I was looking at the cosmetics database for a listing of toxic ingredients today and hydroquinone got a hazard rating of the highest which was a 10! Whereas kojic acid got a hazard rating of 1?

It also depends on the percentage of HQ.
Its just like asking... which is heavier... a bucket of stones or a bucket of cotton?You need to know the % to use to label it dangerous. 2% hq is very minimal both to lighten and to poison!

So you don't think hydroquinone is poisonous at 2%?

Nope!
Will a man with BAC at .03% be in trouble or not?