Environmental toxicology and health effects associated with hexachlorobenzene exposure

The synthetic industrial chemical hexachlorobenzene (HCB) is a white crystalline solid compound. The substance is a bioaccumulative, persistent, and toxic pollutant. Historically HCB was commonly used as a pesticide and fungicide. Although HCB production and use has ceased in many countries, the compound is still generated inadvertently, as a byproduct and/or impurity in the manufacture of various chlorinated compounds, and released into the environment. Hexachlorobenzene is ubiquitous in air, water, soil, and biological matrices, as well as in major environmental compartments. Exposure to this substance is a public health concern because of its association with a wide range of adverse health effects. The International Agency for Research on Cancer and the United States Environmental Protection Agency classify HCB as a probable human carcinogen. Although globally the consumption of HCB-contaminated food is the principal source of environmental exposure, exposure can also occur through the inhalation of HCB-contaminated air, by dermal contact, or through in utero exposure and breast milk. In addition to cancer, the human health effects associated with HCB exposure involve systemic impairment (thyroid, liver, bone, skin), as well as damage to the kidneys and blood cells and the immune, endocrine, developmental, and nervous systems. In this review, we discuss the sources of HCB and the potential for human exposure, as well as systemic, carcinogenic, and teratogenic health effects.