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

..:::::::::: trichlorobenzene
..:::74
31 Trichlorobenzene
� Trichlorobenzene is a group of substances.
Commercial TCB was historically normally a
mixture, containing mostly the 1,2,4 isomer,
now purity is 99,8 %.
� There is no registered use in Norway after
1995.
� A screening of trichlorobenzene should be
done, in order to get an estimate of environmental
levels and potential risks.
Production and use
Globally, commercial trichlorobenzene is a high
volume chemical, it generally comprises of a
mixture of various isomers, mainly 1,2,4- isomer
(80-100 %). It has been used as intermediate
in the production of herbicides, as a solvent
or dye carrier, as additive to PCB and as anticorrosive
agent. No emissions "of significance"
are registered in Norway (Miljøstatus), about
20 kilos in 2002 (SFT). A 20 % drop in emissions
has been estimated since 1995.
Trichlorobenzene is not registered in the
Norwegian Product Register after 1995, and
there is little knowledge on earlier use.
Emissions, discharges,
distribution and hot-spots
There are too few data on trichlorobenzene in
Norway to estimate emissions. The substance
has a long-range transport potential.
Trichlorobenzene has not been found in any
studies in Norway, but it has not been possible
to establish whether any study actually looked
for the substance.
Need for further screening and monitoring
Trichlorobenzene is probably not a problem in
Norway. However, a screening should be done
to establish levels in the environment.
Localities for further screening and monitoring
Trichlorobenzene should be screened in marine
and fresh water sediment and biota.
Analysis
The analysis of trichlorobenzenes is often part
of packages with several other volatile organic
compounds (VOC) or other chlorobenzenes.
A study of the priority substances of the Water Framework Directive
TA-2140/2005
FACTS
Cas no.: 12002-48-1
87-61-6 (1,2,3-trichlorobenzene)
120-82-1 (1,2,4-trichlorobenzene)
108-70-3 (1,3,5-trichlorobenzene)
Synonyms: TCB, Trichlorobenzol, Hostetex L-PEC.
Properties: Colourless liquid or crystalline, solid below
17°C.
Toxic effects: 1,2,4-trichlorobenzene is slightly toxic,
LD50 (rat oral) is 756 mg/kg. TCB is also an irritant, and
it is very toxic to aquatic organisms (LC50 rainbow
trout (Oncorhynchus mykiss) is 1,95 mg/l/48 hour).
Log Kow: 3,93 - 4,2
Persistence: 1,2,4-trichlorobenzene has an atmospheric
half-life of 30 days and half life ranging from
several weeks to a few months in soil and water.
Bioaccumulation in aquatic life forms is high.
Water solubility: 48-100 mg/l
Molecular formula: C 6 H 3 Cl 3
Metabolites: Dichlorobenzenes, monochlorobenzene
via chlorinated phenols and catechols.
Methods
The methods are based on purge-and-trap, or
head-space analysis, or based on direct extraction
with an organic solvent (sediment and
biota) or solid phase extraction (SPE), chromatographic
clean-up and separation and quantification
with GC-based methods: GC/MS or
GC/ECD.
Synergy with other analyses
Sample preparation and quantification can be
co-ordinated with the analysis of other VOC
like compounds or other chlorobenzenes.
References
� HSDB: Trichlorobenzene.
� Miljøstatus: TCB.
� ClassLab, Trichlorobenzene.
� CIRCA, Royal Haskoning Fact sheets on production,
use and release of priority substances in
the WFD, Pentachlorophenol, Final version 31
January 2001
� SFT TCB 1995-2002.
� US EPA: Consumer Factsheet on 1,2,4trichlorobenzene.