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31 October 2022

CRRU update for 2022 – how is rodenticide stewardship going?

TECHNICAL | PPC109 October 2022

Dr Alan Buckle is Chairman of the Campaign for Responsible Rodenticide Use (CRRU) UK. He gives an overview to PPC on where the stewardship scheme is at and where it’s going. 

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Jump to figures.

It is difficult to say when the CRRU-run stewardship regime began, because introduction of its measures occurred in stages. The most logical start point is October 2016, when the first professional rodenticides went onto the market carrying labels requiring proof of competence for purchase and compliance with the CRRU Code of Best Practice when used (see

The regime has been running for six years now, so it’s time to assess what has been achieved and what hasn’t. 

Indeed, as I write, re-assessment of the regime is ongoing after a review meeting in May 2021 between the Health and Safety Executive (HSE), the Government Oversight Group (GOG) and CRRU. 

The parties remain in discussion to determine what changes to the regime are required to enable it to meet its environmental targets

The GOG comprises representatives of the HSE, which holds the Chair, and others from Defra, UK Health Security Agency, Natural England and representatives of devolved administrations in Northern Ireland, Wales and Scotland.

These targets were set at the beginning of the regime by HSE/GOG.

The main one, quoted here from government documents is that: “There should be a significant decrease in the exposure of the sentinel species – barn owl – in terms of sum residues of SGARs (second-generation anticoagulant rodenticides) detected in livers of barn owl carcasses collected over the first four years”. (See

The barn owl was chosen as stewardship’s sentinel species because of the long run of historical data we had on this species before stewardship – allowing before/after comparison.

One of many monitoring requirements, set upon CRRU by HSE/GOG, was that the regime pays for analysis of 100 barn owl samples taken from birds found dead in the UK; these are mostly road casualties and not killed by rodenticides. 

The work is done by the independent UK Centre for Ecology and Hydrology (see

Information gathered is analysed statistically in several different ways against the HSE/GOG targets. But the result is that there has been no significant decrease in exposure of owls, and therefore in residues they carry, over a six-year period of stewardship monitoring. 

Although not one of the formal monitoring metrics, this is most easily seen in the percentage of owls that carry residues of one or more SGARs (see figure 1). 

Independent from CRRU, government departments also monitor SGAR levels in red kites and the picture is pretty much the same (see figure 2). 

Recent research by other workers, including RSPB and UKCEH, has focused on SGARs in kestrels and sparrowhawks.

But a reduction in residues in birds of prey is not the only change that CRRU is required to bring about. Other objectives of stewardship, determined by HSE/GOG, are a “competent workforce”, “governance of the supply chain” and to have in place procedures for “monitoring compliance”.

To support a competent workforce, CRRU has developed a range of codes and guidance documents that explain all aspects of best practice. 

Central to this is the CRRU Code of Best Practice mentioned earlier, which was updated in 2020 to take account of developments in product label recommendations and rodenticide regulation. 

There is also CRRU guidance on the practice of permanent baiting, environmental risk assessments and other aspects of rodenticide use, to support and promote best practice.

Workforce competency

The answers show us that we have travelled a long way since the beginning of stewardship.

Changes in workforce competence are measured in periodic surveys conducted for CRRU by independent market research specialists. 

Every two to three years, hundreds of rodenticide users from three main professional user groups – professional pest management, gamekeeping and farming – are contacted and asked questions designed to test their knowledge, attitudes and practice (KAP). 

The answers show us that we have travelled a long way since the beginning of stewardship. 

Improvements are obvious in almost all measurements of competence across all user groups. 

Figure 3 shows you some of the questions, the answers received and the changes that have presumably occurred. However, these surveys also show where more effort is required to change understanding and practice further. 

Another measure of workforce competence is the number of people each year who take CRRU-approved courses and pass subsequent examinations. 

Up to July 2022, 37,000 people had taken these courses and obtained certification.

These certificates of competence are an essential component of supply chain governance, because only those who possess approved certification can purchase professional rodenticide products. 

Without confidence that these certificates are presented at every sale, we could have no certainty that this requirement is being met on the ground. 

Therefore, on behalf of CRRU, BASIS Registration Limited conducts an administrative audit of every point-of-sale in the UK that sells professional rodenticides. 

There are about 700 BASIS-registered UK outlets and every year, and in each one, BASIS auditors check that necessary documentation was presented during sales of professional rodenticides.

With all these changes for the better, why has this work failed to produce the significant reduction in wildlife exposure we all hoped to see? This is the question at the centre of the ongoing HSE/GOG review of stewardship. 

There are several possible answers and it is likely to be a combination of factors.

This is because we have endeavoured to influence a complex system, involving change to knowledge and consequent behaviour of tens of thousands of individual users; this in turn influences the complicated biological system that is movement of SGAR residues, along different contamination pathways, into wildlife.

One possibility is that we have simply not given it enough time. Although the first stewardship-labelled products came to the market in 2016, it was not until two years later that all provisions and controls of stewardship were fully implemented. 

Obviously, this becomes a less likely explanation as more years pass.

Are we addressing the right people?

I have many times heard those in professional pest management tell me they often see gross misuse of rodenticides by the general public. 

From the outset, CRRU and stewardship were not required to deal with this user group because it was considered by HSE/GOG that they use, comparatively, small quantities of rodenticide baits carrying lower levels of active substance. 

It is a gross generalisation but probably largely true that, among all users of rodenticides, bait applied by the general public is less likely to enter wildlife than that used by professional pest controllers, gamekeepers and farmers out in the countryside.

Did we underestimate the importance of this user group?

Are we focused on the wrong things?

For some time, the practice of permanent baiting, that is the use of baits as a protective barrier at sites without a current rodent infestation, was blamed for wildlife contamination. 

This was because permanent bait stations are often entered by small wild mammals, field mice and voles, and these are a prey base for many wildlife species that we know carry SGAR residues. 

Consequently, UK regulators restricted the use of this practice, and CRRU issued strict guidance on circumstances in which it can and cannot be applied. 

CRRU KAP surveys show that these applications have substantially declined (see figure 3), and this is a good thing, but still it hasn’t reduced wildlife residues as anticipated.

Coinciding with the start of stewardship was a relaxation of a rule in existence for almost 30 years. 

This was that the most potent resistance-breaking SGARs were restricted to use indoors only, virtually disqualifying their use against rats, with the consequent spread of resistance across the UK (see

It was expected that this would bring about an increase in wildlife casualties but thankfully this didn’t happen during stewardship’s early years.

However, there are recent disturbing reports of gross and widespread misuse and abuse of brodifacoum products away from buildings, absolutely contrary to labels of all products carrying this substance. 

This has led to a reported increase in wildlife casualties (see

CRRU has questioned if ‘delinquents’ can be allowed to affect legal use of rodenticides by a competent majority to protect human and animal health.

But what is happening is exactly what was feared when the ‘indoor only’ rule was relaxed.

Throughout, the government has said that the CRRU stewardship regime meets its ‘high-level principles’ and is ‘fit for purpose’. But the failure to meet environmental objectives remains a significant issue (see

CRRU and HSE/GOG are in discussion about the regime, with this looming warning from government issued after each annual review: “Depending on the outcome of the above, changes could range from minor modifications to the Rodenticide Stewardship Regime (eg improved training or awareness), changes to the approved uses (eg amendment of the approval of specific products) or revocation of uses/products.”

The term ‘last chance saloon’ has been used by CRRU to describe the situation; that seems about right!


Figure 1

rodenticide steward fig1

Figure 2

rodenticide steward fig2

Figure 3

rodenticide steward fig3

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