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

26 Pentachlorobenzene
� Pentachlorobenzene is very toxic to aquatic
organisms, persistent and bioaccumulates.
� There is little registered use in Norway, but
pentachlorobenzene is a metabolite of Lindane.
� Monitoring should be done together with
Lindane.
Production and use
Globally, pentachlorobenzene is known as an
intermediate in the production of the fungicide
quintozene, as a flame retardant and as a contaminant
of hexachlorobenzene which has been
used as a fungicide. The substance has also been
used with PCB. There is little registered use in
EU. Pentachlorobenzene is not registered in the
Norwegian Product Register. Quintozene (sometimes
registered in Norway as Kvintosen) has
been in use, data show use from 1974 until the
fungicide lost its license from 1987. From 700
to almost 5000 kilos were sold per year.
Emissions, discharges,
distribution and hot-spots
Pentachlorobenzene may have been present in
discharges from Falconbridge in Kristiansand
and from the Magnesium production plant at
Herøya. Contamination from Quintozene is
possible, but there is no information available.
As the substance is a metabolite of Lindane, it
may be found in areas polluted with Lindane,
especially due to its high persistence and tendency
to accumulate in fish.
Monitoring
Pentachlorobenzene has been monitored in several
studies in Norway.
Marine sediment
Pentachlorobenzene was earlier part of the monitoring
programs for the fjords outside the magnesium
production plant at Herøya and the
nickel smelter Falconbridge in Kristiansand. The
concentrations found were low.
In a study from Sandefjordsfjorden and Indre
Mefjorden, low concentrations of pentachlorobenzene
were found in one sample from
the inner parts.
FACTS
Cas no.: 608-93-5
pentachlorobenzene ::::::::::..
Synonyms: Pentaklorbensen, PeCB; 1,2,3,4,5-pentachlorobenzene,
5CB, PCBz
Properties: Colourless needles, pleasant odour.
Toxic effects: Commercial pentachlorobenzene is an
irritant and slightly toxic. Acute LD50 rat oral is 1000-
1125 mg/kg. It may cause liver and kidney damage.
The substance is very toxic to aquatic organisms
(ClassLab). LC50 guppy (Poecilia reticulata) 0,178
ppm/14 days and LC50 Daphnia magna 4,1-7,2
mg/l/48 h. Lowest concentration with observed
effect on snails and mussels is 0,04 mg/l
(Naturvårdsverket).
Log Kow: 4,8 - 5,18
Persistence: Atmospheric half-life for pentachlorobenzene
is about 277 days (Hydroxyl radicals).
Half life in soil is 200-350 days (lab, HSDB). In
water half life depends on amounts of solids, from
194 to 1250 days (Swedish EPA). 41 % photodegradation
is registered in surface waters in 24 hours. Under
field conditions the strong adsorption to solids may
counteract the photodegradation (CIRCA).
Bioconcentration in aquatic organisms is very high.
Water solubility: 0,56 mg/l at 20°C
Molecular formula: C 6 HCl 5
Metabolites: pentachlorophenol, tetrachlorophenol
(2,3,4,5-tetrachlorophenol, 2,3,4,6-tetrachlorophenol,
1,2,3,4-tetrachlorobenzene, 1,2,4,5-tetrachlorobenzene,
1,2,3,5-tetrachlorobenzene, 2,3,4-trichlorphenol,
2,4,6-trichlorphenol, 3,4,5-trichlorphenol, 1,3,5trichlorbenzene).
Fresh water biota
In a study of fish downstream three municipal
landfills in Eastern Norway, pentachlorobenzene
was found in samples of pike (Esox lucius) liver
and perch (Perca fluviatilis) liver. The levels
were low.
Need for further screening and monitoring
There is no need for a screening of pentachlorobenzene,
but the substance should be
investigated in connection with Lindane monitoring.
A study of the priority substances of the Water Framework Directive
TA-2140/2005
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