Sterilization

Sterilization is a process that destroys or eliminates all forms of microbial life, including bacteria, viruses, fungi, and spores, on or in an object or material, rendering it sterile. It is distinguished from disinfection, which reduces the number of viable microorganisms, and from sanitization, which lowers microbial counts to accepted levels.

Common physical methods include moist heat in steam autoclaves (effective for many instruments and inanimate items), dry heat, and filtration for heat‑sensitive liquids. Ionizing radiation, such as gamma or electron beam, can sterilize certain products. Nonionizing ultraviolet light is generally not reliable for sterilization of complex items due to limited penetration.

Gas and plasma methods, such as ethylene oxide, hydrogen peroxide vapor or plasma, and ozone, are used for heat‑ and moisture‑sensitive devices. Liquid chemical sterilants (for example, high‑level chemical sterilants like glutaraldehyde or peracetic acid) are used for equipment that cannot withstand heat.

Applications span healthcare (medical devices, surgical instruments), laboratories (equipment, media), pharmaceuticals and vaccines, food processing, and water treatment. Sterilization is often performed as terminal sterilization, with validation using biological indicators and chemical indicators to prove process effectiveness; a sterility assurance level commonly targets 10^-6.

Standards and regulation vary by region but commonly include ISO and EN standards for sterilization processes, with oversight by food and drug authorities (for example, the FDA in the United States). Practical limitations include material compatibility, processing time, safety concerns over residues, and cost.