Incurred pesticide residues are residues that are present after exposure under <i>in vivo</i> conditions such as crops grown under production conditions or livestock under animal husbandry conditions. Formation of incurred residues generally cannot be duplicated in a laboratory setting as they are the result of biological and environmental interactions with the pesticide and the organism. Several mechanisms may be involved in the generation of incurred residues. These include chemical modification of the pesticide to form conjugates or other metabolites, chemical binding to various plant or animal components, and non-specific physical entrapment. In many cases these incurred residues are not extractable by simple solvent extractions. Plant and animal metabolism studies required by regulatory authorities worldwide are designed to identify these various residues. Radiolabeled materials are employed so material balance can be monitored and the route of degradation can be determined. Based on these metabolism studies the total toxic residue (TTR) is established. The TTR is composed of the parent pesticide and metabolites of toxicological concern.  Analytical methods are then developed to measure all components of the TTR which are ultimately used for tolerance enforcement. The tolerance enforcement methods must be validated by analyzing actual metabolism samples and showing concurrence with the metabolism study results (radiovalidation). The method must account for ≥ 70% of the TTR in the aged samples, as identified in the metabolism study. The resulting enforcement method thus accounts for incurred residues if present.  This presentation will discuss the importance of metabolism studies for determining incurred and non-extractable residues, leading to subsequent tolerance enforcement method development and radiovalidation. The importance of these methods as they relate to pesticide screening for food safety will be discussed.<br/>

What is extractability? Are non-extractable residues in our food supply?

256th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.