The Effect of Environmental Processes on the Isomeric Composition of DDT-related Compounds.

The pesticide p,p'-DDT (1-chloro-4-[2,2,2-trichloro-1-(4-chlorophenyl) ethyl]benzene) has been used in agriculture, forestry, and vector control for decades. Technical DDT, the purity commonly used for insecticidal applications, contained p,p'-DDT as well as its constitution isomer o,p'-DDT (1-chloro-2-(2,2,2-trichloro-1-(4-chlorophenyl)ethyl] benzene) and several closely related compounds. To investigate the effect of environmental processes on the isomer-specific composition of DDT and its degradation products, we examined previously published and newly acquired quantitative data with regard to o,p'-/p,p'- DDX ratios in different environmental matrices. Isomeric shifts related to the depositional regime, transfer between and within compartments, and microbial transformation were clearly observed. Shifts of the positional isomer ratios potentially can serve as indictors to track the environmental fate of DDX. For an unambiguous assignment of these shifts to specific processes, further systematic studies and complementary lab experiments are necessary. [ABSTRACT FROM AUTHOR]