I don't know about neoprene, but they make wetsuits out of that. You would think that a diver, wearing a suit, would not be exposing his skin, to a carcinogen nor a poison. The suit makers would not be in business long.
Oven mitts: would you wear a mitt and pull an apple pie out of the oven, accidentally touch the pie, and then eat it if it had a poison? The tank is sealed with 100% silicone, and if the mitts say the same, they would be good in the tank.

Woah, decade old thread!!! Nice!

I had a EuroReef that was pretty noisy, so I turned it over and put a little blob of silicone on 4 corners of the bottom of the skimmer body and 4 corners of the bottom of the pump and let it dry before putting it back in the sump. Worked like a charm.