Generally, plutonium has been manufactured to support commercial and military applications involving heat sources, weapons, and reactor fuel. This work focuses on three typical plutonium mixtures while observing the potential of 241Am ingrowth and its effect on internal dose. The term “ingrowth” is used to describe 241Am production due solely to the decay of 241Pu as part of a plutonium mixture, where it is initially absent or present in a smaller quantity. Dose calculation models do not account for 241Am ingrowth unless the 241Pu quantity is specified. This work suggested that 241Am ingrowth be considered in bioassay analysis when there is a potential of a 10% increase to the individual’s committed effective dose. It was determined that plutonium fuel mixtures, initially absent of 241Am, would likely exceed 10% for typical reactor grade fuel aged less than 30 y; however, heat source grade and aged weapons grade fuel would normally fall below this threshold. Although this work addresses typical plutonium mixtures following separation, it may be extended to irradiated commercial uranium fuel and is expected to be a concern in the recycling of spent fuel.