Hmmm. I've read somewhere that speed bumps create more pollution
because of the slow-down/speed-up/slow-down/speed-up driving pattern
that results, but never that they cause any deaths.

Before someone else gets in there. The reason some councils are removing
speed bumps is because emergency service vehicles (especially)
ambulances are being delayed trying to get over the speed bumps. And I
think infact patients have been injured even more going over speed
bumps.
And deaths have been proved to a result of speed bumps. But not in a way
you were probably thinking of.

Actually, one thing that sleeping policemen cause me to do is drive in
the middle of the road instead of the left hand side.

This is on the roads where there are 3 of them, and the one on the
left-hand side is obscured by parked vehicles, so I have to drive over
the middle one.