Uranium and radon in private bedrock well water in Maine: geospatial analysis at two scales.

In greater Augusta of central Maine, 53 out of 1093 (4.8%) private bedrock well water samples from 1534 km(2) contained [U] >30 µg/L, the U.S. Environmental Protection Agency's (EPA) Maximum Contaminant Level (MCL) for drinking water; and 226 out of 786 (29%) samples from 1135 km(2) showed [Rn] >4,000 pCi/L (148 Bq/L), the U.S. EPA's Alternative MCL. Groundwater pH, calcite dissolution and redox condition are factors controlling the distribution of groundwater U but not Rn due to their divergent chemical and hydrological properties. Groundwater U is associated with incompatible elements (S, As, Mo, F, and Cs) in water samples within granitic intrusions. Elevated [U] and [Rn] are located within 5-10 km distance of granitic intrusions but do not show correlations with metamorphism at intermediate scales (10(0)-10(1) km). This spatial association is confirmed by a high-density sampling (n = 331, 5-40 samples per km(2)) at local scales (≤10(-1) km) and the statewide sampling (n = 5857, 1 sample per 16 km(2)) at regional scales (10(2)-10(3) km). Wells located within 5 km of granitic intrusions are at risk of containing high levels of [U] and [Rn]. Approximately 48 800-63 900 and 324 000 people in Maine are estimated at risk of exposure to U (>30 µg/L) and Rn (>4000 pCi/L) in well water, respectively.

Spatial variation of waterborne radon and temporal variation of radon in water at nine Maine schools.

Nine elementary schools in Maine were examined to track the release of 222Rn and to determine the transfer coefficient from water into air. Water-use simulations were performed by running sinks and sprayers for 1 h in a kitchen. The 222Rn in air was measured over 24 h throughout the school. The subsequent release of 222Rn into the kitchen air was measured to be greater than the EPA action level of 0.15 Bq L-1 (4 pCi L-1), but negligible concentrations of 222Rn were found in adjacent classrooms. In two schools, more than 10 222Rn-in-air detectors were placed throughout the kitchen and showed a three-fold spatial concentration variation. During the hour-long simulations, the 222Rn in water concentration was measured periodically, and many of the schools showed an increase in the 222Rn concentration in water before remaining constant. These measured variations suggest that multiple detectors are needed to accurately measure waterborne 222Rn in air, and multiple delayed measurements of 222Rn dissolved in water are needed to obtain a representative groundwater sample.

A laboratory intercomparison of radon in water measurements in Maine.

Naturally occurring radon exists in ground water and drinking water supplies. Many water testing laboratories provide measurements of radon in water for the public. No known national intercomparison program exists to verify the accuracy of the laboratories measuring radon in water in Maine or the Northeast. In recognition of this situation, the State of Maine Radiation Control Program sanctioned an intercomparison study for laboratories registered in Maine to measure radon in water. The University of Maine supplied each laboratory with water samples of various radon concentrations, served as the reference laboratory, and analyzed the results. Of the nine participating laboratories, eight use the liquid scintillation method while the ninth uses the E-PERM method to measure radon in water. Presented here are the results of this intercomparison study with a tabulation of the materials and methods used by the laboratories. The results from five of the nine testing laboratories showed significant discrepancies with those of the reference laboratory, typically due to low measurements.

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.

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.

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).

Waterborne radon in seven Maine schools.

This study investigated the transfer coefficient of radon from water to air in kitchens and bathrooms for seven schools located in Maine. Simulations occurred in water use rooms containing multiple airborne radon detectors. Quantities measured included radon concentration in water (10-960 Bq L(-1), 260-26,000 pCi L(-1)), air (0-3 Bq L(-1), 0-80 pCi L(-1)), volume of water used, emissivities (0.04-0.98), and ventilation rates (0.012-0.066 min). Using these parameters provides the means for calculating the transfer coefficient and by which dose due to waterborne radon can be estimated in other schools. Transfer coefficient values calculated for kitchens and baths ranged from 9.6 x 10(-6) to 2.0 x 10(-2). Multiple detectors showed that the radon concentration varied throughout a room. These measurements represent the first of this type to be done in schools in Maine.

Environmental radon and cancer correlations in Maine.

The distribution of 222Rn has been measured in the sixteen counties of Maine, U.S.A. by liquid scintillation counting of water samples from more than two thousand public and private wells. Three hundred and fifty of these wells have been characterized for geology and hydrology. Airborne radon has been measured in seventy houses with grab samples and in eighteen houses for 5-7 days each with continuously recording diffusion-electrostatic radon detectors. Concentrations of radon in water ranged from 20 to 180,000 pCi/l. Granite areas yielded the highest average levels (mean = 22,100 pCi/l.; n = 136), with considerable intra-granite variation. Metasedimentary rocks yielded levels characteristic of the lithology for metamorphic grades ranging from chlorite to andalusite. Sillimanite and higher-grade rocks yielded higher 222Rn levels, probably due to the intrusion of uranium-bearing pegmatites in these terranes. Airborne 222Rn in homes ranged from 0.05 to 210 pCi/l. At the high end of this range, doses will exceed recommended industrial limits. In some homes only a small fraction of the airborne 222Rn was due to the water supply. Average 222Rn levels in domestic water supplies for each of the 16 counties, calculated by areally averaging rock types and their associated 222Rn levels, were found to be significantly correlated with rates for all cancers combined and rates for lung and reproductive cancers in the counties. Although numerous factors other than cancer induction by indoor daughter exposures may be responsible for the observed correlations, these have not been investigated in detail.

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.

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.

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.

The management of open wounds: acute and chronic.

The history of wound healing dates back thousands of years before Christ to the Ancient Egyptians. Detailed tomb and temple hieroglyphics depict wound treatments of that era. Through the historic milestones set forth by Hippocrates (400 BC) to Lister (1800s), current theory of wound management and trends have evolved. During the last several decades, thanks to breakthroughs in research and technological advances, wound care has taken a giant leap forward.

Addressing wounds.

Learn your options for dressing wounds from the following overview.

Analyzing spatial and temporal (222)Rn trends in Maine.

Prolonged radon exposure has been linked to lung cancer. Cancer registry data indicates excess risk for age-adjusted lung cancer in Maine. Maine's mean residential radon activity exceeds the EPA maximum contaminant level (MCL). This paper describes the application of spatial autocorrelation methods to retrospective data as a means of analyzing radon activity in Maine. Retrospective air and well water radon activity data, sampled throughout Maine between 1993 and 2008, are standardized and geocoded for analysis. Three spatial autocorrelation algorithms-local Getis-Ord, local Moran, and spatial scan statistic-are used to identify spatial, temporal, and spatiotemporal radon activity clusters and/or outliers. Spatial clusters of high air- and well water-Rn activity are associated with Maine's Lucerne and Sebago granitic formations. Spatial clusters of low air- and well water-Rn activity are associated with Biddeford Granite and the metamorphic bedrock formation Silurian Ordovician Vassalboro. Space-time analysis indicates that most spatial clusters persist over the period of sampling. No significant temporal clusters are identified. Persistent spatial variations in radon may help to better understand and predict radon-related health risks associated with Maine residences.