EN ISO 25424:2019

• Abstract:

  1.1 Inclusions; 1.1.1 This document specifies requirements for the development, validation and routine control of a low temperature steam and formaldehyde (LTSF) sterilization process for medical devices using a mixture of low temperature steam and formaldehyde as sterilizing agent and which operates below ambient pressure.; NOTE Although the scope of this document is limited to medical devices, it specifies requirements and provides guidance that can be applicable to other products and equipment.; 1.1.2 This document is intended to be applied by process developers, manufacturers of sterilization equipment, manufacturers of medical devices to be sterilized and the organizations with responsibility for sterilizing medical devices (see ISO 14937:2009, Table E.1).; 1.2 Exclusions; 1.2.1 This document does not specify requirements for the development, validation and routine control of a process for inactivating the causative agents of spongiform encephalopathies such as scrapie, bovine spongiform encephalopathy and Creutzfeldt-Jakob disease. Specific recommendations have been produced in particular countries for the processing of materials potentially contaminated with these agents.; NOTE See ISO 22442‑1, ISO 22442‑2 and ISO 22442‑3.; 1.2.2 This document does not specify requirements for designating a medical device as "STERILE". Such requirements are given in EN 556‑1.; 1.2.3 This document does not specify a quality management system for the control of all stages of production of medical devices.; NOTE It is not a requirement of this document to have a complete quality management system during manufacture or reprocessing, but those elements of such a system that are required are normatively referenced at appropriate places in the text. Attention is drawn to the standards for quality management systems (see ISO 13485) that control all stages of production or reprocessing of medical devices including the sterilization process. Further guidance is given in E.4 of ISO 14937:2009.; 1.2.4 This document does not specify requirements for occupational safety associated with the design and operation of LTSF sterilization facilities.; NOTE 1 Safety requirements for sterilizers are specified in IEC 61010‑2‑040.; NOTE 2 Attention is also drawn to the existence in some countries of regulations stipulating safety requirements.; 1.2.5 This document does not cover analytical methods for determining levels or residues of formaldehyde and/or its reaction products.; NOTE 1 Attention is drawn to EN 14180.; NOTE 2 Attention is drawn to the possible existence in some countries of statutory regulations specifying limits for the level of formaldehyde residues on medical devices and products.; 1.2.6 This document does not cover preparatory measures that might be necessary before sterilization such as cleaning, disinfection and packing.; NOTE For reprocessable medical devices, the manufacturer(s) of these devices can supply information on the preparatory measures (see ISO 17664).

• Status: Published
• Publication Date: 19-Nov-2019
• Withdrawal Date: 30-May-2020
• ICS: 11.080.01 - Sterilization and disinfection in general
• Technical Committee: CEN/TC 204 - Sterilization of medical devices
• Drafting Committee: CEN/TC 204 - Sterilization of medical devices
• Current Stage: 6060 - Definitive text made available (DAV) - Publishing
• Start Date: 20-Nov-2019
• Completion Date: 20-Nov-2019
• Directive: Harmonized Standard2017/745 - Regulation (EU) 2017/745 of the European Parliament and of the Council of 5 April 2017 on medical devices, amending Directive 2001/83/EC, Regulation (EC) No 178/2002 and Regulation (EC) No 1223/2009 and repealing Council Directives 90/385/EEC and 93/42/EEC
  OJ Ref: L, L 256 OJ Date: 19-Jul-2021
• Directive:

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  Harmonized Standard2017/746 - Regulation (EU) 2017/746 of the European Parliament and of the Council of 5 April 2017 on in vitro diagnostic medical devices and repealing Directive 98/79/EC and Commission Decision 2010/227/EU
  OJ Ref: L, L 258 OJ Date: 21-Jul-2021
• Directive:

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  Not Harmonized90/385/EEC - Active implantable medical devices
  OJ Ref: L, L 90 OJ Date: 25-Mar-2020
• Directive:

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  Not Harmonized93/42/EEC - Medical devices
  OJ Ref: LI 90, LI 90/1 OJ Date: 25-Mar-2020
• Directive:

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  Not Harmonized98/79/EC - In vitro diagnostic medical devices
  OJ Ref: L, L 90 OJ Date: 25-Mar-2020
• Mandate: M/023 - Standardization mandate to CEN/CENELEC concerning the development of European standards relating to medical devices
• Mandate: M/575 - Medical devices in support of Regulation (EU) 2017/745 and in vitro diagnostic medical devices in support of Regulation (EU) 2017/746
• Mandate: M/575 Amd 2 - Medical devices in support of Regulation (EU) 2017/745 and in vitro diagnostic medicial devices in support of Regulation (EU) 2017746
• Mandate: M/BC/CEN/89/9 - Joint Standardization request to CEN/CENELEC concerning harmonized standards relating to horizontal aspects in the field of medical devices
• Ref Project: SIST EN ISO 25424:2020 - Sterilization of health care products - Low temperature steam and formaldehyde - Requirements for development, validation and routine control of a sterilization process for medical devices (ISO 25424:2018)

• Replaces: EN ISO 25424:2011 - Sterilization of medical devices - Low temperature steam and formaldehyde - Requirements for development, validation and routine control of a sterilization process for medical devices (ISO 25424:2009)
• Effective Date: 08-Jun-2022
• Refers: ISO 11138-5:2017 - Sterilization of health care products — Biological indicators — Part 5: Biological indicators for low-temperature steam and formaldehyde sterilization processes
• Effective Date: 09-Feb-2026
• Refers: ISO 11138-1:2017 - Sterilization of health care products — Biological indicators — Part 1: General requirements
• Effective Date: 09-Feb-2026
• Refers: ISO 11737-2:2009 - Sterilization of medical devices — Microbiological methods — Part 2: Tests of sterility performed in the definition, validation and maintenance of a sterilization process
• Effective Date: 09-Feb-2026
• Refers: ISO 11140-1:2014 - Sterilization of health care products — Chemical indicators — Part 1: General requirements
• Effective Date: 09-Feb-2026
• Refers: ISO 11737-1:2018 - Sterilization of health care products — Microbiological methods — Part 1: Determination of a population of microorganisms on products
• Effective Date: 09-Feb-2026
• Referred By: EN 556-2:2024 - Sterilization of medical devices - Requirements for medical devices to be designated "STERILE" - Part 2: Requirements for aseptically processed medical devices
• Effective Date: 28-Jan-2026
• Referred By: EN 14180:2025 - Sterilizers for medical purposes - Low temperature steam and formaldehyde sterilizers - Requirements and testing
• Effective Date: 28-Jan-2026
• Referred By: EN 12182:2012 - Assistive products for persons with disability - General requirements and test methods
• Effective Date: 28-Jan-2026
• Consolidated By: ISO 25424:2018 - Sterilization of health care products — Low temperature steam and formaldehyde — Requirements for development, validation and routine control of a sterilization process for medical devices
• Effective Date: 12-Feb-2026
• Amended By: EN ISO 25424:2019/A1:2022 - Sterilization of health care products - Low temperature steam and formaldehyde - Requirements for development, validation and routine control of a sterilization process for medical devices - Amendment 1 (ISO 25424:2018/Amd 1:2022)
• Effective Date: 10-Jun-2020

Overview

EN ISO 25424:2019 (ISO 25424:2018) defines requirements for the development, validation and routine control of a low temperature steam and formaldehyde (LTSF) sterilization process for medical devices. The standard covers LTSF processes that operate below ambient pressure and use a mixture of low temperature steam and formaldehyde as the sterilizing agent. Although focused on medical devices, its requirements and guidance can be applicable to other products and equipment.

Key technical topics and requirements

• Scope of application: Requirements for design, development, validation and routine control of LTSF sterilization processes for medical devices.
• Process validation: Framework for establishing and documenting that an LTSF cycle consistently achieves the intended sterilization performance (development and validation activities are required).
• Routine control: Requirements for ongoing monitoring and control to ensure continued process performance in production/reprocessing.
• Applicable references: The standard is intended to be used alongside other sterilization and quality standards (e.g., ISO 11138 series for biological indicators, ISO 11140 series for chemical indicators, ISO 11737 for microbial reduction and bioburden control).
• Regulatory alignment: Includes European annexes relating to medical device directives and EU regulations, offering a route for presumption of conformity within the limits of the standard’s scope.

Exclusions and important limitations

• Does not cover processes for inactivating prion agents (e.g., CJD, BSE) - special national recommendations apply.
• Does not specify requirements for labeling a device as “STERILE” (see EN 556‑1).
• Does not define a full quality management system (see ISO 13485 for QMS requirements).
• Occupational safety design/operation and analytical methods for formaldehyde residues are excluded (see IEC 61010‑2‑040 and EN 14180 where applicable).
• Preparatory measures such as cleaning, disinfection and packaging before sterilization are not covered (see ISO 17664 for reprocessing information).

Practical applications and who uses this standard

• Process developers designing LTSF sterilization cycles.
• Manufacturers of LTSF sterilization equipment who must demonstrate validated and controlled cycles.
• Medical device manufacturers selecting or validating LTSF as a sterilization method for their devices.
• Sterilization service providers and hospital sterile services responsible for routine sterilization and process control.

Related standards (for implementation)

• ISO 11138 series (biological indicators)
• ISO 11140 series (chemical indicators)
• ISO 11737 series (sterilization - microbial aspects)
• ISO 13485 (quality management for medical devices)
• EN 556‑1 (requirements for claiming “STERILE”)

Keywords: EN ISO 25424:2019, ISO 25424, LTSF sterilization, low temperature steam and formaldehyde, sterilization validation, sterilization process control, medical device sterilization.