Benzalkonium chloride is a cationic surface active agent used in textile dyeing, softeners, antistatic agents, emulsifiers, and conditioners. It functions as a cationic detergent and preservative in pharmaceutical products, including eye, ear, and nasal drops and sprays. It's also a key ingredient in personal care items like hand sanitizers, shampoos, deodorants, and wet wipes. Additionally, it's utilized in research to evaluate its effects on epithelia conjunctival cells in vitro.