> I often see this being used as an excuse to say that because we produce it, it isn't bad for you. Thing is that we produce it in tiny tiny amount

There is a reason we say this, if we produce it naturally our body has mechanisms to metabolize the item. For example acetone isn't very toxic because our body produces it naturally and knows how to deal with it.

(Note I am not disagreeing with you regarding amounts, just pointing out it's not such a foolish thing to say.)