A study of the priority substances of the Water Framework Directive ...

..:::::::::: hexachlorocyclohexane (HCH)
..:::44
18 Hexachlorocyclohexane (HCH)
� HCH is a pesticide which in its raw form as
insecticide against grasshoppers, lice and mites
in buildings.
� HCH consists of alpha, beta and gamma and
delta isomers. The gamma isomer is Lindane.
The alpha and beta isomers are usually byproducts
from production of Lindane. This fact sheet
covers alpha, beta and delta isomers. Lindane is
covered in an own fact sheet.
� There is no registered use in Norway, and low
levels of HCH in the environment.
� No further screening or monitoring of HCH
is considered necessary.
Production and use
HCH has usually been a by-product in Lindane
production. The alpha isomer is normally constitutes
70 % of HCH, beta is up to 10 percent
while the rest is gamma (and delta) isomer and
other substances. HCH has sometimes been
used as an independent insecticide, less effective
but cheaper than Lindane. There is no registered
use in Norway, but HCH isomers can be a
degradation product of Lindane.
Emissions, discharges,
distribution and hot-spots
Probable sources for HCH in Norwegian the
environment are transboundary air pollution
and decomposition of Lindane.
Monitoring
HCH has been studied in several investigations,
but there are no time studies.
Marine sediments
In marine sediments, HCH isomers are investigated
together, at 24 localities along the coast.
The levels are relatively low, the highest levels
are found in Tyssedal in Sørfjorden in
Hordaland County.
Marine biota
All HCH isomers are also investigated together
in marine biota. Horse mussels (Modilus modilus),
blue mussels (Mytilus edulis), cod liver
(Gadus morhua), peregrine falcon (Falco peregrinus)
and gyrfalcon (Falco rusticolus) have
been investigated. The highest levels are in falcons,
but also these levels are relatively low.
A study of the priority substances of the Water Framework Directive
TA-2140/2005
FACTS
Cas no.: 608-73-1 (alfa 319-84-6, beta 319-85-7, delta
319-86-8)
Synonyms: Alpha-hexachlorocyclohexane (alpha-
HCH), Beta-hexachlorocyclohexane (beta-HCH),
Delta-hexachlorocyclohexane (delta-HCH).
Properties: White/yellowish powder/flakes
Toxic effects: Possible carcinogen. Slightly toxic.
Alpha: acute oral LD50 rats between 500-4670
mg/kg. Alpha-HCH has low toxicity for algae. Alpha-
HCH is moderately toxic for invertebrates and fish.
Beta: LD50 rats from 1500 mg/kg (8 g/kg body weight
for rats (neurological intoxication)). Beta-HCH generally
has moderate toxicity for algae, invertebrates
and fish and weak estrogenic effect on rats.
Delta: LD50 rats 1000mg/kg
Log Kow: Alpha: 3,8; Beta 3,78; Delta 4,14
Persistence: Alpha: half-lives of 125 and 48 days
under aerobic and anaerobic conditions, respectively.
Beta is the most persistent isomer with half-life up
to 122 days in soil (calculation). Other tests show
higher persistence. HCH may convert to other isomers.
Adsorbs to suspended solids and sediment in
the water column. High to very high potential for
bioaccumulation.
Water solubility: Alpha 2 mg/l 28°C; Beta 0,2 mg/l
25°C; Delta 31,4mg/l 25°C
Molecular formula: C 6 H 6 Cl 6
Metabolites: Alpha delta-3,4,5,6-tetrachloro-hexene
and pentachlorocyclohexene, urinary metabolite is
2,4,6-tri-chlorophenol.
Fresh water sediments
�-HCH and ß-HCH were investigated in sediments
in several lakes in Nordland, Troms and
Finnmark. Only �-HCH was found, in low concentrations.
Fresh water biota
Pike liver (Esox lucius), perch liver (Perca fluriatilis)
and roach liver (Rutilus rutilus) in three
lakes in Eastern Norway were investigated. �-
HCH was found in low concentration in one
pike liver.