Toxic Tuesdays

Benzidine is a chemical made by humans that does not occur naturally. It is a solid that can appear white, gray, yellow, or red. Benzidine used to be used to make dyes for cloth, leather, and paper. Today, in the United States and many places around the world, benzidine is no longer manufactured or used.

Although benzidine is no longer in use, it can still be present in the environment. If benzidine enters the water or ground in the process of manufacturing, transport, storage, use, or disposal, it can remain in sediment or soil for a long time. Even if it this benzidine was subsequently covered, it can be brought to the surface again through erosion, construction, and development. At least 28 sites on the National Priorities List eligible for cleanup under the Environmental Protection Agency’s Superfund program are known to contain benzidine.

People who live near waste sites containing benzidine or facilities that previously used benzidine could be at risk of exposure through contaminated water or soil. The Environmental Protection Agency, Department of Health and Human Services, and the World Health Organization have all determined that benzidine causes cancer in humans. Working in facilities that manufactured or used benzidine was known to cause high levels of exposure. This occupational exposure has been linked to bladder and pancreatic cancer. In studies of laboratory animals, exposure also caused liver, kidney, brain, and immune system defects.

Benzidine demonstrates how even when a chemical is no longer used, it can pose a threat to human health through its persistence in the environment.