Dietary exposure to DDT of secondary school students in Hong Kong

The aim of this study was to determine the dietary exposure of DDT in foodstuffs consumed in Hong Kong by secondary school students in Hong Kong in 2005. Food samples of domestic or imported food were collected randomly from local markets for the determination of DDT. The analytical method for this survey was based on isotope dilution technique. DDT isomers were determined at parts per billion (microg kg(-1)) levels in foods by pressured fluid extraction followed by gel permeation column cleanup and gas chromatography with mass spectrometry detection. Among the 98 composite samples, 25 were found positive with DDT levels greater than the limit of quantitation (LOQ) (1 microg kg(-1) for each isomer of DDT). Only two of the meat products were found to contain low levels of the metabolites of DDT. A number of fish and shellfish were found to contain not just the metabolites of DDT, but also parent DDT. The main contribution to DDT was from seafood. The dietary intake of DDT for an average and high secondary school student consumers were estimated to be 0.145 and 0.291 microg kg(-1) bwd(-1), respectively. Both levels fell well below the Provisional Tolerable Daily Intake (PTDI) of 10 microg kg(-1) bwd(-1) established by the Joint Food Agriculture Organization/World Health Organization Meeting on Pesticide Residues (JMPR). It was concluded that both the average and high secondary school student consumers were unlikely to experience major toxicological effects of DDT.