Toxic effects in humans caused by BAC and other quaternary ammonium compounds (QACs) are mainly associated with their chemical structure and mechanism of action. Benzalkonium chlorides interact with negatively charged components of bacterial cell membranes, such as phospholipids and lipopolysaccharides, because their nitrogen atoms are positively charged . This interaction is the mechanism of action. Cell death occurs when this interaction compromises the integrity of the cell membrane, which allows cellular contents to seep out .