\▐bī-ә-▐sīd\ n (1947) An agent incorporated in or applied to the surfaces of plastics to destroy bacteria, fungi, marine organisms, etc. Some plastics, e.g., acetals, acrylics, epoxies, phenoxies, ABS, nylons, polycarbonate, polyesters, fluorocarbons and polystyrene, are normally resistant to attack by bacteria or fungi. Others, e.g., alkyds, phenolics, low-density polyethylene, urethanes, and flexible vinyls can under some circumstances be affected by growth of these organisms on their surfaces. Even though the resins themselves might be resistant, additives such as plasticizers, stabilizers, fillers, and lubricants can serve as food for fungi and bacteria. Examples of biocides are organotins, brominated salicylanilides, mercaptans, quaternary ammonium compounds, and compounds of mercury, copper, and arsenic.