ToxFAQs™ for 1,2-Diphenylhydrazine

Spanish: 1,2-Difenilhidracina

CAS#: 122-66-7

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What is 1,2-diphenylhydrazine?

1,2-Diphenylhydrazine is a man-made chemical that was once used in the past in fabric dyes and to make certain medicines.

It does not dissolve easily in water, but when placed in water, 1,2-diphenylhydrazine rapidly breaks down into other chemicals. These include the toxic chemicals, benzidine and azobenzene. 1,2-Diphenylhydrazine does not evaporate easily but may be released to air when attached to dust particles.

How can I be exposed to 1,2-diphenylhydrazine?

Most people are not likely to be exposed to 1,2-diphenylhydrazine. It has limited use, and doesn't last long once released to the environment.

In the past, it was used in medicines for people. However, since it is not used in medication for people anymore, there should not be human exposure from medicine. 1,2-Diphenylhydrazine is still used to make a medicine for animals. People who live near hazardous waste sites where this chemical was once produced, or people who work with this chemical in a manufacturing plant or processing facility may be exposed to higher levels than normally found in the environment.

How can 1,2-diphenylhydrazine affect my health?

There are no studies that looked for health effects in humans.

A small number of studies have tested 1,2-diphenylhydrazine in laboratory animals. They have found harmful effects on the liver, stomach, intestines, and lungs.

No studies have tested to see if 1,2-diphenylhydrazine will have harmful effects on pregnant animals or their young.

Can 1,2-diphenylhydrazine cause cancer?

Liver cancer and cancer of the ear canal have been seen in animals exposed to high doses of 1,2-diphenylhydrazine. These levels of exposure were higher than humans would normally be exposed to in the environment.

The Department of Health and Human Services considers 1,2-diphenylhydrazine to be reasonably anticipated to be a human carcinogen (causing cancer). The U.S. Environmental Protection Agency (EPA) considers that 1,2-diphenylhydrazine is probably a human carcinogen.

Can I get a medical test to check for 1,2-diphenylhydrazine?

There are no medical tests to find out if you have been exposed to 1,2-diphenylhydrazine. If you think that you have been exposed to this chemical, call your doctor, nurse, or poison control center.

How can I protect myself and my family from 1,2-diphenylhydrazine?

Most people don’t need to take any special steps to avoid 1,2-diphenylhydrazine in their daily lives. Keep children from in soil near hazardous waste sites to avoid coming into contact with 1,2-diphenylhydrazine.

For more information:

Call CDC-INFO at 1-800-232-4636, or submit your question online at

Go to ATSDR’s Toxicological Profile for 1,2-Diphenylhydrazine:

Go to ATSDR's Toxic Substances Portal:

Find & contact your ATSDR Regional Representative at

Page last reviewed: November 03, 2020