[jabberwock]

More delicate than human adults certainly - more delicate than human babies? (I'm not qualified to say scientifically)

I guess it's a matter of risk assessment. Having undertaken extensive research we are happy that the Auro woodstain is safe for guinea pigs, especially as it's an environment where they don't spend a large amount of time (has been either too hot or too wet for most of the summer). And, as it turns out, they don't chew the wood anyway. That is our assessment and we're happy with it. Other people on this forum give their pigs soft toys made from plush or other fabrics. I don't because I worry the pigs possibly ingesting flame retardants, azo dyes, formaldehyde or pesticides (specific hazard depends on exact fabric used) if they chew the toys. In this case the treatments have already been applied so one is generally less aware of them, but it doesn't mean they're not present.