Childhood Mercury Poisoning
In the 1940s and 50s children were getting a mysterious disorder called Pink Disease. One quarter of the children affected died. Most of the rest were affected for the rest of their lives with neurological and social problems similar to high functioning autism.
In 1954 it was discovered that Pink Disease was caused by Mercury(Hg) used as a preservative in teething powders. Countries in the western world pulled all baby and children's products containing Hg off the market that same year, but the companies that made them kept selling to other countries (Iraq, Romania, India etc.) until they ran out in 1963.