Closely related chemical story
I attended a meeting in Alaska regarding Dioxin I bring this up just to point out how small amounts can really hose an unintended critter! (not that Dioxin is intended for anything)
According to young women with PhDs Dioxins in amounts as small as .0063 parts per "Quadrillion" rendered Rainbow trout sterile.
Im pretty sure it is not good for trout to be subjected to many chemicals but how in the hell do you measure an amount that small?