isopropanol is widely used, its obvisouly not good for you if you spray it in your eye, But AFAIK the humble photocopier is going to do your more harm!
Its what 'lense cleaning wipes' are soaked in.
As for opening lense up, STRONGLY weigh up the potential benefits before ruining it.
Only lenses I've taken apart was an 80's vivitar series 1 tele zoom lense, manual focus, manual aperture, the ball race that holds the stop down lever disinteegrated inside the glass, so I had to retrieve all the tiny balls. Took me best part of 4-5hours to do it. will not be attempting it again.
Other lense was a late 90's Sigma wide prime, it had a bit of moisture formed inside, fungus would have grown if I didn't clean it. that was easier to take apart as lack of zoom function = more space to get tools & fingers in there.
But still, needed tiny circlip pliers, and still had to file the bits down & bend the end of it with blowtorch to reach in there, and soaked up a gargantuam amount of time, probably about 8hours to take it apart, clean every surface and seal (in spray alcohol, then lubed with a TINY amount of spray silicone, wiped dry, then re-assembled).
will not do it again, too much work.
For modern zoom, autofocus & electro aperture, you will be hard pushed to get them apart. Often they are clipped togehter with little plastic clips, which really are only designed to be clipped together once, and spare clips can be costly and take months to arrive.
