mg/m3: mg/m3 = (ppm) × (molecular weight of the compound)/(24.45).  For 1,2-diphenylhydrazine: 1 ppm = 7.54 mg/m3.

References

  1. Agency for Toxic Substances and Disease Registry (ATSDR). Toxicological Profile for 1,2-Diphenylhydrazine.  Public Health Service, U.S. Department of Health and Human Services, Atlanta, GA. 1990.
  2. U.S. Environmental Protection Agency. Health Effects Assessment for 1,2-Diphenylhydrazine. EPA/600/8-88/033. Environmental Criteria and Assessment Office, Office of Health and Environmental Assessment, Office of Research and Development, Cincinnati, OH. 1988.
  3. U.S. Environmental Protection Agency. Integrated Risk Information System (IRIS) on 1,2-Diphenylhydrazine. National Center for Environmental Assessment, Office of Research and Development, Washington, DC. 1999.
  4. National Cancer Institute. Bioassay of Hydrazobenzene for Possible Carcinogenicity (CAS No. 122-66-7). TR-92. U.S. Department of Health, Education, and Welfare, Public Health Service, National Institutes of Health. 1978.

Jump to main content.