I'd look into some "green" building supply companies across the pond there. Something that is low VOC would be a good starting point.
Additionally, I'm not certain if it's still a practice or not, but if memory serves correct I believe MDF is "glued" with solvent(s) containing formaldehyde and/or other similar compounds. Thus even more reason for sealing.
I'm not too crazed by the green moment as much of it, at least state side, seems rather gimmicky in order to justify additional cost for material. That said, I did look into a green MDF and a non-off gasing variant of linoleum flooring for sealing the interior of cages I like to build.