Phelps' coach wary of Rio's waters

Bob Bowman, longtime coach of Olympic superstar Michael Phelps, says Rio's polluted waters pose a health risk to open-water swimmers that must be addressed before the 2016 Games.

Pollution at beach venues hosting open-water swimming and sailing won't affect swimmers like Phelps in the competition pool.

But Bowman said on Wednesday he has seen first hand the effects it can have on those who are exposed to it.