Rather good, Dan!

[The Drone Ranger]

There are lots of chemicals found in humans which don't belong there and might not be doing us any good.
Here's one
http://www.rense.com/general19/fih.htm

But the real threats come from disease lets say TB and malaria for instance.

If we had some parasite which drank our blood and was around the size of a hedgehog that one might command most of our attention.

So in bees Varroa need most attention then brood diseases then virus, then we can turn our attention to traces of chemicals.
Perhaps that means we miss something important but you wouldn't stop in the middle of a busy motorway to tie your shoelace. Leaving it might trip you up but .....