While there are over 700 assays within the ToxCast program, to our knowledge none of these assays directly address chemical-mediated PPO inhibition nor impacts on hemoglobin production, suggesting that our targeted, whole-organism HCS assay has the potential to identify a unique mechanism (PPO inhibition) and phenotype (anemia) not currently covered by the large battery of existing ToxCast assays. This evidence concerns the gene PPOX and anemia (phenotype).