The chemical led to birds having thin and soft egg shells within which chicks couldn’t survive. When the EPA banned DDT in 1972, the eagle population had a chance to rebound and it did.

But Dr Massaro said by the 1970s "it became apparent that DDT has all sorts of negative effects." "Especially with birds of prey … their egg shells would be extremely thin and they were dying ...

DDT is an insecticide that was widely used in the 1950s and 1960s. The population of birds of prey at the top of food chains were badly affected because it made the shells of their eggs very thin ...