Review on DDT and its residues in Turkey's wetlands

Turkey is a country rich in wetlands (250 wetlands, approximately one million hectares). As it is in many countries, the wetlands in Turkey are threatened by the agricultural activities, loss of habitats due to these activities and by pesticide contamination. After 1940, large quantities of pesticides, especially DDT were used intensively against mosquitoes and pests in most of the wetlands in Turkey causing considerable contamination. In the beginning of 1980's, production, import and use of DDT was forbidden due to its toxicity on non-target organisms, environmental persistence, and accumulation in food chains. The scientific studies made in Turkey on the level of contamination in various environs and organisms by DDTand its metabolites, are limited These limited studies, especially the ones made after 1990's, have shown that we still observe DDT contamination in many wetlands (including internationally important ones like Goksu Delta and Meric Delta) and in organisms like birds and fishes. The data on the concentrations of DDTand its metabolites in the organisms and the biological magnification levels are not adequate since in most of the studies only water and sediment samples were analyzed. Besides, in the few studies made on the organisms, standard methods and suitable indicator organisms were not used. Because of these reasons, it is very difficult to make reliable evaluations on the DDT levels and its effects in the wetlands of Turkey. It is interesting that DDTlevels are higher than its metabolites in water sediment and organism samples in some wetlands which imply the possible use of DDT recently The aim of this review is to summarize the studies made so far on DDT and its residues in the wetlands of Turkey and to shed light on the possible hazardous effects and to propose approaches for future studies.