Stehly, G. R., Landrum, P. F., Henry, M. G., and Klemm, C., 1990, Toxicokinetics of PAHs in Hexagenia: Environmental Toxicology and Chemistry, v. 9, no. 2, p. 167-174. Abstract: The accumulation kinetics of two waterborne polycyclic aromatic hydrocarbons (PAHs), beno(a)pyrene (BAP) and phenanthrene (PHE), were studied in the mayfly nymph (Hexagenia limbata ). The clearance of oxygen from water is inversely and linearly related to the weight of the mayfly nymphs, but oxygen clearances were always much less than the uptake clearances of the PAHs. The high PAH uptake clearance compared to oxygen clearance implies a greater surface area or efficiency for PAH accumulation from water. Keywords: benzoapyrene, phenanthrene, bioaccumulation, kinetics, clearance, Hexagenia-limbata, polycyclic- aromatic-hydrocarbons, toxicology, aquatic-insects, aromatic-hydrocarbons