Cedar/Pine Toys = bad?

I frequently see people advising against toys made of these woods. I understand why not to use them as bedding, because it can cause respiratory problems, but having a toy hanging from the top of the cage made of pine isn't likely to exude enough oil to affect them, especially in a wire cage with good ventilation.

So, my question is, why is having these woods in the cage at all, even as little toys, a bad thing? Is it something other than the oils and the respiratory risks? Is it just softwoods in general that are bad for ratties in some way?