DDT, Chlordane, Toxaphene and PCB Residues in Newport Bay and Watershed: Assessment of Hazard to Wildlife and Human Health - Reviews of Environmental Contamination and Toxicology - page 77

fi sh with levels of DDT comparable to those found in more highly contaminated
sea lion fetuses, increased the neurological response to domoic acid. This model
suggests that high residues of DDT, typically found in sea lions residing near the
Channel Islands may increase susceptibility to domoic acid poisoning.
In summary, several studies have confi rmed the presence of DDT in California
sea lions. Hence, they accumulate DDT primarily via biomagnifi cation by feeding
on contaminated fi sh, as do seals. DDT concentrations have generally been reported
in the parts-per-million range, but have been on the decline in recent years from
discontinuation of its use. The highest DDT level in sea lions world-wide occurred
in the Channel Island area of the southern California bight as a result of past dump-
ing of DDT manufacture wastes there. Similar to harbor seals, toxic effects from
DDT in California sea lions have yet to be conclusively demonstrated.

DDT and Dolphins . Dolphins and porpoises are not likely to spend much time
(if any) in Newport Bay. However, to be conservative they have been included in
this review. There are relatively few published reports of DDT in dolphins and por-
poises that might be relevant to Newport Bay. In 1980 , O'Shea et al. reported DDT
in the blubber, brain and muscle tissues of 69 small cetaceans, including one Pacifi c
bottlenose dolphin ( T. gilli ) that had an excessively high blubber DDT concentration
of 2,695 ppm.
Smyth et al. ( 2000 ) reported concentration ranges of DDT in the blubber and
liver of six common dolphins ( D. delphis ) accidentally caught in fi shing nets off the
coast of Ireland to range from 3,998 to 9,444 ppb and 2,293 to 4,528 ppb, respec-
tively. In 2001 , Borrell et al. reported the DDT concentrations measured in the blub-
ber of common dolphins accidentally caught in fi shing nets along both the Atlantic
and Mediterranean coasts of Spain during a 12-year time span. In dolphins from the
Atlantic, mean DDT concentrations (lipid weight basis) declined signifi cantly
between 1984 and 1996 (1984: 15.54±8.82 ppm; 1996: 7.95±4.49 ppm).
In dolphins from the Mediterranean, mean DDT concentrations of animals sampled
in 1992 through 1994 was 33.40 ± 38.64. Of note was the fact that males in both
regions accumulated signifi cantly higher concentrations than females. In a follow-
up study, Borrell and Aguilar ( 2007 ) reported again on DDT levels in dolphins from
Spain's Mediterranean coast. Levels continued to decrease in bottlenose dolphins, a
reduction from 303 to 13 ppm lipid weight basis from 1978 to 2002. The ratio of
p , p -DDT continued to increase, suggesting the continued breakdown

of DDT with the absence of new releases into the environment.
Castrillon et al. ( 2010 ) reported a sixfold decrease (from approximately
400-70 ppm lipid weight basis) in blubber DDT in striped dolphins ( Stenella coe-
ruleoalba ) dying from two Mediterranean epizootics, due to morbillivirus in 1990
and 2007. The second epizootic was not believed to have been enhanced by DDT or
PCBs residues in the dolphins. Wafo et al. ( 2012 ) reported an average DDT level
(lipid weight basis) of 16 ppm in blubber collected in 2007-2009 from striped dol-
phins stranded along the French Mediterranean coast. Shoham-Frider et al. ( 2009 )
reported DDT levels of 0.92-141 ppm in blubber from bottlenose dolphins stranded
in 2004-2006 along the Israeli coast.

′ -DDE to p , p ′