Pesticide Residues in Birds and Mammals - Pesticides: Evaluation of Environmental Pollution - page 423

occupied by a population and the food web transfer of POPs, increasing approximately
3%-5% between trophic levels, δ 13 C provides some information about the within-ecosystem
compartment that the animal group exploited, such as their particular foraging site, with
terrestrial communities usually being depleted of 13 C when compared to marine commu-
nities and benthic/littoral communities being enriched with 13 C when compared to pelagic
communities (Fisk et al. 2001; Dietz et al. 2004a; Elliott 2005; Borrell et al. 2006; Krahn et al.
2007; Elliott et al. 2009; Ramírez et al. 2009). Similarly, the use of the fatty acid profile, and
especially the ratio of n-3/n-6 (ω3/ω6) polyunsaturated fatty acids (PUFA), can also provide
significant information on the diet and thus on POP exposure (Guitart et al. 1996a; Iverson
et al. 1997; Mateo et al. 2004; Wolkers et al. 2006).
The trophic position certainly plays an important role, but several other factors might
confound with the correct interpretation of spatial variations or temporal trends of insec-
ticide POPs. Age, gender, pregnancy, and nutritional and health statuses of the popula-
tions studied are some of them, as is metabolism, in general, which has also emerged as
significant recently (Fisk et al. 2001; Guruge et al. 2001; Dietz et al. 2004b; Goerke et al. 2004;
Andersen et al. 2006; Shore et al. 2006b; Cid et al. 2007; Gouteux et al. 2008; Vorkamp et al.
2008; Lavoie et al. 2010). Even small differences in the diet may contribute significantly to
variations in the contaminant levels in the samples from the same species collected in dif-
ferent subzones of the same area or between years (Goutner et al. 2001; Galassi et al. 2002;
Mateo et al. 2004; Christensen et al. 2005; Borrell et al. 2006; Anthony et al. 2007; Elliott et al.
2009). Mañosa et al. (2003) showed that a shift in the diet in northern goshawk ( Accipiter
gentilis ) from European rabbits ( Oryctolagus cuniculus ) to birds (mainly Passeriformes), due
to a severe reduction of the population of the first type of preys in Spain, probably masked
any temporal decline in OC levels. In addition, the role of migration to more contaminated
latitudes or zones may, or may not, introduce unexpected changes in the pollutant levels
(Braune et al. 2001; Guruge et al. 2001; Aguilar et al. 2002; Hario et al. 2004; Bustnes et al.
2006; Helgason et al. 2008; van Drooge et al. 2008; Corsolini 2009; Grove et al. 2009; Rajaei et al.
2010a). Last but not the least, a study carried out with glaucous gulls ( Larus hyperboreus )
breeding in the Norwegian Arctic suggested that climate variability, and thus the pre-
dicted climate change, may also influence POP concentrations (Bustnes et al. 2010). In fact,
Geisz et al. (2008) found glacier melting to be a potential source for the movement of ΣDDT
to the Antarctic marine food web as levels have not declined in Adélie penguins ( Pygoscelis
adeliae) from the Western Antarctic Peninsula for more than 30 years.
In the samples either from bird (Wainwright et al. 2001; Henny et al. 2003b, 2008a; Sanpera
et al. 2003; Guitart et al. 2005; Van den Steen et al. 2006; Bustnes et al. 2007; Martínez-López
et al. 2007; Keithmaleesatti et al. 2007; Bouwman et al. 2008; Helgason et al. 2008; Malik et al.
2011) or mammal origin (Hobbs et al. 2003; Tanabe et al. 2003; Kajiwara et al. 2004; Ramu
et al. 2006; Fillmann et al. 2007; Vorkamp et al. 2008; Lemarchand et al. 2010; Moon et al.
2010; Mwevura et al. 2010; Park et al. 2010), usually the residues of the DDT family (o,pʹ-
DDD, p,pʹ-DDD, o,pʹ-DDE, p,pʹ-DDE, o,pʹ-DDT and p,pʹ-DDT) have dominated, among OC
insecticides, in the majority of the reports during the last 10 years. A selection of published
values determined in different species and areas of the world are shown in Tables 14.2 and
14.3 for birds and in Table 14.4 for marine mammals. Total DDT (ΣDDT) concentrations are
the sum of all the DDT family compounds. In this regard, it should be mentioned that the
ratio p,pʹ-DDT/p,pʹ-DDE (or sometimes ΣDDT/p,pʹ-DDE) has been used as an estimate of
the time elapsed since the use of the insecticide, with the ratio increasing over time as the
p,pʹ-DDT degrades.
Other important OC insecticides are the chlordane, cyclodiene, HCH, and toxaphene
families and endosulfan and mirex. Chlordane is a mixture of structurally related OC