Rocky Flats Environmental Technology Site Research Articles

Substructural Components of Organic Colloids from a Pu-Polluted Soil with Implications for Pu Mobilization.

Contaminated soil organic matter from the Rocky Flats Environmental Technology Site (RFETS) has been previously shown to accumulate plutonium (Pu) in a colloidal subfraction and is hypothesized to contain cutin-like chemical structures cross-linked with hydroxamate functionality. The present study further characterizes this high Pu affinity subfraction using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICRMS) and discovers additional substructural components. The Pu-enriched fraction was extracted and purified through a series of ultrafiltration and isoelectric focusing (IEF) electrophoresis steps. Predominantly low H/C and high double-bond equivalence (DBE) aromatic and condensed aromatic molecular formulas were detected, 66% of which are included in a COO Kendrick mass defect (KMD) homologous series. This suggests the existence of polycarboxylated aromatic and condensed aromatic formulas, with CHON-type COO KMD formulas relatively more abundant in the purified subfraction where Pu had been observed than in the crude soil fractions which had successively lower Pu concentrations. Nitrogen contents increased with the progression of purification (bulk soil → crude colloid → IEF colloid) and coincided with the trend of Pu concentration; thus, we propose that these nitrogen and carboxyl functionalities of aromatic compounds may also impart significant Pu chelation character to the colloid.

Performance evaluation of AERMOD, CALPUFF, and legacy air dispersion models using the Winter Validation Tracer Study dataset

The performance of the steady-state air dispersion models AERMOD and Industrial Source Complex 2 (ISC2), and Lagrangian puff models CALPUFF and RATCHET were evaluated using the Winter Validation Tracer Study dataset. The Winter Validation Tracer Study was performed in February 1991 at the former Rocky Flats Environmental Technology Site near Denver, Colorado. Twelve, 11-h tests were conducted where a conservative tracer was released and measured hourly at 140 samplers in concentric rings 8 km and 16 km from the release point. Performance objectives were unpaired maximum one- and nine-hour average concentration, location of plume maximum, plume impact area, arc-integrated concentration, unpaired nine-hour average concentration, and paired ensemble means. Performance objectives were aimed at addressing regulatory compliance, and dose reconstruction assessment questions. The objective of regulatory compliance is not to underestimate maximum concentrations whereas for dose reconstruction, the objective is an unbiased estimate of concentration in space and time. Performance measures included the fractional bias, normalized mean square error, geometric mean, geometric mean variance, correlation coefficient, and fraction of observations within a factor of two. The Lagrangian puff models tended to exhibit the smallest variance, highest correlation, and highest number of predictions within a factor of two compared to the steady-state models at both the 8-km and 16-km distance. Maximum one- and nine-hour average concentrations were less likely to be under-predicted by the steady-state models compared to the Lagrangian puff models. The characteristic of the steady-state models not to under-predict maximum concentrations make them well suited for regulatory compliance demonstration, whereas the Lagrangian puff models are better suited for dose reconstruction and long range transport.

Cleanup, not cover-up, at Rocky Flats

The article “Science-Based Cleanup of Rocky Flats” demonstrates a clear conflict of interest. For the record, the authors worked for Kaiser-Hill Co, the US Department of Energy contractor responsible for cleaning up Rocky Flats; their neutrality is suspect. Independent, scientific reviews of the cleanup have been written by contractors that neighboring municipalities hired, by a consortium of water users, and by DOE-hired experts. 1–3 1. GEI Consultants Inc, Interim Measure/Interim Remedial Action: For Groundwater at the Rocky Flats (rep. prepared for the city of Westminster and the city and county of Broomfield, CO), Glastonbury, CT (10 February 2005).2. S. F. Dwyer, Review of the Original Landfill Closure Design, Specifications, and CQAP for the Rocky Flats Environmental Technology Site, Golden, Colorado (rep. prepared for the Woman Creek Reservoir Authority), Sandia National Laboratories, Albuquerque, NM (23 May 2005).3. Muller Engineering Co Inc, Walnut Creek Drainages Pond Reconfiguration Review (rep. prepared for the city and county of Broomfield, CO), Muller Engineering Co Inc, Lakewood, CO (28 March 2005). All the reviewers expressed concern about the effectiveness of the remediation. Plutonium dioxide is known to exist on the site as a finely dispersed solid. In that form it can be carried as part of a colloidal suspension in the groundwater. It will also be suspended in the air if burrowing animals bring it up from the contaminated rubble left on the site. Additionally, no independent evaluation has been conducted of the bedrock under the 10-square-mile site, which is in an earthquake zone. It is questionable that an area of this size will have no fractures in the event of an earthquake. Two unlined 20-acre, 40-foot-deep landfills were left on the site, covered by only a few feet of soil. Not only do they contain radioactive materials but also other carcinogens such as compounds of beryllium and volatile organic compounds that will eventually contaminate the groundwater. Rocky Flats will be opened to the public for general recreation, and I shudder to think of children playing at this site. As a former member of the Rocky Flats Citizens Advisory Board and a chemist, I find this unacceptable. This isn’t a cleanup, it’s a cover-up.REFERENCESSection:ChooseTop of pageREFERENCES <<1. GEI Consultants Inc, Interim Measure/Interim Remedial Action: For Groundwater at the Rocky Flats (rep. prepared for the city of Westminster and the city and county of Broomfield, CO), Glastonbury, CT (10 February 2005). Google Scholar2. S. F. Dwyer, Review of the Original Landfill Closure Design, Specifications, and CQAP for the Rocky Flats Environmental Technology Site, Golden, Colorado (rep. prepared for the Woman Creek Reservoir Authority), Sandia National Laboratories, Albuquerque, NM (23 May 2005). Google Scholar3. Muller Engineering Co Inc, Walnut Creek Drainages Pond Reconfiguration Review (rep. prepared for the city and county of Broomfield, CO), Muller Engineering Co Inc, Lakewood, CO (28 March 2005). Google Scholar© 2007 American Institute of Physics.

Rocky Flats closure: The role of models in facilitating scientific communication with stakeholder groups

The Rocky Flats Environmental Technology Site (RFETS) was a U.S. Department of Energy (DOE) environmental cleanup site for a previous manufacturing plant that made components for the U.S. nuclear weapons arsenal. The facility was shut down in 1989 to address environmental and safety concerns, and left behind a legacy of contaminated facilities, soils, surface and ground water. In 1995, the Site contractor established the Actinide Migration Evaluation (AME) advisory group to provide advice and technical expertise on issues of actinide behavior and mobility in the air, surface water, groundwater, and soil. Through a combination of expert judgment supported by state-of-the-art scientific measurements, it was shown that under environmental conditions at Rocky Flats, plutonium and americium form insoluble oxides that adhere to small soil, organic, and mineral particles and colloids, or are colloidal materials themselves. A series of models ranging from conceptual, geostatistial, and large-scale wind and surface water erosion models were used to guide stakeholder interactions. The nature of these models, and their use in public communication is described.

XANES identification of plutonium speciation in RFETS samples

Using primarily X-ray absorption near edge spectroscopy (XANES) with standards run in tandem with samples, probable plutonium speciation was determined for 13 samples from contaminated soil, acid-splash or fire-deposition building interior surfaces, or asphalt pads from the Rocky Flats Environmental Technology Site (RFETS). Save for extreme oxidizing situations, all other samples were found to be of Pu(IV) speciation, supporting the supposition that such contamination is less likely to show mobility off site. EXAFS analysis conducted on two of the 13 samples supported the validity of the XANES features employed as determinants of the plutonium valence.

AWWA Members Among 2006 AAEE Award Winners

This article announces the 2006 Excellence in Environmental Engineeringμ Awards competition winners that ranged from a cleanup of a Superfund site in Colorado to a seawater desalination facility in California to an advanced wastewater treatment facility in Virginia. The top 2006 award, the Superior Achievement for Excellence in Environmental Engineering Award, was won by Kaiser‐Hill Co. LLC, a joint venture between AWWA member CH2M HILL and IFC Kaiser, for its cleanup of the Rocky Flats Environmental Technology Site.

Vertical migration of 134Cs bearing soil particles in arid soils: implications for plutonium redistribution

Vertical migration of plutonium in soils at the Waste Isolation Pilot Plant (WIPP) and the Rocky Flats Environmental Technology Site (RFETS) was evaluated based on observed 134Cs migration in soil column experiments. After applying 134Cs-labeled soil particles to the surfaces of large, undisturbed soil cores collected from each site, resulting soil columns were subjected to experimental cycles of irrigation plus drying (treatment columns) or to cycles of irrigation only (control columns). Mean losses of 134Cs inventory from soil surfaces were 3.1 ± 0.6% cycle −1 and 0.7 ± 0.6% cycle −1 respectively for RFETS treatment and control columns. WIPP columns had mean respective losses of 1.3 ± 1.2% cycle −1 and 0.5 ± 0.2% cycle −1. Bulk transport of labeled soil particles through soil cracks was an important process in RFETS soils, accounting for 64–86% of total 134Cs migration. Colloidal transport processes governed migration in WIPP soils.

Actinides in deer tissues at the rocky flats environmental technology site

Limited hunting of deer at the future Rocky Flats National Wildlife Refuge has been proposed in U.S. Fish and Wildlife planning documents as a compatible wildlife-dependent public use. Historically, Rocky Flats site activities resulted in the contamination of surface environmental media with actinides, including isotopes of americium, plutonium, and uranium. In this study, measurements of actinides [Americium-241 (241Am); Plutonium-238 (238Pu); Plutonium-239,240 (239,240Pu); uranium-233,244 (233,234U); uranium-235,236 (235,236U); and uranium-238 (238U)] were completed on select liver, muscle, lung, bone, and kidney tissue samples harvested from resident Rocky Flats deer (N = 26) and control deer (N = 1). In total, only 17 of the more than 450 individual isotopic analyses conducted on Rocky Flats deer tissue samples measured actinide concentrations above method detection limits. Of these 17 detects, only 2 analyses, with analytical uncertainty values added, exceeded threshold values calculated around a 1 x 10(-6) risk level (isotopic americium, 0.01 pCi/g; isotopic plutonium, 0.02 pCi/g; isotopic uranium, 0.2 pCi/g). Subsequent, conservative risk calculations suggest minimal human risk associated with ingestion of these edible deer tissues. The maximum calculated risk level in this study (4.73 x 10(-6)) is at the low end of the U.S. Environmental Protection Agency's acceptable risk range.

Recovery of Plutonium from Refractory Residues Using a Sodium Peroxide Pretreatment Process

:The recycle of plutonium from refractory residues is a necessary activity for the nuclear weapon production complex. Traditionally, high-lired plutonium oxide (PuO2) was leached from the residue matrix using a nitric acid/fluoride dissolving flow sheet. The recovery operations were time consuming and often required multiple contacts with fresh dissolving solution to reduce the plutonium concentration to levels where residual solids could be discarded. Due to these drawbacks, the development of an efficient process for the recovery of plutonium from refractory materials is desirable. To address this need, a pretreatment process was developed, which utilizes a sodium peroxide (Na2O2) fusion to oxidize plutonium from the 4+ to the 6+ valence forming an acid-soluble ternary oxide. The development program utilized a series of small-scale experiments to optimize processing conditions for the fusion process and demonstrate the plutonium recovery efficiency using ceramic materials developed as potential long-term storage forms for PuO2 and an incinerator ash from the Rocky Flats Environmental Technology Site (Rocky Flats) as test materials.Process optimization studies using high-fired PuO2 demonstrated that the efficiency of plutonium recovery increased with the Na2O2 fusion temperature (up to 700°C), increasing Na2O2 to PuO2 ratio and a decrease in the Na2O2 particle size. Complete recovery of high-fired PuO2 was obtained by dissolving the fused product in 8 M nitric acid following fusion at 700°C for 2h with 100% excess in the amount of Na2O2 required for complete conversion to the ternary oxide.In the initial demonstration of the process, the plutonium-containing ceramics were fused with Na2O2 and dissolved in 8 M nitric acid. Plutonium recovery efficiencies ranged from approximately 95% to essentially complete recovery. The second demonstration of the fusion process was performed using incinerator ash from Rocky Flats.In experiments with ash containing 17-18wt% plutonium, 90-95% recovery was obtained following dissolution of the fused product in 8 M nitric acid. In subsequent experiments with ash containing only 8-9 wt% plutonium, the recovery efficiencies were significantly less, ranging from 60-90% for experiments performed using similar conditions. The general reduction in the recovery efficiency was attributed to at least a two- to three-fold increase in the silicon dioxide (SiO2) concentration. Because the ash was predominately SiO2, a material which reacts with Na2O2, it is doubtful that sufficient Na2O2 was added to completely oxidize the plutonium.

Actinides in Deer Tissues at the Rocky Flats Environmental Technology Site

Limited hunting of deer at the future Rocky Flats National Wildlife Refuge has been proposed in U.S. Fish and Wildlife planning documents as a compatible wildlife-dependent public use. Historically, Rocky Flats site activities resulted in the contamination of surface environmental media with actinides, including isotopes of americium, plutonium, and uranium. In this study, measurements of actinides [Americium-241 (241Am); Plutonium-238 (238Pu); Plutonium-239,240 (239,240Pu); uranium-233,244 (233,234U); uranium-235,236 (235,236U); and uranium-238 (238U)] were completed on select liver, muscle, lung, bone, and kidney tissue samples harvested from resident Rocky Flats deer (N = 26) and control deer (N = 1). In total, only 17 of the more than 450 individual isotopic analyses conducted on Rocky Flats deer tissue samples measured actinide concentrations above method detection limits. Of these 17 detects, only 2 analyses, with analytical uncertainty values added, exceeded threshold values calculated around a 1 × 10−6 risk level (isotopic americium, 0.01 pCi/g; isotopic plutonium, 0.02 pCi/g; isotopic uranium, 0.2 pCi/g). Subsequent, conservative risk calculations suggest minimal human risk associated with ingestion of these edible deer tissues. The maximum calculated risk level in this study (4.73 × 10−6) is at the low end of the U.S. Environmental Protection Agency's acceptable risk range.

Characterization of organic-rich colloids from surface and ground waters at the actinide-contaminated Rocky Flats Environmental Technology Site (RFETS), Colorado, USA

Colloids, i.e. nanoparticles and macromolecules, play an important role in the environmental dispersion of actinides. Thus, colloids (3 kDa–0.5 μm) were collected and purified from three different environments, i.e. surface water, pond water and near-surface ground water at the Rocky Flats Environmental Technology Site, Colorado, where elevated actinide concentrations had previously been documented. Their chemical composition was determined in order to better understand their role in actinide migration. All three types of colloid samples were found to be similar in chemical composition, with a higher percentage of organic carbon, OC (5–18%), than any other measured component, and only small amounts of Si, Mn, Al, and Fe (1.5% or below). Analytically determined components account for 40–56% of the colloidal matter, with water likely making up the difference. Transmission electron microscopy (TEM) images of colloidal material from all three sample types indicate the presence of cellulose or chitin, likely from plant (terrestrial and/or aquatic) material. Other major components include humic acid type particles, with only small amounts (<5%) of mineral particles. Our findings of colloids high in organic and low in inorganic matter content agree with previously reported results on Pu(IV) associated with an acidic natural macromolecular organic compound that also contains small amounts of Fe. Pu/OC and Fe/OC ratios both showed a steady decrease from surface water to pond water to groundwater, with a more marked decrease in the Fe/OC ratio, but no significant change in overall colloidal organic carbon (COC) concentrations.

QUANTIFICATION OF ACTINIDE MIGRATION PATHWAYS AT ROCKY FLATS, COLORADO1

ABSTRACT: Migration of plutonium, americium, and uranium (actinides) in the environment at the Rocky Flats Environmental Technology Site (RFETS) is the subject of ongoing studies to develop effective strategies for cleanup and regulatory closure of the Department of Energy facility. The Actinide Migration Evaluation pathway analysis quantified actinide transport processes to validate a qualitative conceptual model of environmental actinide transport. Major actinide transport mechanisms evaluated include surface water, ground water, airborne, and biological pathways. Relative quantities of actinide movement via different pathways were compared in terms of actinide loads delivered off the RFETS, using a combination of monitoring data, predictive transport models and results from historic RFETS studies. Results indicate air and surface water constitute the dominant transport mechanisms for plutonium and americium. In ground water, shallow alluvial flow is a limited pathway for plutonium and americium because of the low aqueous solubility of these actinides and their tendency to sorb to soil. However, localized flow in shallow alluvium is a more significant pathway for uranium movement, because of the relatively higher solubility of uranium (VI) species, though isotopic ratios indicate much of the uranium is from natural sources. Biological transport of actinides by mammals, birds, fish, and arthropods is small compared to the other pathways.

Resolving global versus local/regional Pu sources in the environment using sector ICP-MS

Sector inductively coupled plasma mass spectrometry is a versatile method for the determination of plutonium activities and isotopic compositions in samples containing this element at fallout levels. Typical detection limits for 239 + 240Pu are 0.1, 0.02 and 0.002 Bq kg−1Pu for samples sizes of 0.5 g, 3 g, and 50 g of soil, respectively. The application of sector ICP-MS-based Pu determinations is demonstrated in studies in sediment chronology, soil Pu inventory and depth distribution, and the provenance of global fallout versus local or regional Pu sources. A sediment core collected from Sloans Lake (Denver, Colorado, USA) exhibits very similar 137Cs and 239 + 240Pu activity profiles; 240Pu/239Pu atom ratios indicate possible small influences from the Nevada Test Site and/or the Rocky Flats Environmental Technology Site. An undisturbed soil profile from Lockett Meadow (Flagstaff, Arizona, USA) exhibits an exponential decrease in 239 + 240Pu activity versus depth; 240Pu/239Pu in the top 3 cm is slightly lower than the global fallout range of 0.180 ± 0.014 due to possible regional influence of Nevada Test Site fallout. The 239 ± 240Pu inventory at Lockett Meadow is 56 ± 4 Bq m−2, consistent with Northern Hemisphere mid-latitude fallout. Archived NdF3 sources, prepared from Polish soils, demonstrate that substantial 239 + 240Pu from the 1986 Chernobyl disaster has been deposited in north eastern regions of Poland; compared to global fallout, Chernobyl Pu exhibits higher abundances of 240Pu and 241Pu. The ratios 240Pu/239Pu and 241Pu/239Pu co-vary and range from 0.186–0.348 and 0.0029–0.0412, respectively, in forest soils (241Pu/239Pu = 0.2407·[240Pu/239Pu] − 0.0413; r2 = 0.9924).

Inverse dependency of particle residence times in ponds to the concentration of phosphate, the limiting nutrient

234Th, a commonly used short-lived particle-reactive tracer in marine systems, was measured in three different holding pond series at the Rocky Flats Environmental Technology Site (RFETS), Colorado, along with its parent nuclide 238U, to determine steady-state residence times of particle-reactive actinides such as Pu, and of particles. Series B ponds, which received industrial effluent that includes ortho-phosphate (PO 4) and actinides, differed from series A and C ponds, which did not. This difference was also evident in the calculated particle residence times, which were <1 day for the ponds B4 and B5, where PO 4 concentrations were higher (1.4 and 1.8 mg/l), and 3 and 3.4 days for ponds A3 and C2, respectively, where ortho-phosphate concentrations were lower (<0.1 mg/l). Particle residence times thus showed an inverse relationship with the concentration of ortho-phosphate, the limiting nutrient in fresh water systems. The same relationship to the concentration of ortho-phosphate or any of the other nutrient elements was not evident for the residence times of dissolved 234Th, which ranged between 0.1 and 2 days. This can be attributed to higher concentrations of dissolved and particulate ligands with greater binding potential for actinides such as four-valent Th and Pu in ponds with higher ortho-phosphate concentrations. Regardless of actual ortho-phosphate concentration, however, at water residence (holding) times of 1 month in these ponds, particles and associated actinides would be expected to be completely removed from the pond water to sediments.

MARSSIM vs. DOE Order 5400.5: the Final Status Survey plan at the Rocky Flats Environmental Technology Site.

A challenge unique to the decommissioning of Department of Energy (DOE) facilities involves the compromise between the existing and newly recommended standards for the unrestricted release of property and materials. The Rocky Flats Environmental Technology Site (RFETS) is currently decommissioning numerous plutonium contaminated facilities. The default DOE standard for unrestricted release, Order 5400.5, defines surface activity guidelines as averaged over a 1-square-meter area with a maximum value defined for any given 100-square-centimeter area. While the Order was initially developed to release property and materials from an operating site, it is restrictive in its use when performing Final Status Survey and, to date, no new complex wide standard has been developed. However, the RFETS stakeholders selected the MARSSIM, which provides a progressive method to demonstrate compliance with the defined "dose-based" limits for a specific site, as the governing document in developing a final survey method. The end result is a hybrid final status survey plan that incorporates the requirements of both documents. This plan represents several years of development and negotiation between the contractor, the DOE, the Colorado Department of Public Health and Environment, the Rocky Flats stakeholders, and other interested parties.

Cost-Benefit of Final Radiological Survey Versus Radioactive Waste Disposal

A significant portion of the cost for D&D is related to low-level waste disposal, decontamination, and final radiological survey. For that reason, a careful cost-benefit analysis must be performed weighing the cost of decontaminating and radiologically surveying the building media for release against the cost of disposing of the material as radioactive waste. This cost-benefit analysis visibly came into play at the Rocky Flats Environmental Technology Site during the recent D&D of two facilities.

Anthropogenic 236U at Rocky Flats, Ashtabula river harbor, and Mersey estuary: three case studies by sector inductively coupled plasma mass spectrometry

236U (t 1/2=2.3×10 7 y) is formed as a result of thermal neutron capture by 235U. In naturally occurring U ores, where a high neutron flux is present from spontaneous fission of 238U, 236U/ 238U atom ratios are ~10 −4 ppm. In the natural Earth’s crust, unaffected by nuclear fallout, these ratios are expected to be on the order of 10 −8 ppm. Reactor-irradiated U, however, exhibits high 236U/ 238U atom ratios approaching 10 4 ppm. As a result, the presence of very small quantities of reactor-irradiated U will significantly enhance the ‘background’ 236U/ 238U atom ratio. When sufficiently elevated 236U/ 238U ratios are present, the determination of 236U/ 238U by rapid inductively coupled plasma mass spectrometric (ICPMS) methods is attractive. We have used sector ICPMS at medium resolving power (R=3440) to measure 236U/ 238U atom ratios with a determination limit of 0.2 ppm. The limiting factors in the measurement are the 235U 1H + isobar and background signal at m/z 236 arising from the 238U + peak tail. Based upon the analysis of replicates and considerations of possible systematic errors, uncertainties of ±5% are found for 236U/ 238U atom ratios of 1−100 ppm. This procedure has been demonstrated in studies of anthropogenic 236U in the environment at three locations: (a) offsite soils from the vicinity of the Rocky Flats Environmental Technology site (Golden, Colorado, USA); (b) sediments from the Ashtabula River (Ohio, USA); and (c) sediments from the Mersey estuary (Liverpool, UK). In each of these three locations, definite plumes of elevated 236U/ 238U are identified and characterized. Maximum 236U/ 238U atom ratios observed in RFETS-vicinity soils, the Ashtabula River, and the Mersey Estuary are 2.8, 140, and 4.4 ppm, respectively.

Actinide Migration from Contaminated Soil to Surface Water at the Rocky Flats Environmental Technology Site

:Surficial soils of the Rocky Flats Environmental Technology Site (RFETS) contain elevated levels of 239,240Pu and 241Am due to wind dispersal of soil particles, contaminated in the 1960's by leaking drums stored on the 903 Pad. Over the past 4 years, actinide mobility in the surface environment at RFETS, Golden, Colorado, USA, was examined through field and laboratory experiments. From measurements of total 239,240Pu and 241Am concentrations in storm runoff and pond discharge samples, collected during spring and summer times, it was established that most of the actinide transport from contaminated soils to streams occurred in the particulate (0.45μm) and colloidal (3kDa – 0.45μm) phases. Controlled laboratory investigations of soil resuspension, indicated that remobilization of colloid-bound Pu during soil erosion events can be enhanced by humic acidsl).2-D Polyacrylamide Gel electrophoresis (PAGE) experiments of radiolabeled colloidal organic and inorganic matter, extracted from RFETS soils, suggested that colloidal Pu, which was focused at pHIEP p of 4.5, is mainly associated with organic (humic acids) colloids of 10-15 kDa molecular weight. Pu(IV) oxide and inorganic colloids such as iron and aluminum oxides have pHIEP of 8-10. While some clay minerals also have pHIEP of 3-5, no Al was found coincident with Pu. This finding has important ramifications for possible remediation, erosion controls, and land-management strategies.

Assessment of community contamination: a critical approach.

The purpose of this paper is to review data from two Superfund sites and describe the latitude of interpretation of "environmental risk" by residents living in the area, governmental agencies, and the media. The first community was located within a 5-mi perimeter of the Rocky Flats Environmental Technology Site (RFETS) outside Denver, Colorado. The second community was located on the south side of Tucson, Arizona, adjacent to the Tucson International Airport area (TIAA) Superfund site. Critical theory was the perspective used in this analysis and proposal of public health actions to attain social justice. Differences between the two populations' experiences with risk and contamination coincided with divergent levels of trust in government. RFETS residents demanded monitoring, whereas the minority residents at TIAA were ambivalent about their trust in government cleanup activities. Unraveling the purpose of "facts" and the social force of "truth" can direct nurses to address environmental justice issues. By policing governmental and business activities in halting or cleaning up environmental contamination, nurses may become mouthpieces for the concerns underlying the fragile surface of "virtual trust" in contaminated communities. Cutting through competing rhetoric to police environmental safety, the core function of assurance becomes what nurses do, not what they say.

Risks to the public from historical releases of radionuclides and chemicals at the Rocky Flats Environmental Technology Site

This paper summarizes the methods and results of estimating risks of cancer incidence resulting from plutonium, carbon tetrachloride, and beryllium releases from operations at the Rocky Flats Environmental Technology Site, near Denver, Colorado, from 1953 through 1989. The key findings show that people who lived near the facility were exposed to plutonium mainly through inhalation during routine operations, from a major fire in 1957, and from plutonium resuspended from contaminated soil from an outdoor drum storage area, called the 903 Area. Results were presented for five exposure scenarios that were location-independent. Individuals described by the laborer scenario received the highest risk of all scenarios considered. Upper bound (95th percentile) incremental lifetime cancer incidence risks for the laborer scenario were in about the 10(-4) range (1 chance in 10,000) for developing cancer from Rocky Flats plutonium releases during a lifetime. At the 5th percentile level, the maximum cancer risk was about 10(-7) (1 chance in 10 million) for developing cancer during a lifetime. Estimated cancer risks at the 95th percentile level are within the range of for acceptable risks established by the US Environmental Protection Agency of 10(-6) to 10(-4). Carbon tetrachloride was found to be the chemical that presented the highest risk to the public. The 5th and 95th percentile risk values for exposure to carbon tetrachloride were 9.2x10(-7) and 2.5x10(-5), respectively.