I know someone brought up the theory that the Zika virus was linked to larvacide use recently (here or on backtalk, I think). BBC has an article that talks about that and the evidence for/against it, which I found interesting.

http://www.bbc.com/news/world-lat…

Basically, health authorities have looked into the possibility, but say there are too many areas where the larvacide isn’t used but birth defects are on the rise, and vice versa, for them to really believe it. Now they’re looking into a two-problem origin of microcephaly: the idea that getting the virus and having some unknown factor at the same time might cause it.