Let there be light!

[ppppenguin]

Life is hazardous. Whether it's arsenic or tigers. We have to accept a sensible balance between utility and safety.

The amount of mercury in fluorescents was pretty small, probably a lot less than the amount released from the coal burning power stations that powered them. Commercial quantities of florries should have been recycled properly. Dentists in the UK (and likely elsewhere in the 1st world) have to dispose of old fillings properly. I believe that crematoria are significant source of mercury pollution. Composite resin fillings are rather better than amalgam.

NiCd batteries were superceded by NiMH as much for better performance as lower toxicity.

Lead from car batteries is largely recycled, it helps here that the supply chain can readily act as a return chain. Car batteries also contain significant amounts of arsenic.

There's a little online about arsenic in e-waste: https://sites.google.com/site/dukeewaste/arsenic http://ewasteguide.info/hazardous-substances
Whether the electronics waste stream is a significant cause of arsenic pollution is another question. Mining the stuff is certainly nasty.