Second Generation Anticoagulant Rodenticides (SGARs): Stewardship Scheme, Conditions of Use and Reporting

Summary

SGARs work by blocking vitamin K recycling, which prevents blood from clotting. Death typically occurs 4–10 days after lethal ingestion, making it impossible to observe immediate effects and easy to over-bait. Because rodents accumulate high concentrations of the active ingredient in their liver before death, predators and scavengers that eat poisoned rodents can receive a lethal secondary dose. This secondary poisoning has been linked to population-level impacts on barn owls, red kites, polecats, foxes, and stoats across the UK — documented by the Wildlife Incident Investigation Scheme (WIIS) run by the Health and Safety Executive (HSE) and Natural England.

The CRRU UK Stewardship scheme was established in 2012 and significantly tightened in 2016 and 2020 in response to evidence of wildlife contamination. Under current stewardship requirements, professionals must complete a mandatory training module before purchasing or using SGAR products from participating distributors, carry out and document a pre-treatment environmental risk assessment, use only approved tamper-resistant bait stations outdoors, and report any non-target animal incidents. The scheme is voluntary in the sense that it is not a statutory regulation — but in practice, distributors require stewardship compliance as a condition of sale, and product labels include use restrictions that are legally binding under the Control of Pesticides Regulations 1986.

First Generation Anticoagulant Rodenticides (FGARs) — difacinone, chlorophacinone, warfarin, coumatetralyl — are less potent, less persistent in body tissue, and generally considered lower risk for secondary poisoning. However, widespread FGAR resistance in UK rat populations (particularly the L120Q and Y139C mutations in Rattus norvegicus) means SGARs remain the go-to professional tool for difficult infestations.

Key Facts

• SGAR active ingredients (UK approved) — brodifacoum, bromadiolone, difenacoum, difethialone, flocoumafen
• FGAR active ingredients — warfarin, coumatetralyl, chlorophacinone, diphacinone (difacinone)
• Mechanism of action — inhibit vitamin K 2,3-epoxide reductase; blood cannot clot; death by internal haemorrhage
• Time to death — typically 4–10 days after lethal ingestion
• Secondary poisoning risk — SGAR residues persist in liver tissue for months; proven cause of barn owl, red kite, and polecat deaths in UK
• CRRU UK Stewardship — industry scheme governing professional SGAR use; launched 2012, tightened 2016 and 2020
• Mandatory stewardship training — professionals must complete a recognised training module (BASIS PROMPT integrates CRRU content)
• Indoor use — SGARs can be used indoors (buildings, vehicles, sewers) with appropriate bait security; restrictions less onerous than outdoors
• Outdoor use restrictions — SGARs may only be used outdoors in the open where there is no practicable alternative; maximum 35-day treatment period before re-assessment; must use tamper-resistant bait stations
• Bait security — bait must be enclosed in tamper-resistant bait stations accessible only to the target species; bait must not be spilt or left accessible
• Record-keeping — pest controllers must record: location, product, lot number, quantity placed, quantity removed, dates, evidence of activity, outcome
• Non-target incident reporting — any suspected non-target poisoning must be reported to WIIS (Wildlife Incident Investigation Scheme) via the HSE Chemicals Incidents Line
• Control of Pesticides Regulations 1986 — product label requirements are legally binding; using a product contrary to label instructions is a criminal offence
• RRAG — Rodenticide Resistance Action Group; monitors resistance, publishes resistance maps for UK rat and mouse populations
• Resistance prevalence — studies indicate L120Q VKORC1 mutation (conferring FGAR resistance) present in up to 75% of rats in some Welsh and central England populations; SGAR resistance (Y139C, L128Q) also detected and increasing

Quick Reference Table

Detailed Guidance

CRRU UK Stewardship: What Professionals Must Do

The current (2020 onwards) CRRU stewardship requirements for professional pest controllers using SGARs:

1. Training and qualification Complete the CRRU mandatory e-learning module (available via CRRU website) before purchasing or using SGAR products from stewardship-compliant distributors. The module covers the ecology of secondary poisoning, correct bait station use, and reporting. BASIS PROMPT CPD integrates this content, so qualified professionals who keep their CPD current are typically already compliant.

2. Pre-treatment environmental risk assessment Before any outdoor SGAR use, complete a documented environmental risk assessment. This must consider:

• Proximity to water courses (minimum 1.5 m from any open water body; greater distance recommended near sensitive habitats)
• Presence of non-target species in the area (bird feeders, bird nesting areas, livestock, companion animals)
• Whether FGARs or non-chemical methods have been tried and ruled out, with reasons recorded
• Whether bait stations can be secured against non-target species

3. Bait station requirements All bait placed outdoors must be in tamper-resistant bait stations. The station must:

• Prevent access by children, dogs, cats, and birds
• Keep bait dry (wet bait deteriorates rapidly and is less palatable)
• Be labelled with the pest controller's contact details
• Be anchored so it cannot be dragged away or tipped over
• Be placed along runs, in burrow entrances, or in areas of confirmed activity — not scattered or broadcast

4. Bait quantity and duration Outdoor SGAR treatment should not exceed 35 days without reassessment. At reassessment, the operative must evaluate whether:

• Activity has decreased (positive outcome — adjust or conclude treatment)
• Activity is unchanged (consider whether source is being addressed; check for new entry points or harbourage)
• Activity has increased (review bait security, check for bait shyness, consider product change)

Do not leave bait in stations indefinitely. Remove all bait and stations once activity ceases. Bait left in place after control is achieved is a source of unnecessary wildlife exposure.

5. Record-keeping For every SGAR treatment, maintain a contemporaneous record including:

• Site address
• Target pest species
• Product name and active ingredient
• Batch/lot number
• Quantity of product placed (in grams or number of sachets)
• Location of each bait station (keyed to a site plan)
• Date placed and date checked/removed
• Evidence of bait take at each visit
• Outcome (activity ceased / active / referred)

Records must be retained for a minimum of 3 years (CRRU stewardship requirement); COSHH requires 5 years for hazardous substance records.

6. Non-target incident reporting If any non-target animal (bird, mammal, domestic pet) is found dead or showing symptoms of anticoagulant poisoning near a treatment site, report it to WIIS immediately. Do not dispose of the carcass — it can be submitted for laboratory analysis. Reporting is not an admission of liability; it is a professional obligation and provides evidence for the CRRU and WIIS to monitor the stewardship scheme's effectiveness.

Conditions for Indoor vs Outdoor Use

Indoor use (buildings, roof voids, wall cavities, sewers, vehicles):

• SGARs can be used with fewer restrictions than outdoors
• Bait must still be secured so it is inaccessible to non-target species (pets, children)
• Use lockable bait stations even indoors — a cat that enters a treated building and eats dead rodents is at secondary poisoning risk
• Do not place loose bait on open surfaces

Outdoor use in the open (garden, field, around the building perimeter):

• Full stewardship conditions apply (see above)
• The professional must record the justification for SGAR use over alternatives
• Never broadcast bait across open ground

Sewers and drains:

• Rodenticide use in sewers is a specialist application; local authority drainage teams and approved contractors carry this out
• Sewer treatment avoids many of the secondary poisoning risks because rodents dying in sewers are less accessible to surface predators

Resistance Testing and Product Choice

Anticoagulant resistance is a growing problem in the UK. The RRAG publishes resistance distribution maps that show the prevalence of known resistance mutations by county. Before choosing a product, check the RRAG map for the area:

• If FGAR resistance is prevalent (common across Wales, Midlands, Yorkshire): use an SGAR
• If SGAR resistance (L128Q, Y139C) is suspected (increasingly reported): consider combining an SGAR with non-chemical trapping, or consult the RRAG for current guidance
• Resistance should be suspected if bait is being consumed at normal rates but activity is not declining after 14–21 days

There is no simple field test for resistance. Clinical signs in surviving rodents (roughed fur, lethargy, sub-clinical bleeding) can indicate sub-lethal exposure rather than resistance. Laboratory confirmation requires sending a carcass to a RRAG partner laboratory.

Alternatives to SGARs

The stewardship scheme requires professionals to consider alternatives before using SGARs outdoors. Document your reasoning. Common alternatives:

• FGARs — appropriate where resistance is not suspected; less secondary poisoning risk; require multiple feeding events (rodents must feed on bait on at least 5 separate occasions for warfarin); less effective for resistant populations
• Snap traps — highly effective for mice; appropriate for targeted indoor use; no secondary poisoning risk; labour-intensive for large infestations
• Live capture traps — appropriate where humane capture is required (e.g. protected species accidentally caught); requires a plan for release or humane destruction
• Electronic traps — single-kill; appropriate for indoor use; high capital cost
• Proofing and exclusion — the only permanent solution; should always accompany any rodenticide programme
• Ultrasonic devices — no credible evidence of effectiveness; do not count as an alternative for stewardship purposes

Disposal of Rodenticide Bait and Carcasses

Unused bait: Return to original container and store securely. Do not dispose of in domestic waste or down drains. Arrange disposal through a licensed waste contractor or return-to-manufacturer scheme if available.

Dead rodents: Wear gloves when handling. Bag and dispose of in residual waste (domestic wheelie bin is acceptable for small numbers of rodents in a domestic setting). If submitting for WIIS testing, seal in a double bag and refrigerate — do not freeze.

Contaminated bait stations: Wipe out bait residue and bag before disposal. Bait stations can usually be cleaned and reused.

Frequently Asked Questions

Can a homeowner buy SGAR products?

Most SGAR products are restricted to professional use only. A small number of SGAR products containing bromadiolone at low concentrations are available to amateur buyers in limited pack sizes, but these are subject to mandatory label warnings and use restrictions. Since the 2020 CRRU stewardship tightening, the practical availability of SGARs to non-professionals has been significantly reduced. FGARs (particularly coumatetralyl-based products) remain available to consumers.

How long should a treatment programme last?

A typical rat infestation programme runs 3–4 visits over 3–6 weeks. Mice, being faster-reproducing, may resolve in 2–3 visits or extend longer in a multi-unit building. For outdoor treatments, reassess every 35 days. A treatment programme should never be open-ended — if activity is not declining after 3–4 visits, the source and approach need to be reviewed, not simply more bait added.

What counts as a "non-target incident" I need to report?

Any wild animal, bird, or domestic animal found dead or showing signs of anticoagulant poisoning (weakness, subcutaneous bleeding, bloody discharge) near or at a treatment site. This includes dead barn owls found nearby even if you are not certain of the cause. The WIIS team will assess whether laboratory testing is warranted. Contact the HSE Chemicals Incident Line: 0344 892 0108.

Do I need to tell the customer about SGAR risks?

Yes. The product label requires users to inform occupants of treated buildings about the products in use, their hazards, and precautions. For domestic customers with pets or young children, this conversation is especially important. Document that you have provided this information — note it on the job sheet.

Is SGAR use permitted near children's play areas?

With extreme caution only. Bait stations must be anchor-secured and fully tamper-resistant; verify the station meets the British Standard for tamper-resistance applicable to children [verify]. An alternative approach is to use snap traps (no secondary poisoning, no chemical hazard) in children's play areas and reserve SGAR treatment for adjacent non-play areas. Document the decision and the controls applied.

Regulations & Standards

• Control of Pesticides Regulations 1986 (as amended) — product label conditions are legally binding; using a product contrary to its label is a criminal offence

• Control of Substances Hazardous to Health (COSHH) Regulations 2002 — risk assessment required; records retained 5 years

• CRRU UK Stewardship 2020 — industry stewardship scheme; compliance required for professional SGAR purchase from participating distributors

• Wildlife and Countryside Act 1981 — secondary poisoning of protected species (barn owls, polecats, raptors) can constitute an offence if reckless; stewardship compliance demonstrates due diligence

• Environmental Protection Act 1990 — waste rodenticide and contaminated materials must be disposed of lawfully

• CRRU UK — Campaign for Responsible Rodenticide Use — stewardship scheme, mandatory training module, guidance documents

• HSE — Rodenticides and wildlife — Wildlife Incident Investigation Scheme, reporting

• Rodenticide Resistance Action Group (RRAG) — resistance monitoring, maps, and guidance

• BPCA — Rodenticide Stewardship — professional guidance and stewardship resources

• Natural England — Barn owl and anticoagulant rodenticides — secondary poisoning evidence base

• pest control risk assessment — site survey and risk assessment requirements before SGAR use

• pest control in domestic properties — product use in homes; customer communication

• fumigation regulations — alternative pest control methods for severe infestations