The sediment samples associated with TPC discharges also contained the phthalate ester
DEHP. Furthermore, a number of highly chlorinated compounds (octachlorostyrene and
chlorinated benzenes) were also identified in these sediments, though at trace levels.
These chlorinated compounds, though not identified in TPC effluents at the time of
sampling, can be formed as by-products of industrial processes involving chlorine
compounds. They are highly persistent in the environment and many are able to
accumulate in the bodies of animals and humans, particularly the higher chlorinated
pentachlorobenzene and hexachlorobenzene (HCB). These chlorinated compounds exhibit
a range of toxic effects in humans and animals.
The presence within canal sediments of organic pollutants and elevated concentrations
metals that were also found in discharged wastewaters indicates their environmental
accumulation as a result of ongoing discharges. The identification of additional
organochlorines in sediments associated with TPC suggests these have been released from
this facility at other times. As many of these contaminants are environmentally persistent,
their presence in the east canal suggests ongoing inputs to the Gulf of Thailand as waters
and associated sediments are discharged.