Mechanistic research excluded direct effects on thyroid peroxidase (TPO) inhibition and demonstrated a dose concordance between the rat thyroid effects and induction of liver enzymes (including UDPGT activity), hepatocellular hypertrophy, and increased liver weights, providing a weight of evidence that any liver and thyroid tumor potential of this new ACCase insecticide would be secondary to liver enzyme induction. The gene discussed is TPO; the disease is thyroid tumor.