Ethylene oxide sterilization is a low-temperature chemical process in which ethylene oxide, abbreviated EO, acts as a gaseous sterilizing agent on the packaged product. It is used when products cannot withstand thermal or radiation exposure, such as plastic catheters, tubing systems, electronic components, or products with long, narrow lumens. EN ISO 11135 specifies the requirements for development, validation, and control of the application of an EO sterilization process for medical devices. Because ethylene oxide has alkylating and carcinogenic properties, the process is additionally governed by residue limits according to EN ISO 10993-7 and by occupational safety requirements. <\/p>\n
Ethylene oxide inactivates microorganisms through alkylation of proteins and nucleic acids. The process is not a single step, but a chain of defined phases: preconditioning outside the chamber, conditioning in the chamber with establishment of temperature and relative humidity, gas exposure with defined EO concentration and dwell time, pressure changes and purging for gas removal, and desorption, also called aeration, until specified residue levels are reached. Critical parameters are EO concentration, temperature, relative humidity, pressure profile, and time. Humidity is as critical as gas concentration, because desiccated spores are significantly more difficult to inactivate. <\/p>\n
Validation comprises installation, operational, and performance qualification. Physical performance qualification demonstrates that the critical parameters are achieved throughout the entire loading pattern; microbiological performance qualification demonstrates the microbicidal effect. EN ISO 11135 describes two microbiological approaches for this purpose: the half-cycle method, which leads to a conservative overkill approach via half the exposure time without evidence of surviving microorganisms, and a bioburden-based method. Biological indicators with spores of Bacillus atrophaeus are used, usually in process challenge devices that replicate the most difficult location in the load. Loading configuration, packaging, and product density are part of the validation; changes to these trigger revalidation. <\/p>\n
After exposure, ethylene oxide and its conversion product ethylene chlorohydrin, abbreviated ECH, remain in the product. EN ISO 10993-7 specifies permissible limits, measurement methods, and conformity assessments and distinguishes according to contact duration: short-term contact up to 24 hours, prolonged contact up to 30 days, and permanent contact. For ethylene oxide, the maximum values are 4 mg in the first 24 hours, 60 mg in the first 30 days, and 2.5 g over the lifetime for permanent contact, supplemented by average daily doses; for ECH, separate, less stringent values apply. The desorption time is therefore not freely selectable, but a validated release condition whose compliance is demonstrated analytically. <\/p>\n
The process requires gas-permeable packaging, typically a sterile barrier system with nonwoven web and sealing film, so that gas and moisture can reach the product and subsequently escape again. Liquid-filled or gas-tight sealed products are not suitable. Material compatibility must be assessed in two ways: on the one hand, with regard to deformation, discoloration, and mechanical properties due to moisture, temperature, and vacuum; on the other hand, with regard to residue uptake, which is significantly higher in thick-walled elastomers. Since ethylene oxide is classified as carcinogenic, facilities and personnel are subject to strict emission and exposure requirements, which in practice concentrates these processes among specialized service providers. <\/p>\n
Compared to the moist heat process described in the entry Steam Sterilization of Medical Devices, ethylene oxide sterilization operates at low temperature and also reaches narrow lumens, but requires days instead of hours and generates toxicologically relevant residues. Compared to radiation sterilization, material damage from ionizing radiation is eliminated, but packaging permeability and desorption are mandatory. The choice of process is a design decision that must be justified in risk management and biological evaluation. The uniform target value for all processes is addressed in the entry Sterility Assurance Level for Medical Devices; the packaging and labeling requirements in the entry Sterile Medical Device. <\/p>\n
When investigational products are sterilized with ethylene oxide, validation status and residue data are part of the safety documentation of the application according to Annex XV of Regulation (EU) 2017\/745. The residue assessment must be linked to the biological evaluation, because the permissible values depend on the contact duration in the study protocol: a product that remains in the study longer than originally planned changes contact category and thus the limit value set. The supply chain is also relevant, because desorption often takes place at the service provider and determines the earliest release date for the study supply. <\/p>\n
In study operations, traceability must additionally be ensured: sterilization lot, cycle record, release date, and residue testing must be assignable to the product used at the site. If loading, packaging, or sterilization location change, it must be assessed before further use whether validation and residue evidence remain valid. Full-service CROs such as Mediconomics support sponsors and manufacturers in preparing sterilization and residue evidence for study applications, in linking these data with risk management and biological evaluation, and in batch traceability and medical writing. <\/p>\n
Why does release take so long after EO sterilization?<\/strong><\/p>\n Because desorption is part of the process. The product may only be released once ethylene oxide and ethylene chlorohydrin fall below the limits according to EN ISO 10993-7. Depending on material and packaging, this takes days to weeks. <\/p>\n What packaging is required?<\/strong><\/p>\n A gas-permeable sterile barrier system that admits gas and moisture during exposure and releases them again during desorption. Gas-tight packaging and liquid-filled products are not suitable for the process. <\/p>\n What triggers revalidation?<\/strong><\/p>\n Changes to product, material, packaging, loading pattern, chamber, or location, as well as deviations in bioburden. EN ISO 11135 also requires periodic assessment of the maintenance of the validated state. <\/p>\n Ethylene oxide sterilization is a low-temperature chemical process in which ethylene oxide, abbreviated EO, acts as a gaseous sterilizing agent on the packaged product. It is used when products cannot withstand thermal or radiation exposure, such as plastic catheters, tubing systems, electronic components, or products with long, narrow lumens. EN ISO 11135 specifies the requirements […]<\/p>\n","protected":false},"author":10,"featured_media":0,"parent":0,"template":"","meta":{"_acf_changed":false,"site-sidebar-layout":"default","site-content-layout":"","ast-site-content-layout":"default","site-content-style":"default","site-sidebar-style":"default","ast-global-header-display":"","ast-banner-title-visibility":"","ast-main-header-display":"","ast-hfb-above-header-display":"","ast-hfb-below-header-display":"","ast-hfb-mobile-header-display":"","site-post-title":"","ast-breadcrumbs-content":"","ast-featured-img":"","footer-sml-layout":"","ast-disable-related-posts":"","theme-transparent-header-meta":"","adv-header-id-meta":"","stick-header-meta":"","header-above-stick-meta":"","header-main-stick-meta":"","header-below-stick-meta":"","astra-migrate-meta-layouts":"default","ast-page-background-enabled":"default","ast-page-background-meta":{"desktop":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"ast-content-background-meta":{"desktop":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"tablet":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""},"mobile":{"background-color":"var(--ast-global-color-5)","background-image":"","background-repeat":"repeat","background-position":"center center","background-size":"auto","background-attachment":"scroll","background-type":"","background-media":"","overlay-type":"","overlay-color":"","overlay-opacity":"","overlay-gradient":""}},"footnotes":""},"glossary-cat":[24],"class_list":["post-7859","glossary","type-glossary","status-publish","hentry","glossary-cat-medizinprodukte-ivd"],"acf":[],"related_terms":"","external_url":"","internal_reference_id":"","_links":{"self":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/7859","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary"}],"about":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/types\/glossary"}],"author":[{"embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/users\/10"}],"version-history":[{"count":0,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary\/7859\/revisions"}],"wp:attachment":[{"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/media?parent=7859"}],"wp:term":[{"taxonomy":"glossary-cat","embeddable":true,"href":"https:\/\/mediconomics.com\/en\/wp-json\/wp\/v2\/glossary-cat?post=7859"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}Regulatory References<\/h2>\n
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