Persistent Organic Pollutants in Little Egret Eggs from Selected Wetlands in Pakistan C. Sanpera, 1 X. Ruiz, 1 L. Jover, 2 G. Llorente, 1 R. Jabeen, 3 A. Muhammad, 4 E. Boncompagni, 5 M. Fasola 5 1 Department of Animal Biology—Vertebrates, Faculty of Biology, University of Barcelona, Diagonal, 645, Barcelona 08028, Spain 2 Department of Public Health—Biostatistics, Faculty of Medicine, University of Barcelona, Casanovas, 143, Barcelona 08036, Spain 3 World Wildlife Fund—Pakistan, 606 – 607 Fortune Center, P.E.C.H.S., Shahra-e-Faisal, Karachi 75400, Pakistan 4 Pakistan Agriculture Research Council, P.O. Box 1031, Islamabad 45500, Pakistan 5 Dipartimento Biologia Animale, Universita `, Piazza Botta 9, I-27100 Pavia, Italy Received: 5 March 2002 /Accepted: 19 August 2002 Abstract. The main goal of the present work has been to study the use of egret eggs to assess environmental pollution by POPs (HCB, HCHs, cyclodienes, DDTs and PCBs) in three Pakistani wetlands that are presumed to be affected by different types of pollution. Taunsa Barrage, affected mainly by agricultural pollut- ants; Karachi Harbor because of the supposed exposure to indus- trial activity-related POPs; and Haleji Lake as a relatively pristine area because of its location in a stony desert. Taunsa Barrage and Haleji Lake are wetlands of international importance according to the Ramsar Convention, while the Karachi Harbor is of interest because of the large human population living there. Eggs of the white (Egretta garzetta garzetta) and dark (Egretta garzetta gu- laris) morphs of Little Egrets were used as monitoring tools. Concentrations were also determined in several prey in this spe- cies’ diet and in the sediments collected in their foraging areas. Differences in egg pollutant content among the three localities were significant for all the compounds. Overall, the eggs from Haleji Lake and Karachi showed, respectively, the lowest and highest percentages of detection and organochlorine concentra- tions. Biomagnification from sediments to prey and then to eggs has been documented in the three areas studied and is accompa- nied by higher percentages of detection of different compounds through the compartments. Differences in the biomagnification factor among the areas were small, even when differences in pollutant concentrations were high, suggesting that eggs are reli- able indicators of POPs in the environment. The values found were generally lower than those reported for the eggs of large herons from North America or the Mediterranean basin, and are about the same order of magnitude that those of other medium- sized egrets from other parts of the world. Organochlorine compounds are still used by developing coun- tries, mainly for the treatment of agricultural pests and for the control of malaria vectors (Scholtens et al. 1990). Some fea- tures of tropical ecosystems, such as high temperatures and heavy rain, affect the environmental fate of these pollutants by increasing their dispersion rate (Iwata et al. 1994; Kannan et al. 1995; Custer 2000). Despite their widespread use, little infor- mation is available on the impact of persistent organic pollut- ants in tropical areas. In Pakistan, the use of agricultural pesticides is presently concentrated on cotton fields, located mainly in the Punjab and Sindh provinces and to a lesser extent in Baluchistan. Lesser amounts of pesticides are applied to other crops, such as vegetables and fruits. Most of these pesticides are insecticides against white flies, jassids, aphids, bollworms, and other harm- ful insects. The estimated use in Pakistan ranged from 13,000 metric tons for 1990 –1, to 30,471 metric tons for 1995– 6 (STAT-USA on the Internet, United States Department of Commerce). Predatory birds, such as egrets and herons (Family Ardeidae), are at the top of the aquatic food webs, and are therefore particularly susceptible to pollutant bioaccumulation. Since they accumulate organochlorines over time, these water- birds have often been used as indicators of ecosystem health (De Lucca-Abbot et al. 2001). Several authors argued that the eggs of predatory birds are effective materials for monitoring both the exposure to and the effects of the contaminants (Kush- lan 1993; Cobb et al. 1995; Aurigi et al. 2000; Erwin and Custer 2000; De Luca-Abbot et al. 2001). Moreover, egg sampling outweighs the shortcomings of experimental studies on contamination (Blus and Henny 1997). During 1999 and 2000, we conducted a research project aimed to assess the pollution status of selected wetlands in Pakistan and China. In this paper the use of egret eggs for assessing the general environmental pollution by persistent organochlorine pollut- ants (POPs) is evaluated and the contamination levels for three Pakistani wetlands that are presumed to be subject to different types of pollution. We collected eggs of the Little Egret (Egretta garzetta) as our main study material. In order to estimate the exposure of the birds to pollutants, we also ana- Correspondence to: C. Sanpera; email: sanpera@porthos.bio.ub.es Arch. Environ. Contam. Toxicol. 44, 360 –368 (2003) DOI: 10.1007/s00244-002-2044-z ARCHIVES OF Environmental Contamination and T oxicology © 2003 Springer-Verlag New York Inc.