Is there any evidence of bio-accumulation in the case of DDT?

Yes, many animals and plants have been tested and proven to contain DDT years after it was applied to crops many miles away. The most notable case is that of the American Bald Eagle, whose eggshells were weakened by DDT contamination, threatening the entire Bald Eagle population for years. Some years after DDT was banned in the US, the eagle's normal reproductive cycle was restored, as the DDT levels in their blood was reduced.