Please don’t buy into the political lies about DDT. Actual science experiments found no causal link between egg shell thinning and DDT, even with massive doses.
Check out section VI here. http://junkscience.com/1999/07/26/100-things-you-should-know-about-ddt/
Here’s another source: http://www.freerepublic.com/focus/f-news/710158/posts
Then HOW did the eagle come back?