Entry into the marine environment
Chlorinated ethylenes are produced in large quantities
and widely used in industry in the production of
food packaging, synthetic fibres and industrial
The major route by which chlorinated ethylenes
enter the environment is by volatilisation during
production and use. Their presence in water may
result from a direct discharge or atmospheric deposition.
They may also be formed during the chlorination
of water. In addition, diffuse inputs chlorinated
ethylenes used in food packaging from land fill
sites could occur.
Recorded levels in the environment
Some information on concentrations in UK marine
water is available. Pearson and McConnell (1975)
reported concentrations in Liverpool Bay of up to
2.6 µg l-1 (and average
of 0.38 µg l-1). A mean
concentration in the range 1-100 ng l-1
(highest concentration of 43 microg l-1)
has also been reported for river and estuarine samples
of 80 sites in the UK (SAC Scientific 1987).
Marine sediment samples form Liverpool Bay taken
in 1972 contained tetrachloroethylene at concentrations
of 0.02 - 4.8 microg/kg
(Pearson and McConnel, 1975).
Monitoring data from the National Rivers Authority
and the National Monitoring Programme Survey of
the Quality of UK Coastal Waters are presented in
Appendix D. Water column concentrations for trichloroethylene
and tetrachloroethylene were all found to be below
the EQS values (see Appendix D). Monitoring data
were not available for sediments or biota.
The available data suggest that concentrations
of chloroethylenes in UK coastal and estuarine waters
appear unlikely to exceed relevant quality standards
derived for the protection of saltwater life.
Fate and behaviour in the environment
Chlorinated ethylenes are unsaturated, low-molecular
weight C2 compounds in which one or more
hydrogen atoms have been replaced with chlorine.
With the exception of monochloroethylene, all chlorinated
ethylenes are low-boiling liquids that have high
vapour pressures and are moderately soluble in water.
Vapour pressures and water solubility decrease with
increasing chlorine substitution (CCME 1992).
Volatilisation is considered to be the main removal
process from water. For example, the major sink
tetrachloroethylene appears to be to the atmosphere,
where it undergoes oxidation by reaction with hydroxyl
radicals (half-life < 0.4 year). The half-life
is sufficiently long, however, to allow a small
proportion of the tetrachloroethylene released into
the atmosphere to reach the stratosphere (Brooke
et al 1993).
In addition, evaporative half-lives below 1 hour
for chloroethylenes at an aqueous concentration
of approximately 1 mg l-1 have been
reported (Dilling et al 1975).
Direct photolysis oxidation and hydrolysis are
not considered to be important removal processes.
Few data have been found on the degradation of chloroethylenes
in the aquatic environment, and what are available
suggest that, while some degradation may occur,
in general, chlorinated ethylenes are fairly resistant
to biodegradation (CCME 1992). In addition, limited
sorption capacity has been reported for chlorinated
ethylenes (CCME 1992).
For example, Brooke et al (1993) reviewed
the environmental fate and behaviour of tetrachloroethylene.
The authors concluded that the major removal process
from aquatic systems appeared to be volatilisation
to the atmosphere, with half-lives ranging from
a few minutes to a few days, depending on the conditions.
Degradation of tetrachloroethylene appears to occur
under anaerobic conditions when a suitable carbon
source is present. There is less conclusive evidence
for degradation of tetrachloroethylene under aerobic
Effects on the marine environment
Toxicity to marine organisms
An exhaustive literature review on the toxicity
of chlorinated ethylenes to marine organisms has
not been carried out for the purposes of this profile.
The information provided in this section is taken
from existing review documents (CCME 1992, Brooke
et al 1993). The most sensitive groups of
organisms have been identified.
CCME (1992) reported that there appeared to be
a degree of correlation between the degree of chlorination
of ethylenes and toxicity, with tetrachloroethylene
more toxic than dichloroethylene. The toxicity of
trichloroethylene is intermediate between the toxicities
of the dichloroethylenes and tetrachloroethylene.
Data for tetrachloroethylene suggest moderate toxicity
to marine plants, invertebrates and fish.
For the marine alga Skeletonema costatum ,
96 hour EC50s value of 509 mg l-1
for chlorophyll-A content and 504 mg l-1
for cell numbers have been reported (US EPA 1978).
Greater sensitivity has been exhibited by Phaeodactylum
tricorntum, with a 50% reduction in carbon uptake
from CO2 in photosynthesis occurring
at a concentration of 10.5 mg l-1.
Pearson and McConnel (1975) reported a 48 hour
LC50 of 3.5 mg l-1 for barnacle
larvae Eliminius modestus. For the mysid
shrimp Mysidopsis bahia, a 96 hour LC50 of
10.2 mg l-1 and a chronic value
(tested over a whole life stage) of 0.45 mg l-1
(US EPA 1980).
For fish, 95 hour LC50 of 5 and >29-<52 mg l-1
have been reported for dab and sheepshead minnow
No data could be located for sediment-dwelling
Brooke et al (1993) reviewed data on the
bioaccumulation of tetrachloroethylene in aquatic
organisms and found low to moderate (generally <100)
bioconcentration factors in a variety of aquatic
Since most of the chloroethylenes have small octanol/water
coefficients, bioaccumulation can be expected to
Potential effects on interest
features of European marine sites
Potential effects include:
- toxicity of tri- and tetrachloroethylene to
algae, invertebrates and fish at concentrations
above the EQS of 10 µg l-1
(annual average) in the water column.