Bioaccumulation of organochlorine pesticides in the liver of birds from Boraphet wetland, Thailand

The accumulation of toxic and persistent organochlorine pesticides (OCPs) in the liver tissues of nine species of birds collected from the wetland, Bueng Boraphet, central Thailand was studied during April 2007 to September 2010. Contamination at different trophic levels (in carnivorous, omnivorous, and insectivorous birds) was also analysed. The study indicates that birds in the Boraphet wetland are still subject to OCP contamination. Total dichlorodiphenyltrichloroethane and metabolites (ΣDDTs) and total aldrin (ΣALD) accumulated the most, followed successively by total hexachlorocyclohexanes (ΣHCH) and total chlordane compounds (ΣCHL). Carnivorous birds were at highest risk of contamination by OCPs due to their highest trophic level. Omnivorous birds were contaminated with moderate levels of ΣALD and ΣHCH. The insecticide usage seems to be well managed, as insectivorous birds were the least contaminated, with only low concentrations of ΣALD and ΣHCH. Regular monitoring of OCP contamination is recommended due to a continued usage of OCPs in agriculture around the Boraphet wetland.