How could the Howe Caverns be dangerous?

Following a quick shufti at its publicity web-site it's hard to see any real, obejctive dangers! Most of it is a show-cave, so has artificial paths, lighting, etc. It has an "adventure caving" route (similar to some show caves here in the UK) but you, as a visitor would be equipped properly and led by experienced guides. So I'm puzzled by your question. Visit it - either as a straightforward show-cave tourist or on the "adventure" route - and enjoy it!