You can hand wash them using Retayne to set the dyes, or using Synthrapol (which suspends unset dye particles in water so they can be washed away instead of settling into the whites).
Test colorfastness by dipping a corner into a glass of water. Look for dye release into the water. Also rub the wet area with a white cloth to see if any dye is taken up by the white cloth. If the fabrics pass both of these tests, I would hand wash in Synthrapol.
Synthrapol and Retayne are widely available in quilt stores or online. Amazon has Synthrapol; not sure about Retayne.
You can Google for more information, but here is one website I found:
http://www.quiltbus.com/retayne.htm