decidedly thinner than usual. A DDT concentration of 79 mg/kg (or 907 mg/kg, based
on the fat content) was found to be present in the eggs. In the pelican farther to the
south, the amount of DDT decreased in proportion to the distance they were
from the Santa Monica Bay.
The plant of the only company that manufactures DDT in the USA, the Montrose
Chemical Corporation, is located in the Los Angeles area. In 1970, it furnished
approximately two-third of the world's DDT need. From 1953 on, this plant had
been releasing its effluents into the public sewage canal that flowed into Santa
Monica Bay near White Point. Water samples were analyzed from the canal above the
DDT plant'S point of effluent introduction: DDT-concentration was 34 /lg/l, corresponding to a daily amount of 3.3 kg of DDT. Below the point of introduction, the
amount was found to be 297 kg per day. The cause of the DDT contamination of the
fish, pelicans, and sea lions in the Santa Monica Bay was determined through these
samples. In April, 1970, changes in the effluents system were begun, resulting in a
reduction of the DDT-amount to 13 kg per day by October, 1971 (Macgregor 1974).
A good study case for the pollution by DDT effluents of an ocean area of over
100 km is the lantern fish of the family Myctophidae. They have been collected at
many research vessel stations since 1950 and were later analyzed for their DDT content. In 1950, the DDT concentrations were around 0.5-1 mg/kg. Up to the period
of 1961-1966, they rose to around 4 mg/kg (Fig. 31). After the effluents of DDT
were drastically reduced in 1970, the DDT and DOD components in the meat oflantern fish have decreased while no distinct tendency had been established by 1972 for
DOE (Fig. 32).
Reproduction by the California sea lion, Zalophus californianus, on San Miguel Island
off the coast of California, U.SA., had also been disturbed. More and more stillbirths
had been noted since 1968; in 1971,348 cases in a colony of 10,000-15,000 animals.
The amount of DDT was much higher in stillborn than in live pups: 824 mg/kg as
against 103 mg/kg in the fat; 25 mg/kg as against 6.7 mg/kg in the liver; 2.4 mg/kg as
against 1.2 mg/kg in the brain (Delong et al. 1973). Stillbirths have been observed
even after the ban on DDT. This can be due to high concentrations of mercury and
PCB in the same animals which have high DDT concentrations (see Chap. 7.2 and 9.4).
Or it could be that sea lions feed as well on demersal fish. The surface sediment of a
50 km 2 area of the ocean around the Los Angeles point of effluent introduction still
contained 200 t of DDT in 1971 (Fig. 33).
Although the amounts of DDT which reach the ocean via the Los Angeles sewage
treatment plant were reduced by a sixth, and the PCB (polychlorinated biphenyl)
unit count by a twentieth between 1972 and 1975, 11 mg/kg of DDT and 1.1 mg/kg
of PCB's were still found to be present in Microstomus pacificus sole in 1975 as compared with 17 mg/kg of DDT and 2.3 mg/kg of PCB's in 1972 (Young et al. 1977).
Obviously, DDT remains present a long time in sediment and contaminates those
organisms which live in contact with the bottom of the ocean.
These findings could explain why, in 1976, all sea gulls and cormorants of Los Angeles
zoo died from DDT poisoning; sea gulls had 430 mg/kg DDT in their brain, cormorants 220 mg/kg. Such concentrations in the brain are comparable to concentrations
which caused death in falcon fed experimentally with DDT-contaminated meat. In
the zoo, the birds had, for years, been fed with queensfish (Seriphys) caught close to
49
on the fat content) was found to be present in the eggs. In the pelican farther to the
south, the amount of DDT decreased in proportion to the distance they were
from the Santa Monica Bay.
The plant of the only company that manufactures DDT in the USA, the Montrose
Chemical Corporation, is located in the Los Angeles area. In 1970, it furnished
approximately two-third of the world's DDT need. From 1953 on, this plant had
been releasing its effluents into the public sewage canal that flowed into Santa
Monica Bay near White Point. Water samples were analyzed from the canal above the
DDT plant'S point of effluent introduction: DDT-concentration was 34 /lg/l, corresponding to a daily amount of 3.3 kg of DDT. Below the point of introduction, the
amount was found to be 297 kg per day. The cause of the DDT contamination of the
fish, pelicans, and sea lions in the Santa Monica Bay was determined through these
samples. In April, 1970, changes in the effluents system were begun, resulting in a
reduction of the DDT-amount to 13 kg per day by October, 1971 (Macgregor 1974).
A good study case for the pollution by DDT effluents of an ocean area of over
100 km is the lantern fish of the family Myctophidae. They have been collected at
many research vessel stations since 1950 and were later analyzed for their DDT content. In 1950, the DDT concentrations were around 0.5-1 mg/kg. Up to the period
of 1961-1966, they rose to around 4 mg/kg (Fig. 31). After the effluents of DDT
were drastically reduced in 1970, the DDT and DOD components in the meat oflantern fish have decreased while no distinct tendency had been established by 1972 for
DOE (Fig. 32).
Reproduction by the California sea lion, Zalophus californianus, on San Miguel Island
off the coast of California, U.SA., had also been disturbed. More and more stillbirths
had been noted since 1968; in 1971,348 cases in a colony of 10,000-15,000 animals.
The amount of DDT was much higher in stillborn than in live pups: 824 mg/kg as
against 103 mg/kg in the fat; 25 mg/kg as against 6.7 mg/kg in the liver; 2.4 mg/kg as
against 1.2 mg/kg in the brain (Delong et al. 1973). Stillbirths have been observed
even after the ban on DDT. This can be due to high concentrations of mercury and
PCB in the same animals which have high DDT concentrations (see Chap. 7.2 and 9.4).
Or it could be that sea lions feed as well on demersal fish. The surface sediment of a
50 km 2 area of the ocean around the Los Angeles point of effluent introduction still
contained 200 t of DDT in 1971 (Fig. 33).
Although the amounts of DDT which reach the ocean via the Los Angeles sewage
treatment plant were reduced by a sixth, and the PCB (polychlorinated biphenyl)
unit count by a twentieth between 1972 and 1975, 11 mg/kg of DDT and 1.1 mg/kg
of PCB's were still found to be present in Microstomus pacificus sole in 1975 as compared with 17 mg/kg of DDT and 2.3 mg/kg of PCB's in 1972 (Young et al. 1977).
Obviously, DDT remains present a long time in sediment and contaminates those
organisms which live in contact with the bottom of the ocean.
These findings could explain why, in 1976, all sea gulls and cormorants of Los Angeles
zoo died from DDT poisoning; sea gulls had 430 mg/kg DDT in their brain, cormorants 220 mg/kg. Such concentrations in the brain are comparable to concentrations
which caused death in falcon fed experimentally with DDT-contaminated meat. In
the zoo, the birds had, for years, been fed with queensfish (Seriphys) caught close to
49