While there are many organisms that were affected by DDT, the organism with the highest concentration of DDT in their bodies was the Peregrine Falcon**.

Here's why:

* Biomagnification: DDT is a persistent pesticide that doesn't break down easily in the environment. It accumulates in organisms over time. This accumulation becomes more pronounced as you move up the food chain.

* Top Predators: Peregrine Falcons are apex predators, meaning they sit at the top of the food chain. They consume birds that have already accumulated DDT in their bodies, leading to a high concentration in the falcon.

The impact of DDT on Peregrine Falcons was significant. It caused thinning of their eggshells, leading to reproductive failure and a drastic decline in their populations. The banning of DDT in many countries has helped the species recover, but it serves as a stark reminder of the harmful effects of persistent pesticides.