It was formerly used to produce iodoform, bromoform, and even chloroform industrially. Methylidyne can be prepared from bromoform. Of highest concern are haloketones and trihalomethanes (THMs) of those the predominant form being bromoform. Other bioactives found were bromoform, dibromochloromethane, bromochloroacetic acid and dibromoacetic acid. PHC is made from bromoform, a liquid halocarbon that is commercially manufactured from methane. Only small quantities of bromoform are currently produced industrially in the United States. The EPA classified bromoform as a probable human carcinogen. The chloroform may also be replaced by bromoform, bromal, chloral, or carbon tetrachloride or tetrabromide. The essential oil of the Hawaiian alga "Asparagopsis taxiformis" consists of 80% bromoform. Liquids used include bromoform, tetrabromoethane, tribromoethane, methylene iodide, and polytungstate liquids. Bromoform can be absorbed into the body by inhalation and through the skin. If a base is present, bromoform is obtained instead, by the haloform reaction.