Written by: Daniel Schröer
In three publications, the UBA has published reports in recent weeks on studies dealing with the use of rodenticides in pest control:
In the investigations it is described that exactly the active substances applied by pest controllers in rodenticide baits can be detected in many animals.
As vPBT substances, they accumulate both via primary and secondary poisoning in non-target animals and via the food chain.
In the case of the investigated channel baiting, a survey on municipal rat control revealed that, although less extensive than in the previous reference period, the method of implementation was largely unchanged in that it was controlled using shaped baits hung in the channel with wire.
It was found that the methodology used was often inadequate and contradictory to RMM:
without prior detection of infestation, with baits exposed to water, without removing the baits after control and without monitoring the success.
And that although general experience shows that only a small proportion of the baits are eaten, the baits soften and disintegrate or are torn off and end up directly in the sewage treatment plant.
It is likewise shown that conventional purification plants cannot filter out rodenticides completely, so that they are to be found both in the sewage sludge and in the cleaned municipal waste water led back into the rivers.
The accumulation of anticoagulants from rodent control in the livers of fish is dramatic: 97% of the 58 fish liver samples examined from 9 different rivers contained at least one active ingredient!
As a result, the substance is passed on in the food chain to fish-eating birds and mammals, including humans.
The investigated external baiting with rodenticides shows that this process also contributes to the environmental impact in several ways:
even if baits are correctly designed according to RMM, heavy rainfall and flooding events lead to the leaching of active ingredients into 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, too, alarming figures: almost 30% of the songbirds examined were contaminated with residues of anticoagulant active substances from pest control, above all robins, hedge sparrows, great tits and chaffinches.
On the one hand, they invade the bait stations in search of food and, on the other hand, feed on invertebrates that had previously eaten from the bait. Also songbirds carry the load further over the food chain (predators).
Possible secondary poisoning was investigated using red foxes, in which almost 60% of the examined animals were contaminated!
And even if the rat, which had previously eaten from the bait, is not found by a predator but dies somewhere undercover, the active ingredient it contains contributes to the environmental pollution.
Alternatives to rodenticide use have been available for years: mature, effective, economical:
The published study results clearly show that there is an urgent need to minimize the release of anticoagulants 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 that are constantly improving their reliability and suitability for practical use.
In my opinion, anticoagulant rodenticides can no longer be used responsibly in most cases: the need for them is often non-existent and the environmental risks are far too high.
It would be good for the industry to look at the alternatives and try them out, instead of remaining biased in old habits.
The situation reminds me a little of the automotive industry. The prolonged adherence to outdated business models until the legislator and innovative competitors, some of them from completely different industries, force you to rethink - whereby the drastic loss of market share and jobs to be expected there should give food for thought.