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PubMed1988

Radionuclide transport from soil to air, native vegetation, kangaroo rats and grazing cattle on the Nevada test site.

Between 1970 and 1986 the Nevada Applied Ecology Group (NAEG), U.S. Department of Energy, conducted environmental radionuclide studies at weapons-testing sites on or adjacent to the Nevada Test Site. In this paper, NAEG studies conducted at two nuclear (fission) sites (NS201, NS219) and two nonnuclear (nonfission) sites (Area 13 [Project 57] and Clean Slate 2) are reviewed, synthesized and compared regarding (1) soil particle-size distribution and physical-chemical characteristics of 239 + 240Pu-bearing radioactive particles, (2) 239 + 240Pu resuspension rates and (3) transuranic and fission-product radionuclide transfers from soil to native vegetation, kangaroo rats and grazing cattle. The data indicate that transuranic radionuclides were transferred more readily on the average from soil to air, the external surfaces of native vegetation and to tissues of kangaroo rats at Area 13 than at NS201 or NS219. The 239 + 240Pu resuspension factor for undisturbed soil at Area 13 was three to four orders-of-magnitude larger than at NS201 and NS219, the geometric mean (GM) vegetation-over-soil 239 + 240Pu concentration ratio was from ten to 100 times larger than at NS201, and the GM GI-over-soil, carcass-over-soil and pelt-over-soil 239 + 240Pu ratios for kangaroo rats were about ten times larger than at NS201. These results are consistent with the finding that Area 13, compared with NS201 or NS219, has a higher percentage of radioactivity associated with smaller soil particles and a larger percentage of resuspendable and respirable soil. However, the resuspension factor increased by a factor of 27 at NS201 when the surface soil was disturbed, and by a factor of 12 at NS219 following a wildfire. The average (GM) concentration of 239 + 240Pu for the GI (and contents) of Area 13 kangaroo rats and for the rumen contents of beef cattle that grazed Area 13 were very similar (400 vs. 440 Bq kg-1 dry wt, respectively) although the variability between individuals was very large. The GM carcass-over-GI 239 + 240Pu concentration ratio for kangaroo rats at Area 13, Clean Slate 2, and NS201 were similar in value (approximately 2 X 10(-2)), as were the GM GI-over-vegetation concentration ratios (approximately 2 X 10(0)) (no statistical differences).(ABSTRACT TRUNCATED AT 400 WORDS)

Air Pollutants, Radioactive↗

PubMed1990

Historical estimates of external gamma exposure and collective external gamma exposure from testing at the Nevada Test Site. II. Test series after Hardtack II, 1958, and summary.

The historical data on the cumulative individual external gamma exposures are tabulated for communities around the Nevada Test Site for the time periods of 1961 to the signing of the Limited Test Ban Treaty on 5 August 1963, and from then until 1975. The collective exposures during the two time periods are calculated to be 610 and 320 person-R, respectively. The total collective external gamma exposure from 1951 through 1975 for these communities s calculated to be 86,000 person-R. The area considered includes the countries of Clark, Lincoln, Nye, and White Pine in Nevada and the countries of Iron and Washington in Utah; inclusion of Salt Lake City would have substantially increased the calculated collective exposure because of the large population. The methods of calculation are reviewed. Also, the historical data on the assessment of dose via ingestion are reviewed with emphasis on the dose to the thyroid of infants living in St. George, UT, at the time of fallout from event HARRY on 19 May 1953.

Environmental Exposure↗

PubMed1990

Estimates of exposure rates and fallout arrival times near the Nevada Test Site.

One of the tasks of the Off-Site Radiation Exposure Review Project (ORERP) was to estimate doses to individuals resulting from exposure to fallout from nuclear testing at the Nevada Test Site (NTS). Dose estimates are based on estimates of the exposure rate 12 h post-detonation (H + 12) and the time of fallout arrival from events producing discernible fallout at locations off the NTS. These estimates are derived from both published fallout patterns and survey meter readings taken by monitors in the field. Each fallout pattern is digitized, and kriging is used to interpolate estimates of exposure rate and arrival time onto a 10-km grid covering the contours of the pattern. These grid values are then used to calculate estimates at any location of interest within the pattern. Exposure rate is also estimated from the survey meter readings for a particular nuclear event by decay-correcting the measurements near a selected location to H + 12 and then aggregating them into one estimate. Estimates of discernible exposure rate and time of fallout arrival from 74 nuclear events at the NTS are contained in the Town Data Base. Estimates are given for 352 locations in Arizona, California, Nevada, and Utah. Each record in the data base contains estimates for a specified event and location. The distribution of exposure rate is represented by a geometric mean and standard deviation; the distribution of fallout arrival time is represented by an arithmetic mean and standard deviation. A more extensive description and a listing of the Town Data Base are included in a separate report.

Arizona↗

PubMed1990

Estimates of fallout in the continental U.S. from Nevada weapons testing based on gummed-film monitoring data.

During periods of weapons testing at the Nevada Test Site (NTS) between 1951 and 1958, the Environmental Measurements Laboratory (EML) monitored daily fallout at about 100 sites in the U.S. using gummed-film collectors. These gummed-film data represent the only comprehensive set of actual measurements of fallout during this period for areas outside the immediate vicinity of the NTS. The measured beta activities originally reported by EML have been reviewed and reevaluated. This reevaluation corrected a number of errors in the original data set and allowed fairly accurate estimates to be made of specific radionuclide depositions from individual NTS shots. Estimates of the geographical and temporal variations in cumulative 137Cs and 131I depositions from all NTS shots through 1957 are presented, as well as estimates of the relative impact of particular shots and test series. The revised gummed-film estimates of total NTS fallout depositions are compared with estimates based on contemporary and historical soil sample analyses. These reevaluated gummed-film fallout deposition estimates are being extensively utilized in a number of ongoing programs to reconstruct the radiation exposure of the U.S. population from Nevada weapons testing.

Cesium Radioisotopes↗

PubMed1994

Radon in outdoor air in Nevada.

Measurements of radon at 50 sites with varying geology indicate that outdoor air in Nevada is comparable to that measured nationwide by Hopper et al. (1991). The statewide median of 15 Bq m-3 (0.4 pCi L-1) is essentially the same as the nationwide median. The range is considerable: from 2.6-52 Bq m-3 (0.07-1.40 pCi L-1). Variations in these measurements can generally be correlated with different concentrations of radon in soils and uranium and its progeny in rocks. Silica-rich igneous rocks (rhyolites and granites) appear to be the main sources of high levels of radon in outdoor air in Nevada. Concentrations of radon in outdoor air generally correlate with levels of radon in soil gas. Measurements taken from heights of 0.5, 1.0, and 2.0 m above the ground suggest that radon in outdoor air reflects the local geology throughout this range of heights. Towns for which > 20% of the homes have indoor-air radon concentrations > 48 Bq m-3 (4 pCi L-1) generally have relatively high soil-gas radon, relatively high outdoor-air radon, or both.

Air Pollutants, Radioactive↗

PubMed1996

Ingestion of Nevada Test Site fallout: internal dose estimates.

This paper summarizes individual and collective dose estimates for the internal organs of hypothetical yet representative residents of selected communities that received measurable fallout from nuclear detonations at the Nevada Test Site. The doses, which resulted from ingestion of local and regional food products contaminated with over 20 radionuclides, were estimated with use of the PATHWAY food-chain-transport model to provide estimates of central tendency and uncertainty. The thyroid gland received much higher doses than other internal organs and tissues. In a very few cases, infants might have received thyroid doses in excess of 1 Gy, depending on location, diet, and timing of fallout. 131I was the primary thyroid dose contributor, and fresh milk was the main exposure pathway. With the exception of the thyroid, organ doses from the ingestion pathway were much smaller (< 3%) than those from external gamma exposure to deposited fallout. Doses to residents living closest to the Nevada Test Site were contributed mainly by a few fallout events; doses to more distantly located people were generally smaller, but a greater number of events provided measurable contributions. The effectiveness of different fallout events in producing internal organ doses through ingestion varied dramatically with seasonal timing of the test, with maximum dose per unit fallout occurring for early summer depositions when milk cows were on pasture and fresh, local vegetables were used. Within specific communities, internal doses differed by age, sex, and lifestyle. Collective internal dose estimates for specific geographic areas are provided.

Adolescent↗

PubMed2001

Prevalence of thyroid diseases in Nevada counties with respect to perchlorate in drinking water.

Perchlorate is well-known to inhibit the uptake of iodine by the thyroid and has been shown to do so at doses in the milligrams-per-day range and higher. Perchlorate has been found in the water supply of Clark County (Las Vegas), Nevada, at 4 to 24 micrograms/L (parts per billion) and may provide exposure dosages in the tens of micrograms per day. An analysis of the Medicaid database from Nevada was undertaken to determine whether an increase in the prevalence of any thyroid disease was associated with that level of perchlorate content. The prevalence of persons being seen for thyroid disease or for specific thyroid diseases (goiter, nodule, thyrotoxicosis, congenital hypothyroidism, acquired hypothyroidism, thyroiditis, and other thyroid disorders) and for thyroid cancer among the Medicaid-eligible population of each county was calculated for the 2-year period 1997 to 1998. The prevalences in Clark County were compared with those in Washoe County (i.e., Reno), the second most populous county in the state, and with those for the rest of the state. There was no evidence of an increased rate of thyroid disease (or of any specific thyroid disease) associated with perchlorate exposure. Generally, the prevalences in the metropolitan parts of the state were lower than for the rest of the state, particularly for acquired hypothyroidism. This analysis found no evidence that perchlorate-containing drinking water at the given level increased the prevalence of acquired hypothyroidism or of any other thyroid condition.

Humans↗

PubMed1997

The vulnerability of the Nevada visitor economy to a repository at Yucca Mountain.

This article reviews the studies commissioned by the Nevada Nuclear Waste Project Office to estimate the economic impact of a high-level nuclear waste repository at Yucca Mountain. Case studies found that visitor impacts occur for some analogous facilities, but not for others. Assessments of behavioral intent indicate that at least some economic agents would avoid visiting Nevada under repository scenarios. A third set of studies tested the risk-aversion and negative-imagery models of visitor decision making; people avoid visiting places associated with either a significant health risk or negative imagery, but it has yet to be shown that a repository would induce these perceptions in nearby places. In sum, the NWPO-sponsored studies suggest the potential for visitor impacts, but do confirm that these effects will occur.

Humans↗

PubMed2025

Do Snow-Adapted Prey Facilitate Coexistence of the Sierra Nevada Red Fox With Sympatric Carnivores?

Specialist species in alpine ecosystems may be increasingly threatened by climate-driven habitat loss and encroachment by generalist competitors. Ecological theory predicts that niche differentiation through dietary specialisation can facilitate coexistence with generalist competitors. We quantified dietary overlap between a high-elevation specialist, the Sierra Nevada red fox (SNRF; Vulpes vulpes necator) and a widespread generalist, the coyote (Canis latrans), as well as other sympatric carnivores. We were especially interested in dietary items that were themselves specialised to alpine habitats, as we expected them to be most critical to SNRF. To characterise diet, we used DNA metabarcoding for vertebrate and plant-based food items of 789 carnivore scats collected from the sites of two SNRF populations (Lassen, Sierra Nevada). As expected for potential competitors, SNRFs exhibited substantial dietary overlap with coyotes overall. Dietary niche overlap was lower between SNRF and both bobcats (Lynx rufus) and martens (Martes caurina). Compared to coyotes, however, SNRF more frequently consumed snow-adapted prey, including white-tailed jackrabbits (Lepus townsendii) and American pika (Ochotona princeps) (SIMPER p ≤ 0.005), especially during periods of deep snow. Whitebark pine (Pinus albicaulis; presumably seeds) also appeared more regularly in SNRF winter diets compared to coyotes. These findings support the hypothesis that co-adapted subalpine prey facilitate coexistence between specialist and generalist carnivores by increasing the competitive advantage of specialists under snowier conditions. This environment-mediated shift in competitive dynamics implies that the fates of locally adapted predator and prey may be tightly linked, an important consideration for conservation planning in alpine ecosystems.

Animals↗

PubMed2004

Nonmarine crenarchaeol in Nevada hot springs.

Glycerol dialkyl glycerol tetraethers (GDGTs) are core membrane lipids of the Crenarchaeota. The structurally unusual GDGT crenarchaeol has been proposed as a taxonomically specific biomarker for the marine planktonic group I archaea. It is found ubiquitously in the marine water column and in sediments. In this work, samples of microbial community biomass were obtained from several alkaline and neutral-pH hot springs in Nevada, United States. Lipid extracts of these samples were analyzed by high-performance liquid chromatography-mass spectrometry and by gas chromatography-mass spectrometry. Each sample contained GDGTs, and among these compounds was crenarchaeol. The distribution of archaeal lipids in Nevada hot springs did not appear to correlate with temperature, as has been observed in the marine environment. Instead, a significant correlation with the concentration of bicarbonate was observed. Archaeal DNA was analyzed by denaturing gradient gel electrophoresis. All samples contained 16S rRNA gene sequences which were more strongly related to thermophilic crenarchaeota than to Cenarchaeum symbiosum, a marine nonthermophilic crenarchaeon. The occurrence of crenarchaeol in environments containing sequences affiliated with thermophilic crenarchaeota suggests a wide phenotypic distribution of this compound. The results also indicate that crenarchaeol can no longer be considered an exclusive biomarker for marine species.

Archaea↗

PubMed2005

Violence and legalized brothel prostitution in Nevada: examining safety, risk, and prostitution policy.

This article examines violence in legalized brothels in Nevada. Debates over prostitution policies in the United States have long focused on questions of safety and risk. These discourses inevitably invoke the coupling of violence and prostitution, though systematic examinations of the relationship between the two are sparse. This article explores the issue of violence in the Nevada brothel industry. By drawing on interviews with prostitutes, managers, and policy makers, this article examines both prostitutes' perceptions of safety and risk and brothel managers' practices designed to mitigate violence. Discourses relate to three types of violence: interpersonal violence against prostitutes, violence against community order, and sexually transmitted diseases as violence. The authors conclude by arguing that the legalization of prostitution brings a level of public scrutiny, official regulation, and bureaucratization to brothels that decreases the risk of these 3 types of systematic violence.

Culture↗

PubMed2004

Practices of vitamin D recommendation in Las Vegas, Nevada.

Reports of vitamin D deficiency rickets, although rare in the United States, have increased over the past few years, including in children living in climates with abundant sunshine. The purpose of this study was to describe vitamin D recommendation practices among pediatric health care providers in Las Vegas, Nevada. Of the 155 providers surveyed, 52.3% did not recommend vitamin D for exclusively breastfed babies. Providers who were more likely to recommend supplementation were doctors of medicine, were female, specialized in pediatrics, were of Hispanic ethnicity, had previously practiced and trained in states less sunny than Nevada, had graduated from training 21 or more years previously, had taken histories of infants' sun exposure, and had clinical experience with cases of rickets. Providers demonstrated a knowledge deficitforquestions that dealt with preventive measures.

Clinical Competence↗

PubMedDate not supplied

Air pollution and health effects in northern Nevada.

The issue of adverse health effects of ambient air pollution has been extensively studied and reported worldwide over the past two decades. The urban area of Reno and Sparks in northern Nevada is one of two major urban centers in Nevada; the other is Las Vegas. The northern area, which has undergone a rapid population growth in the last decade, has special geographic characteristics and air pollution patterns. We conducted environmental epidemiological studies spanning the 1990s. This report summarizes the evidence and discusses the findings in relation to other studies. Ambient air pollution levels, even when below federal standards, have a marked potential to impact human health adversely. Air pollution was associated with (1) emergency room visits for asthma; (2) hospitalization for chronic obstructive pulmonary disease; (3) hospitalization for cardio-vascular disease; (4) elementary school absenteeism; and (5) low birth weight, preterm birth, and other adverse birth outcomes.

Absenteeism↗

PubMed2001

Integration of genotoxicity and population genetic analyses in kangaroo rats (Dipodomys merriami) exposed to radionuclide contamination at the Nevada Test Site, USA.

We examined effects of radionuclide exposure at two atomic blast sites on kangaroo rats (Dipodomys merriami) at the Nevada Test Site, Nevada, USA, using genotoxicity and population genetic analyses. We assessed chromosome damage by micronucleus and flow cytometric assays and genetic variation by randomly amplified polymorphic DNA (RAPD) and mitochondrial DNA (mtDNA) analyses. The RAPD analysis showed no population structure, but mtDNA exhibited differentiation among and within populations. Genotoxicity effects were not observed when all individuals were analyzed. However, individuals with mtDNA haplotypes unique to the contaminated sites had greater chromosomal damage than contaminated-site individuals with haplotypes shared with reference sites. When interpopulation comparisons used individuals with unique haplotypes, one contaminated site had greater levels of chromosome damage than one or both of the reference sites. We hypothesize that shared-haplotype individuals are potential migrants and that unique-haplotye individuals are potential long-term residents. A parsimony approach was used to estimate the minimum number of migration events necessary to explain the haplotype distributions on a phylogenetic tree. The observed predominance of migration events into the contaminated sites supported our migration hypothesis. We conclude the atomic blast sites are ecological sinks and that immigration masks the genotoxic effects of radiation on the resident populations.

Animals↗

PubMed1991

Acquired immunodeficiency syndrome and human immunodeficiency virus infection in Nevada.

We summarize information from three sets of epidemiologic data: the Nevada AIDS [acquired immunodeficiency syndrome] Surveillance System, which contains information about every case identified within the state boundaries through September 1989; the human immunodeficiency virus (HIV) seroprevalence reporting systems, which currently include data on all HIV-positive reports submitted statewide to public health authorities; and surveys on the knowledge, attitudes, and behaviors of Nevadans concerning HIV-related disease. The Nevada State AIDS Task Force outlined major policy recommendations, nearly half of which concerned testing; only 2 dealt with preventing HIV transmission. Greater efforts should go into education, particularly directed toward groups at greatest risk of exposure to HIV, and to improve community-based care of infected persons.

Acquired Immunodeficiency Syndrome↗

PubMed1982

Training the internist for primary care: a view from Nevada.

The recent establishment of primary care residencies at the University of Nevada School of Medicine has raised important questions about local priorities in the training of physicians to provide primary care for adults. Because the amount of money available for health care training is decreasing, these questions also have national importance. Primary care internal medicine, not synonymous with general internal medicine, offers distinct advantages to patients over family practice adult care and primary care offered by internist subspecialists. The University of Nevada has a singular opportunity to organize a strong primary care internal medicine residency, but national problems of internal medicine emphasis exist. Nationwide changes in internal medicine residency programs (ongoing) and American Board of Internal Medicine nationalization of the fledgling primary care internal medicine fellowship movement are suggested. Specifically proposed is an extra year for primary care training with a single examination after four years, producing general internists with a primary care "minor." Alternately, and ideally, there would be a full two-year primary care fellowship with a separate internal medicine primary care subspecialty board examination. Either of the above options would provide necessary training and academic credibility for primary care internists, and would redirect internal medicine certification and training.

Fellowships and Scholarships↗

PubMed1993

Expanding the DOCLINE network to include nonmedical libraries in the state of Nevada.

Most libraries cannot meet patron demands for biomedical information using only their in-house collections. Consequently, many types of libraries request biomedical information through interlibrary loan, and these include not only academic health sciences libraries, hospital and special libraries, but also general libraries. In Nevada, with its small population spread over a large geographic area, it has become critical to develop a statewide network for sharing biomedical information. As the state resource library, the Savitt Medical Library launched an effort to establish a network, via DOCLINE, of all Nevada libraries that have health-related collections. The process of convincing academic and community college libraries to join DOCLINE and the resulting benefits of improved resource sharing and cooperative collection development are discussed.

Computer Communication Networks↗

PubMedDate not supplied

Motor vehicle crashes, restraint use, and severity of injury in children in Nevada.

INTRODUCTION: Data from the population-based Nevada State Trauma Registry were used to examine rates and determinants of restraint use in children who were involved in a car crash and seriously injured. Patterns of injuries in these children are also assessed. METHODS: Data were obtained from children 14 years of age or younger who entered the Nevada State Trauma Registry because of a serious injury caused by a car crash. The study period was from January 1, 1989, to December 31, 1992. RESULTS: Average annual age-specific crash injury rates per 100,000 were higher in rural areas than in urban areas. In children younger than two years old, 61% were restrained at the time of the crash; however, only about one third of all children over the age of three were restrained. In ages 0-4 years, only 5.3% of the African-American children were restrained at the time of the crash compared with 47.2% of the Caucasian children. Children who were not restrained were more likely to have more adverse outcomes and to have different types of injury compared with their restrained counterparts. CONCLUSIONS: The use of restraining devices in children who suffer a serious injury in a motor vehicle crash continues to be low and appears to be related to specific demographic characteristics. The findings indicated that restraint use at the time of the crash was related to less severe injury as indicated by certain outcome variables.

Accidents, Traffic↗