Structure of the life-stage pyrethroid PBPK model. QLIVGI, QLIVH, QRP, QSP, QFAT, QBRN refer to blood flow to each tissue compartment. QLIV is the sum of QLIVGI and QLIVH (the liver has a dual blood supply from arterial and venous blood). QALV refers to the alveolar ventilation rate. Brain, fat, and slowly perfused tissue compartments are described as diffusion-limited tissues, whereas all other tissue compartments are described as flow limited.