[en] This report provides an initial evaluation of the dependence on chemical forms of estimates of health effects from radionuclides in high-level waste (HLW). Discussion is limited mainly to a review of studies of plutonium, americium, neptunium, and strontium that may be useful in identifying (a) chemical forms of these radionuclides that are likely to reach humans after migration from a waste repository and (b) differences in metabolism and organ doses that result from intake of various chemical forms of these radionuclides; we also attempt to identify research needs in these two areas. In addition to providing a limited review of the literature, this report identifies some of the problems involved in determining speciation of these radionuclides in the environment and provides a general picture of the potential errors that may be involved in applying models assumed to be independent of chemical form to estimate metabolism and dose from exposure to different chemical species of a radionuclide. 76 references, 2 figures, 4 tables