DDT metabolite bis(chlorophenyl)acetic acid:: The neglected environmental contaminant

Up to the present date, DDA (2,2-bis(chlorophenyl)acetic acid) resulting from the degradation of DDT (2,2-bis(chlorophenyl)-1,1,1- trichloroethane) residues in the environment has been neglected as an environmental contaminant of the aquatic system. More than 60 years after the invention of DDT as an insecticide and more than 25 years after its use was banned in most of the developed countries, DDA was found as major contaminant up to the microgram per liter level in the surface water of the Teltowkanal in Berlin, Germany. DDA is formed together with some other intermediates of DDT such as DDD (2,2-bis(chlorophenyl)-1,1 -dichloroethane), DDE (2,2-bis(chloraphenyl)-1,1 -dichloroethylene), DDMU (2,2-bis(chlorophenyl)-1-chloroethylene), DDOH (2,2-bis(chlorophenyl)ethanol), DDMS (2,2-bis(chlorophenyl)-1-chloroethane), DDCN (2,2-bis(chlorophenyl)acetonitrile), and DBP (dichlorobenzophenone), which were identified at lower concentrations in surface water of the canal. Our results add some new aspects to the ongoing controversy over the fete of DDT in the natural environment and confirm some laboratory experiments about the natural remediation of DDT residues. Moreover, the polar degradation product DDA is also a potential problem for drinking water production because it is the only DDT derivative that also leaches into the groundwater wells of a neighboring drinking water plant at concentrations exceeding the European maximum tolerance levels for pesticide residues in drinking water.