Hexachlorocyclohexane (C6H6Cl6)

1,2,3,4,5,6-Hexachlorocyclohexane (HCH)

Other names

HCH, benzene hexachloride, 666

CAS Number

608-73-1

Properties

• white or yellow powder
• mouldy odour
• mixture of alpha, beta, gamma and delta isomers: differing three-dimensional arrangement of the chorine atom on the cyclohexane ring
• differ greatly in their biological activity
• alpha-, beta- and gamma-HCH are persistent organic pollutants
  

Main sources

• agriculture: insecticide

Thresholds for the reporting requirement of facilities in accordance with Annex 2 PRTRO

(Ordinance on the Register relating to Pollutant Release and the Transfer of Waste and of Pollutants in Waste Water)

• Air               10 kg/year
• Water          1 kg/year
• Soil              1 kg/year

Impacts

• carcinogenic
• toxic to humans, animals and aquatic organisms
• alpha- and gamma-HCH: affect the central nervous system (effect of mixture depends on the exact composition)
• beta- and delta-HCH: sedative (effect of mixture depends on the exact composition)
• bioaccumulation
• has a long half-life, very persistent in the environment
  

Measures

• all isomers banned in Switzerland since 2005
• included on the list of banned substances by the Stockholm Convention in May 2009