DDT's highly stable nature and chemical properties allow for its migration over long distances and explain its tendancy to bioaccumulate. The mechanisms for such phenomenon are discussed in the materials' links below. The investigations on DDT persistence are extensive and the materials accessed were chosen to present a broad overview of both past and ongoing discussions.

The Ritter report extract - DDT Persistence  (full report text)

Microbial Degradation of Pesticides - from Northern Arizona University lectures on Environmental Chemistry

Pesticide residues in food 2000 : DDT - International Programme on Chemical Safety, 2000