A medical device manufacturer whose products are sterilized by irradiation buys ISO 11137-1, reads it, and believes the standard is now covered. A quarter of it is. The ISO 11137 series has four parts, only one of them carries requirements, and the one explaining how to set the sterilization dose is not the first.
This is not an editorial detail. It is why validation files reach audit with a perfectly measured dose and no document justifying why that dose and not another.
What Part 1 covers, and what its title says by omission
The full title of ISO 11137-1:2025 is "Sterilization of health care products. Radiation. Part 1: Requirements for the development, validation and routine control of a sterilization process for medical devices".
Three moments, then, and they do not overlap. Development establishes what the process must achieve. Validation demonstrates that it does, in the actual facility and on the actual product. Routine control demonstrates that it keeps doing so, run after run. A system treating validation as a single event, ticked once, has missed the third.
The scope covers processes using irradiators with cobalt 60 or caesium 137, a beam from an electron generator, or a beam from an X-ray generator. Four technologies, one set of requirements.
And here is what the title does not mention: the method for determining the sterilization dose. This document states that a dose must be established and justified. It is not the document telling you how to establish it.
The dose is set in Part 2
ISO 11137-2:2013 carries that subject, and its title leaves no room for doubt: "Sterilization of health care products. Radiation. Part 2: Establishing the sterilization dose".
The consequence is very concrete. An organization that bought only Part 1 holds the process requirements and does not hold the methods that answer the main one. The file is then built on whatever the irradiation provider was willing to explain, or on a dose carried over from a neighbouring product without the transfer being justified. Both show up in audit, and both are expensive to repair once production has started.
The most common shortcut is to take a reference dose found in the literature and treat it as settled. A dose is not a property of the radiation, it is a conclusion drawn from the product's bioburden. It is demonstrated on your product, manufactured under your conditions.
Parts 3 and 4 are guidance, not requirements
ISO 11137-3:2017 carries "Guidance on dosimetric aspects of development, validation and routine control". ISO/TS 11137-4:2020 carries "Guidance on process control".
Two things to take from those titles. First the word guidance: these documents accompany, they do not require. Then the ISO/TS prefix on Part 4, which marks a technical specification and not an International Standard: that is a different status, and it shows in the designation before you even open the document.
The distinction is not academic, it plays out in the audit room. An auditor raising a finding on the basis of guidance has the wrong document, and an auditee unable to say so accepts a nonconformity that is not one. Conversely, an organization ignoring these two parts deprives itself of the only texts explaining in detail how to measure what it claims to control.
The 2025 edition replaces the 2006 one
ISO 11137-1:2025 is the second edition of this document. It cancels and replaces ISO 11137-1:2006, which had received two amendments during its life, Amendment 1:2013 then Amendment 2:2018.
What follows fits in one sentence: a documented system still referencing "ISO 11137-1:2006" and its two amendments references a withdrawn edition. That is corrected in the manual, in the procedures, in the validation reports and in the contracts with the irradiation provider, and it is never a plain string replacement, because a new edition can renumber what it keeps.
What we will not state here. We have not read the 2025 text. Lists of changes are circulating, sometimes precise, sometimes contradictory. We are not repeating them: on a subject where a mistyped value ends up inside a validation file, the only source that counts is the text itself. Obtain it before deciding anything, or work with someone who has it.
Where to start, concretely
Before buying anything, it helps to know where you stand. Our radiation sterilization readiness checklist walks through the nine stages such a process plays out in: the quality management system around it, characterization of the sterilizing agent, characterization of the process and equipment, product definition, process definition and its dose, validation in three qualifications, routine monitoring, product release, and maintaining effectiveness over time.
Forty-three self-assessment points, a conformity rate that computes itself, four languages. It is an HEMC methodological aid, not a reproduction of the normative text, and it replaces neither the standard nor professional support. It serves one precise purpose: finding the gaps before an auditor finds them for you.
If your situation calls for an outside view, write to us; and if you are looking for other standards, all our free checklists are freely available.
This article is provided for information only and is neither regulatory advice nor a reproduction of the normative text. The reference documents prevail: consult the official ISO publications cited above.