β-Hexachlorocyclohexane (β-HCH) is an

organochloride Organochlorine chemistry is concerned with the properties of organochlorine compounds, or organochlorides, organic compounds that contain one or more carbon–chlorine bonds. The chloroalkane class (alkanes with one or more hydrogens substituted ...

which is one of the isomers of hexachlorocyclohexane (HCH).Toxicological Profile for Alpha-, Beta-, Gamma-, and Delta-Hexachlorocyclohexane
U.S. Department of Health and Human Services, Agency for Toxic Substances and Disease Registry, August 2005 It is a byproduct of the production of the

insecticide Insecticides are pesticides used to kill insects. They include ovicides and larvicides used against insect eggs and larvae, respectively. The major use of insecticides is in agriculture, but they are also used in home and garden settings, i ...

lindane (γ-HCH). It is typically constitutes 5–14% of technical-grade lindane, though it has not been produced or used in the United States since 1985. As of 2009, the

Stockholm Convention on Persistent Organic Pollutants Stockholm Convention on Persistent Organic Pollutants is an international environmental treaty, signed on 22 May 2001 in Stockholm and effective from 17 May 2004, that aims to eliminate or restrict the production and use of persistent organi ...

classified α-hexachlorocyclohexane and β-HCH as persistent organic pollutants (POPs), due to the chemical's ability to persist in the environment,

bioaccumulative Bioaccumulation is the gradual accumulation of substances, such as pesticides or other chemicals, in an organism. Bioaccumulation occurs when an organism absorbs a substance faster than it can be lost or eliminated by catabolism and excretion. ...

, biomagnifying, and long-range transport capacity. This pesticide was widely used during the 1960s and 1970s, particularly on cotton plants. Although banned as a pesticide more than 30 years ago, traces of beta-HCH can still be found in water and soil. Animal studies show that organochlorine pesticides, including beta-HCH, are

neurotoxic Neurotoxicity is a form of toxicity in which a biological, chemical, or physical agent produces an adverse effect on the structure or function of the central and/or peripheral nervous system. It occurs when exposure to a substance – specifical ...

, cause

oxidative stress Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and a biological system's ability to readily detoxify the reactive intermediates or to repair the resulting damage. Disturbances in the normal ...

, and damage the brain's dopaminergic system. Human studies show that exposure to beta-HCH is linked to

Parkinson's Parkinson's disease (PD), or simply Parkinson's, is a neurodegenerative disease primarily of the central nervous system, affecting both motor and non-motor systems. Symptoms typically develop gradually and non-motor issues become more prevalen ...

and

Alzheimer's disease Alzheimer's disease (AD) is a neurodegenerative disease and the cause of 60–70% of cases of dementia. The most common early symptom is difficulty in remembering recent events. As the disease advances, symptoms can include problems wit ...

. β-HCH was present in elevated levels in some patients as recently as 2009. It was manufactured by exhausting chlorination of

benzene Benzene is an Organic compound, organic chemical compound with the Chemical formula#Molecular formula, molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar hexagonal Ring (chemistry), ring with one hyd ...

and for this reason was called erroneously β-BHC. This synonym still persists. In March 2005, the Italian National Monitoring System on Chemical Residuals in Food of Animal Origin detected levels of the pesticide β-HCH that were 20 times higher than the legal limit of 0.003 mg/kg in bulk milk from a dairy farm in the

Sacco River The Sacco is a river of central Italy, a right tributary of the Liri. It flows between the Metropolitan City of Rome Capital and the province of Frosinone in Lazio. Territory The river originates from the Prenestini Mountains, formed by th ...

valley. β-HCH, a lindane

isomer In chemistry, isomers are molecules or polyatomic ions with identical molecular formula – that is, the same number of atoms of each element (chemistry), element – but distinct arrangements of atoms in space. ''Isomerism'' refers to the exi ...

and possible human

carcinogen A carcinogen () is any agent that promotes the development of cancer. Carcinogens can include synthetic chemicals, naturally occurring substances, physical agents such as ionizing and non-ionizing radiation, and biologic agents such as viruse ...

, was subsequently found in milk from several neighboring farms. A study was therefore undertaken to evaluate the extent and risk factors for contamination.

References

External links

beta-Hexachlorocyclohexane (beta-HCH) - Integrated Risk Information System
– US EPA
Cyclohexane, 1,2,3,4,5,6-hexachloro-, (1α,2β,3α,4β,5α,6β)-
–

NIST The National Institute of Standards and Technology (NIST) is an agency of the United States Department of Commerce whose mission is to promote American innovation and industrial competitiveness. NIST's activities are organized into physical s ...

{{DEFAULTSORT:Hexachlorocyclohexane, Beta- Organochlorides Persistent organic pollutants under the Stockholm Convention Persistent organic pollutants under the Convention on Long-Range Transboundary Air Pollution

See also

References

External links