An independent review and prioritization of past radionuclide and chemical releases from the Los Alamos National Laboratory--implications for future dose reconstruction studies.

From 1999 through 2010, a team of scientists and engineers systematically reviewed approximately eight million classified and unclassified documents at Los Alamos National Laboratory (LANL) that describe historical off-site releases of radionuclides and chemicals in order to determine the extent to which a full-scale dose reconstruction for releases is warranted and/or feasible. As a part of this effort, a relative ranking of historical airborne and waterborne radionuclide releases from LANL was established using priority index (PI) values that were calculated from estimated annual quantities released and the maximum allowable effluent concentrations according to The U.S. Nuclear Regulatory Commission (USNRC). Chemical releases were ranked based on annual usage estimates and U.S. Environmental Protection Agency (USEPA) toxicity values. PI results for airborne radionuclides indicate that early plutonium operations were of most concern between 1948 and 1961, in 1967, and again from 1970 through 1973. Airborne releases of uranium were found to be of most interest for 1968, from 1974 through 1978, and again in 1996. Mixed fission products yielded the highest PI value for 1969. Mixed activation product releases yielded the highest PI values from 1979 to 1995. For waterborne releases, results indicate that plutonium is of most concern for all years evaluated with the exception of 1956 when (90)Sr yielded the highest PI value. The prioritization of chemical releases indicate that four of the top five ranked chemicals were organic solvents that were commonly used in chemical processing and for cleaning. Trichloroethylene ranked highest, indicating highest relative potential for health effects, for both cancer and non-cancer effects. Documents also indicate that beryllium was used in significant quantities, which could have lead to residential exposures exceeding established environmental and occupational exposure limits, and warrants further consideration. In part because of the close proximity of residents to LANL, further study of historical LANL releases and the potential impact to public health is recommended for those materials with the largest priority index values; namely, plutonium, uranium, and selected chemicals.

Characterization of the world's first nuclear explosion, the Trinity test, as a source of public radiation exposure.

The world's first atomic bomb was tested in New Mexico on 16 July 1945. From 1999 through 2008, scientists working for the Centers for Disease Control and Prevention gathered information relevant to past releases from Los Alamos activities, including the Trinity test. Detonation on a 30.5 m tower enhanced radioactive fallout, and terrain and wind patterns caused "hot spots" of deposition. Several ranchers reported that fallout resembling flour was visible for 4 to 5 d after the blast, and residents living as close as 19 km from ground zero collected rain water from metal roofs for drinking. Pressures to maintain secrecy and avoid legal claims led to decisions that would not likely have been made in later tests. Residents were not warned before the test or informed afterward about potential protective actions, and no evacuations were conducted. Occupied homes were overlooked on the day of the blast. Exposure rates in residential areas were recorded as high as 1.4 microC kg s (20 R h) using instruments that were crude, ill suited to field use, and incapable of effectively measuring alpha contamination from about 4.8 kg of unfissioned plutonium that was dispersed. Vehicle shielding and contamination were recognized but not corrected for. To date, the post-shot field team measurements have not been rigorously evaluated, cross-checked, adjusted, or subjected to uncertainty analysis. Evaluations of Trinity fallout published to date have not addressed internal doses to members of the public following intakes of contaminated air, water, or foods. The closing of these data gaps appears feasible with the information that has been assembled and would support placement of the Trinity event in perspective as a source of public radiation exposure and more defensible evaluation of the potential for human health effects.