The management and control of rats and mice.

Prevention of Damage by Pests Act 1949 (PDPA) 

Housing Act 2004

Food safety legislation

Control of Pesticides Regulations 1986, as amended 1997 (COPR) 

Health and Safety at Work etc. Act 1974

Health and Social Care Act 2008

Environmental Protection Act 1990 (EPA), as amended by Clean Neighbourhoods and Environment Act 2005 (statutory nuisance)

Environmental Protection Team/ Citywide services working alongside NCSL Pest Control Officer

The local authority has a statutory responsibility under the Prevention of Damage by Pests Act 1949 (PDPA) for ensuring, as far as practicable, that its district is kept free from rats and mice. This duty includes a proactive requirement for inspection of its area in addition to providing a response to requests for service. This procedure covers the rodent management and control measures that local authorities should operate to meet this statutory requirement.

If the local authority needs to take formal action to fulfil its responsibilities under PDPA, the process is set out in the ‘Prevention of Damage by Pests Enforcement’ procedure.

Requests for service

1. The local authority may receive requests for service to deal with rodents in domestic and commercial properties. The local authority should deal with requests for service in accordance with its service standards and agreed, publicised timescales. The authority may respond, offering advice, a service and/or an inspection/investigation. For the general approach to dealing with requests see: Administration procedure ‘Investigating Complaints and Service Requests’. 

2. The local authority should ensure that staff are suitably experienced and trained to undertake efficient questioning techniques to establish the nature and extent of any infestation and offer suitable advice or services where appropriate, for example, mice in domestic properties and rats in commercial operations.

3. Verbal advice should be supported with written advice sheets to cover amateur treatment and proofing, for example, for mice in domestic properties.

4. In circumstances where the rodent species is not known, where previous records indicate the presence of rats or where a particular risk is identified, it will be necessary to undertake a detailed inspection/investigation.

5. The options for dealing with service requests must be covered by a risk assessment to ensure the service offered will address potential risks.

6. Inspections and investigations must be undertaken by suitably qualified staff, i.e. Royal Society for Public Health/British Pest Control Association Level 2 Certificate in Pest Management. BASIS is an independent organisation that assesses the standards in the pest control industry, specifically in relation to the storage and transportation of pesticides and the competence of staff. The local authority may wish to register with BASIS Prompt Professional Pest Control Register and that operatives undertake continuous professional development (CPD) to ensure that their knowledge is up to date.

7. An inspection should look for signs of rodent activity, the causes of an infestation and conditions that may be attractive or favourable to rodents. The correct identification of the species is important before considering remedial measures. Detailed guidance on investigations and treatment is contained in the Pest Control Procedures Manual: Rodents (CIEH, May 2009).

8. Prior to an inspection, records should be checked for information on previous activity at, adjacent to or near the site location. The extent of the inspection should be determined having taken account of these records.

9. The on-site information to gather:

• Rodent species
• Locations
• Numbers
• Extent of infestation
• Risk to public health
• Possible control measures appropriate to the circumstances, including the risks to children, domestic animals and known target species
• Potential entry/access points
• Possible exclusion options
• Hygiene and housekeeping issues
• Storage of waste and disposal processes 
• Significant occupier information e.g. young, old, illnesses.

10. The investigating officer shall determine whether existing health and safety risk assessments cover the situation, or whether a new risk assessment needs to be undertaken because of particular hazards such as restricted access.

11. When looking for evidence of rodent activity, the following should be considered:

• Droppings – aid species identification, assessment of numbers and may indicate recent activity
• Live or dead rodent sightings
• Odour of dead rodents or rodent urine tracks, runs, smears from greasy fur, burrows
• Gnawing damage, on wood, card, paper or food
• Noises in roof and sub-floor spaces.

12. Information on rodent activity can be gathered by the installation of baiting stations containing a non-toxic bait that contains fluorescent dye. The bait stations should be monitored until rodent activity is confirmed. The dye within the bait will be passed through the rodent and this will allow the investigating officer to identify if droppings are fresh, which would indicate an active infestation.

13. In certain circumstances and where the point of ingress is unknown, the use of tracking dust may be beneficial to identify the presence of rodents and their access points.

14. Where the infestation is identified in a premises where specific legislation is enforced, i.e. food business, private rented property, and the infestation is deemed to be significant, then the appropriate enforcing authority should be notified.

Identification

Rats 

15. There are two species that are important as pest species within the United Kingdom, the brown and black rat.

The brown rat (Rattus norvegicus) 

16. Also known as the Norwegian rat, this is the most common species. The brown rat is known as such due to the colour of its fur. It weighs 300–500 grams and is generally 250–390 mm in length, with a scaly tail that is shorter than its body length. The brown rat has small ears. Brown rats are commonly found throughout the UK.

The black rat (Rattus rattus)

17. Also known as the ship or roof rat, the black rat is a much smaller and slimmer rodent than the brown rat and has a body length of 150–240 mm, weighing 150–200 grams. Whilst the black rat can have black fur, it may also be brown, though in each case will have a lighter underside of grey or beige. Other than size, the other main differences are that the black rat has much larger, more prominent ears and a tail that is as long as its body. The black rat is much less common in the UK, having been displaced by its brown cousin, though they can still be found occasionally in ports.

18. Rats are omnivorous, though the black rat prefers a fruit-based diet. Unlike mice, they need to drink daily; therefore, removing a water source will help make a habitat less appealing.

19. Rats suffer from neophobia – they are very wary of new objects. Therefore, any new additions to the rats’ environment, such as bait boxes, will take some time for them to become used to and take bait from.

20. Rats will live for approximately 18 months and have on average 4 litters of up to 8 young per litter.

21. Rat droppings are approximately 10 mm in length and rugby-ball shaped. Rat droppings are not always easy to find as they are more secretive, choosing to generally use a single latrine. They are generally smooth and when fresh have a sheen and are pliable.

Mice

The house mouse (Mus domesticus)

22. The house mouse is the smallest of the pest rodents at 75–120 mm in length and 10–25 grams. House mice are brown or grey in colour with a lighter underside. They have a long thin tail that is as long as the body and they have large ears.

23. Mice are omnivorous, although they particularly like seeds.

24. Mice live for just a few months and are mature at between 6 and 10 weeks. Gestation takes only 21 days. Therefore, 10 litters per year is not uncommon with each litter having on average 5 young.

25. Mouse droppings are similar in size and shape to a grain of rice and are brown/black in colour. Unlike rats, mice drop indiscriminately and constantly urinate as they move around their environment, increasing the potential for contamination.

Significance

26. All rodents can transmit disease, including food-poisoning pathogens, toxoplasmosis and, in the case of rats, leptospirosis. Contamination is by direct contact or the depositing of droppings and urine on work surfaces and directly onto food.

Exclusion/restriction

27. Buildings can be designed to deny access and harbourage, giving attention to rodent-proofing to ensure there are no holes that lead through the structure of the premises that are greater than 5 mm in diameter, i.e. holes around service and waste pipes, under exterior doors and air bricks. Specific areas such as drainage, waste disposal and food storage should be inspected to ensure that they are maintained in such a manner as to deny access to rodents. Food/water sources should be removed where possible. Ongoing protection can be aided through effective cleaning and maintenance schedules. Consideration should be given to external issues such as landscaping, environmental management, ponds, watercourses and waste storage, ensuring potential food and water sources and harbourage are removed.

28. When investigating potential rat infestations, particular attention must be given to drainage installations. The inspection should ensure that wastewater gullies are covered, unused connections and rodding eyes suitably capped and toilet waste pipes are free of damage between the water trap and connection to the drain. Where a drainage defect is identified, it may be necessary to resolve the defect by the service of notice via the Building Act 1984, section 59, and potentially undertake the work in default. The investigation should include checking for burrows in soil/grassed areas adjacent to the building and near inspection chambers, which may indicate a link between sewers and the surface. 

29. Rodent control management will need to be employed during the remediation of sites, particularly at brownfield locations where there has been waste disposal, during the demolition of buildings and where there are ponds or watercourses.

30. Where a domestic rodent control service is not provided for the treatment of mouse infestations, the local authority should provide an advice leaflet with practical advice on how to treat a mouse infestation, identification of potential points of ingress and advice on how proofing can be undertaken. This may also be used to support verbal advice.

Sewer management

31. Sewer treatment is an essential element of an integrated programme for the control of rats. Sewers provide an environment where rats will live and multiply. Surface infestations are often linked to defective drainage systems. An integrated sewer monitoring and baiting programme will reduce the numbers and reduce the amount of surface activity.

32. A national protocol has been developed between Water UK and the Local Government Association (LGA) to help joint working between water companies and local authorities. Within this protocol, water authorities and local authorities should share information on the work they are undertaking. The work that each organisation is doing should complement that of the other.

33. Water companies have responsibility to ensure that their sewers are free of rats and that their sewers are maintained. As part of the investigation of surface rat infestations, consideration should be given to the potential for a link to a defective sewer. When attempting to demonstrate a link, suitable investigation techniques should be utilised; these may include:

• Smoke tests
• Dye tests
• CCTV drainage investigations
• A combination of the above.

34. As part of their responsibility, water companies should undertake sewer-baiting programmes directly or by employing contractors, which may include some local authorities working on behalf of the water company. For the sewer-baiting programme to have maximum impact, it should be linked to surface infestations identified by the local authority, paying particular attention to infestations that have been linked to drainage defects.

General treatment methods

35. A site assessment needs to establish the most appropriate treatment method. Rodenticidal treatments may not be safely applied in some situations, for example, where there are risks to young children, pets, and birds of prey or protected species of animals or plants. COPR require that a person using pesticides takes all reasonable precautions to protect the health of human beings, creatures and plants and safeguard the environment. A comprehensive risk assessment should be undertaken to consider each individual treatment.

36. Any treatment undertaken must be done so by pest control technicians holding the appropriate certificate of competence.

37. There are a number of non-chemical control methods that can be used, either where rodenticides are not able to be used safely or where a non-toxic solution is deemed to be the best option. These include suitably baited spring and cage traps.

38. Another option is glue boards. There is a code of practice covering the use of glue boards as there is a debate about the suitability because of the suffering caused by use of this method. In brief the code of practice states:

• All other options should be considered before glue boards are used
• Technicians using glue boards must be specifically trained in their use
• Glue boards must be checked at least daily
• There must be a record of glue boards laid to allow traceability
• Any rodents caught on glue boards must be humanely dispatched 
• On the completion of the treatment, all boards must be accounted for and suitably disposed of.

39. Rodenticides in current use are chronic poisons that work as anticoagulants. The issue of resistance is an important consideration in the choice of poison and the methods to be employed.

40. First-generation baits include warfarin, coumatetralyl and chlorophacinone, where there is now a great deal of resistance in the rat population.

41. Second-generation chemicals such as brodifacoum, bromadiolone, flocoumafen, difehialone and difenacoum are therefore more commonly used where there is warfarin-resistance. Second-generation baits are much more potent, and a single feed should deliver a lethal dose.

42. The formulation of the bait will take account of the target species. A dye and bittering agent are generally added as a safety measure, together with a mould inhibitor. Bait formulation may be in the form of grain, most commonly blocks or gels.

43. Liquid baits are an option where there is restricted access to water, for example in grain silos.

44. Contact dusts and wicks provide alternatives, though it is difficult to identify the level of activity. Both work in a similar manner with rodenticide being transferred onto the rodent’s fur. As rodents spend almost a fifth of their waking time grooming, the rodenticide is then ingested during grooming.

45. In external situations, at least 3 m away from buildings and where every other option has been discounted, gassing of sealed burrows is an option. This may only be carried out by an operative trained in this technique. Tablets of aluminium phosphide are placed into rodent burrows that are then sealed. When the tablets become moist, phosphine gas is released from the tablets, causing asphyxiation. This should be undertaken only as a last response when no alternative is available and the risk to non-target species has been fully assessed.

46. External baiting should take place in purpose-designed fixed and locked bait boxes. In some instances where there is no alternative (e.g. a secured bait box) and a suitable risk assessment has been undertaken, baiting can be undertaken directly in rat holes. There needs to be a system of programmed baiting that minimises the impact on non-target species. Permanent baiting stations should be avoided where practicable. However, in some circumstances, such as within food businesses, they are an important aspect of preventative pest control.

47. Where trial baits and rodenticides are used, the stations should be checked regularly (at least weekly), followed up with repeat baiting and removal of rodent bodies as necessary. Repeat visits are normally undertaken until there have been a number of clear visits (dependant on the authority’s procedures), though normally two. All rodenticide and rodent carcasses removed must be suitably disposed of, i.e. by incineration, to prevent secondary poisoning of non-target species once activity has ceased.

48. Written records need to be kept regarding the programme, rodenticide used, COSHH information including safety data sheets, station locations (including plan), amount of activity, bait removal and disposal.

49. Environmental controls are critical to the success of the treatment process and include the removal of harbourage and sources of food and water. Structural works to prevent access should consider services such as pipe and cable ducting and drainage in addition to the rodent-proofing of walls, floors, ceilings and doors.

50. Consideration should always be given to neighbouring properties, which should be inspected for signs of rodent activity and treated accordingly. When undertaking block treatments, it may be necessary to take formal action to ensure that work is undertaken.

Rodents in and around houses: application of HHSRS

51. In addition to the local authority’s duties under PDPA, the control of pests comes within the Housing Health and Safety Rating System (HHSRS) of the Housing Act 2004. Of the 29 potential hazards that come within the assessment, pest-related matters come within Category 15: Domestic hygiene, pests and refuse. This covers health hazards due to poor design, layout and construction, access into and harbourage within the dwelling for pests, and inadequate and unhygienic waste storage and disposal.

52. The assessment of the severity of the hazard has to be decided on a case-by-case basis, but the health risk from rodents and the problems of infestations will tend towards a Category 1 hazard. In addition to the PDPA requirements, HHSRS may be applied to ensure structural works are undertaken to make properties rodent-proof, and suitable measures are undertaken to prevent recurrence by removing harbourage and attractions to rodents, such as the provision of effective waste storage and disposal (see ‘Pest Control Procedures in the Housing Sector’ (NPAP and CIEH, January 2010) in Further Guidance below).

Rodents in and around food premises: Food hygiene regulations

53. Food hygiene regulations require the layout, design and construction of food premises to permit good food hygiene practices including protection against contamination and pest control. As part of a documented food safety management system, the control of pests must be considered following the principles of hazard analysis and critical control points (HACCP).

54. In addition, food businesses must take all reasonable precautions to prevent pests from gaining entry into food storage and preparation areas. Food business operators must ensure that the structural integrity of the premises is sound with no holes in the structure that may allow the ingress of pests. Any gaps and holes to external doors, windows, pipes, drains, etc. must be filled or covered with a solid, durable material in order to minimise pest entry points into food preparation and storage areas.

55. Food businesses should be advised to employ the services of a suitably qualified pest control contractor to provide preventative pest control services as part of the documented food safety management system.

56. The food business will need to put rodent control measures in place, and the suitability and effectiveness of these measures will form part of an inspection by an environmental health practitioner (or other suitably qualified food safety officer) responsible for food safety. Local authority pest control officers’ involvement with such premises will be in coordination with, or at the request of, the investigating officer.

Rodents in and around the workplace:  Health and Safety at Work etc. Act 1974

57. The Health and Safety at Work etc. Act 1974 requires that it shall be the duty of every employer to ensure, so far as is reasonably practicable, the health, safety and welfare at work of all employees. This includes the provision and maintenance of a working environment for employees that is, so far as is reasonably practicable, safe, without risks to health, for example, pests.

The Health and Social Care Act 2008

58. There is a health and safety risk posed by the presence of rodents themselves, i.e. transmission of disease and by their behaviour and, for example, gnawing on cables, which may pose other hazards.

59. The Health and Social Care Act 2008 requires that effective systems are in place to protect patients and staff from the risk of acquiring healthcare-associated infection. Therefore, good pest control procedures are required within healthcare establishments such as hospitals.

Note: The general process for the management of pest control services is set out in the ‘Managing Pest Control Services Enforcement’ procedure.

See ‘Prevention of Damage by Pests Enforcement’ procedure.

Enforcement may also be appropriate/more appropriate under premises-specific legislation, i.e. Food Safety Act 1990.

See ‘Prevention of Damage by Pests Enforcement’ procedure

Food Safety Act 80, section 32

Health and Safety at Work, etc. Act, 1974, section 20

Housing Act 2004, section 279

See: Pest Control / National Policy and Guidance / Rodents

Pest Control Procedures Manual Rodents (CIEH, May 2009)

The Control of Rats with Rodenticides: A Complete Guide to Best Practice Natural England 2002

Rats and Mice: Rural Development Service Technical Advice Note 05 House Mice (Defra, August 2006)

Pest Control: The Role of Pest Management in Environmental Health (CIEH, 2003)

Rats and Mice: Rural Development Service Technical Advice Note 34 Rats – Options for Controlling Infestations (August 2006)

Rat Poison and the Threat to Wildlife (RSPB Birdlife International)

Public Information: Good Composting Practice – Guidance on Composting Without Attracting Rodents (CIEH, 2009)

Code of Best Practice Humane Use of Rodent Glue Boards (Pest Management Alliance, February 2010)

Rats and Mice: Rural Development Service Technical Advice Note 35 Rats – Control on Livestock Units (August 2006) 

Code of Best Practice for Rodent Control and Safe Use of Rodenticides. The Campaign for Responsible Rodenticide Use (CRRU, 2015)

National Sewer Baiting Programme: Best Practice and Guidance Document (CIEH, April 2013)

Code of Conduct (BPCA, September 2013)

Code of Best Practice – Pesticide waste (BPCA, February 2019)

Housing

Pest Control / National Policy and Guidance / Pest Control Housing Sector

Pest Control Procedures in the Housing Sector (NPAP and CIEH, January 2010)

Food Safety

Pest Control / National Policy and Guidance / Pest Control Food Premises

Pest Management: Pest Control Procedures in the Food Industry (NPAP and CIEH, January 2009)

Public Information: Pest Minimisation – Best Practice for the Hospitality Industry (CIEH, April 2009)

Social Care

Pest Control / National Policy and Guidance / Pest Control Social Care Sector

Pest Control Procedures in the Social Care Sector (CIEH, 2011)

Construction

Pest Control / National Policy and Guidance / Pest Control Construction Industry

Public Information: Urban Pests: Pest Minimisation – Best Practice for the Construction Industry (CIEH, September 2008)

Pest Control / National Policy and Guidance / Pesticides

Pest Control / National Policy and Guidance / Pest Control Management

British Pest Control Association www.BPCA.org.uk

See: Environmental Health / Pest Control / Documents / Pest Control Risk Assessment

Pest Control Risk Assessment Template

Environmental Health / Pest Control / Documents / Pest Control Treatment

Pest Control Treatment Record Template

Environmental Health / Pest Control / Documents / Rodents

Rodent Advice Sheet: Rats

See: Environmental Health / Pest Control / Procedures / Prevention of Damage by Pests

Prevention of Damage by Pests Enforcement

Environmental Health / Pest Control / Procedures / Pest Control Services

Managing Pest Control Services

Environmental Health / Pest Control / Procedures / Insects

Management and Control of Insects