Open-access content Thursday 25th October 2012
New pest control rodenticides have been approved under the EU Biocidal Products Directive. Mark Cosh explains the results and restrictions of the consultation on usage.
29 October 2012
Anticoagulant rodenticides are the mainstay of the chemical control of rodents in the UK and across the European Union.
Under the EU Biocidal Products Directive, the active substances (brodifacoum, bromadiolone, difenacoum, difethialone and flocoumafen) of five, second-generation anticoagulant rodenticides (SGARs) have recently been reviewed under the EU review programme.
It was agreed that these active substances should be included on the approved list of active substances that had been shown to be without unacceptable risk to people or the environment, despite some risks identified to humans, non-target animals and the environment.
The final decision about how and where SGARs can be used within individual EU countries was delegated to member states.
The HSE therefore carried out a risk assessment looking at the environmental effects of the five SGARs, which identified a high concern for primary and secondary poisoning of non-target species through the food chain. It concluded that since is not possible to rank the active substances in terms of risk, all five SGARs should be treated in the same way and risk mitigation measures be put in place around their use.
It concludes that options might therefore need to be considered that provide less than the maximum protection for non-target species and the environment to allow this public health goal to be achieved.
The consultation document about the proposed use of SGARs was published in August 2012 and closes on 2 November 2012. It includes the following recommendations.
Restriction of user type
The HSE believes that non-professionals should be able to continue to use rodenticide baits for the control of mouse infestations and minor rat infestations in the interests of public health. It therefore does not propose a blanket restriction on user type and considers that, where appropriate, SGARs should be available to all users.
It believes that trade associations such as the British Pest Control Association and other stakeholder organisations have an important role to play in increasing the competence and understanding of non-specialised users.
Restriction of outdoor situation of use
Insufficient information is available to robustly rank baits based on the five SGARs for potency. Also, some outdoor use needs to be retained to maintain public and animal hygiene.
The HSE proposes that SGAR use is restricted to in and around buildings and sewers.
- Help to address concerns that open area use of Difenacoum and Bromadiolone under the Control of Pesticides Regulations (COPR) is a major contributor to the residues seen in wildlife carcasses
- Permit SGARs (including those previously restricted to indoor use under COPR) to be used outdoors in a restricted and targeted way, i.e. where there is a high public hygiene 'need', enabling the rapid control of resistant rodent populations.
Restriction of bait formulation type
In terms of bait placement, it is proposed that the following phrases are included on the labels of all SGAR bait products to ensure that non-target animals cannot gain access or access is restricted to a minimum:
- Prevent access to bait by children, birds and non-target animals (particularly dogs, cats, pigs and poultry)
- For use in areas that are inaccessible to infants, children, companion animals and non-target animals.
This is in addition to the EU Annex I phrase: "baits must be securely deposited in a way so as to minimise the risk of consumption by other animals or children. Where possible, secure baits so that they cannot be dragged away."
Restriction of maximum duration of baiting
In order to minimise the risks of wildlife exposure and the development of resistant populations of rodents, it is proposed that the following phrases be included on all SGAR product labels following the EU Annex I phrase mentioned above:
- "In most cases, anticoagulant bait should have achieved control within 35 days. Should activity continue beyond this time, the likely cause should be determined and documented"
- "Unless under the supervision of a pest control operator or other competent person, do not use anticoagulant rodenticides as permanent baits".
This has become known as the 35-day rule and some product manufacturers are already including these phrases on their products.
Frequency of revisiting bait points
Due to variations in baiting practices, the HSE does not consider it appropriate to set a statutory minimum frequency for revisiting all SGAR bait points. However it proposes that the following phrases should be included on all SGAR product labels following the EU Annex I phrase:
- "Daily inspection may be required in some cases"
- "Search for and remove dead rodents at frequent intervals during treatment, at least as often as when baits are checked and/or replenished".
Although these are still proposals at this stage and further consultation is likely before these recommendations become law, pest control best practice is moving away from permanent baiting.
For further information visit www.hse.gov.uk