The dorms were having an epidemic of head lice, which most of the staff had never even heard of before. At the school nurse's suggestion, the counselors had tried using various medicines to kill the lice, but nothing seemed to help. Probably because all the children's combs and brushes were washed in the same tub of water each week, the horrible creatures continued to infest everyone. Finally, in desperation, one of the dormitory counselors went to the Public Health Department and returned with something they had assured her would eliminate the lice.
That's why we spent the very first Earth Day putting DDT on the heads of all the children.
(Yes, it worked, but I'm sure nobody will ever celebrate Earth Day by doing that again.)