Surco Portable Sanitation’s odorless additive, Metazene, is an effective and environmentally safe odor neutralizer used in portable toilet deodorant products to control odors at the molecular level, according to the manufacturer. After neutralizing unpleasant odors, the new, heavier molecule sinks and evaporates over time. Metazene does not contain formaldehyde and is used in Surco’s odor contol deodorant liquids, toss packets, and other odor-control products. 800/556-0111; www.surco.com.