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Biomedical subjects

C T Hess

Publications and source records attributed to C T Hess.

At least 37 records · Page 2Linked to original sources
PubMed1997

A compartmental model of water radon contamination in the human body.

A multicompartmental model is developed to simulate the biokinetics in the human body following the ingestion of an inert gas. It was assumed that 100% of the radon ingested appears in the stomach, from which it is transported through the body to different organs via the blood stream. Each of these organs absorbs and releases radon differently, and, amongst all, the fat retains radon for the longest time. To test the model, the information on elimination rates of 222Rn in expired breath was obtained from other experiments done at the University of Maine. The data included male and female participants with a wide range of ages and physical activity levels. The radiation doses in the different organs and tissues were computed. As was expected, the stomach sustained the maximum dose. In this study, the highest stomach dose to any volunteer was evaluated as 115 mSv y(-1).

Adolescent↗
PubMed1997

Fundamental strategies for skin care.

The Agency for Health Care Policy and Research (AHCPR) identified the need to develop clinical practice guidelines for the prevention and treatment of pressure ulcers, a segment of wound and skin diagnoses. The skin is the first line of defense in protecting the body from constant changes in the environment. Far too often, the attention needed for the skin is only realized after the integrity has been disrupted. This article examines the anatomy and physiology of the skin, factors that affect the skin (aging, bathing, cleansers, dryness, friction, lotions, moisturizers, nutrition, soaps and shearing forces), indications and contraindications of topical skin care products, and AHCPR's recommended interventions. These elements are integral to clinicians in proactively developing sound skin care prevention strategies. Yet without a thorough understanding of all components, the skin's integrity remains at risk.

Humans↗
PubMed1992

Measurement of the biotransfer and time constant of radon from ingested water by human breath analysis.

Forty-one tests were performed on 38 volunteers to measure elimination rates of 222Rn in expired breath. Participants ranged from ages 9 to 85 y, with 16 males and 22 females. The levels of physical activity of the subjects ranged from very inactive to marathon level. Calibration of our flow-through scintillation cell was accomplished using a medical ventilator and 222Rn reservoir for 5-15 L min-1 flow rates. We found a wide range of percent elimination (12-68%) in 30 min. The percent elimination has a mild correlation with the predicted forced expiratory volume in 1 s and with time passed since eating. Our observations of bio-retention half-times range from 17-400 min. The whole-body dose calculations yield a mean of 2.70 +/- 3.43 nGy Bq-1, and the stomach dose calculations yield a mean of 276 +/- 186 nGy Bq-1. These means range beyond those previously reported.

Adolescent↗
PubMed1989

An activated charcoal-based, liquid scintillation-analyzed airborne Rn detector.

An inexpensive, easy-to-use detector for measuring airborne 222Rn based on 222Rn diffusion and absorption in activated charcoal is presented. The detector uses chemical extraction and liquid scintillation for measurement of the 222Rn concentration, is designed to be insensitive to temperature and humidity effects, and obtains sensitivity levels of 675 CPM (Bq L-1)-1 [25 CPM (pCi L-1)-1] at room temperature.

Air Pollutants↗
PubMed1985

The occurrence of radioactivity in public water supplies in the United States.

Examination of the collected data for radionuclide concentration measurements in public water supplies in the United States show more than 51,000 measurements for gross alpha-particle activity and/or Ra, 89,900 measurements for U, and 9,000 measurements for Rn. These measurements were made as part of national and state surveys of radionuclide concentrations in utility water supplies for Ra and Rn; and the National Uranium Resource Evolution (NURE) survey for U which included non-utility water supplies. Surface water has low values for Ra and Rn but levels comparable to ground water for U. Separate isotope measurements were not taken for much of the Ra and U data. Because 226Ra to 228Ra ratios and 238U to 234U ratios are not fixed in water, further measurements are needed to establish the specific isotopic concentrations by region. Analysis of the state average values in geological provinces shows the highest provincial areas for Ra are the Upper Coastal Plain, the glaciated Central Platform, and the Colorado plateau. For U, the highest areas are the Colorado plateau, the West Central Platform, and the Rocky Mountains. For Rn, the highest provinces are New England and the Appalachian Highlands-Piedmont. Regional hydrogeological and geochemical models are suggested for guiding the formulation of regional standards and monitoring strategies. Utility supplies serving small populations have the highest concentration for each radionuclide and have the lowest fraction of samples measured, which shows a need for further measurements of these small population water supplies. Risk estimates for the average concentration of Ra in utility ground water give about 941 fatal cancers per 70.7-yr lifetime in the United States. Risk estimates for the average concentration of U in utility surface and ground water give about 105 fatal cancers per 70.7-yr lifetime in the United States. Using 1 pCi/liter in air for 10,000 pCi/l in water, the Rn in utility water risk estimate is for 4,400-22,000 fatal cancers per 70.7-yr lifetime in the United States.

Air Pollutants, Radioactive↗
PubMed1985

Field and laboratory tests of etched track detectors for 222Rn: summer-vs-winter variations and tightness effects in Maine houses.

Effects of tightness of homes and of bedrock character on indoor 222Rn concentrations were sought in 70 homes in the state of Maine by means of four 6- to 8-month-long surveys over a 1.5-yr period. Laboratory experiments were also performed that document the reliability of the track etching system used for the measurements. In this survey the Rn in tight homes was on the average 3.5 times that in drafty ones, and areas with granitic bedrock led to homes having 2.3 times the Rn as for homes on chlorite-biotite-rich bedrock. Winter-to-summer ratios ranged from 0.5-7, and averaged 1.5, implying that surveys of individual homes require a full year of monitoring.

Air Pollutants↗