Laina Salonen

Bone as a possible target of chemical toxicity of natural uranium in drinking water.

Uranium accumulates in bone, affects bone metabolism in laboratory animals, and when ingested in drinking water increases urinary excretion of calcium and phosphate, important components in the bone structure. However, little is known about bone effects of ingested natural uranium in humans. We studied 146 men and 142 women 26–83 years of age who for an average of 13 years had used drinking water originating from wells drilled in bedrock, in areas with naturally high uranium content. Biochemical indicators of bone formation were serum osteocalcin and amino-terminal propeptide of type I procollagen, and a marker for bone resorption was serum type I collagen carboxy-terminal telopeptide (CTx). The primary measure of uranium exposure was uranium concentration in drinking water, with additional information on uranium intake and uranium concentration in urine. The data were analyzed separately for men and women with robust regression (which suppresses contributions of potential influential observations) models with adjustment for age, smoking, and estrogen use. The median uranium concentration in drinking water was 27 μg/L (interquartile range, 6–116 μg/L). The median of daily uranium intake was 36 μg (7–207 μg) and of cumulative intake 0.12 g (0.02–0.66 g). There was some suggestion that elevation of CTx (p = 0.05) as well as osteocalcin (p = 0.19) could be associated with increased uranium exposure (uranium in water and intakes) in men, but no similar relationship was found in women. Accordingly, bone may be a target of chemical toxicity of uranium in humans, and more detailed evaluation of bone effects of natural uranium is warranted.

Radon and other natural radionuclides in drinking water and risk of stomach cancer: A case-cohort study in Finland

Very high concentrations of naturally occurring radionuclides are encountered in Finnish groundwaters and wells. Radon ingested through drinking water can cause considerable radiation to the stomach. We assessed the effect of natural uranium and other radionuclides in drinking water on the risk of stomach cancer. Subjects (n = 144,627) in the base cohort had lived outside the municipal tap water system during 1967–1980. A subcohort of 4,590 subjects was formed for use as a reference group by random sampling of the base cohort, with stratification by age and sex. Within the subcohort, 371 subjects had used drinking water from drilled wells prior to 1981. Stomach cancer cases within the subcohort were identified through a cancer registry, and cases using water from drilled wells were selected. Activity concentrations of radon, radium‐226 and natural uranium in the drinking water were analyzed using radiochemical and alpha spectrometric methods. The median activity concentration of radon in well water was 130 Bq/l for both the 88 stomach cancer cases and the 274 subjects in the subcohort. Median radium concentrations were 0.007 Bq/l for cases and 0.010 Bq/l for the subcohort, with a median uranium concentration of 0.07 Bq/l for both groups. Risk of stomach cancer was not associated with exposure to radon or other radionuclides. The hazard ratio of stomach cancer was 0.68 for radon (95% CI 0.29–1.59 at 100 Bq/l water), 0.69 per Bq/1 for radium‐226 (95% CI 0.33–1.47) and 0.76 per Bq/1 for uranium (95% CI 0.48–1.21). Our results do not indicate an increased risk of stomach cancer from ingestion of radon or other natural radionuclides through drinking water at these exposure levels.

Uranium and other natural radionuclides in drinking water and risk of leukemia: a case–cohort study in Finland

Objective: We assessed the effect of natural uranium and other radionuclides in drinking water on risk of leukemia. Methods: The subjects (n = 144,627) in the base cohort had lived outside the municipal tapwater system during 1967–1980. A subcohort was formed as a stratified random sample of the base cohort and subjects using drinking water from drilled wells prior to 1981 were identified. A case–cohort design was used comparing exposure among cases with leukemia (n = 35) with a stratified random sample (n = 274) from the subcohort. Activity concentrations of uranium, radium-226, and radon in the drinking water were analyzed using radiochemical and alpha-spectrometric methods. Results: The median activity concentration of uranium in well water was 0.08 Bq/L for the leukemia cases and 0.06 Bq/L for the reference group, radon concentrations 80 and 130 Bq/L, respectively, and radium-226 concentrations 0.01 Bq/L for both groups. The hazard ratio of leukemia for uranium was 0.91 (95% confidence interval 0.73–1.13) per Bq/L, for radon 0.79 per Bq/L (95% CI 0.27–2.29), and for radium-226 0.80 (95% CI 0.46–1.39) per Bq/L. Conclusions: Our results do not indicate an increased risk of leukemia from ingestion of natural uranium or other radionuclides through drinking water at these exposure levels.

Removal of natural radionuclides from drinking water by point of entry reverse osmosis

Abstract A small commerical POE (point of entry) reverse osmosis (RO) equipment was tested for removing simultaneously water radioactivity and salinity from a bedrock water in a private household. The functioning of this equipment was monitored over an eight month period. The RO equipment was able to remove most of the elements almost completely. The reduction of main water constituents was above 94%, except for gaseous radon.

Comparison of two direct LS methods for measuring 222Rn in drinking water using α/β liquid scintillation spectrometry

Direct liquid scintillation (LS) methods are widely used for surveying (222)Rn in drinking water. Two direct methods are used that differ in sample composition. In a two-phase sample, water lies below a water-immiscible cocktail, while in a homogeneous sample water is mixed with an emulsifying cocktail. Although these methods were developed in the late 1970s, their performances have not been simultaneously tested. Here, the methods were compared in two ways: by preparing both types of sample similarly from (222)Rn-bearing groundwater in one emulsifying and in three organic cocktails, and by calibrating the methods with a (226)Ra standard according to their respective procedures. The samples were measured using alpha/beta LS spectrometry. The standard deviations of parallel samples and the repeatability of the measurements were excellent for both methods, except two-phase (226)Ra samples, whose efficiencies decreased slightly over time. This instability was due to interference from (210)Pb, (210)Bi and (210)Po, which accumulated in the (226)Ra standard, and possibly also to the migration of (214)Pb and (214)Bi into the aqueous phase and deficient transfer of (222)Rn from the water to the cocktail.

Calibration of the direct LSC method for radon in drinking water: Interference from 210Pb and its progenies accumulated in 226Ra standard solution

The standard ASTM method is the most commonly applied method for determining (222)Rn in drinking water. The method is calibrated with a (226)Ra standard solution that usually contains variable amounts of (210)Pb, (210)Bi and (210)Po if the standard has not recently been purified. Until now it has not been experimentally confirmed that these progenies do not interfere when the method is calibrated. In this study, interference was examined using three different organic cocktails and alpha/beta liquid scintillation spectrometry to separately assess the effect of three radionuclides. The interference from (210) Po was 4% for one of the cocktails if the (226)Ra standard had been purified 5 years earlier. The interferences from (210)Pb and (210)Bi were negligible compared to that of (210)Po.

Radon Removal from Different Types of Groundwater Applying Granular Activated Carbon Filtration

Granular activated carbon (GAC) filters were installed in 12 private homes or vacation homes for removing unacceptably high concentrations of radon from household water. Radon removal efficiency was nearly 100% in most locations, although different water types were encountered. Other radionuclides such as uranium, radium, lead and polonium were removed less efficiently. Treated water quality remained good and no significant external radiation dose was caused to the residents.

Prevention measures against radiation exposure to radon in well waters: analysis of the present situation in Finland.

Naturally occurring radioactive elements are found in all groundwaters, especially in bedrock waters. Exposure to these radioactive elements increases the risk of cancer. The most significant of these elements is radon which, as a gas, is mobile and dissolves in groundwater. In Finland, water supply plants are obliged to carry out statutory monitoring of the water quality, including radon. Monitoring of private wells, however, is often neglected. In this paper, we outline the problem by reviewing the outcomes of the studies conducted in Finland since the 1960s. We also summarise the development of legislation, regulations and political decisions made so far that have affected the amount of public exposure to radon in drinking water. A review of the studies on radon removal techniques is provided, together with newly obtained results. New data on the transfer of radon from water into indoor air are presented. The new assessments also take into account the expanding use of domestic radionuclide removal units by Finnish households.