Hi Dileo,
Welcome to the Mattress forum 
and thanks for your posts. I moved this thread the General Mattress Questions. (Thanks Sweet Dreams for your Haven Mattress analysis. We appreciate your contributions.)
You may have read this already but just in case you haven’t … there is more information in selecting children’s mattress and the topics it links to about mattresses and children and “suitable” and “safe” materials including a link to some general guidelines for children in post #2 here. It also includes a number of links to the better forum posts and topics about mattress and children as well which have more information about many good options for children which would be well worth considering.
Any mattress that uses materials that are durable enough and are in a suitable firmness range and that has a reliable safety certification and you consider to be safe enough would be a suitable choice for a child regardless of whether it has an organic certification.
As always, our trusted mattress members are an excellent source to look for suitable and safe mattresses for you and your children. I say this with confidence because of the transparency of our members with the materials they use, which is not something Haven Mattress likes to disclose to consumers.
Good luck and let us know if you have any more questions.
Phoenix.