You can use warm water, just not hot water, for Retayne treated fabrics.
The "known carcinogen" found in Retayne is a small amount of formaldehyde. Formaldehyde is also found in fire retardant, waterproof and permanent press fabrics, clothing, cosmetics, furniture, carpeting, draperies, plywood, particle board, adhesines, disinfectants, and many other things that you probably come into contact with every day.