Re sassafras: The amount required to actually be meaningfully carcinogenic is .. pretty large (and interestingly enough its an anti-carcinogen for some types of cancer causing agents). The liver toxicity similarly requires a large dose and both problems require ingestion, not topical application. Personally I still use it to make root beer (it just tastes better so there
) after having spent an inordinate amount of time reviewing the possible risks and the amount I use is ridiculously below the threat level. For using the wood in order to have liver or cancer problems you'd have to inhale enough that you'd have other problems (like plugged lung) way before then. Note I'm not suggesting that anyone do anything rash or not review the data themselves, but the risk here is imho somewhat hyperbolized at reasonable exposure levels (possibly due to some other uses of safrole).
Charts like this are useful as guidelines but will vary in specifics, which unfortunately really depend on the person... Most types of toxins react in different ways so a universal good/bad is pretty hard to apply (i.e. some may be contact irritants and generally annoying, others may be long term problem causers, others may only be an irritant when inhaled, etc..). A good friend is seriously allergic to urushiol which is not only found in poison oak/ivy but also Mangoes (both fruit sap and wood)!! She LOVES mangoes and can actually eat them - she just can't touch them with her hands or lips; so she has someone cut them for her and then carefully eats them with a toothpick which is fine. I have other friends who can wade through straight poison oak with no apparent problems.
The bad news on Maple is that ~most of what I can find is that the spalted variety is the most common problem with plain maple rarely being an issue and the effects are usually respiratory in nature (makes sense, mold is bad mmmkay and maple does love to spalt), its not widely reported (on anything I can find anyway...) as a problem on skin contact.
This chart breaks the reactions down more by type and commonality:
http://www.hobbywoods.com/wood_toxicity.htm
As does this to a more limited extent but somewhat different manner:
http://www.hse.gov.uk/pubns/wis30.pdf
Based on what I'm reading here, if you're reacting to Maple that's pretty .. unfortunate. I'd take any other exposure very very cautiously and in very limited amounts until I saw what happened.