Good questions... And all PU isn't the same. Regular PU for furniture won't work as it's not meant for liquids... Haha... I am on it but I can't give away all my secrets as I am thinking about making this a business.
Just rest assured when/if I come out with a new type mapito, all these questions will be addressed so that it will be a quality product. I am currently working with an expert in the foam industry (here in the USA, not China) that assures me a safe/effective/inert solution to this will not be a problem