December 14, 2021

Insight 7: Substantiating biocidal product efficacy

Samantha Walker, Senior Biocides Consultant at TSG Consulting looks at how to identify and rectify efficacy data gaps that could hinder authorisation and renewal of authorisation for biocidal products in the European Union, Norway, Switzerland and Great Britain.

When biocidal products sold in the EU, Norway, Switzerland and GB enter first authorisation or renewal, they often face different efficacy standards to when they were previously registered under transitional rules or authorised under the Biocidal Products Directive No 98/8. This can lead to data gaps that may slow down or even prevent authorisation under the Biocidal Products Regulation No 528/2012 if they’re not resolved.

The importance of data gap analysis

It’s sometimes necessary to conduct new efficacy studies to satisfy current requirements of the EU Biocidal Products Regulation (BPR) and its GB equivalent. Data gap analysis is an essential step before any studies are commissioned to come up with the best/smartest efficacy testing strategy to support the product’s claims.

Timing is also a critical factor. For instance, some study types, such as field tests for insecticides and repellents, are influenced by seasonal variations. And, at present, laboratory testing for disinfectant products is delayed by a backlog following increased demand driven by COVID-19.

Efficacy data gap analysis reduces risk and enhances cost control by ensuring the right studies are conducted in the right way to generate relevant data in a timely manner. It should be the top priority for companies preparing for authorisation once the product’s core dataset has been established. (Read about how to build a core dataset for a biocidal product here).

Start with performance claims

Claims made in product specifications, on labels and packaging are the starting point for efficacy data requirements. To enable the assessment and evaluation process of the competent authority body, all claims should be properly supported by data, or a robust and scientifically reasoned case.

Efficacy Guidance on the BPR published by the European Chemicals Agency (ECHA) in 2018 states:

Efficacy data are a fundamental component in the regulatory management and decision making process for biocidal products. Efficacy data are required to establish the benefit arising from the use of biocidal products and must be balanced against the risks their use poses to man and the environment. Authorisation of a biocidal product will only be granted…if that product is shown to be sufficiently effective.

At the minimum, companies must prove that any proposed outcomes can be achieved in the intended applications. The nature of the product’s claimed effect on target organisms is significant here, ranging from ‘control’ or ‘repel’ to ‘prevent’ or ‘kill’.

Depending on the claims made, there may be additional, more complex factors to evidence as well. These might include speed of effectiveness or residual protection. It may also be necessary to demonstrate efficacy levels related to the type of surface onto which the product is applied e.g. porous and non-porous surfaces.

Interrogate historic studies

We often find that companies’ historic efficacy studies no longer meet current regulatory guidelines. Criteria related to the safe and sustainable use of biocidal products have become far more stringent in the EU and GB over the past decade leading to reduction in application rates or active substance concentration in the biocidal products. Other changes may have been introduced as well, for instance broad general claims for groups of insects such as mosquitoes may require more species to be included in the tests and consideration will be needed for claims for use in tropical regions.

Serious problems can arise if earlier studies which fall short of requirements are used as the basis for risk assessments in the authorisation dossier. It’s vital that the data stands up to scrutiny during assessment.

One important consideration is determining the quantity or concentration of product needed to deliver the intended efficacy. This is a key area where requirements are likely to have changed since earlier authorisations. So, while historic instructions for an insecticide powder might say to ‘shake liberally in areas with crawling insects’ it is now necessary to specify exactly how much powder is needed, where it should be applied and which insects the product is effective against. This in turn leads to mode of application and the ability of users to dispense a precise amount in a controlled manner.

A fine balance is required here. According to the ECHA’s Guidance on the BPR, while there is a requirement to limit use to the ‘minimum necessary’ it is also ‘crucial that the biocide in question delivers the expected effect’.

Develop an efficacy testing strategy

Once efficacy data gaps have been established, a testing strategy can be devised to address them in the most efficient and cost-effective way. The core product property – preservation, disinfection, pest control etc. – needs to be substantiated in a way that corroborates product claims and satisfies the depth and breadth of BPR requirements. Study types specified for BPR product authorisation can include laboratory studies, simulation tests and field tests, carried out in accordance with existing standards or protocols. However, for some uses such as products used for preservation of liquid-cooling system or control of slime growth on materials, the guidance and testing methods are vague or even still non-existent. Using specialists with specific experience for product authorisations before commissioning studies could therefore be extremely valuable for non-guideline test methods. In theory, such testing approaches should be discussed with the competent authority evaluating the application for authorisation before starting the test but in practice this not always possible due to timings as testing may need to start before an authority is even selected.

According to EU timescales, when the Biocidal Product Committee has given a positive opinion for the approval of an active substance for a specific Product Type, there is a two-year window before the substance is approved, the date at which an application for authorisation for products containing the substance/Product Type combination and already on the market must be submitted. For product authorisation renewal, renewal application must be submitted 550 days before the authorisation expiry date. However, there is nothing to prevent a company initiating data gap analysis beforehand. In fact, we’d strongly advise this in circumstances like those mentioned above where seasonal factors or laboratory capacity could impact timings. What’s more, efficacy has a bearing on wider aspects of biocidal product authorisation, such as human health and environmental factors. The uses, target organisms, application rate, and treatable areas used to conduct risk assessments will be derived from the results of the efficacy tests. As such, it is prudent to begin focused efficacy testing at the earliest opportunity.

This is part of a series on authorisation for biocidal products in the EU and GB. We’ve previously looked at How to get a head-start on biocidal product authorisation. Next month, we’ll focus on environmental considerations and human health risk assessments.

A robust efficacy testing strategy is the cornerstone of biocidal product authorisation. TSG’s regulatory specialists and scientists have the experience and insights to help companies make well-informed and effective decisions that help the process run smoothly from start to finish. Contact us at to find out more.

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