In situ generation: Active substances vs biocidal products

In situ generation

In situ generation is all about biocides that are generated at the point of use. More specifically, in situ generation is the reaction of one or more precursors to generate an active substance at the place of use and for direct application without isolation, purification, storage or transport.

Not in situ generation

In situ generation does not include biocides that are generated by the reaction of one or more precursors but then bottled before they are placed on the market or used.

In situ generation also does not include active substance releasers (substances that release an active substance when they are used). Active substance releasers rely on a reaction that takes place because of certain conditions which often cannot be controlled, such as environmental factors. An example of an active substance releaser is aluminium phosphide which relies on moisture in the air/soil to release the active substance phosphine.

Types of in situ biocidal products

In situ biocidal products may:

In situ biocidal products generating one or more active substances (type 1)

Examples of in situ biocidal products that generate one or more active substances include:

In situ biocidal products that are generated from substances or mixtures that do not meet the definition of a biocidal product themselves (type 2)

The precursors (substances or mixtures) that are used to generate the active substance(s) are not supplied with the intention that they are used to generate a biocide. The active substances generated are therefore considered to be biocidal products.

Examples of in situ biocidal products that are generated from substances or mixtures that do not meet the definition of a biocidal product themselves include:

Precursors that are not supplied for biocidal purposes might include:

Identify the functions: active substance, biocidal product and precursor

The first part of any in situ generation is the precursor(s). A precursor might be a substance or a mixture and, depending on whether it is supplied for biocidal purposes, might also be the biocidal product.

The purpose of any in situ generation is to generate an active substance. Whether you are mixing precursors or using a device, the biocide that is generated will always be the active substance. Depending on whether the precursors are supplied for biocidal purposes, the active substance might also be the biocidal product.

Symbol for biocidal product - precursor supplied for biocidal purposes

Biocidal product - precursor supplied for biocidal purposes

Symbol for general chemical - precursor not supplied for biocidal purposes

General chemical - precursor not supplied for biocidal purposes

Symbol for active substance - generated from precursor(s) supplied for biocidal purposes

Active substance - generated from precursor(s) supplied for biocidal purposes

Symbol for active substance and biocidal product - generated from precursor(s) not supplied for biocidal purposes

Active substance and biocidal product - generated from precursor(s) not supplied for biocidal purposes

Symbol for unmarketable precursor - precursor is not supplied at all but is extracted from the surrounding environment at the time of generation

Unmarketable precursor - precursor is not supplied at all but is extracted from the surrounding environment at the time of generation

In situ generation type 1

Two or more precursors that are mixed together

P1 (symbol for biocidal product) mixed with P2 (symbol for biocidal product) generates AS (symbol for active substance)

P1 (symbol for general chemical) mixed with P2 (symbol for biocidal product) generates AS (symbol for active substance)

One or more precursors that are used in a device

P1 (symbol for biocidal product) added to a device to generate AS (symbol for active substance)

A coating that generates free radicals when exposed to light

*The biocidal product is a coating containing the catalyst.

In situ generation type 2

Two or more precursors that are mixed together

p1 plus p2 mixing goes to AS

Precursors that are used in a device

Air (symbol for unmarketable precursor) used by a device to generate AS (symbol for active substance and biocidal product)

P1 (symbol for general chemical) added to a device to generate AS (symbol for active substance and biocidal product)

Devices

Sometimes in situ generation involves the use of specialist equipment or technology. Devices (or machines) may allow users to set different parameters, such as pressure or temperature, that might affect the chemical reactions and the exact composition of the active substance generated in situ. Dosing systems that are only used to control the ratio of precursors for mixing, are not considered to be in situ devices or machines.

Devices do not meet the definition of a biocidal product (as they are not a substance or mixture) and are therefore not authorised as biocidal products under the GB Biocidal Products Regulation (GB BPR). However, a device may be considered as part of any in situ product authorisation process and the conditions of the authorisation may specify the use of a specific device and/or the parameters it should be set with.

Product authorisation

Like all product authorisations under GB BPR, in situ product authorisations may be granted for single products or families. In situ product authorisation should consider the in situ generation system as a whole - if the in situ generation system would generate different concentrations of the active substance, then this could be authorised as a product family. The different elements that make up an in situ generation system include:

Depending on the type of in situ generation, it is therefore possible for any of the companies involved at the various stages to be the authorisation holder, eg:

In any case, the duty to ensure that the in situ generation system has a valid product authorisation falls to:

This page will be updated with more details about the information needed for an in situ product authorisation - sign up to our e-bulletin for free email updates.

GB Article 95

GB Article 95 applies where there is any supply of a biocidal product with the intention of generating the active substance in-situ, such as to precursors that are supplied with the intention that they are used to generate a biocide (biocidal products) or the supply of a coating containing a catalyst such as titanium dioxide intended to generate free radicals in the presence of light.

The exception to this is where the GB Article 95 entry does not specify a precursor, but rather a general chemical action, such as acidification or oxidation. A biocidal product supplied in such cases is considered an unspecified precursor and is not subject to GB Article 95.

GB Article 95 also does not apply to:

In the example of “chlorine dioxide generated from sodium chlorite by acidification”, GB Article 95:

Action for suppliers of precursors or other biocidal products, eg catalyst coatings

Before you supply any biocidal products for the purposes of in situ generation in Great Britain, either as precursor chemicals or other products (eg a coating containing a catalyst), you should check the requirements you need to comply with below. Use the GB List of Active Substances to check your active substance.

You are supplying a biocidal product as a precursor

You may supply the biocidal product in Great Britain if:

You must:

You may not supply the biocidal product in Great Britain if:

You are supplying a biocidal product other than a precursor, eg catalyst coating

You may supply the biocidal product in Great Britain if:

You must:

You may not supply the biocidal product in Great Britain if:

Action for suppliers of in situ generation machines/devices

In situ generation via a device (or machine) can typically be defined as type 2 use, however in some circumstances it could be type 1 generation (eg if you supply precursors intended for use in the device it would be type 1) - if you do supply precursors for use with the device you are supplying a biocidal product and need to comply with the duties in the 'You are supplying a biocidal product as a precursor' section above, including the need to get the product authorised when necessary.

For type 2 use, as in situ generation machines/devices do not meet the definition of a biocidal product, you may supply your device in Great Britain regardless of the status of the active substance under GB BPR. However, you should be aware that your device may only be used to generate an in situ biocidal product in Great Britain if certain requirements are met - check the actions for users below. Where these requirements are not met, anyone using your device to generate an in situ biocidal product in Great Britain may be committing an offence.

Once the active substance that is generated by your device is approved, use of the biocide generated from the device must be authorised under GB BPR if users of the device want to generate/continue to generate and use the biocide.

As the manufacturer or supplier of the device, you may wish to get the Product authorisation on behalf of all your customers - you should consider the likelihood that your customers may move to a competitor (that does have product authorisation) if you do not. If you do wish to get product authorisation, you should contact your customers to get details of how they use/intend to use the device, and what they use/intend to use it for, so you can make sure their specific use is covered in your application.

You could:

Remember, if you are not willing or able to get the authorisation on behalf of your customers, anyone using your device to generate an in situ biocidal product in GB may be committing an offence and enforcement action may be taken against them - you should therefore keep your customers updated on the actions you intend to take regarding product authorisation.

Action for generators/users of in situ biocidal products

Before you generate and use an in situ biocidal product in Great Britain, you should check the requirements you need to comply with below. Use the GB List of Active Substances to check your active substance.

Type 1 generation - you are being supplied with a precursor or other biocidal product, eg catalyst coating

You may generate and use the in situ biocidal product in Great Britain if:

Once the active substance is 'approved' under GB BPR for the relevant product type, you will need to ensure your use has a valid product authorisation to continue generating and using the in situ biocidal product in Great Britain. Talk to your supplier to ensure they are getting product authorisation to cover your use.

You may not generate and use the in situ biocidal product in Great Britain if:

Type 2 generation - you are using only general chemicals or unmarketable precursors, ie you are not being supplied with a biocidal product

You may generate and use the in situ biocidal product in Great Britain if:

Once the active substance is 'approved' under GB BPR for the relevant product type, you will need to ensure your use has valid product authorisation to continue generating and using the in situ biocidal product in Great Britain. Find out more about the action you may need to take below.

You may not generate and use the in situ biocidal product in Great Britain if:

What to do once the active substance is 'approved'

Users of precursors and other biocidal products (type 1 generation)

Where a biocidal product is being supplied and used, the supplier of the biocidal product will need to apply for product authorisation. You should contact your supplier to confirm if they will be getting the necessary product authorisation. If they are going to do this, you should give them details of how you use the product, and what you use/intend to use it for, so they can make sure your specific use is covered in their application.

Where your supplier is not willing or able to get the authorisation, if they supply/continue to supply the biocide and you use/continue to use the biocide without the necessary authorisation, both you and your supplier could be committing an offence and enforcement action may be taken.

Users of in situ generation machines/devices (typically type 2 generation, but may also include type 1)

Where a device is being used, the manufacturer of the device may choose to get the product authorisation on behalf of all their customers. You should contact the manufacturer of the device to confirm if they will be getting the necessary product authorisation. If they are going to do this, you should give them details of how you use/intend to use the device, and what you use/intend to use it for, so they can make sure your specific use is covered in their application.

Where the device manufacturer is not willing or able to get the authorisation, you as the generator/user of the in situ biocidal product will have to make sure your use is authorised if you want to use/continue to use the biocide. You could:

Users of general chemicals (type 2 generation)

Where you are using only general chemicals to generate the in situ biocidal product (ie you are not being supplied with a biocidal product), you as the generator/user will have to make sure your use is authorised if you want to use/continue to use the biocide. You could:

Whichever type of user you are, we advise you to start your planning as soon as possible, and not to assume 'somebody else' will be taking action on your behalf. Remember that once the active substance is approved for the relevant product type and product authorisation is required, if you use/continue to use the biocide without the necessary authorisation you could be committing an offence and enforcement action may be taken.

Still not sure?

If you're still not sure whether you are generating or supplying a biocidal product, or what requirements you need to comply with, you can contact us for advice.

In your email, please provide us with as much detail as you can, including:

Updated 2022-03-30