There are only two ways a sterilized load can be released: on the evidence of the process itself, or on the evidence of a biological indicator that was killed by it. They are not interchangeable, they are governed by different clauses of different standards, and one of them is available to a dental or clinic sterilizer while the other is largely an industrial manufacturer's tool. This article sets out the requirements and the documentation behind each route, gives the record fields each one has to produce, and marks the boundary that decides which route a Canadian clinic can actually use. It is written for the sterilizer operator, the infection control lead and the clinic manager who signs off a load.
Quick facts
- The vocabulary standard for sterilization, ISO 11139:2018, defines parametric release as "a declaration that product is sterile based on records demonstrating that the sterilization process variables were delivered within specified tolerances."
- Biological indicator release works the other way: a load is held until the indicator result is known, and the indicator is the release evidence. ISO 11138-1:2017 records that biological indicators "play a key role in the routine release of sterilization loads."
- Ontario does not leave the choice open in a dental office. The provincial standard of practice requires a biological indicator in a process challenge device each day the sterilizer is used and for each type of cycle that is used, and states that items in a reprocessed routine load should not be released until the results of the biological indicator test are available. Where quarantine pending that result is not possible, the standard sets out a substitute route built on a Type 5 or Type 6 chemical indicator together with the specific cycle physical parameters.
- Parametric release is authorised against a validated industrial process, typically by a regulator, and depends on continuous process data rather than on a microbiological test. It is not a substitute for the Ontario biological monitoring requirement.
Table 1 — The two release routes side by side
| Dimension | Parametric release | Biological indicator (BI) release |
|---|---|---|
| Release evidence | Records showing the process variables were delivered within specified tolerances | The result of a biological indicator exposed to the load |
| Definition source | ISO 11139:2018 vocabulary | ISO 11138-1 and ISO 11138-7 |
| Process standards involved | ISO 17665 for moist heat, ISO 11135 for ethylene oxide, ISO 14937 for sterilizing agents generally | ISO 11138 series for the indicator; ISO 17665 and ISO 11135 for the process |
| When it can be used | Where a validated process and the monitoring of its variables can be demonstrated against the specification, usually for industrial or otherwise authorised production | Wherever a sterilizer load has to be released and the organisation is following a monitoring programme |
| Typical user | Manufacturer or contract sterilizer operating under a regulator's authorisation | Health care facility, clinic and dental office running an autoclave |
| Time to release | On cycle completion once the data are within limits | After the indicator is incubated and read |
| Record centre of gravity | Process variable data, calibration and change control | The indicator result, the control result and the cycle record |
| Ontario dental office | Not the release basis for routine clinic loads | The required basis, at the daily monitoring frequency set by the standard of practice |
The two columns answer different questions. Parametric release asks "did the machine deliver what was validated?" Biological indicator release asks "did the load kill the most resistant organism we can put in it?" For a clinic, only the second question can be answered at the clinic's own bench, which is why the two routes do not compete there.
What is parametric release?
Parametric release is a declaration of sterility based on records rather than on a microbiological test. The vocabulary standard puts it in one sentence: it is "a declaration that product is sterile based on records demonstrating that the sterilization process variables were delivered within specified tolerances."
Health Canada uses the same term in its guidance on validating terminal sterilization processes for drugs, where the glossary defines a parametric release as "a sterility release system based on effective control, monitoring, documentation and batch records review of validated sterilization process. This is in lieu of release procedures based on end-product sterility testing." The Canadian framing is therefore the international one: the release evidence is a reviewed record of a controlled and validated process.
Three elements have to be in place before that sentence can be true.
- A validated process. The cycle specification, including the process and cycle variables, is established during performance qualification. ISO 17665:2024 structures this as validation in installation qualification, operational qualification and performance qualification, and its Annex C addresses the establishment and evaluation of a process based primarily on the measurement of physical parameters.
- Routine monitoring against the specification. ISO 11135:2014 requires documenting "the criteria for designating conformance of the sterilization process used for a particular sterilization load," which includes "confirmation that the data recorded during routine processing meet the sterilization process specification."
- A record and release decision. ISO 17665:2024 carries a clause on product release from sterilization and a separate clause on record retention, so that the release decision rests on retained data rather than on an operator's recollection.
The industrial origin of the concept is visible in the guidance built around it. ISO/TS 21387:2020 provides guidance on how the requirements of ISO 11135 apply when parametric release is used to release product after exposure to the ethylene oxide process, and it allows for mixed loads and different load configurations provided the variations have been characterised. In the pharmaceutical sector the same idea appears as real time release testing: the European Medicines Agency's guideline on real time release testing, which replaced the earlier guidance on parametric release, describes it as applicable to sterility where the manufacturer can show that a process is reliably and consistently delivered. None of this is available to a clinic that has not validated a process as an industrial producer would.
What is biological indicator release?
Biological indicator release makes the indicator the release evidence. The general standard for indicators, ISO 11138-1:2017, specifies the production, labelling, test methods and performance characteristics of biological indicators and records, in its own summary of their role, that they are required for the demonstration of sterility assurance levels as part of validation studies and "also play a key role in the routine release of sterilization loads." ISO 11138-7:2019 supplies the guidance for the selection, use and interpretation of results, and ISO 11138-8:2021 addresses reduced incubation time by requiring the faster result to be verified against a seven-day reference and the resistance of the test organism.
For a facility, BI release has three practical requirements:
- A control. Ontario's standard of practice states that a control test must also be used when spore testing is performed, and the results recorded alongside the test result. A positive control that is incubated with the load confirms that the incubator reached temperature and that the medium supports growth; without it, a negative result proves nothing about either.
- A process challenge device. A biological indicator is placed inside a process challenge device so that it is exposed to the same challenge as the most difficult item in the load, rather than to the easiest.
- A defined reading. A self-contained indicator gives a visual or fluorescent readout within its stated incubation window, and the result is read against the incubator's and the manufacturer's instructions rather than against a guess.
The difference from parametric release is not a matter of rigour. It is a matter of what the evidence is made of: a killed spore population on the one hand, process variable data on the other.
Which release route applies to a Canadian clinic?
In Ontario, the choice is made for the clinic by the standard of practice, and it is made in favour of biological monitoring.
The provincial standard of practice for infection prevention and control in the dental office requires a biological indicator to be placed in a process challenge device and used to test the sterilizer each day that it is used and for each type of cycle that is used, with the manufacturer's directions on the placement of the indicator to be followed. The same requirements state that a biological indicator must be in every load containing implantable devices, and that implantable devices must be quarantined until the biological indicator test results are known.
For routine loads the standard is explicit about release. Items in the reprocessed load should not be released until the results of the biological indicator test are available. If quarantine pending the biological indicator result is not possible, the standard allows a substitute route: evaluation of a Type 5 or Type 6 chemical indicator together with the specific cycle physical parameters must be used to justify release, and the standard then works through the cases that decide how the release is justified.
- If the load will be quarantined, a Type 4, Type 5 or Type 6 chemical indicator must be placed in each package.
- If the load will not be quarantined and the sterilizer has a recording device, one process challenge device with a Type 5 or Type 6 chemical indicator may be used to justify the release of the reprocessed load, and a Type 4, Type 5 or Type 6 chemical indicator must also be placed in each package.
- If the load will not be quarantined and the sterilizer has a recording device but a process challenge device is not used, a Type 5 or Type 6 chemical indicator must be placed in each package to be released.
- If the load will not be quarantined and the sterilizer does not have a recording device, a Type 5 or Type 6 chemical indicator must be placed in each package to be released.
That substitute route is still not parametric release — it is a chemical and physical release of a routine load, and it exists only because quarantine is not possible, not because the biological monitoring requirement has been waived.
Provincial guidance for health care settings states the same architecture: a biological indicator shall be used to test the sterilizer each day that it is used and with each type of cycle that is used that day; a biological indicator shall be included in every load sterilized with ethylene oxide and in every load containing implantable devices; items in the processed load should not be released until the results of the biological indicator test are available; and implantable devices shall be quarantined until those results are available. The guidance's recommendation set carries this as a requirement tied to the sterilizer monitoring standard, which is why a clinic cannot write its own release policy that omits the daily indicator.
Table 2 — Release requirements: Canadian clinic against United States practice
| Requirement | Canada (Ontario) | United States (baseline) |
|---|---|---|
| Biological monitoring frequency | A biological indicator in a process challenge device each day the sterilizer is used, and for each type of cycle used that day | The published national baseline uses a weekly cadence for routine monitoring, and daily for implant loads and certain processes; a facility follows its accreditation and state requirements |
| Implant loads | Biological indicator in every load containing implantable devices; implants quarantined until the result is known | Indicator in every load containing implants, with the load quarantined until the result is known |
| Routine-load release | Not released until the biological indicator result is available; a Type 5 or 6 chemical indicator plus the specific cycle physical parameters may justify release only where quarantine is not possible | Released against a documented monitoring programme that includes physical, chemical and biological monitors |
| Ethylene oxide | Biological indicator in every load | Biological indicator in every load |
| Release by process data alone | Not the clinic-level route; parametric release belongs to a validated industrial process and its authorisation | Permitted where the manufacturer has characterised and validated the process and the regulator accepts parametric release |
| Records | Log book maintained for at least 10 years from the last entry for the sterilizer's daily operation | Records retained per the facility's programme and its accreditation and state requirements |
The table is where most of the confusion in the field comes from. A weekly cadence is widely quoted from United States practice and from national standards used in that market; it is not the Ontario requirement, and a clinic that adopts it as its own policy has adopted a monitoring interval that does not match the standard of practice it is measured against.
What records does each release route require?
The single most useful way to separate the two routes is to list what each one has to be able to produce after the fact. The record is the release; a release that cannot be re-read is a release that did not happen.
Table 3 — Record fields, by release route
| Field | Biological indicator release | Parametric release |
|---|---|---|
| Sterilizer identifier | Required | Required |
| Cycle type and programme | Required, for each type of cycle used | Required, against the validated specification |
| Date and time of cycle | Required | Required |
| Physical parameters of the cycle | Required where they are used to justify a release without quarantine | The core evidence: time, temperature and pressure within specified tolerances |
| Chemical indicator used and result | Required where used to justify release | Typically used as a monitor, but not the release basis |
| Biological indicator lot number | Required | Not the release basis |
| Test organism and resistance data | Held with the indicator lot | Established during validation |
| Incubation temperature and duration | Required | Not applicable |
| Incubator identifier | Required | Not applicable |
| Positive control result | Required whenever a test is performed | Not applicable |
| Indicator result and reading time | Required | Not applicable |
| Load contents and configuration | Required | Required; validated loading configurations |
| Release decision and signature | Required | Required, from a review of the batch record |
| Deviation and corrective action | Required after a positive or invalid result | Required for any out-of-specification variable |
| Validation and requalification records | Held at programme level | Held at programme level, with change control |
| Calibration records | Held for incubator and sterilizer instruments | Held for all process instrumentation |
| Retention period | At least 10 years from the last entry for the sterilizer log book in Ontario | Per the applicable quality system and the authorising regulator |
Read the two columns down and the difference is structural. The biological indicator route records a result that only exists because an organism was killed; the parametric route records a process that only releases product because every variable stayed inside a limit that was established during validation. A clinic can build the first record set from a log book, an incubator and an indicator supply. The second record set cannot be built without a validated process, calibrated instrumentation and a change control system, which is precisely why it is not a clinic tool.
How do you decide which release route is available to you?
Ask three questions in order, and stop at the first one that does not have an answer.
- Has this process been validated as a process, not just accepted after a test? Validation means installation, operational and performance qualification against a defined product and load, not a passing indicator result.
- Can you monitor every critical variable continuously and retain the data? If the variables are not measured, recorded and retained for each cycle, there is no parametric record to release against.
- Has the release basis been authorised for your setting? Parametric release is applied where the process and the product have been characterised and where the applicable regulator accepts it. A clinic sterilizer in Ontario is not that setting.
If any answer is no — and for a dental or clinic sterilizer the first and third are no — the available route is biological indicator release, at the daily monitoring frequency the standard of practice sets, with the control test that makes the result meaningful and the log book that makes it auditable.
For clinics rebuilding the monitoring side of this record set, the sterilization compliance hub collects the standards and monitoring material in one place, and the sterilization monitoring collection groups the indicators, incubators and readers that support the biological route. The indicators most clinics start with are the 24-hour self-contained biological indicator and the three-hour rapid readout biological indicator, supported by the dry-block incubator; teams evaluating the programme against the standard can begin with the biological indicator 5-pack trial and can move to case-level ordering through a wholesale account.
CliniEco Medical supplies biological indicators, incubators and sterilization monitoring consumables for Canadian care settings (MDEL #35334). This article describes standards and guidance published by third parties and is not a substitute for the standard of practice that governs your setting, your sterilizer manufacturer's validated instructions, or the requirements of your provincial regulator.
Record the release decision, not just the result. Release is a documentation obligation before it is a monitoring obligation: under the Ontario standard of practice the daily log book and every biological indicator result, together with its control and any corrective action, are written down and kept for at least 10 years from the date of the last entry. The printable sterilization log sheet lays out the four record groups an inspector looks for — load log, service and maintenance log, malfunction log and package label set — and the load log and label generators turn a month of cycles into a dated page you can print or export, with no account required.
Have a question about your own facility? Send it in and you will get a written answer specific to your setup, with the regulation or standard it is based on cited. Ask your compliance question.
Related reading
- ISO 11138 Series: Biological Indicator Standards for Steam, EO and VHP Explained
- Biological Indicator Kill Time Explained
- PCD Explained: Why Ontario Dental Offices Use a Process Challenge Device
- Sterility Assurance Level and D-Value: What the Numbers Mean
- Autoclave Spore Test FAQ: Incubation and Failed Results
- ISO 11138 Series Explained: What Parts 1, 2, 3 and 4 Require
Frequently Asked Questions
Can a dental office use parametric release instead of biological monitoring?
No. Parametric release is a declaration of sterility based on process records from a validated process, and it is applied where a process and product have been characterised and the applicable regulator accepts it. Ontario's standard of practice requires a biological indicator in a process challenge device each day the sterilizer is used, and does not offer parametric release as a substitute for that monitoring.
What is the difference between parametric release and biological indicator release?
Parametric release releases a load on records that show the process variables were delivered within specified tolerances. Biological indicator release releases a load on the result of a biological indicator exposed to that load. The first is a process record; the second is a microbiological result, and the two are governed by different standards.
What does ISO 11139 say parametric release is?
ISO 11139:2018, the sterilization vocabulary standard, defines parametric release as "a declaration that product is sterile based on records demonstrating that the sterilization process variables were delivered within specified tolerances."
If a load cannot be quarantined for a biological indicator result, what can be used instead?
Ontario's standard of practice allows evaluation of a Type 5 or Type 6 chemical indicator together with the specific cycle physical parameters to justify the release of a routine load when quarantine is not possible. Implantable devices are not covered by that substitute: they must be quarantined until the biological indicator result is known.
How long do sterilizer records need to be kept in Ontario?
The daily operation of every sterilizer must be reviewed and documented in a log book, and the log book must be maintained for at least 10 years from the date of the last entry. A positive biological indicator result also has to be recorded with the corrective action taken.
Does a biological indicator test need a control, and why?
Yes. A control test must also be used when spore testing is performed, and its result recorded. The control confirms that the incubator reached the correct temperature and that the culture medium supports growth; without it, a negative test result cannot distinguish a successful sterilization from a failed incubation.
Sources
- ISO 11139:2018 — sterilization vocabulary, definition of parametric release
- ISO 11138-1:2017 — biological indicators, general requirements (AAMI preview copy, PDF)
- ISO 11138-7:2019 — guidance for the selection, use and interpretation of biological indicators
- ISO 11138-8:2021 — reduced incubation time verification of biological indicators
- ISO 17665:2024 — moist heat sterilization, product release and record retention (official preview, PDF)
- ISO 17665:2024 — standard record
- ISO 11135:2014 — ethylene oxide sterilization process standard
- Principles of Parametric Release: emphasis on data collection and analysis (Journal of Validation Technology / PMC)
- European Medicines Agency — guideline on real time release testing, formerly guideline on parametric release (PDF)
- Royal College of Dental Surgeons of Ontario — infection prevention and control standard of practice (PDF)
- Royal College of Dental Surgeons of Ontario — how often spore testing must be done
- Royal College of Dental Surgeons of Ontario — infection prevention and control resources
- Public Health Ontario — provincial guidance on cleaning, disinfection and sterilization in health care settings, biological monitoring (PDF)
- Public Health Ontario — reprocessing topic page
- 3M Attest 1492V biological indicator — instructions for use, positive control and readout (PDF)
- Health Canada — guide to validation of terminal sterilization process, glossary definition of parametric release
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