Testing of chemicals

OECD Good Laboratory Practice: Frequently asked questions (FAQ)



 Test Facility organisation and personnel (Sponsor/CRO/Sub-Contractor Responsibilities - Including IT Providers) 


1.                 Can the organisation chart of a test facility include functions other than those described in the GLP Principles, such as head of department, coordinator of the study directors, laboratory technician, personnel responsible for veterinary services, etc.?

It can but there is no requirement for this in the GLP Principles. The GLP responsibilities and who fulfils these GLP roles must be described and this can be in the organisational chart or other documents. (Posted on 15 June 2020)


2.                 What are the responsibilities of Test Facilities (TF) and sponsors with respect to overseeing the work and ensuring the qualifications of the full range of GLP service providers / subcontractors (e.g. those who supply commercial assay kits to Contract Research Organisations (CROs))?

The sponsor’s responsibilities for provided services are described in OECD Advisory Document No. 11: The Role and Responsibilities of the Sponsor in the Application of the Principles of GLP and in the OECD GLP Principles Document No 1 paragraph 2.2, point no. 5. If a sponsor is a test facility, the test facility management’s obligations also include assessing the supplied services. (Posted on 28 February 2018).


3.                 Some TF activities may be performed by external suppliers (e.g. IT services, eArchive, metrology, computer system validation).  What are the responsibilities of TFs with regard to these types of suppliers when these suppliers are not GLP certified (i.e. the suppliers are not included in a national GLP compliance monitoring programme)?

Test facility management has overall responsibility to ensure that the facilities, equipment, personnel and procedures are in place to achieve and maintain the validated status of computerised systems in order to establish “GLP compliant” study results. This includes the responsibility for internally as well as externally provided services (e.g. third parties, vendors, internal IT departments, service providers including hosting service providers). Depending on the provided services, a supplier’s facility need not  be  part  of  a  GLP  compliance monitoring program or conform to GLP regulations,  but  it must  have  a  documented  quality  system  verified  as  acceptable  by  test  facility management with input from its quality assurance unit. (Posted on 28 February 2018).


4.                 Do the responsibilities of a TF include IT facilities/services and archive/e-archive facilities?

Elements of a Test Facility such as IT services and archives can be an integral part of the Test Facility or be outsourced by written agreements. Test Facility management should have an overview of all suppliers relevant for IT services. Electronic archiving is a GLP relevant service (OECD Document No 17, paragraph 34, 109 – 118 and OECD Document No 15). It is the responsibility of Test Facility management to evaluate the service and to estimate risks to data integrity and data availability. (Posted on 28 February 2018).


5.                  What are the roles and responsibilities of a TF and IT provider when GLP data are retained by an IT provider that is not part of a GLP monitoring program?

Written agreements (contracts, service level agreements) should define roles and responsibilities within a relationship between Test Facility management and a supplier (OECD Document No 17, paragraph 34). A documented risk-based approach should be used to assess suppliers providing a GLP-relevant computerised system infrastructure, platforms, or software to a test facility.

Vendor assessment is the responsibility of Test Facility management and may result in an audit of a supplier. Vendor assessment should be properly scaled, based upon a risk assessment and be performed by suitable personnel (input from the Test Facility management‘s quality assurance unit may be considered). The assessment should estimate risks to data integrity. (Posted on 28 February 2018)


The answer to questions 6 and 7 are detailed below question 7:


6.                 What are the responsibilities of a TF when third parties subcontract non-GLP hosting services with data acquisition systems used in GLP studies (e.g. data storage such as “e-archiving as a service”)?  What is considered acceptable?

7.                 If a data centre uses an IT service provider to only provide infrastructure for the data centre (e.g. space, power, controlled environmental conditions, etc.) or hosting servers of a contracted GLP test facility (i.e. access to the GLP data is only possible via the Test Facility), is this data centre considered to be part of the TF (and not a third party)?  Would such a data centre need to be part of the test facility audits?

Hosted services (e.g. platform, software, data storage, archiving, backup or processes as a service, cloud computing etc.) should be treated like any other supplied services (OECD Document No 17, paragraph 39). Written agreements are required which describe the roles and responsibilities of each party and proper documentation to ensure adequate risk control and risk mitigation. Uncontrolled use of hosted services may carry risks to integrity, availability, ownership, and confidentiality of data and may not be acceptable.

The need for, and extent of, vendor assessment should be based upon a risk assessment taking into account the complexity of the computerised system and the criticality of the business process supported by the computerised system. The need for an audit should also be based on a documented risk assessment. It is test facility management's responsibility to justify the requirement for and type of audits based on risk. (Posted on 28 February 2018)


8.                 Should an IT service provider that offers software as a service be considered a TF and therefore be included in a national GLP compliance monitoring programme?

Whether or not an IT service provider is considered to be part of a test facility by a GLP compliance monitoring authority will depend on various factors including the extent of the service provider’s involvement in GLP studies. If they are part of a test facility then the GLP compliance monitoring authority may also decide that they will be subjected to GLP inspections.

Depending on the services provided, audits by test facility management may be necessary for the contracted IT service. These may include the assessment of its computerised systems management, in general, and of the specific computerised systems, where such systems impact a study (e.g. risk assessment, validation approach and qualification). Suppliers are addressed in detail within OECD Document No 17, paragraphs 34 – 40. (Posted on 28 February 2018)


 Quality Assurance


(See also OECD Consensus Document No.4: Quality Assurance and GLP

1. Which roles can be amalgamated by or allocated to one person (for example study director and test facility manager, test facility manager and QA, archivist and study director) and which roles cannot?

2. What should appear on a quality assurance statement?

3.  Who should sign the QA statement?

4.  How should the frequency of QA audits be determined?

5. Is an audit of QA activities required?

6. When is it appropriate to look at the contents of a QA report?


o Quality Assurance Statements

1.                  Which roles can be amalgamated by or allocated to one person (for example study director and test facility manager, test facility manager and QA, archivist and study director) and which roles cannot?

For QA, the GLP Principles underline that QA should be independent of the conduct of the studies, which includes the study environment. This requirement means that QA personnel should be under the direct responsibility of the test facility management and cannot serve any other role than auditor. If QA assumes other responsibilities than the QA programme (like archives or management of the SOP), it should be audited by independent individuals.

QA cannot assume responsibilities that are directly involved in the studies (i.e. study director, study personnel and test facility manager). However, in small test facilities, it is acceptable for individuals involved in studies to perform the QA function for GLP studies conducted in other departments within the test facility.

The other scenarios of amalgamating functions should be considered on a case-by-case basis, taking into account the workload of each individual. The accumulation of multiple GLP roles is likely to be something which should be discussed with the relevant GLP Monitoring Authority, and individual situations would need to be assessed. (Posted on 15 June 2020)


2.                  What should appear on a quality assurance statement?

The quality assurance statement should clearly identify the study and include all the types of inspections that are relevant to the study (including inspections performed as part of a study phase(s)). Associated information should include the dates the inspections were performed and the dates inspection results were reported to management, the study director and if applicable the principal investigator. Some monitoring authorities will require the quality assurance statement to include confirmation that facility audits have been performed.

The statement should confirm that the final report reflects the raw data and some monitoring authorities will require this fact to be clearly stated in the statement.

Verification of the study plan by QA personnel should be documented (see OECD Principles on Good Laboratory Practice, No. 1). This would also apply to study plan amendments. The GLP Principles do not formally require that these verifications are included in the quality assurance statement but this is often the case (posted on 15 July 2014).


3.                  Who should sign the QA statement?

The OECD Principles on GLP (Section II, Par. 2.2.1.f) require QA personnel to sign the statement. The Principles do not restrict this responsibility to specific QA employees such as, for example, the manager of a QA department. However, the procedures for compiling the statement and the responsibility for signing the statement should be described in QA procedures (posted on 15 July 2014).


o Audit of the QA department

4.                 How should the frequency of QA audits be determined?

The OECD GLP Principles require that every study plan is verified by QA and every report audited. A definitive frequency for other audits is complicated as it will depend on many factors including: the different types and number of studies conducted, the complexity of a study, staff, etc.

When developing the QA Program, facilities may wish to apply any relevant quality assurance tools such as corrective and preventive action processes and risk based auditing. (Posted on 28 February 2018)


5.                  Is an audit of QA activities required?

As is the case for all operative procedures covered by the GLP Principles, the QA programme of inspections and audits should be subject to management verification. What constitutes verification will differ from one monitoring authority to another. In some cases verification will include a requirement for the independent inspection of QA activities. In all cases both QA staff and management should be able to justify the methods used for the conduct of the audit programme (posted on 15 July 2014).


o Access to QA reports

6.                 When is it appropriate to look at the contents of a QA report?

National GLP monitoring authorities may request information relating to the types of QA inspections conducted and the dates they were performed and reported to management. They may also request the names of the QA auditors who performed specific activities so that their training records can be reviewed. However, QA inspection findings will not normally be examined by inspectors as this is likely to have a negative impact on the way in which some QA personnel report findings. Nevertheless, some national monitoring authorities may occasionally require access to the contents of inspection reports in order to verify the adequate functioning of QA or to verify that management has received and acted upon reports from QA concerning problems that are likely to seriously affect the quality or integrity of the facility or a study.

Under no circumstances should QA reports be inspected as an easy way to identify inadequacies within the facility or problems associated with a specific study.

Compliance monitoring authority inspectors will need to verify the effectiveness of QA activities as part of the inspection of QA. In order to do this it is highly likely that they will routinely review QA procedures and other supporting records (with the exception of the inspection report). These documents will be used to verify key requirements including the independence of QA from study specific activities, that critical study phases are monitored in accordance with the facility’s policies and that the frequency of audits is sufficient etc. (posted on 15 July 2014).


 Equipment and computerized systems


o IT Issues

1.                  According to OECD Advisory Document 17, any function involved in the validation of a computerised system (e.g. system owner, process owner), needs to be part of the test facility organisation chart. Does this include personnel who are external to the test facility but still within the same company?

Personnel who are performing a role within the validation of a GLP relevant computerised system (and one which can have an impact on compliance of a test facility and studies) and who are not directly part of the GLP test facility (e.g. external contractors, IT department staff) are providers of services, even if they are within the same company. Such arrangements should be included in the organisation chart and/or described in a service agreement and/or in a test facility management delegation agreement depending on the provided services and the way the arrangement is implemented. (Posted on 15 June 2020)


2.                  How should hosted services (“cloud” computing) and the retention of electronic data be treated in the context of GLP.

Hosted services (cloud services, e.g. platform, software, data storage, archiving, backup or processes as a service) should be treated like any other supplier service and require written agreements describing the roles and responsibilities of each party. It is the responsibility of test facility management to evaluate the relevant service and to estimate risks to data integrity and data availability. Test facility management should be aware of potential risks resulting from the uncontrolled use of hosted services. (OECD Document No 17, paragraph 39). Written agreements (contracts) should exist between the test facility and the supplier. These agreements should include clear statements outlining the responsibilities of the supplier as well as clear statements about data ownership. (OECD Document No 17, paragraph 34) (Posted on 28 February 2018)


3.                 For some national GLP compliance monitoring programmes, it is acceptable to archive electronic data in a primary database with the use of appropriate access rights (i.e. read only permission for the study director / the study staff/QA and full rights for the archivist etc.). For other national programmes, data can be physically transferred to another location or to a storage medium (also with the corresponding access right modifications) for archiving. Are both acceptable?

Archived electronic data should be protected physically and logically in order to meet the requirements of a GLP archive. Electronic data should be accessible and readable, and its integrity maintained, during the archiving period (OECD Document No 17, paragraph 112).

Electronic records may be moved from the production part of a computerised system to a discrete, secure archive area on the same computer system (e.g. physically separated file record systems), or explicitly marked as archived (e.g. logically separated database record systems). Records should be locked such that they can no longer be altered or deleted without detection. Records archived in this way must be under the control of a designated archivist and be subject to equivalent controls to those applied to other record types (OECD GLP Document 15 Section 8.3). (Posted on 28 February 2018)


4.                 If a GLP inspector requests information retained in an archive, can a test facility respond by retrieving electronic records from a company’s global electronic archiving system (physically located in another country)? 

The response would be satisfactory as long as all required records can be retrieved from the archive. All electronic records should be verifiable on screen in human readable format and retained (OECD Document No 17, paragraph 79).

The GLP Principles for archiving must be applied consistently to electronic and non-electronic data. It is therefore important that electronic data is stored with the same levels of access control, indexing and expedient “retrieval” as non-electronic data (OECD Document No 17, paragraph 110).

Electronic data should be accessible and readable, and its integrity maintained, during the archiving period (OECD Document No 17, paragraph.112). (Posted on 28 February 2018)


5.                 Would such global archives need to be declared by each test facility to their national GLP compliance monitoring authority? 

The use of a global archive should be included in the appropriate SOPs.  Test Facility SOPs must define and describe the archive facilities and processes, including contracted archiving services or storage at a different physical location. Routine Quality Assurance inspections and audits should be conducted of the services provided.

In the event of the closure of a test facility or an archive contracting facility, any data transfer to an archive within another country should include informing both GLP monitoring authorities in order to ensure the coverage by the GLP compliance monitoring program if required by that country [OECD Guidance Document 15 Section 11]. (Posted on 28 February 2018)


o Validation of Software Programmes which Support OECD Test Guidelines

6.                 Do software programmes which have been developed by outside vendors or academia to support calculations by test facilities using an OECD Test Guideline, and are referenced in OECD Test Guidelines, need to be validated by test facilities?

It is important to note that use by test facilities of the software programmes for these Test Guidelines is voluntary. That is, a test facility is not required to use the programmes to complete a test.  However, if a test facility uses such a programme it must have the appropriately scaled validation documentation of risk assessment, user requirement specifications, acceptance testing records, and a listing in the computerised systems inventory.

Currently, software programmes have been developed for four OECD Test Guidelines:

While these software programmes were not developed by OECD, they are referenced in the Test Guidelines, and can be downloaded for free on the OECD public website. These software programmes are provided as a courtesy of the developers of the test methods, but have not been validated, reviewed or approved by OECD. The developer, and not the OECD, should be described as the supplier of the software. In addition, the maintenance of the software or of the calculation sheets is not guaranteed by OECD.

If a test facility does use one of these products, and if that facility wishes its test results to be compliant with OECD GLP, it must follow the guidance as described in Advisory Document 17 Application of GLP Principles to Computerised Systems.

These software programmes are considered “Commercial Off-The-Shelf products (COTS)”, as described in OECD Advisory Document 17. Therefore, they require appropriate validation depending on the risk and the complexity of any customisation. If an application (e.g. a spreadsheet) is not complex, it might be sufficient to verify functions against user requirement specifications. In addition, user requirement specifications should be written for any application that is based on a COTS product. Documentation supplied with a COTS product should be verified by test facility management to ensure it is able to fulfill user requirement specifications.

A test facility should perform a validation of a COTS software programme to ensure that it meets their needs, depending on prior validation by the provider. There must be documentation from the supplier that they have done the validation. Documentation must be available on the validation performed by the test facility.

Therefore, if a test facility uses one of the software programmes to support data intended for a regulatory submission or to support a regulatory decision, and a validation has not been conducted by the vendor or documentation to support that validation is not available, there would be an expectation that the test facility would perform a full validation to ensure that it meets their needs as described in Advisory Document 17.  Even if a validation has been conducted by the vendor, and documentation exists, it is still the test facilities' responsibility to determine whether that is sufficient and, thus, further validation is not necessary.  As mentioned above, the extent of the validation would likely depend upon prior validation (and documentation to support such a validation) as well as adaptation by the test facility (configuration) to meet their individual needs. And, if the user modifies the software programmes (customisation), there would be an expectation that the test facility would perform a full validation to ensure that it meets their individual needs.  Documentation must be available on the full validation performed by the test facility. (Posted on 27 March 2017)


 Test items, reference items and samples/specimens (including Biotechnology, GMOs, etc.)


1.                Does concentration, homogeneity and stability of test items in a vehicle need to be done for all test item that are prepared during a study? 

a)    General situation 

If a test item is prepared in a vehicle for a GLP study and data on homogeneity, concentration and stability are not determined, this constitutes a deviation to GLP and the study director should report it in the GLP compliance statement of the final report and assess the impact of this deviation on the validity of the study (see OECD Principles Section 6.2.5 of Document No 1 - The OECD Principles of GLP and Section 8.2 of Document No 19 - Advisory Document of the Working Group on Good Laboratory Practice on the Management, Characterisation and Use of Test Items). 

The following paragraphs describes how this can be interpreted for specific cases 

b)    Formulations used in field studies 

Although the study director may not have determined homogeneity, concentration, and stability of the test item in a vehicle for their study, they must still ensure that the test item is appropriate for use. This includes knowing that the processes to be used to prepare the test item for application are appropriate. The study director should also know of any restrictions relating to the application and use of the test item and these should be specified in the study plan. 

The required information including data on homogeneity, concentration, and stability and/or information on how to prepare the test item before application may be provided in different ways. If these data are to be determined in a GLP study, this will be detailed in a study plan, however, these data may also be determined through separate laboratory experiments. For some studies, the sponsor may provide it via a report, certificate of analysis or other documents. For crop studies sufficient information may be available on the label information or package insert as these products are already registered for use in other crops. Regardless, the source of the data should be clear in the final report. 

Homogeneity, concentration, and stability of tank mixes in used field crop studies does not need to be determined for every residue trial. For these trials, the test item is normally added to water and/or other dispersants in the field, immediately prior to application, to mimic the normal conditions of use. Collecting, transporting, and analysing samples of tank mixes is therefore often impractical. Actual values of preparation of the test item and its application, including volumes of each component added, as well as the time of mixing and the termination of the application, should be recorded in the raw data. Document No 6 - The Application of the GLP Principles to Field Studies provides further information. 

If the study director does not have sufficient information to know if the test item was prepared correctly or the source of this information is not known, then this constitutes a deviation from the Principles. This should be reported in the compliance statement in the final report and the impact on the validity of the study be assessed. 

c)    Determination of concentration, homogeneity and stability of test items in a vehicle and OECD guidelines for the testing of chemicals 

Some OECD test guidelines do not require the concentration, homogeneity and stability of test items in a vehicle to be determined. However, if the study is to be claimed as compliant with the Principles the general situation as describe in a) above applies. (Posted on 11 October 2022)


2.                   If a test item is provided by a sponsor as a “ready-to-use” formulation, should a sample from each batch be retained and archived (for long term studies)?

The GLP Principles state that a sample from each batch of a test item should be retained for analytical purposes, except for short-term studies. This also applies to test items that are provided as prepared and ready-to-use. (Posted on 15 June 2020)


3.                   How can an internal standard used in bioanalysis without the expiry date be managed?

The GLP Principles require the reference items or the reagents used in studies to be labelled with information including expiry date. If a reagent or a reference item is used out of expiry date or without any known expiry date (or any other stability indicator), this point constitutes a deviation of the GLP Principles. The final report should explain and justify why this deviation does not have an impact on the study data (i.e. by demonstrating the suitability for use of the reagent or reference items). (Posted on 15 June 2020)


4.                   Under what scenarios should the accountability of the use of formulated test or reference items be performed?

The goal of the traceability of the use of test or reference items is to ensure that the correct quantities have been used for the preparation of the doses administered or applied to the test system. The GLP Principles require accountability for test and reference items. If the test item is supplied as a prepared test item, accountability of this should also be maintained. For further preparations of the test item in the test facility, the traceability of consumptions of the preparations of test and reference items administrated or applied to the test systems would be a mechanism to monitor the exact amount of applied/administrated test and reference item to the test systems. (Posted on 15 June 2020)


5.                   How should samples/specimens collected during a GLP study for exploratory research outside of the GLP study be handled and reported?

Some sponsors may request a test facility to collect samples of the preparations of the test item or of specimens for exploratory research purposes. Such tasks may be scheduled in the study plan to inform the study personnel of such specific handling. In such a case, the final report should be transparent about the aspects of the exploratory research (e.g. where samples or specimens have been transferred from the GLP study). The study director is expected to explain in the final report that such sampling and handling was out of the scope of the GLP study. She/he should also confirm that it did not interfere with the conduct of the study or jeopardise the GLP compliance of the study.

If the decision to use study specimens for exploratory research is taken after the study has been completed and, as a result, the GLP compliance of the study could be jeopardised, the study director should issue an amendment to the final report. (Posted on 15 June 2020)


6.                   Can the residual samples from bioanalysis be retained for a limited period, outside the archive, after the report is finalised and then be destroyed provided this is clearly stated in the study plan and report?

Residual samples from bioanalysis are specimens from a GLP study and therefore should be retained as study materials as long as their quality permits evaluation (e.g. at least until the end of their validated stability period). They should be stored in the conditions that ensure their stability. The study plan should include the list of records to be retained and the final report should mention the location of the archived items.

All study materials such as raw data, records and documents must be archived. However, the decision of what study material should be deposited in the archives to fully reconstruct the study remains the responsibility of the study director (Subsection 1.2.2.i of the GLP Principles). If specimens are discarded before the end of their stability period, the justification for this should be included in the study plan and in the final study report, except if national regulations provide for the disposal of labile specimens.

If the study is completed when the decision is taken to dispose study specimens, the study director should issue an amendment to the final report to describe it. (Posted on 15 June 2020)


7.                  Which Test Facility “area of expertise” should be used for Biologicals/GMOs?

GLP studies on biologicals/GMO test items that are currently performed in accordance with the OECD Principles of GLP can be assigned to one of the existing nine areas of expertise, as defined in the OECD Guidance Document No. 2: Guidance for GLP monitoring authorities - Revised Guides for compliance monitoring procedures for GLP, Appendix to Annex III, No. 4.

These areas of expertise are of a general nature and can be used for many product types (e.g. industrial chemicals, pharmaceuticals, plant protection pesticides etc.). In general, a product type will not have a specified area of expertise.

The existing areas of expertise are therefore sufficient to also describe studies conducted using biologicals/GMOs which may be either in vivo, in vitro or concern environmental toxicity, behaviour in the environment or bioaccumulation. There may also be GLP studies on safety testing of biologicals/GMOs (e.g. of gene therapy medical products).

The area of expertise No. 9  - “Other, specify“  is being increasingly used to specify study types in connection with molecular biology, genetic engineering or GMOs (e.g. cell-based systems for the detection of biological parameters, bioactivity testing, immunogenicity testing, patch clamp test, cell culture based biocompatibility test, test for microbial contamination, DNA sequencing for genotyping, etc.).

Biologicals/GMOs are a new test item type, albeit different to conventional chemicals, however GLP studies on biologicals/GMOs are neither a specific type of GLP study nor a specific area of expertise. They are no different to other “new” products such as nanomaterials or medical devices. It is therefore reasonable to regard biologicals/GMOs as just another product type. (Posted on 28 February 2018)


8.                 Should new OECD Test Guidelines be developed for Biologicals/GMOs?

In every area of expertise listed in the OECD Guidance Document No. 2: Guidance for GLP monitoring authorities - Revised Guides for compliance monitoring procedures for GLP, Appendix to Annex III, No. 4 - there may be many kinds of studies that can be performed.  For example, the area of expertise No. 2 - “Toxicity Studies” - includes studies conducted using the OECD Test Guidelines No. 401- 453, listed in Section 4 “Health Effects“.

The development of new OECD Test Guidelines for specific tests involving biologicals/GMO may help to reduce the use of area of expertise No. 9 - “Other, specify“.  However, the OECD Working Group of the National Coordinators of the Test Guidelines Programme (WNT) is responsible for the development of Test Guidelines, not the OECD Working Group on GLP.

Biologicals/GMO can be listed in the table indicating the scope of a national GLP compliance monitoring programme and it is not necessary to create additional areas of expertise for one product type.

The OECD Advisory Document No. 14: The Application of the Principles of GLP to in vitro Studies is very comprehensive and applicable to biologicals/GMO. The revised OECD Advisory Document on the Characterisation of Test Items – currently under development - will also address some specific aspects of biological test items. (Posted on 28 February 2018)


9.                 Are Biologicals/GMOs test items or test systems?

Biologicals/GMOs can serve both as a test item and as a test system, depending on the circumstances, and this distinction can only be made on a case-by-case basis. For example, there are studies in which a GMO is used as a test system for characterising properties of a chemical  test item, e.g. an Ames test under area of expertise No. 3  - “Mutagenicity testing“.

There are also other studies in which biologicals/GMO, or parts thereof, are used as test items such as when environmental or health effects of a biological/GMO are being investigated. Some other examples include wild-type biological agents in virus validation studies, environmental fate studies of a GMO product and feeding studies. Another example of a biological/GMO being used as a test item would be in a study to determine the concentration of a known gene product of a transgenic sequence. 

The identification of the test item is one of the pivotal aspects of GLP studies. Due to the biological nature of such test items (e.g. stem cells or viral vectors) the unequivocal identification may require a more complex analysis than for a chemical substance. Nevertheless, the characterisation of a biological test item would not qualify for a new area of expertise.

It should also be noted that it is not within the remit of the OECD Working Group on GLP to give guidance on the expectations of regulators with regard to biologicals/GMOs. The national/local receiving authority should be contacted regarding this. It is however acknowledged that some countries have established rules on the content of dossiers for the authorisation of novel foods or GMO (e.g. Regulation (EU) Nr. 503/2013 of the European Commission). (Posted on 28 February 2018)




1.                  Must the review of SOPs be performed by QA personnel or can it be performed by personnel with other functions? Is there a limitation on the number of signatures that can be included in an SOP?

The GLP Principles require the SOPs to be approved by test facility management. Part of this responsibility can be delegated to an individual other than QA (with the exception in some countries for QA Programme SOPs). Such delegations should be documented.

Apart from that requirement, the provisions taken by the test facility to issue SOPs should be described in a SOP that should be implemented and followed. It should be noted that the verification or review of the SOPs by QA is not a GLP requirement, but desirable according to OECD GLP consensus document No 4 in order to assess their clarity and compliance with GLP Principles. (Posted on 15 June 2020)


 Management of the study


o Data Integrity

1.                  In the last few years, guidance on data integrity has been developed in the fields of Good Manufacturing Practice (GMP) and Good Clinical Practice (GCP). Could similar guidance on data integrity in GLP be developed? 

The OECD Working Group on GLP is currently developing a document regarding data integrity in the context of GLP. Once ready, a draft will be posted on the OECD GLP website for public comment. (Posted on 15 June 2020)


o Multi-site

2.                  Why are there still inconsistencies in the way different national GLP compliance monitoring programmes inspect multi-site studies?

Where inconsistencies continue to arise, these may be the result of a country’s specific regulatory requirements and should be discussed with the Compliance Monitoring Authority (CMA) concerned. (Posted on 28 February 2018)


o Study Reporting

3.                   Under what circumstances can a GLP study be reopened after the final report has been finalised?

The OECD Principles of Good Laboratory Practice (GLP) provide provisions for errors in the final report to be corrected and admissions to be addressed by issuing a study report amendment. However, it would not be appropriate to use a study report amendment to facilitate the reanalysis of data or add new data to a final report except under exceptional circumstances.

Exceptional circumstances will include requests from receiving authorities to reopen a GLP study. Such requests are usually made so that data can be reanalysed. For example, studies may be reopened to reassess statistical analyses or to review histology findings.

Monitoring authorities will usually not allow a study to be reopened if the test facility or study sponsor wants to reanalyse or add data. However, most monitoring authorities will assess each request to reopen a study on a case-by-case basis.

If a GLP study is reopened, any changes to the original text or the addition of new text must be presented in the form of a report amendment. All the original data must be retained in the final report and the reason for reopening the study should be documented in the amendment. If additional work is performed that was not required in the original study plan, it should be covered by a study plan amendment.

As detailed in Section 9, Part 9.1 (5) of The OECD Principles of GLP, reformatting of the final report to comply with the submission requirements of a national registration or regulatory authority does not constitute a correction, addition or amendment to the final report (posted on 21 January 2016).


4.                    Following the early termination of a GLP study is there a requirement to produce a final report?

The early termination of a study may occur prior to, or after, the completion of the experimental phase of the study, but before the data has been assessed or incorporated in a final report. In both situations, a study plan amendment must be produced in order to provide an explanation of why the study was terminated. Some compliance monitoring authorities may expect that the key findings up to the point of termination are summarised and that the summary report is subject to a Quality Assurance (QA) audit (posted on 21 January 2016).


o Method Validation 

5.                   Should method validation be completed prior to the initiation of a GLP study? 

There is no requirement to finalise the validation of all methods that will be used to conduct a GLP study before the initiation of the study. However, there is an expectation that methods are fully validated before the results of the study are considered to be valid. (posted on 21 January 2016)


6.                    What standard should be applied to the validation of methods which are used in GLP studies and how should it be applied?

Unless stipulated in national regulations, there is no requirement to perform method validation in compliance with GLP. Since parameters of the validated method are used in the GLP study (for example threshold, linearity, accuracy, precision, stabilities, equipment settings, etc.), data should be accurately recorded and stored in a manner that protects its integrity. Validation data may be required for study reconstruction and, consequently, it should be retained for an appropriate period of time. (posted on 21 January 2016)



o Digital Histopathology

Technical improvements allow histopathology slides to be digitised as an electronic replica or whole slide images (WSI). The life cycle of WSI consists of digitisation of the histology slide by a slide scanner and transfer or migration of the image to a viewer, which could also be remote from the location of the digitisation and storage.


1.                 Is there any objection from the GLP compliance monitoring authorities to implement digital pathology in GLP studies?

The OECD Principles of GLP do not preclude the use of digitised histopathology slides in GLP studies for the histopathological assessment of tissue samples. This would include the initial read of tissue slides by the study pathologist and histopathology peer reviews, either prospectively or retrospectively.

Nevertheless, the following points associated with the use of whole slide images in GLP studies should be considered:

-        the digitized slides should be a faithful replica of the original histology slides, so that the reading of the whole slide image should be equivalent to that of the histology slide;

-        the digitisation process should ensure traceability from the tissue sample to the digitised slides;

-        integrity of the digitised slides should be ensured during the different steps of the process;

-        equipment used for digitisation and viewing of the whole slide image/digitised slide should be fit for purpose and adequately maintained;

-        computerised systems implemented to manage equipment and store, transfer or migrate the digitised slides should be validated;

-        when the digitised slides are transmitted to a remote location from where they were generated, (e.g., for review by an external pathologist), the validation of the system for transfer should include both the sender and the receiver;

-        study personnel and pathologists involved in this process and QA personnel should be trained;

-        SOPs describing the whole process, including quality control steps if relevant, should be implemented; and

-        the use of digitised slides for histopathology assessment and the computerised systems involved should be detailed in the study plan and the final study report.

 (Posted on 15 June 2020)


2.                  Should digitised slides be retained in the archives if used in GLP studies?

Some preliminary considerations are:

-        all study materials essential to reconstruct the study should be retained in the archives;

-        study specimens and the histology slides should be archived;

-        the dated and signed histopathology raw data (or the dated and signed pathology report) are/is the final contribution of the study pathologist;

-        when a prospective or contemporaneous histopathology peer-review is conducted, the final contribution is the result of an agreement between the study pathologist and the peer-reviewer(s) under the final responsibility of the study pathologist; and

-        when a retrospective peer-review is conducted, comments by the peer-reviewer(s) result in an amendment of the study pathology contribution or report.

If the study pathologist uses digitised slides for the initial read or if the peer-reviewer uses them for the retrospective peer-review, they should be retained in the archive for as long as the other study materials as they were used to generate raw data.

Digitised slides should be archived in an electronic format that ensures their integrity over time and allows their review if required for regulatory purpose. (Posted on 15 June 2020)


o Peer Review of Histopathology

3.                  Section 2.5 of OECD Advisory Document Number 16 (Guidance on the GLP Requirements for Peer Review of Histopathology) indicates that all correspondence regarding the histopathological evaluation of the slides used for peer review between the sponsor and the representative of the test facility and the peer reviewing pathologist should be retained in the study file. Could the interpretation of this requirement be clarified?

The clarification is as follows: Correspondence refers to any communication that is needed to reconstruct how slides were selected and reviewed. This should include communications regarding the interpretation of any observations (preliminary or final) on adverse or non-adverse effects made during the review. 

(Posted on 27 March 2017)


4.                  Section 2.8 of OECD Advisory Document No. 16: Guidance on the GLP Requirements for Peer Review of Histopathology indicates that where the peer reviewing pathologist’s findings were significantly different from the original interpretation of the study pathologist, a description of how differences of interpretation were handled and changes made to the study pathologist’s original interpretation should be discussed in the final report. Does this apply to both retrospective and contemporaneous peer review?

The clarification is as follows: Section 2.8 relates specifically to a retrospective peer review. For a contemporaneous peer review, there is an expectation that all correspondence (letters, e-mail etc.) relating to differences in the interpretation (preliminary or final) of slides between the original pathologist and the peer reviewing pathologist which may impact on the conclusions of the study (e.g. NOEL/NOAEL) are to be retained in the study file.

(Posted on 27 March 2017)

 Archives Including E-Archives


1.                 Can a system administrator conduct electronic archiving of GLP data?

Electronic archiving is under the responsibility of the archivist. It could be delegated by test facility management to a suitable person (e.g. a system administrator), within the test facility, usually because she/he has the specific technical competence. This person works under the supervision of the designated archivist and the respective tasks, duties and responsibilities have to be specified and detailed in SOPs. Test facility management should ensure that potential conflicts of interest are avoided for any person within the test facility.

Test facilities are expected to perform a thorough risk assessment – including taking into account that there are no limitations on the system administrator’s privileges with respect to the use of a computer system - and to apply suitable risk control procedures. (Posted on 15 June 2020)


2.                  How is GLP applied to traceability and archiving of communications between study director, sponsor, principal investigators and pathologists in the context of new information technology tools (such as client portals, encrypted documents, electronic messaging, social networks tools)?

It does not matter how GLP compliance is met as long as it is met. Generally speaking, the GLP Principles are neutral towards communication technology. GLP relevant lines of communication should be described clearly regardless of how the communication is carried out.

If GLP relevant communication is encrypted or is integrated in a personal messaging system, the test facility should describe how the communication is appropriately archived.  This would need to include a description of the way in which the completeness of the information could be ensured and its integrity remains intact.

If information necessary for the reconstruction of studies is shared through media that could not be archived as such, test facility management should implement a processes for the faithful transcription in a retainable format.

Archiving cannot be carried out if it is not possible to: (1) archive the information in a readable format; (2) transfer information from the messaging system to the GLP documentation system in a secure manner; or (3) implement a process for a faithful transcription in a retainable format. (Posted on 15 June 2020)


3.                  Is it possible to harmonise retention times for archived records?

Retention period harmonisation across countries is not anticipated given that the periods “defined by an applicable regulatory authority” are based on: country-specific legal requirements of the registration receiving organisation, the nature of the specific GLP program (human health, animal health, agricultural chemicals, GMO etc.) and approaches aimed at minimising burdens on the regulated industry.

Study records must be retained in compliance with the requirements of receiving authorities.  Study records and other supporting material should be retained for as long as regulatory authorities might request GLP audits of the respective studies. (Posted on 28 February 2018)


4.                 What are the responsibilities of TF management with respect to support records?

See sections 4.2 and 7.2.2 within OECD GLP Advisory Document No. 15: Establishment and Control of Archives that Operate in Compliance with the Principles of GLP (2007).

GLP records and materials include both the study and the facility records.  Facility records (support records, or related records and materials) would include non-study specific records such as equipment maintenance, staff training, organisational charts, SOPs, Master Schedules, Quality Assurance inspections, validation for computerised systems, environmental monitoring, and archiving processes (record transfers, specimens or electronic media disposals). (Posted on 28 February 2018)  

 Monitoring Test Facility compliance by GLP CMAs


1.                 How can the GLP compliance status of a test facility or test site be checked?

Many CMAs have publicly available information with details of facilities that are in their GLP programs.  (Contact points for national CMAs can be found here.)  Some CMA’s also issue GLP certificates; however, this is not a requirement of the Principles. (Posted on 28 February 2018)


2.                 What is a physical/chemical test system?

The OECD GLP Principals define a physical/chemical test system as an “apparatus used for the generation of physical/chemical data”.  It is the equipment or apparatus to which the test item or reference item is applied during the conduct of a study. Due to the number of different types of studies that are conducted, a complete list is not possible. However, some examples of physical/chemical test systems which may be used to evaluate the physical/chemical properties of a test item may include basic equipment such as pH meters, spectrophotometers and other analytical equipment and/or highly sophisticated and complex equipment such as gas chromatography–mass spectrometry, or those which utilise amplification and analysis of genetic material. (Posted on 28 February 2018)


3.                 Is there a standard format and content for the Study Director’s statement?

The OECD GLP Principles only require that the statement clearly describes what aspects of the study have been conducted in accordance with the Principles (or not) and, where applicable, what other standards/ guidelines were used (if the Principles were not). It should be noted that some CMAs may also have their own requirements due to national requirements. (Posted on 28 February 2018)


4.                 Can GLP studies be done in facilities that utilise other quality standards (GMP, GCP, ISO etc.)?

The implementation of other standards within a facility (cGMP, GCP etc.) should not preclude the use of the OECD GLP Principles within that facility. Most quality standards contain requirements which are compatible with the OECD Principles. Test facility management must ensure, however, that for any GLP studies that are conducted, the OECD GLP Principles are fully adhered to. Sponsors who commission the study with the CRO should also be aware of their role in ensuring that the facility complies with the Principles for GLP. (Posted on 28 February 2018)






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