AusPen Eco–Friendly Whiteboard Marker
When I painted our monolithic chalkboard wall in our kitchen I was under the impression that dry erase markers were toxic. It turns out they were but these days are non–toxic.
Better than that, these whiteboard markers from AusPen are not only non–toxic but they are refillable. A whole kit (6 markers of various colors and 6 refills) will run you $70… but each marker can be refilled 40 times before another refill is necessary.