Radionuclides in soil and water near a low-level disposal site and potential ecological and human health impacts

Material Disposal Area G is the primary low-level radioactive waste disposal site at Los Alamos National Laboratory, New Mexico, and is adjacent to Pueblo of San Ildefonso lands. Pueblo residents and Los Alamos scientists are concerned about radiological doses resulting from uptake of Area G radionuclides by mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus), then consumption of deer and elk meat by humans. Tissue samples were collected from deer and elk accidentally killed near Area G and were analyzed for 3H, 90Sr, total U, 238Pu, 239,240Pu, 241Am, and 137Cs. These data were used to estimate human doses based on meat consumption of 23 kg y(-1). Human doses were also modeled using RESRAD, and dose rates to deer and elk were estimated with a screening model. Dose estimates to humans from tissue consumption were 2.9 x 10(-3) mSv y(-1) and 1.6 x 10(-3) mSv y(-1) from deer and elk, respectively, and RESRAD dose estimates were of the same order of magnitude. Estimated dose rates to deer and elk were 2.1 x 10(-4) mGy d(-1) and 4.7 x 10(-4) mGy d(-1), respectively. All estimated doses were significantly less than established exposure limits or guidelines.

Radionuclides in deer and elk from Los Alamos National Laboratory and the doses to humans from the ingestion of muscle and bone

This paper summarizes radionuclide concentrations (3H, 90Sr, 137Cs, 238Pu, 239,240Pu, 241Am, and totU) in muscle and bone tissue of mule deer (Odocoileus hemionus) and Rocky Mountain elk (Cervus elaphus) collected from Los Alamos National Laboratory (LANL), Los Alamos, New Mexico, lands from 1991 through 1998. Also, the committed effective dose equivalent (CEDE) and the risk of excess cancer fatalities (RECF) to people who ingest muscle and bone from deer and elk collected from LANL lands were estimated. Most radionuclide concentrations in muscle and bone from individual deer (n = 11) and elk (n = 22) collected from LANL lands were either at less than detectable quantities (where the analytical result was smaller than two counting uncertainties) and/or within upper (95%) level background (BG) concentrations. As a group, most radionuclides in muscle and bone of deer and elk from LANL lands were not significantly higher (p < 0.10) than in similar tissues from deer (n = 3) and elk (n = 7) collected from BG locations. Also, elk that had been radio collared and tracked for two years and spent an average time of 50% of LANL lands were not significantly different in most radionuclides from road kill elk that have been collected as part of the environmental surveillance program. Overall, the upper (95%) level net CEDEs (the CEDE plus two sigma for each radioisotope minus background) at the most conservative ingestion rate (50 lbs of muscle and 13 lbs of bone) were as follows: deer muscle = 0.22 mrem y-1 (2.2 microSv y-1), deer bone = 3.8 mrem y-1 (38 microSv y-1), elk muscle = 0.12 mrem y-1 (1.2 microSv y-1), and elk bone = 1.7 mrem y-1 (17 microSv y-1). All CEDEs were far below the International Commission on Radiological Protection guideline of 100 mrem y-1 (1000 microSv y-1), and the highest muscle plus bone net CEDE corresponded to a RECF of 2E-06, which is far below the Environmental Protection Agency upper level guideline of 1E-04.