Pesticide Residues in Birds and Mammals - Pesticides: Evaluation of Environmental Pollution - page 426

More surprisingly, deaths due to OC insecticides of adult birds are still being diagnosed
even in the United States: in New York, potentially lethal levels of chlordane, dieldrin, and
DDTs were detected in the brains of 165 birds representing 15 species, mainly blue jays
( Cyanocitta cristata ), American crows ( Corvus brachyrhynchos ), and Cooper's hawks ( Accipiter
cooperii ) (Okoniewski et al. 2006).
It is known that most biotransformation processes of p,pʹ-DDT in vertebrates end up
as p,pʹ-DDE. This is the most persistent metabolite and the major representative of the
insecticide DDT-group in almost all published data (Mateo et al. 2000; Muñoz-Cifuentes
et al. 2003; Van den Steen et al. 2006, 2010; Jiménez et al. 2007; Keithmaleesatti et al. 2007;
Bouwman et al. 2008; Cortinovis et al. 2008; Gómara et al. 2008; Helgason et al. 2008;
Henny et al. 2008a; Clark et al. 2009; Vorkamp et al. 2009; Ahmad et al. 2010; Champoux
et al. 2010), Greece being an intriguing exception with the highest proportion of o,pʹ-DDD
(Konstantinou et al. 2000; Goutner et al. 2001, 2005; Albanis et al. 2003) and Pakistan with
DDD, mostly the p,pʹ-isomer (Malik et al. 2011).
The notorious and well-documented effect of eggshell thinning caused by DDE, result-
ing in crushed eggs and breeding failure, showed extreme interspecific differences in sen-
sitivities (Bernanke and Köhler 2009). Blus (1996) proposed as calculated no-effect level for
DDE in eggs in a range between 100 ng/g WW for the brown pelican ( Pelecanus occidentalis )
and 2000 ng/g WW for the peregrine falcon, while Mañosa et al. (2003) suggested values
between 1000 and 2000 ng/g WW for the goshawk. However, the effect on eggshell thick-
ness is an important but no exclusive factor related to reproductive success in wild birds.
Elliott et al. (2001) found that the highest concentration of DDE in osprey eggs that hatched
was 9200 ng/g WW, whereas the highest concentration in eggs that did not hatch was
22,900, and proposed that the levels of DDE that affect hatching success ranged between
6,000 and 10,000 ng/g WW. In brown pelicans, 3000 ng/g WW is associated with near total
reproductive failure (Blus 2003). Recently, Best et al. (2010) suggested a critical value associ-
ated with a decrease in nest success below 0.7 young/occupied territory at 4500 ng/g WW
DDE for bald eagles ( Haliaeetus leucocephalus ). Using two Ardeid species, the little egret
( Egretta garzetta ) and the black-crowned night heron ( Nycticorax nycticorax ), Connell et al.
(2003) established a threshold level of 1000 ng/g WW at which there was a significant level
of reduction in the survival of the young.
With these (and many others estimated or calculated) critical levels, DDTs were still con-
sidered to pose a hazard for many avian species. Yates et al. (2010), for example, indicate
that white-faced ibis ( Plegadis chihi ) nesting at Carson Lake, Nevada, might represent the
worst-case scenario for continuing DDE problems, due to the extreme sensitivity to DDE
in the eggs of this species. Similar problems were described for white-faced ibises from
Cibola Lake, Arizona (King et al. 2003). However, other nonraptorial species such as the
red-legged partridge ( Alectoris rufa ) in Spain (Herrera et al. 2000); the purple heron ( Ardea
purpurea ) in Greece (Sakellarides et al. 2006); the African darter ( Anhinga rufa ) in South
Africa (Bouwman et al. 2008); the green heron ( Butorides virescens ) in the United States
(Wainwright et al. 2001); the little egret in Romania (Aurigi et al. 2000), Hong Kong (Connell
et al. 2003), and Greece (Sakellarides et al. 2006); the intermediate egret ( Egretta interme-
dia ) in Pakistan (Sanpera et al. 2002); the lesser black-backed gull ( Larus fuscus ) in Finland
(Hario et al. 2004); the brown-hooded gull ( Larus maculipennis ) in Chile (Muñoz-Cifuentes
et al. 2003); the black-crowned night heron in Hong Kong (Connell et al. 2003), China (Dong
et al. 2004), and Greece (Sakellarides et al. 2006); the greater flamingo ( Phoenicopterus ruber )
in Greece (Sakellarides et al. 2006); and the great crested grebe ( Podiceps cristatus ) in Italy
(Galassi et al. 2002; Cortinovis et al. 2008) have also been considered at risk due to the high
DDE (or ΣDDTs) residue concentrations detected in recent times.