Serum DDT and DDE levels in Singapore general population

A simple and fast method was used to determine 1,1′-(2,2,2-trichloroethylene)-bis(4-chlorobenzene) (DDT) and 1,1′-(2,2-dichloroethylidene)-bis(4-chlorobenzene) (DDE) in blood serum. Serum samples pre-treated with formic acid were extracted with n-hexane and determined by gas chromatography (GC-ECD), using PTE-5 capillary column. Detection limits for DDT and DDE were 0.5 ppb. Recovery with a fortified pooled sample at 1 ppb level was 107.0% for DDT and 106.0% for DDE. At 10 ppb level, the recoveries for DDT and DDE were 96.1% and 92.7%, respectively. Eighty-nine random blood samples collected from volunteers were analyzed. The geometric mean (GM) serum level of DDT was 1.9 ppb (0.2–8.9 ppb) and that of DDE was 10.8 ppb (1.5–88.1 ppb). There was a positive correlation between DDE and DDT level (r = 0.33, P < 0.01). The serum DDE level was positively correlated with age (r = 0.49, P < 0.01) and DDT × Age (r = 0.62, P < 0.01). No correlation was observed between DDT and age. These results suggest that DDE, a metabolite of DDT, is cumulative in the body. Therefore blood DDE could be used as a cumulative exposure marker for DDT, whereas blood DDT may be used to reflect its recent exposure.