Hungarian researchers have found high concentrations of rodenticides in liver samples from deceased polecats. They also discovered that while the accumulation of anticoagulant toxicants in polecats from Hungary is lower than in other European countries, more animals in Hungary had toxic residues. Experts emphasise the importance of more careful and responsible use of rodenticides, as well as the need for thorough monitoring.
A common method of pest control worldwide is the use of coumarin-type anticoagulant rodenticides (ARs) in agricultural and residential areas. However, these toxicants, which are often applied improperly, such as being scattered on surfaces, pose a serious threat to animals that consume the rodents, including rare and endangered species of carnivorous mammals and birds of prey.
Hungarian researchers have examined the concentrations of various rodenticides in liver samples from mostly road-killed steppe polecats and European polecats. The study, published in the scientific journal STOTEN, involved two researchers from the HUN-REN Balaton Limnological Research Institute (BLRI), Zsolt Pirger and József Lanszki.
A similar study had not yet been carried out for steppe polecats, while this was the first in Central Europe for European polecats. Residues of various substances were detected in nearly half (46%) of the liver samples examined, often with multiple types of residues present. Higher concentrations were found in steppe polecats, whereas European polecat samples exhibited a more diverse accumulation of these compounds. The accumulation of ARs correlated positively with the human population density of the surrounding areas and negatively with the extent of more natural habitats (e.g., grasslands, wetlands, forests) in both species.
HUN-REN BLRI researcher József Lanszki stated that it is concerning that second-generation rodenticides, especially those used today, are lethal even in small quantities. Once these substances enter the bodies of predators, even if they do not cause immediate death, they significantly contribute to early mortality. Anticoagulants impair the body's defences against disease, may cause movement coordination problems (leading to more frequent vehicle collisions), and reduce hunting success.
The research also showed that AR accumulation in European polecats in Hungary was lower than in other European countries. However, once these toxins enter the food web, they are harmful to organisms even in small quantities. The researchers therefore stress the importance of banning environmentally harmful pesticides, or at least their significantly reduced and more prudent use, as this is the only way they can benefit both wildlife and humans. The study also revealed that in other European countries, far fewer samples contained residues, although the concentration of toxicants in these samples was much higher than in samples from Hungary.