Sterilant

A sterilant is a chemical agent that achieves sterilization, the complete destruction of all forms of microbial life, including bacterial endospores, on inanimate objects under specified conditions. Sterilants are used to sterilize heat- or moisture-sensitive equipment and materials where physical methods such as steam autoclaving are impractical.

Sterilants are distinguished from disinfectants and antiseptics by the level of microbial kill they are designed to achieve. Sterilants aim for true sterilization, while high-level disinfectants kill most pathogens but do not reliably eliminate spores, and antiseptics are intended for living tissue.

Common chemical sterilants include ethylene oxide gas, hydrogen peroxide–based sterilants (including hydrogen peroxide gas plasma systems), peracetic acid solutions, and liquid glutaraldehyde or formaldehyde for certain devices with extended exposure. Each agent requires validated cycles with specific parameters for concentration, temperature, exposure time, and humidity, and must be compatible with the item being sterilized.

Validation and process control rely on biological indicators (such as spores of Bacillus species) and chemical indicators to verify that the cycle reached sterilization conditions. After use, some sterilants may leave toxic residues or off-gassing, requiring aeration or venting before items can be handled.

Safety and regulation are important considerations, as many sterilants are toxic, irritants, or flammable. Proper ventilation, handling procedures, and occupational exposure controls are essential. Sterilants are widely used in healthcare to sterilize instruments and equipment, in laboratories, and in other industries that require reliable sterilization of sensitive devices.