The Impact of Pesticides - Academy Publish

the liver, mainly to p,p'-DDE and p,p'-DDD (Gold and Brunk, 1982). DDE is themost stable and toxic metabolite of DDT and the most frequently found in tissues. InSpain DDT was widely used in agricultural applications but, similarly to otherEuropean countries, its use was restricted in the late 1970s and finally banned in1994 (Orden de 22 de Marzo de 1971 and Orden 4 de Febrero de 1994). However,indoor residual spraying (IRS) with DDT are still being used in certain endemicmalarial areas to minimize the incidence and spread of this disease by controllingmosquitoes (Bouwman, 2004). Most of these countries are localized in Africa,where there is a high incidence rate of malaria cases. In 2004, an estimated 350–500million people contracted malaria globally, of whom more than a million died (80–90% in Africa) (WHO and UNICEF, 2005; WHO, 2007). In this sense, the fact thatthe prohibition and legal restrictions on the use of organochlorine pesticides inSpain did not reduce levels in eggs, especially at Doñana, leads one to think that themigration of these species towards Africa was responsible for the presence of thesecompounds in said specimens (Gómara et al., 2004; Negro et al., 1993). However,several authors have demonstrated that levels are similar in migratory and sedentaryspecies (Hernández et al., 1986, 1988; Van Drooge et al., 2008).Donaldson et al. (1999), found DDE concentrations in plasma of prefledged baldeagle (Haliaeetus leucocephalus) from Canadian Great Lakes ranging from 25 to 60μg/l. In that study, there were no indications that concentrations of contaminantsdetected were adversely affecting productivity in the populations. In our study, DDEblood concentrations were similar to those found by Van Wyk et al. (2001) in bloodof African whitebacked vulture (Pseudogyps africanus) (Table 1). On the otherhand, these concentrations have been considered as low concentrations, since theoverall mean for the whole study period were 4-5 times lower than those describedby Donaldson et al. (1999). As such, and unlike other studies, DDT concentrationswere similar or higher to those for DDE. In general, no significant differences werefound between years ( 2 =7.64; p=0.106), although a general tendency to increasethe ∑DDT levels was observed throughout the studied period (Table 1). Thisincrease was mainly due to increased concentrations of DDD in 2003 withoutstatistically differences. The major detoxification pathway of DDT is viadechlorination to DDD which readily degrades to 2,2-bis(p-chlorophenyl) aceticacid (DDA) and is rapidly excreted as detoxification product (Baselt, 1982),Since the biological half-lives for elimination of these compounds are ranked asfollows: DDE > DDT > DDD, detection of higher ratios of DDD or DDT to DDE isbelieved to indicate more recent exposure while lower ratios are believed tocorrelate with long-term exposure and storage capacity (Morgan and Roan 1971).The mean p,p´-DDT/p,p´-DDE ratio in our samples was 1.83 ± 0.78 meanwhile thatp,p´-DDD/p,p´-DDE was 1.92 ± 1.2 (Table 1). The Booted eagle is considered atrans-Saharan migratory species which overwinters in African countries, from midOctober to mid March (Martínez, 2002), where malaria and the use of DDT iscommon (Del Hoyo et al., 1994). Although it seems there is a positive tendency ofwintering in Mediterranean areas instead of migrating to Africa (Martínez andSánchez-Zapata, 1999; Sunyer and Viñuela, 1996).AcademyPublish.org - The Impact of Pesticides326