hydrocarbons. However, the approach of using examples is pursued with the caveat that movement of
each of the chlorinated hydrocarbons through the
environment, and biological effects associated with
each chemical, are specific in important details for
each chemical. Although not discussed further here, it
is important to note that these chemicals can and
have been used as tracers of general processes acting
on naturally occurring organic chemicals in marine
ecosystems.
History
DDT
DDT (dichlorodiphenyltrichloroethane) is not a naturally occurring compound. It was first synthesized in
1874 and its insecticidal properties were discovered in
1939. Initial large use of DDT as an insecticide began
in 1944 and continued into the late 1960s. It was used
with success against vectors of human diseases such as
malaria and with dramatic effect in agriculture around
the world in controlling insect pests. The environmental problems associated with DDT in terms of
adverse effects on nontarget organisms such as birds
were brought to popular attention in the highly influential book ‘Silent Spring’ by Rachael Carson in
1962. Further studies of DDT in the mid 1960s to early
1970s documented the presence of DDT and several
other chlorinated pesticides in marine organisms at all
major sectors in the marine food web. Analyses of
samples from organisms dwelling in the deep part of
the oceans, for example 4000–5000 m depth in the
North Atlantic, and from Arctic and Antarctic marine
ecosystems contained measurable concentrations of
DDT. Evidence of adverse effects on nontarget terrestrial, freshwater and marine organisms, especially
birds, resulted in curtailed use or bans on the use of
DDT in several developed countries in the early 1970s.
The legacy of past releases to the environment is present in marine ecosystems in the form of measurable
concentrations of DDT compounds. In addition, the
use of DDT continues in a few countries.
PCBs
PCBs (polychlorinated biphenyls) have been used industrially since 1929. Industrial mixtures of PCBs are
known by commercial names, e.g., Aroclors (United
States), Kaneclor (Japan), Chlophen (Germany),
Sovol (former USSR), Fenchlor (France). PCBs were
widely used in insulating fluids in transformers and
capacitors, as well as hydraulic systems, surface
coatings, flame retardants, inks and other minor uses.
Concerns about human health effects associated
with halogenated aromatic compounds such as PCBs
and halowax (polychlorinated naphthalenes) date to
the 1930s and 1940 with the reports of rashes and
liver abnormalities for workers in manufacturing
plants and electricians. The identification of polychlorinated biphenyls (PCBs) as chemicals of environmental concern dates to the late 1960s when
they were reported nearly simultaneously by three
different research groups to be present in seabirds and
seabird eggs in three different coastal ecosystems.
Subsequent research in the late 1960s and early
1970s confirmed the widespread presence of PCBs in
numerous ecosystems, their relative persistence in the
environment, and several instances of known or
suspected adverse effects associated with various
organisms exposed to and incorporating PCBs into
their tissues, e.g., mink and chickens fed on fish or
fish meal. In 1968, contamination of rice oil used in
food preparation at a location in western Japan by
PCBs from a leaking transformer caused human
health effects for people who consumed the polluted
food; this was designated the Yusho incident. A
similar incident occurred in 1979–81 in Taiwan: the
Yuncheng incident. Detailed studies of the PCB oil
involved in these incidents suggested that some or all
of the observed adverse effects may have resulted
from the presence of small amounts of chlorinated
bibenzonfurans or chlorinated dibenzodioxins.
By 1971, the concerns about human health and
environmental impacts led Monsanto, the producer
of PCBs in the United States, to a voluntary ban on
sales of PCBs except for closed systems use. Monsanto ceased all production in 1977 and there was no
large-scale increase in imports. PCBs were banned
from production and further use in the United States
in 1978. Equipment that already contained PCBs,
e.g., transformers, were allowed to remain in use but
restrictions were placed on the disposal of PCBs
when the equipment was decommissioned. Delegates
from 122 countries completed a draft treaty on persistent organic pollutants (POPs) in December 2000.
The POPs that were initially addressed and banned
from further use include chlordane, DDT, dieldrin,
endrin, heptachlor, mirex, toxaphene, PCBs,
hexachlorbenzene, chlorinated dibenzofurans, and
chlorinated dibenzodioxins. Limited selective use of
DDT for human disease vector control is allowed in
some countries.
Distribution in the Marine
Environment
Early 1970s
Analyses during the early 1970s of various species of
marine biota for DDT family chemicals and PCBs
CHLORINATED HYDROCARBONS 165
each of the chlorinated hydrocarbons through the
environment, and biological effects associated with
each chemical, are specific in important details for
each chemical. Although not discussed further here, it
is important to note that these chemicals can and
have been used as tracers of general processes acting
on naturally occurring organic chemicals in marine
ecosystems.
History
DDT
DDT (dichlorodiphenyltrichloroethane) is not a naturally occurring compound. It was first synthesized in
1874 and its insecticidal properties were discovered in
1939. Initial large use of DDT as an insecticide began
in 1944 and continued into the late 1960s. It was used
with success against vectors of human diseases such as
malaria and with dramatic effect in agriculture around
the world in controlling insect pests. The environmental problems associated with DDT in terms of
adverse effects on nontarget organisms such as birds
were brought to popular attention in the highly influential book ‘Silent Spring’ by Rachael Carson in
1962. Further studies of DDT in the mid 1960s to early
1970s documented the presence of DDT and several
other chlorinated pesticides in marine organisms at all
major sectors in the marine food web. Analyses of
samples from organisms dwelling in the deep part of
the oceans, for example 4000–5000 m depth in the
North Atlantic, and from Arctic and Antarctic marine
ecosystems contained measurable concentrations of
DDT. Evidence of adverse effects on nontarget terrestrial, freshwater and marine organisms, especially
birds, resulted in curtailed use or bans on the use of
DDT in several developed countries in the early 1970s.
The legacy of past releases to the environment is present in marine ecosystems in the form of measurable
concentrations of DDT compounds. In addition, the
use of DDT continues in a few countries.
PCBs
PCBs (polychlorinated biphenyls) have been used industrially since 1929. Industrial mixtures of PCBs are
known by commercial names, e.g., Aroclors (United
States), Kaneclor (Japan), Chlophen (Germany),
Sovol (former USSR), Fenchlor (France). PCBs were
widely used in insulating fluids in transformers and
capacitors, as well as hydraulic systems, surface
coatings, flame retardants, inks and other minor uses.
Concerns about human health effects associated
with halogenated aromatic compounds such as PCBs
and halowax (polychlorinated naphthalenes) date to
the 1930s and 1940 with the reports of rashes and
liver abnormalities for workers in manufacturing
plants and electricians. The identification of polychlorinated biphenyls (PCBs) as chemicals of environmental concern dates to the late 1960s when
they were reported nearly simultaneously by three
different research groups to be present in seabirds and
seabird eggs in three different coastal ecosystems.
Subsequent research in the late 1960s and early
1970s confirmed the widespread presence of PCBs in
numerous ecosystems, their relative persistence in the
environment, and several instances of known or
suspected adverse effects associated with various
organisms exposed to and incorporating PCBs into
their tissues, e.g., mink and chickens fed on fish or
fish meal. In 1968, contamination of rice oil used in
food preparation at a location in western Japan by
PCBs from a leaking transformer caused human
health effects for people who consumed the polluted
food; this was designated the Yusho incident. A
similar incident occurred in 1979–81 in Taiwan: the
Yuncheng incident. Detailed studies of the PCB oil
involved in these incidents suggested that some or all
of the observed adverse effects may have resulted
from the presence of small amounts of chlorinated
bibenzonfurans or chlorinated dibenzodioxins.
By 1971, the concerns about human health and
environmental impacts led Monsanto, the producer
of PCBs in the United States, to a voluntary ban on
sales of PCBs except for closed systems use. Monsanto ceased all production in 1977 and there was no
large-scale increase in imports. PCBs were banned
from production and further use in the United States
in 1978. Equipment that already contained PCBs,
e.g., transformers, were allowed to remain in use but
restrictions were placed on the disposal of PCBs
when the equipment was decommissioned. Delegates
from 122 countries completed a draft treaty on persistent organic pollutants (POPs) in December 2000.
The POPs that were initially addressed and banned
from further use include chlordane, DDT, dieldrin,
endrin, heptachlor, mirex, toxaphene, PCBs,
hexachlorbenzene, chlorinated dibenzofurans, and
chlorinated dibenzodioxins. Limited selective use of
DDT for human disease vector control is allowed in
some countries.
Distribution in the Marine
Environment
Early 1970s
Analyses during the early 1970s of various species of
marine biota for DDT family chemicals and PCBs
CHLORINATED HYDROCARBONS 165