The contamination by organochlorine pesticides (OCPs) of water, sediments, rice grains and leaves, and animals of different trophic levels, collected from rice paddies surrounding Bueng Boraphet wetland, central Thailand, was studied during November 2009 to February 2010. The levels of total dichlorodiphenyltrichloroethanes (ΣDDT) were too low to be detected in any samples. High levels of total hexachlorocyclohexanes (ΣHCH) and total aldrins (ΣALD) and low levels of total chlordanes (ΣCHL) were detected in both sediments and rice grains. α-HCH, β-HCH, γ-HCH, and aldrin in rice grains exceeded the acceptable limits set by the Ministry of Public Health of Thailand. Rice grains were at high risk of contamination due to the direct spraying of OCPs. Fishes were contaminated with moderate levels of aldrin. Continued surveys of pesticide contamination in water, sediments, and organisms of each trophic level are recommended to more effectively monitor and control agricultural pesticide usage around Bueng Boraphet wetland and to further assess the ecological risks and impacts on human health.

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.