How long do vertebrate pesticides persist in living mammals? Priorities for research

Abstract

We review the pharmacokinetic literature for 12 vertebrate pesticides available (or in the registration process) for broad-scale use in New Zealand and summarise their likely persistence in sub lethally exposed animals. Vertebrate pesticides differ in the way they are absorbed, metabolised, distributed and excreted, as well as the length of time that these processes take in different animals. Understanding persistence times helps to manage two sources of contamination risk to the human food chain relating to wild and farmed animals, both of which have implications for food safety and trade. Wild animals such as deer (Cervus spp.) and pigs (Sus scrofa) may be hunted for food and caution periods are set in areas where pesticide operations have been carried out to inform hunters that residues may be present. Livestock do not normally have access to vertebrate pesticides but may be accidentally exposed; withholding periods are required to ensure residues are excreted prior to slaughter. Sublethal persistence time is the focus of this review, but it is not the only determinant of food safety risks. The period of risk to the human food chain also includes how long pesticide baits and lethally poisoned carcasses remain toxic in the field. This review classifies vertebrate pesticides of similar halflife and/or persistence time into three groups: fast—cyanide, zinc phosphide, sodium nitrite, para-aminopropiophenone (PAPP), and sodium monofluoroacetate (1080); moderate to slow—phosphorus, pindone, diphacinone, coumatetralyl and cholecalciferol; and very slow— brodifacoum and bromadiolone. Gaps in the literature are identified, the most important of which relate to pindone and PAPP.