Anticoagulant rodenticides have long been the primary control measure in urban and rural areas. There are major problems associated with the extensive use of these compounds, namely, the risk to non-target domestic, wildlife and livestock species. This can occur by directly ingesting poisonous bait, indirectly by consuming poisoned rodents, or by consuming animal feed contaminated with faecal residues from poisoned rodents. Second-generation anticoagulant rodenticides (SGARs) are highly efficient in controlling warfarin-resistant rodents. However, there are increased concerns with high levels of reliance on these compounds and the risks associated with their use, particularly, the long-lasting persistence in the liver tissue of baited rodents (see Table 16).
Current SGARs are synthesised as a mixture of diastereomers. This means that they are essentially a mixture of compounds with the same molecular formula but with differing three-dimensional structures. Research on the toxicological properties of different diastereomers shows that while they do not differ in acute toxicity, they do differ in the rates at which they are metabolised. Therefore, the development of baits containing only the less persistent diastereomer would minimise the ecotoxicological risk associated with their use without reducing their efficacy (Damin-Pernik et al., 2016, 2017). Research on these compounds is currently in development and no compounds are produced commercially. Amidst increasing awareness of the problems associated with extensive use of anticoagulant rodenticides, future compounds have to be ethical, effective and environmentally suitable. Stronger regulations and soaring development costs have weakened commercial justification for developing new anticoagulants.