The conventional practice for the estimation of residues of insecticides in the milk of dairy cattle relies upon dietary burden calculations coupled with milk transfer factors often obtained from livestock feeding studies. Additional exposure pathways for dairy livestock commonly include animal health treatments using sprays, dips, or ear tags impregnated with insecticides to prevent stresses to the animals from biting insects. When combining these pathways, the easiest and most conservative approach is to combine maximum estimated milk residues arising from dietary sources with maximum milk residues arising from animal health sources. Human acute dietary assessments conducted from these maximum combined milk residue point estimates will be overly conservative and will present an overestimate of exposure. This presentation demonstrates a simple technique to better estimate potential human dietary exposures via milk residues from multiple pathways through the use of a probabilistic approach. This technique for combining estimated milk residues from livestock dietary burden sources with actual ear tag magnitude-of-residue data for use in acute dietary human exposure assessments is still adequately conservative and is suitable for use in regulatory assessments in support of U.S. EPA pesticide registrations.

Probabilistic dietary assessment technique for refining combined milk residues resulting from livestock dietary burden sources with milk residues resulting from insecticide-impregnated ear tags to mitigate potential acute dietary exposures

256th National Meeting (2018)

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