Some of the people promoting DDT drank spoonfuls of it to prove how safe it was, but it turned out to be very toxic to nature.

https://m.youtube.com/watch?v=gtcXXbuR244

> DDT was less effective in tropical regions due to the continuous life cycle of mosquitoes and poor infrastructure. It was not applied at all in sub-Saharan Africa due to these perceived difficulties.

https://en.m.wikipedia.org/wiki/DDT#Use_in_the_1940s_and_195...