A Toxic History Lesson 

Sometimes an old message can provide a fresh perspective.

A 1940s marketing film for DDT helped do just that for CNN producers as we began investigating the potential risks of toxic chemicals. In the hourlong special report "Toxic Childhood," Dr. Sanjay Gupta examines the large number of chemicals our children are exposed to -- even before they're born -- and assessed what we know and don't know about their impact on our children's health.

One of the many things we noticed in our investigation is that in the past, assurances that certain chemicals are completely safe have often turned out to be false.