Table 1.

Mode of action, advantages and disadvantages of biocides.

Biocide	Mode of Action	Advantages	Disadvantages
Quaternary Ammonium Compounds	Cationic action destabilizes cell membrane resulting in cell lysis [11,12,13,14].	Does not produce free radicals; therefore, they are not carcinogenic or genotoxic [11,12]. Generally inexpensive to use [1].	Less effective against biofilms [16]. Efficacy can be strain specific [19]. Efficacy may vary with temperature [17,20].
Polyhexamethylene Biguanides	Adherence to lipids within cell membranes leading to non-specific cell membrane disruption, allowing cellular entry of PHMB [25,26].	Broad antimicrobial specificity [24]. Low toxicity [25,26,27]. Water soluble, thermostable and pH stable [26]. Presents activity against certain biofilms including that of antimicrobial resistant strains [27].	Efficacy is temperature sensitive [28]. Efficacy may be altered by presence of organic matter [29,31].
NaOCl	Oxidative damage to cell membrane, as well as intracellular proteins and amino acids. Membrane damage leads to entry of NaOCl to damage organelles [33,35].	Suitable for household use due to appropriate shelf life and stability at average household temperatures [34,35]. Safe for human hygiene [35].	Efficacy may be altered by presence of organic matter [38]. Efficacy may be altered depending on contaminated surface material [41,47,48].
ClO2 (chlorine dioxide gas)	Oxidative damage to cell membrane, as well as intracellular proteins and amino acids. Membrane damage leads to entry of ClO2 to damage organelles [33].	Safe for human hygiene. Not cytotoxic. Can be active against biofilms. Oxidative mechanism is greatly specific thus less product is required. [58]	Gas generation is expensive [58]
Hypochlorous acid (HClO)	Oxidative damage to cell membrane, as well as intracellular proteins and amino acids. Membrane damage leads to entry of HClO to damage organelles [33,46].	Generally inexpensive and non-toxic [33]. Safe for human hygiene [46]. Can be effective against enveloped viruses [58].	Reduced oxidative specificity means more product is required [58].
Peroxides (H2O2)	Hydroxyl radicals cause oxidative damage to cell membrane components as well as intracellular molecules [48,49].	Only degrades into water and hydrogen—environmentally friendly [48]. Broad antimicrobial specificity [55]. Can be applied in aqueous or vaporized form [54]. Vaporized form enables disinfection of ‘hard to reach’ places [53,54].	Typically unstable therefore difficult to store [54]. Presents strain specificity [49]. Efficacy varies with application method [48].
Ozone (gas)	Induces cell lysis via membrane oxidation [56].	Broad antimicrobial specificity [55]. Easy to produce with a 20-min half -life [56]. Enables easier disinfection of ‘hard to reach’ places [56].	Toxic at high concentrations [55]. Efficacy may vary in the presence of organic matter depending on whether the ozone is in gaseous or aqueous form [55,57].