Formalin is considered to be:

Formalin is recognized as an unsafe material previously used for fumigation due to its hazardous properties. Specifically, it is a solution of formaldehyde in water and is known to be toxic and carcinogenic. Its use in fumigation has largely been discontinued in favor of safer alternatives that do not pose the same health risks to humans or the environment.

While formalin has historically been used for its disinfectant properties, its safety profile has led to a reevaluation of its use in various settings, particularly in cosmetic and personal care environments where client safety is paramount. This context helps clarify why formalin, despite its effectiveness as a disinfectant, is not considered safe for applications like fumigation and why the focus has shifted towards safer and more effective sanitizing agents.