I have opened an ordinary battery to get the carbon rod and the black
powdery stuff around it stained my drawer. I had some nicads in there
and I was wondering if the nicads would be affected?

Some of the batteries did have some white stuff on the positive
terminals, but this could be down to old age or misuse.

Should I be concerned?

I assume you mean it stained your desk drawer, and not your intimate
apparel.

I probably tore open a hundred batteries as a kid for carbon rods, and
haven't suffered any ill effects so far. Some of the things I did with
those rods were a lot more hazardous though. Anyone remember the "build
your own arc lamp" project from the 70s?

Non-rechargeable batteries contain manganese oxide or potassium
hydroxide, which are not particularly deadly, but you shouldn't let the
kids play in them. If your other batteries are crusting over, it may be
because they're old, and vapor is leaking out through the metal cases,
which means it's time to dispose of them in a responsible manner. The
case gets thinner over time and will eventually rupture. They're okay
to use in a flashlight, but you don't want them bursting inside your
favorite walkman.

eswnl wrote:
I have opened an ordinary battery to get the carbon rod and the black
powdery stuff around it stained my drawer. I had some nicads in there
and I was wondering if the nicads would be affected?

Some of the batteries did have some white stuff on the positive
terminals, but this could be down to old age or misuse.

Should I be concerned?

Yeah, some of the nicads in the drawer had some white stuff on the
positive caps, I just hope that the nicads leaked because they were OLD
and not because of the slight manganese dioxide that might have been in
contact with them.