Human health perspectives on environmental exposure to benzidine: a review

Benzidine, an odorless, white to slightly reddish-white crystalline organic compound, is an environmental contaminant that has been identified at about 30 National Priorities List (NPL) hazardous waste sites in the United States. In the environment, it is usually found attached to suspended particles either in its "free" state or as chloride or sulfate salts. In the past, U.S. industries used large quantities of benzidine to produce dyes for paper, clothes, and leather. Since the ban on its production and use in the United States in the 1970s, this compound is imported for specialty uses. People living near hazardous waste sites might be exposed to benzidine by drinking contaminated water, by inhaling contaminated air, or by swallowing or touching contaminated dust. People can also be exposed by using benzidine dyes on paper, clothes, and other materials. Human occupational data and studies of laboratory animals suggest that people exposed to benzidine may develop adverse systemic health effects or cancer. The U.S. Environmental Protection Agency (EPA), the U.S. Department of Health and Human Services, the International Agency for Research on Cancer (IARC), and the World Health Organization (WHO) have classified benzidine as a carcinogen. Urinary bladder cancer is the most common form of cancer caused by exposure to benzidine. The stomach, kidneys, brain, mouth, esophagus, liver, and gallbladder might also be targets. The information presented in the article may help public health officials, physicians, and toxicologists evaluate and develop the health information materials on the nature of benzidine in the environment and its potential impact on public health.