Hexachlorocyclohexane

HCH; 1,2,3,4,5,6-Hexachlorocyclohexane; benzene hexachloride; formula: C6H6Cl6; CAS Registry Number: 608-73-1
General Structure of Hexachlorocyclohexane
Source: GSBL Joint Substance Database

Several isomeric compounds among the group of chlorinated hydrocarbons

Commercial production of Hexachlorocyclohexane (HCH) started after the 2nd world war. During the process of synthesis which requires benzene and chlorine, a mixture of different isomers evolves. This so called technical HCH consists of 65-70% α-HCH, 7-20% β-HCH, 14-15% γ-HCH, 6-10% δ-HCH , and 1-2% ε-HCH. Of all isomers, only γ-HCH has insecticidal properties. A product consisting of at least 99% γ-HCH is called Lindane.

Technical HCH has been banned in the Federal Republic of Germany in 1977 and the uses of the insecticide Lindane are restricted to date. In the former German Democratic Republic (GDR) lindane was, next to DDT, the most widely used insecticide since the 1970s. Considerable amounts of lindane were produced in the GDR itself but it was also imported from other Eastern Bloc States.

HCH contamination of the environment is a result of former uses of products containing HCH or lindane, e.g. in agriculture and forestry, in veterinary medicine and in households. Furthermore, residues from lindane production are still present in the environment. The production of one metric ton of lindane generates about nine tons of non-insecticidal isomers which were often improvidently disposed on dumping grounds.

The three main HCH-isomers alpha, beta and gamma were included in the Stockholm POP-Convention in 2009.

Substances

alpha-HCH The main constituent of technical HCH
Lindane (gamma-HCH) Highly effective insecticide that was banned from agricultural use in 2002 and restricted in pharmaceutical use in 2007
beta-HCH Most persistent HCH-isomer with the highest potential for biomagnification

Specimen

Zebra mussel Common mussel species as invasive animal in rivers and lakes with high information level for water pollution
Bream Bioindicator in rivers and lakes
Suspended particulate matter Fine insoluble mineral or organic particles in the water phase
Blue mussel One of the most important edible mussel species common in the North and Baltic Sea
Eelpout As the only viviparous fish in German nearshore waters, it is a bioindicator in nearshore coastal marine ecosystems.
Herring gull Inshore, the herring gull mainly feeds from the sea: upon fish, mussels, and crabs.
Roe deer, one-year-old The roe deer is the most common of the larger herbivores (first order-consumer) to be found in the wild in Europe.
Feral pigeon A pigeon species home in nearly every city.
Soil Soil is livelihood and biosphere for humans, animals, plants and soil organisms. All the substances brought in are transported, transformed and/or accumulated in the soil.

Sampling area

BR/NP Berchtesgaden The only high mountains national park in Germany and an area of the Limestone Alps with international relevance
Saarländischer Verdichtungsraum Important, old-industrialised conurbation in Germany.
Bornhöveder Seengebiet Main water divide between the North- and Baltic Sea
Rhein Longest river in Germany
NP Bayerischer Wald Germany's first national park
NP Vorpommersche Boddenlandschaft National Park in the largest brackish water (Bodden) habitat of the world.
BR/NP Wattenmeere National park in the world largest connected sand and mud flats.
Elbe Fourth largest river basin in Central Europe
Verdichtungsraum Halle-Leipzig Region in the chemical triangle of Central Germany
NP Harz Germany's largest forest national park
Solling Second highest and largest low mountain range in Northern Germany
BR Pfälzerwald Germany's largest connected forest area in a range of low mountains
Oberbayerisches Tertiärhügelland The Upper Bavarian Tertiary Uplands are a part of the Southern German Molasse Basin
Donau Second largest river in Europe

Sampling period

1985 - 2018