Free symmetric group algebras in division rings generated by poly-orderable groups

We show that the canonical involution on a nonabelian poly-orderable group G extends to the Hughes-free division ring of fractions D   of the group algebra k[G]k[G] of G   over a field kk and that, with respect to this involution, D contains a pair of symmetric elements freely generating a free group subalgebra of D   over kk.