POPs hot spot

Like other chemicals of the persistent organic pollutant (POP) group, dichlorodiphenyltrichloroethane (DDT), a pesticide, is also persistent in nature and does not readily degrade in the environment by biological, physical, or chemical processes. In view of the known toxicity, accumulative, persistent characteristics, and adverse environmental and health impacts of DDT, an extensive survey of the soil was undertaken in and around a demolished DDT factory at Nowshera, NWFP, to examine DDT levels of the contaminated soil. For the present study, 81 soil samples were collected within a half-kilometer distance from the old gate of the factory and at different depths in eight different directions. Analytical data indicated that 90.91% of the soil samples studied were contaminated with DDT, with 66.6% of the samples indicating residual DDT levels higher than DDT minimum risk level (MRL) in soil (0.05 microg/g). Soil in the southeast direction appeared to be the most contaminated (average 6.70 +/- 1.25 microg/g), showing 5.19 microg/g residual DDT in a soil sample collected as far away as 520 m from the factory. Soil in the south direction also appeared highly contaminated, with an average DDT residual level of 7.16 +/- 1.70 microg/g between 65 and 390 m from the factory. For soil between the surface and a depth of 0.60 m, the highest residual DDT level (5.78 +/- 3.94 microg/g) was observed in samples from the northwest direction, followed by samples from the west direction (4.88 +/- 3.80 microg/g).