Written by: Thomas Kniep, Regional Manager South Biotec Klute GmbH, Member of the DpS Editorial Advisory Council
In three publications in recent weeks, UBA has published reports on studies dealing with the use of rodenticidesin pest control:
The studies describe that the active ingredients applied by pest controllers during rodenticide baiting, can be detected in many animals. As vPBT substances (persistent, bioaccumulative and toxic) they accumulate both via primary and secondary poisoning in non-target animals, so as via the food chain.In the study about the investigated sewer baiting, a survey on municipal rat control showed that, although less extensive than in the previous reference period, the methods used to control the rats were largely unchanged in terms of implementation, with shaped baits hung in the sewer with wires. It was established that the methodology used was often inadequate and contradictory to the RMMs ( risk mitigation measurements) : Without prior detection of infestation, with baits exposed to water, without removing the baits after control and without monitoring the results. This is despite the fact that, according to general experience, only a small proportion of the baits are eaten. They soften and disintegrate or break off and end up directly in the treatment plant.It is also shown that conventional sewage treatment plants are not able to filter out rodenticides completely, so that they are found both in the sewage sludge and in the treated municipal wastewater returned to the rivers. The accumulation of anticoagulants from rodent control in the livers of fish is dramatic: 97% of the 58 fish liver samples from 9 different rivers tested contained at least one active substance! As a result, it is passed down the food chain to fish-eating birds and mammals, including humans.
The external baiting with rodenticides investigated clearly shows that this method also contributes to environmental impact in several ways: Even if baits are correctly designed according to the RMM, heavy rainfall and flooding events lead to leaching of the active substances into the surface water. In addition to the known primary poisoning in non-target animals such as shrews, the exposure of songbirds was included and investigated for the first time. Here some alarming figures: Almost 30% of the songbirds examined were contaminated with residues of anticoagulant active substances from pest control, especially robins, hedge sparrows, great titmice and chaffinches.
On the one hand, they enter the bait stations in search of food and on the other hand, they feed on invertebrates that have previously eaten from the bait. Songbirds also carry the burden further along the food chain (predators). Possible secondary poisoning was investigated using red foxes, in which almost 60% of the animals investigated were contaminated! And even if the rat, which had previously eaten from the bait, is not found by a predator and dies somewhere undercover, the active substance it contains contributes to environmental pollution.
Alternatives to the use of rodenticides have been available for years. Mature, effective, economical:
The published study results clearly show that there is an urgent need to minimise the application of anticoagulant substances classified as vPBT substances. For years, the market has offered mechanical and electrical trapping systems for the monitoring and control of rodents, which have proven themselves in practice in many applications. In addition, innovative market players are continuously developing new systems whose reliability and suitability for practical use are constantly increasing. In my opinion, anticoagulant rodenticides can no longer be used responsibly in most cases: There is often no need and the environmental risks are far too high.It would be good for the industry to look at and try out the alternatives rather than remaining biased in old habits. The situation reminds me a little of the car industry: the prolonged adherence to outdated business models until the legislator and innovative competitors, some of them from completely different sectors, force the industry to rethink - although the drastic loss of market share and jobs to be expected there should give food for thought.
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