ROUTINE METHOD FOR THE DETERMINATION OF TRACE AMOUNTS OF 226Ra IN URINE BY ALPHA SPECTROMETRY.

226Ra is considered one of the most radiotoxic naturally occurring radionuclides. A new routine method was developed to measure traces of 226Ra in urine. Radium was pre-concentrated from a 2 l urine sample using manganese oxide (MnO2) particles. The MnO2 precipitate was dissolved and the organic matter was broken down. Then, potential radiological interferents were removed using DGA and AGMP1 stacked resin columns. A barium sulphate (BaSO4) micro-precipitation was performed before measuring the sample by alpha spectrometry. A good recovery of 60 ± 10% and excellent alpha resolution were obtained. The minimum detectable activity (MDA) was 0.2 ± 0.1 mBql-1. The method was validated using spiked samples and can be completed in 5 hours.

Exposure assessment of natural uranium from drinking water.

The uranium concentration in the drinking water of the residents of the Jaipur and Ajmer districts of Rajasthan has been measured for exposure assessment. The daily intake of uranium from the drinking water for the residents of the study area is found to vary from 0.4 to 123.9 µg per day. For the average uranium ingestion rate of 35.2 µg per day for a long term exposure period of 60 years, estimations have been made for the retention of uranium in different body organs and its excretion with time using ICRP's biokinetic model of uranium. Radioactive and chemical toxicity of uranium has been reported and discussed in detail in the present manuscript.

Urinary excretion of uranium in adult inhabitants of the Czech Republic.

The main aim of this study was to determine and evaluate urinary excretion of uranium in the general public of the Czech Republic. This value should serve as a baseline for distinguishing possible increase in uranium content in population living near legacy sites of mining and processing uranium ores and also to help to distinguish the proportion of the uranium content in urine among uranium miners resulting from inhaled dust. The geometric mean of the uranium concentration in urine of 74 inhabitants of the Czech Republic was 0.091 mBq/L (7.4 ng/L) with the 95% confidence interval 0.071-0.12 mBq/L (5.7-9.6 ng/L) respectively. The geometric mean of the daily excretion was 0.15 mBq/d (12.4 ng/d) with the 95% confidence interval 0.12-0.20 mBq/d (9.5-16.1 ng/d) respectively. Despite the legacy of uranium mines and plants processing uranium ore in the Czech Republic, the levels of uranium in urine and therefore, also human body content of uranium, is similar to other countries, esp. Germany, Slovenia and USA. Significant difference in the daily urinary excretion of uranium was found between individuals using public supply and private water wells as a source of drinking water. Age dependence of daily urinary excretion of uranium was not found. Mean values and their range are comparable to other countries, esp. Germany, Slovenia and USA.

Measurements of (234)U and (238)U in hair, urine, and drinking water among drilled bedrock well water users for the evaluation of hair as a biomonitor of uranium intake.

Hair is evaluated and compared with urine as a biomonitor for human intake of uranium. Concentrations of U and U and the activity ratio between them are measured in the hair, urine, and drinking water of 24 drilled bedrock well water users in Östergötland, Sweden. The samples are measured with α-spectrometry after radiochemical preparation using liquid-liquid separation with tributylphosphate. The results show that there is a stronger correlation between the uranium concentrations in the drinking water of each subject and the hair of the subject (r = 0.50) than with the urine (r = 0.21). There is also a stronger correlation between the activity ratios of water and hair (r = 0.91) than between water and urine (r = 0.56). These results imply that hair may serve as a robust indicator of chronic uranium intake. One obvious advantage over sampling urine is that hair samples reflect a much longer excretion period: weeks compared to days. The absorbed fraction of uranium, the f value, is calculated as the ratio between the excreted amount of uranium in urine and hair per day and the daily drinking water intake of uranium. The f values stretch from 0.002 to 0.10 with a median of 0.023.

Hair analysis as an indicator of exposure to uranium.

Medical examinations performed on four monks of a monastery in the northern Greece revealed heavy metal contamination. Hair analysis, performed by a toxicological laboratory abroad, indicated, among other, the presence of uranium. The uranium concentrations determined in a laboratory of "Elemental Hair Analysis' indicated a uranium level that was about five times the maximum value of the reference range, which has been adopted by the measuring laboratory. After these diagnostic findings, on request of 10 monks, uranium determination in hair and urine samples was performed by means of alpha spectrometry in GAEC's laboratory. The measured uranium concentrations in hair varied from 0.15 to 2.10 mBq g(-1), which correspond to 12.1 and 170 ng g(-1), respectively. The uranium concentrations in urine were between 41 and 174 ng d(-1). For comparison purposes, urine and non-dyed hair samples from the staff of the laboratory were analysed. Because one of the major sources of uranium intake is through drinking water, water samples were also analysed. The mean value of the uranium concentration in the two drinking water samples collected from the residence area was found to be 2.35 µg l(-1).

A compartmental model of uranium in human hair for protracted ingestion of natural uranium in drinking water.

To predict uranium in human hair due to chronic exposure through drinking water, a compartment representing human hair was added into the uranium biokinetic model developed by the International Commission on Radiological Protection (ICRP). The hair compartmental model was used to predict uranium excretion in human hair as a bioassay indicator due to elevated uranium intakes. Two excretion pathways, one starting from the compartment of plasma and the other from the compartment of intermediate turnover soft tissue, are assumed to transfer uranium to the compartment of hair. The transfer rate was determined from reported uranium contents in urine and in hair, taking into account the hair growth rate of 0.1 g d(-1). The fractional absorption in the gastrointestinal tract of 0.6% was found to fit best to describe the measured uranium levels among the users of drilled wells in Finland. The ingestion dose coefficient for (238)U, which includes its progeny of (234)Th, (234m)Pa, and (234)Pa, was calculated equal to 1.3 x 10(-8) Sv Bq(-1) according to the hair compartmental model. This estimate is smaller than the value of 4.5 x 10(-8) Sv Bq(-1) published by ICRP for the members of the public. In this new model, excretion of uranium through urine is better represented when excretion to the hair compartment is accounted for and hair analysis can provide a means for assessing the internal body burden of uranium. The model is applicable for chronic exposure as well as for an acute exposure incident. In the latter case, the hair sample can be collected and analyzed even several days after the incident, whereas urinalysis requires sample collection shortly after the exposure. The model developed in this study applies to ingestion intakes of uranium.

The mean concentration of uranium in drinking water, urine, and hair of the occupationally unexposed Finnish working population.

Uranium concentrations in the household water, urine, and hair of the occupationally unexposed Finnish working population were determined using inductively coupled plasma mass spectrometry (ICP-MS). The age of the randomly selected participants ranged from 18 to 66 y. The mean concentrations of uranium in water, urine, and hair were 1.25 microg L(-1), 0.016 microg L(-1), and 0.216 microg g(-1), respectively. The mean uranium concentration in hair of the Finnish working population was from 3- to 15-fold higher than the values reported in the literature, while the mean uranium concentration in urine was similar to those measured elsewhere in Europe. The observed large variation in the uranium concentrations in hair and urine can be explained by the variation in the uranium concentration in drinking water. Exceptionally high concentrations have been measured in private drilled wells in the granite areas of Southern Finland.

Nephrotoxicity of uranium in drinking water from private drilled wells.

OBJECTIVES: To investigate the association between uranium in drinking water from drilled wells and aspects of kidney function measured by sensitive urine tests. METHODS: Three hundred and one of 398 eligible subjects (75.6%) aged 18-74 years with daily drinking water supplies from private drilled wells located in uranium-rich bedrock (exposed group) volunteered to participate along with 153 of 271 local controls (56.4%) who used municipal water. Participants responded to a questionnaire on their water consumption and general health, and provided a morning urine sample and drinking water for analysis. RESULTS: The uranium content of well water samples (n=153) varied considerably (range <0.20-470 microg/l, median 6.7 microg/l, 5% >100 microg/l), while uranium levels in all samples of municipal water (n=14) were below the limit of quantification (0.2 microg/l). Urinary levels of uranium were more than eight times higher in exposed subjects than in controls (geometric means 38 and 4.3 ng/l, respectively; p<0.001), but their mean urine lead levels were not significantly different. There was a strong curvilinear correlation between uranium in drinking water and in urine (r2=0.66). Levels of albumin, beta(2)-microglobulin, protein HC as well as kappa and lambda immunoglobulin chains in urine from exposed and controls were similar. The N-acetyl-beta-d-glucosaminidase (NAG) activity was significantly lower in the exposed group vs. controls, possibly secondary to differential storage duration of samples from the two groups. Even in regression models adjusting for gender, age and smoking no association of uranium in water and the kidney function parameters was observed. Using uranium in urine in the entire study group as a marker of exposure, however, a tendency of exposure-related increases of beta(2)-microglobulin, protein HC and kappa chains were noted. This tendency was enhanced after exclusion of subjects with diabetes mellitus from the analysis. CONCLUSIONS: Uranium levels in urine were strongly correlated to levels in drinking water from drilled wells. There were no clear signs of nephrotoxicity from uranium in drinking water at levels recorded in this study, but some indications of an effect were observed using uranium in urine as a measure of overall uranium exposure. The clinical relevance of these findings remains unclear.

Screening methods for estimating tritium dose.

Tritium intake may occur in certain workplaces by design or by accident. If the health physics staff has developed a formal bioassay program, then it is likely that dose estimates from tritium intake are readily determinable. However, in the case of tritium intake at a facility where no formal program exists, it may be necessary to make simple confirmatory estimates of dose due to tritium exposure. Lifetime dose estimates may be calculated by using data from urine samples taken over a period of time. If urine data are unavailable, estimates of committed dose equivalent may be made with air sample data and knowledge of workplace activities.

Grand rounds: nephrotoxicity in a young child exposed to uranium from contaminated well water.

CONTEXT: Private wells that tap groundwater are largely exempt from federal drinking-water regulations, and in most states well water is not subject to much of the mandatory testing required of public water systems. Families that rely on private wells are thus at risk of exposure to a variety of unmeasured contaminants. CASE PRESENTATION: A family of seven--two adults and five children--residing in rural northwestern Connecticut discovered elevated concentrations of uranium in their drinking water, with levels measured at 866 and 1,160 microg/L, values well above the U.S. Environmental Protection Agency maximum contaminant level for uranium in public water supplies of 30 microg/L. The uranium was of natural origin, and the source of exposure was found to be a 500-foot well that tapped groundwater from the Brookfield Gneiss, a geologic formation known to contain uranium. Other nearby wells also had elevated uranium, arsenic, and radon levels, though concentrations varied widely. At least one 24-hr urine uranium level was elevated (> 1 microg/24 hr) in six of seven family members (range, 1.1-2.5 microg/24 hr). To assess possible renal injury, we measured urinary beta-2-microglobulin. Levels were elevated (> 120 microg/L) in five of seven family members, but after correction for creatine excretion, the beta-2-microglobulin excretion rate remained elevated (> 40 microg/mmol creatinine) only in the youngest child, a 3-year-old with a corrected level of 90 microg/mmol creatinine. Three months after cessation of well water consumption, this child's corrected beta-2-microglobulin level had fallen to 52 microg/mmol creatinine. SIGNIFICANCE: This case underscores the hazards of consuming groundwater from private wells. It documents the potential for significant residential exposure to naturally occurring uranium in well water. It highlights the special sensitivity of young children to residential environmental exposures, a reflection of the large amount of time they spend in their homes, the developmental immaturity of their kidneys and other organ systems, and the large volume of water they consume relative to body mass.

Uranium gastrointestinal absorption: the f1 factor in humans.

The present investigation was undertaken by the Department of Health, Canada, to determine the most appropriate value to use for uranium gastrointestinal absorption (f1) in setting the guideline for drinking water. Fifty participants, free from medical problems, were recruited from two communities: a rural area where drinking water, supplied from drilled wells, contained elevated levels of uranium and an urban area where the water supplied by the municipal water system contained < 1 microg l(-1). Uranium intake through food, drinking water and other beverages was monitored using the duplicate diet approach. Intake and excretion were measured by inductively coupled plasma-mass spectrometry (ICP-MS) in samples collected concurrently from the same individuals over a 3 d period. The range of f1 values was between 0.001 and 0.06, with a median of 0.009. These values were independent of gender, age, duration of exposure, daily total uranium intake and allocation of intake between food and water. Consistent with the recommendation of ICRP Publication 69, 78% were below 0.02.

A biokinetic model for predicting the retention of 3H in the human body after intakes of tritiated water.

Scarce published data on the long-term excretion of tritiated water from the human body have been re-evaluated in order to develop a biokinetic model describing the retention in the human body of 3H from tritiated water (HTO) that could be used for both prospective and retrospective radiation protection. A three-component exponential function is proposed to describe the elimination of 3H from HTO with biological half-times of 10 d (99.00%), 40 d (0.98%) and 350 d (0.02%) respectively. The model predicts a committed effective dose of 1.7 x 10(-11) Sv Bq(-1), comparable with that of the current ICRP Publication 56 and 72 models, and estimates the retention of 3H to within a factor of about 2 of the measured values up to 40 d after intake and about 5 at times longer than 100 d. The derivation of the model and the uncertainties associated with the various parameters are discussed.

Dosimetric implications of atmospheric dispersal of tritium near a heavy-water research reactor facility.

An estimate of the tritium dose to the public in the vicinity of the heavy water research reactor facility at AECL-Chalk River Laboratories, Ontario, Canada, has largely been accomplished from analyses on regularly-collected samples of air, precipitation, drinking water and foodstuffs (pasture, fruit, vegetables and milk) and environmental dose models. To increase the confidence with which public doses are calculated, tritium doses were estimated directly from the ratio of tritiated species in urine samples from members of the general public. Single cumulative 24 h urine samples from a few adults living in the vicinity of the heavy-water research reactor facility at Chalk River Laboratories, Canada were collected and analysed for tritiated water and organically bound tritium. The participants were from Ottawa (200 km east), Deep River (10 km west) and Chalk River Laboratories. Tritiated water concentrations in urine ranged from 6.5 Bq.l-1 for the Ottawa resident to 15.9 Bq.l-1 for the Deep River resident, and were comparable to the ambient levels of tritium-in-precipitation at their locations. The ultra-low levels of organically bound tritium in urine from these same individuals were measured by 3He-ingrowth mass spectrometry and were 0.06 Bq.l-1 (Ottawa) and 0.29 Bq.l-1 (Deep River). For Chalk River Laboratories workers, tritiated water concentrations in urine ranged from 32 Bq.l-1 to 9.2 x 10(4) Bq.l-1, depending on the ambient levels of tritium in their workplace. The organically bound tritium concentrations in urine from the same workers were between 0.08 Bq.l-1 and 350 Bq.l-1. With a model based on the ratio of tritiated water to organically bound tritium in urine, the estimated dose arising from organically bound tritium in the body for the Ottawa and Deep River residents was about 26% and 50%, respectively, of the body water tritium dose. The workers in a reactor building at Chalk River Laboratories had less than 10% dose contribution from organically bound tritium, but had higher overall tritium dose due to frequent intakes of tritiated water vapour in the workplace. The results of this study suggest that most of the tritium dose to workers at Chalk River and general population near Chalk River is the result of tritiated water intakes and not due to dietary intake of organically bound tritium.

Accelerator mass spectrometry for the detection of ultra-low levels of plutonium in urine, including that excreted after the ingestion of Irish sea sediments.

Currently, most methods for the quantitative assessment of (239)Pu have minimum detection levels (25 microBq for alpha-particle spectrometry) that are much higher than the levels of this isotope in many human bioassay and environmental samples. Accordingly, a priority has existed to develop methods that are more sensitive. Fission-track and ICP-MS methods have been used, but these can suffer either from an uncertain level of removal and/or recovery of uranium or from isobaric mass interferences. Accelerator mass spectrometry (AMS) has no such disadvantages, and its demonstrated detection limits for plutonium isotopes approach levels of attograms, equivalent to about 500 nBq for (239)Pu. This paper describes the application of AMS to the measurement of (239)Pu in urine produced by youths living in London (3.5 microBq day(-1)) and by adults (approximately 2-260 microBq day(-1)), some of whom were exposed occupationally. In addition, an experiment was undertaken to measure the fasted absorbed fraction of ingested plutonium after the ingestion of 15 g of Irish Sea sediment by a volunteer. The measured absorbed fraction was 4.5 x 10(-5). It is concluded that accelerator mass spectrometry is a suitable method for the ultra-trace detection of plutonium.