Hair And Dust

I don't think so, maybe in a really really long time?

Hair certainly could. It contains sulfur-containing compounds which are released as the hair degrades with time. I can't say I've ever noticed it, but a single hair would probably leave a thin "worm-trail" of oxidation across the surface of a coin, particularly a shiny copper or silver one, if left in contact with it for prolonged periods.

Dust is an unknown quantity. Most of it is probably harmless, but some particles may be composed of something that will damage or stain a coin.

In short, I wouldn't be too worried about it in the short and medium term, but for long term storage, and for your higher quality proof and unc coins, I'd take the time to try to exclude the hairs and dust.

Often I find that there is dust on a new 2X2 that is actually from the cardboard part of the holder. IN other words, it seems that during the process of cutting the large sheet holders during production leaves particles of the cardboard on the plastic part. Do you think that this material would harm the coin?

Not exactly true. Of course if you purchase them separately, then any dust may have just fallen off. I've purchased 2x2's by the 100 in boxes and from several different manufacturers. So far every time I open those boxes there is some dust probably from the manufacturing process or boxing. Regardless of the reason and regardless of the price or manufacturer, I've always found some dust in the package.