Interesting to the see that “foam” isn’t the only way to insulate a foundation. Check out where a product such as Roxul might work as a good, safe alternative.
“Most green builders who need a layer of horizontal insulation under a concrete slab specify expanded polystyrene (EPSExpanded polystyrene. Type of rigid foam insulation that, unlike extruded polystyrene (XPS), does not contain ozone-depleting HCFCs. EPS frequently has a high recycled content.”