Neptunium: The Neglected Actinide: A Review of the Biological and Environmental Literature

from that of other transuranic elements. It is more mobile environmentally and more readily absorbed by man, although some of the higher reported values for gastrointestinal absorption appear to have been influenced by the very high mass levels of 237Np required for experimental study. In studies with experimental animals its ratio of deposition in bone/liver is greater than that of other transuranic elements. Its long-term toxicity in experimental animals is similar to that of other transuranics. Contents. Introduction. Measurements of neptunium in the environment. Experimental studies relating to neptunium in the environment. Environmental chemistry. Studies relating to food chains. Animal biokinetic studies. Absorption from and retention in the gastrointestinal tract. Absorption from and retention in the lung. Absorption from and retention in the skin and subcutaneous tissues. Deposition and retention in systemic organs (blood, bone, liver, kidney, spleen, adrenal, gonads, placenta-fetus, other tissues, excreta, enhanced excretion). Radiation dosimetry. Animal toxicity studies. Early effects. Late effects. Conclusions relative