Sterilisation Chemical Monitoring in Healthcare
Ethylene oxide (EtO) is used in hospitals and medical device reprocessing facilities to sterilise heat-sensitive instruments and equipment. IARC classifies ethylene oxide as a confirmed human carcinogen (Group 1). Under the new WEL framework, ethylene oxide is listed as a non-threshold genotoxic carcinogen (NTGC), meaning there is no safe exposure level and PCBUs must eliminate or minimise exposure as far as reasonably practicable. Glutaraldehyde remains widely used for high-level disinfection of endoscopes and instruments despite being a potent respiratory sensitiser with a WES ceiling of 0.05 ppm. Peracetic acid is increasingly used as an alternative to glutaraldehyde but introduces its own respiratory irritation hazards. Air monitoring in sterilisation departments, endoscope reprocessing units, and stores areas where freshly sterilised items off-gas verifies that engineering controls are effective.
Key Hazards
Primary exposure hazards requiring monitoring in Australia.
Ethylene oxide sterilisation
EtO steriliser loading, cycle operation, and unloading generate worker exposure to this Group 1 carcinogen. Aeration cabinets and ventilated storage areas are required to allow residual EtO to off-gas from sterilised items before handling. Steriliser door seals, aeration system exhaust, and handling of freshly sterilised items are the primary exposure points. Under the new WEL framework, EtO is classified as an NTGC with no safe exposure level.
Glutaraldehyde in endoscope reprocessing
Glutaraldehyde at 2% concentration is used for high-level disinfection of flexible endoscopes. It is a potent respiratory sensitiser with a ceiling limit of 0.05 ppm. Automated endoscope reprocessors reduce but do not eliminate exposure — manual decanting, topping up, and disposal of glutaraldehyde solutions generate vapour. LEV over soak troughs and reprocessors is essential.
Peracetic acid disinfection
Peracetic acid is used as an alternative to glutaraldehyde in some facilities and for environmental disinfection in high-risk areas. It is a respiratory irritant with an incoming WEL of 0.4 ppm STEL. Concentrated peracetic acid is corrosive to skin and eyes.
Formaldehyde in histology and pathology
Formaldehyde is used as a tissue fixative in histology and pathology laboratories. IARC Group 1 carcinogen. WES 1 ppm TWA, 2 ppm STEL. Tissue processors, grossing stations, and specimen storage areas are the primary exposure sources. Fume extraction at grossing stations must be verified.
Common Analytes
Substances typically included in occupational hygiene sampling proposals for this sub-category.
Typical Worker Groups
Common similar exposure groups (SEGs) assessed for this sub-category.
Regulatory Context
Healthcare facilities are workplaces under the WHS Act. Ethylene oxide is classified as an NTGC under the new WEL framework, meaning PCBUs must eliminate or minimise exposure — there is no safe threshold. Health monitoring is required for workers exposed to ethylene oxide, formaldehyde, and glutaraldehyde. The Code of Practice for Managing Risks of Hazardous Chemicals applies to all sterilisation and disinfection operations. AS/NZS 4187 governs reprocessing of reusable medical devices and specifies requirements for staff protection during cleaning, disinfection, and sterilisation.
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