B-Hexachlorocyclohexane

B-Hexachlorocyclohexane (β-HCH) is an organochloride compound that is classified as a persistent organic pollutant (POP). It is a byproduct of the production of the insecticide lindane (γ-HCH).

Chemical Structure and Properties

β-HCH is a cyclohexane derivative that is substituted by chlorine atoms at positions 1, 2, 3, 4, 5, and 6. It is a colorless, crystalline solid with a slight, characteristic odor. It is not soluble in water but is very soluble in fat and most organic solvents.

Production and Uses

β-HCH is not produced intentionally but is a byproduct in the production of the insecticide lindane. Lindane is produced by selective chlorination of benzene, during which a mixture of different isomers of hexachlorocyclohexane is formed. β-HCH is the most stable and most abundant of these isomers.

Despite its toxicity, β-HCH has been used in the past as an insecticide, especially for the treatment of seeds and soil. However, due to its persistence in the environment and its potential for bioaccumulation, its use has been banned or restricted in many countries.

Health Effects

Exposure to β-HCH can occur through ingestion, inhalation, or skin contact. It is toxic to the liver and can cause a variety of symptoms, including nausea, vomiting, headache, dizziness, muscle weakness, and seizures. Long-term exposure can lead to chronic health effects, such as liver damage, cancer, and neurological disorders.

Environmental Impact

β-HCH is very persistent in the environment and can remain in soil for many years. It can also bioaccumulate in the food chain, leading to high concentrations in predatory animals. Due to its high toxicity and persistence, β-HCH is listed as a persistent organic pollutant under the Stockholm Convention.

See Also

• Lindane
• Persistent organic pollutant
• Organochloride
• Stockholm Convention