PubMed Health⌕ Search

Biomedical subjects

S B Webb

Publications and source records attributed to S B Webb.

At least 19 recordsLinked to original sources
PubMed2002

A comparison of 90Sr and 137Cs uptake in plants via three pathways at two Chernobyl-contaminated sites.

Foliar absorption of resuspended 90Sr, root uptake and contamination adhering to leaf surfaces (i.e. soil loading) were compared at two Chernobyl-contaminated sites, Chistogalovka and Polesskoye. Although foliar absorption of resuspended 90Sr was quantifiable, its contribution amounted to less than 10% of the plants' total, above-ground contamination. Root uptake was 200 times greater than foliar absorption at the near-field site of Chistogalovka and eight times greater at Polesskoye, where the fallout consisted of the more soluble condensation-type, rather than fuel particles. Strontium's bioavailability exceeded that of 137Cs (analyzed in the same plants) by orders of magnitude when compared using concentration ratios. Simplistic, cumulative effective dose calculations for humans ingesting 90Sr- and 137Cs-contaminated plants revealed that the dose at Chistogalovka was greater from 90Sr (185 mSv vs. 3 mSv from 137Cs), while at Polesskoye the dose from 137Cs (66 mSv) was 30 times greater than from 90Sr (2 mSv).

Absorption↗
PubMed2002

Variability in background levels of surface soil radionuclides in the vicinity of the US DOE waste isolation pilot plant.

Concentrations of radionuclides were measured in soils from a grid of locations surrounding the US Department of Energy Waste Isolation Pilot Plant (WIPP) in southeastern New Mexico and from a grid on a reference site approximately 20 km southeast of the WIPP site. Each of the two grids has 16 sampling locations (grid nodes) systematically distributed within an area of 16.580 ha. Sampling was conducted prior to the arrival of the first waste shipment at WIPP. Thus, the 137Cs and 23,240Pu in the soil are expected to have been deposited as global fallout, although the Gnome Site, 8.8 km southwest of the WIPP, is also a potential source of 239,240Pu and fission products. The reference grid has significantly higher concentrations of fallout and natural radionuclides than the WIPP grid. Up to 80% of the total variability in radionuclide concentrations across the two grids is attributable to differences between grid nodes. Differences between replicates within a location account for 44-50% of the variability in concentrations of the uranium isotopes, but only 11-17% of the variability in the concentrations of the other radionuclides. Samples having similar abundance of radionuclides were spatially aggregated across the terrain. The activity concentrations of the radionuclides were strongly correlated with the concentrations of Al and Pb, and with the percentages of sand, silt and clay in the soil. Normalizing radionuclide concentrations to the concentration of Al or percent fine particles can help adjust for differences in soil textures among samples and facilitate the detection of gradients or temporal changes in soil concentrations.

Aluminum↗
PubMed1997

Contributions of Rocky Flats releases to the total plutonium in regional soils.

Total 239,240Pu and the 240Pu:239Pu atom ratio were measured in soil samples from around the Rocky Flats Environmental Technology Site (RFETS) during 1992-1994. Mass isotopic data provided a sensitive technique to resolve low levels of RFETS 239,240Pu superimposed on plutonium from global fallout. Concentrations of 239,240Pu within this sample set ranged from 1.1 Bq kg(-1) offsite to 57 Bq kg(-1) onsite, and the 240Pu:239Pu atom ratio increased from 0.055 onsite to 0.123 at approximately 19 km east of the RFETS boundary. The relationship between 24OPu:239Pu atom ratios and distance indicated that a measurable RFETS contribution may have extended to > or = 19 km offsite in the easterly direction. Although the RFETS contribution to total plutonium at the offsite locations ranged from 24-90%, the overall inventory was relatively small. Total inventory estimates, for one transect, based on 239,240Pu and from 240Pu:239Pu atom ratio measurements were not significantly different.

Colorado↗
PubMed1997

A three-dimensional spatial model of plutonium in soil near Rocky Flats, Colorado.

The horizontal and depth distribution of plutonium was measured in soil east of the Rocky Flats Environmental Technology Site (formerly the Rocky Flats Plant) near Denver, Colorado, during 1992-1994. The study area was centered on the eastern plume of plutonium contamination and included transects extending from 0.2 km east of the primary origin of the contamination (the 903 Pad) to distances of up to 19 km northeast, east, southeast and south-southeast of the 903 Pad. Soil was collected in 3 cm layers down to 21 cm at exponentially increasing distances along the four transects. Plutonium concentrations decreased rapidly with depth, distance from the 903 Pad, and angle from due east. Depth distributions were independent of distance and angle from the 903 Pad, and our profile model can be used to adjust to a common basis, historical measurements made from sampling to different depths. Based on a total of approximately 1,400 independent measurements, mathematical functions were developed to describe the distance, directional, and depth relationships. These equations, combined with soil density and rock measurements, provided a new method to estimate the plutonium concentration or total deposition per unit area anywhere within the study area. Total deposition per unit area measurements at 50 sites provided an independent test of the model's predictive accuracy. Sampling coefficients of variation based on replicate samples at the main sampling locations averaged 33%, but ranged from 12 to 98%. The analytical measurement coefficient of variation averaged 8%. Mean 0-3 cm soil concentrations of (239,240)Pu among 10 Front Range "background" and 11 community locations near Rocky Flats were 2.1 and 2.3 Bq kg(-1), respectively.

Plutonium↗
PubMed1981

Psychological response to acute spinal cord injury: an epidemiological study.

This study empirically examines psychological reactions to spinal cord injury from a coping and adaptation perspective. Ego defensive, affective and coping reactions, and long-term personality reactions are described at the time of discharge from the acute care hospital (n = 190). These psychological reactions are examined for their association with neurological function on admission, at discharge, and changes in neurological status during hospitalisation. Affective reactions to injury were still evident in this sample and related positively to severity of motor and, to a lesser degree, sensory disability. Affective reactions were also generally associated with negative coping responses which could interfere with successful rehabilitation therapy. The study indicates that intensive psychological counselling is required by many patients during acute hospitalisation and prior to transfer for rehabilitation.

Acute Disease↗
PubMed1978

First year hospitalisation costs for the spinal cord injured patient.

This retrospective, descriptive study presents the actual first year hospitalisation costs for a series of 85 spinal cord injured patients, covered by Workmen's Compensation Insurance and cared for in a variety of United States institutions. Mean first year hospital costs for all patients was $35,767. For quadriplegics, $42,240; and paraplegics, $32.619. During initial hospitalisation only, the average length of stay was 184 days and mean cost was $28.637. Room and board comprised 52 per cent of cots; special services, 36 per cent and professional services, 11 per cent. Major special service costs were private duty nursing, medications, medical supplies, respiratory and physical therapy. Major professional charges were centred in the surgical and physical medicine specialties. Home care costs averaged $4000 per patient or $37.00 per day. When compared with the other studies, the costs presented here are higher though the differential is reduced markedly when median rather than mean costs are presented. When compared with the one other known study based on actual and not estimated costs, the results are markedly similar. Differences in costs between this and other studies and the reasons for same are discussed.

Costs and Cost Analysis↗
PubMed1978

Classification of the severity of acute spinal cord injury: implications for management.

Sensory and motor function scales using a comprehensive neurological examination in emergency departments were developed during a 5-year prospective study of the epidemiology of acute spinal cord injury. Cross-classification of the scales on 133 patients identified 18.8 per cent who had severe motor impairment but minimal or no sensory loss. This discrepancy was not associated with older age or comorbidity but these patients tended to have a higher prevalence of fracture dislocations, hyperesthesia and Brown-Sequard Syndrome. The discrepancy between sensory and motor function was almost certainly due to the pathology of the cord lesion. Overall, motor function was more likely than sensory function to show improvement during the acute hospitalisation. This was especially true for patients admitted with good sensory but poor motor function. These patients need to be delineated soon after injury if we are to fully understand the aetiology of spinal cord injury and appropriately manage and evaluate different therapeutic modalities.

Acute Disease↗
PubMed1978

Retrospective versus prospective audit: a trial of two methods.

Retrospective and prospective approaches to collecting information were compared in a study of spinal cord injury. The data show that the retrospective approach resulted in some underestimation of cases; that it was a very lengthy, time-consuming process; and that it produced significantly fewer useful clinical data than the prospective method.

Connecticut↗
PubMed1975

Objective criteria for evaluating occupational health programs.

An objective scoring system is proposed as a single and flexible method of evaluating occupational health programs to appraise the extent to which existing programs approach a basic standard of excellence as defined by a theoretical model based on published and professionally acceptable guidelines and standards. This proposed system emphasizes the importance of an interdependent relationship between four program components: (1) guiding philosophy and policy; (2) organizational structure; (3) resources; (4) occupational health services, and it stresses the importance of long range health commitments to employee health status in contrasts to short range health commitments aimed primarily at an economic payoff to a sponsoring agency, institution, or company. The proposed evaluation scheme should enable self-evaluation by individual programs. Additionally, programs can utilize this evaluative tool to examine their influence on such important questions as employee hospital utilization and other specific elements of employee health in an objective, relatively simple manner.

Evaluation Studies as Topic↗