Those fireworks classified by the State Fire Marshal as safe and sane prior to January 1, 1974 may continue to bear that designation and may be sold as safe and sane fireworks until 12 noon on July 6, 1974. All fireworks previously designated as safe and sane which are offered for sale or sold during the 1974 retail license year and thereafter shall bear the State Fire Marshal label with the classification of safe and sane fireworks.