Renato Falcomer

Uranium in Drinking Water: Renal Effects of Long-Term Ingestion by an Aboriginal Community

ABSTRACT The authors conducted a study of an aboriginal community to determine if kidney func-tion had been affected by the chronic ingestion of uranium in drinking water from the communitys drilled wells. Uranium concentrations in drinking water varied from < 1 to 845 ppb. This nonin-vasive study relied on the measurement of a combination of urinary indicators of kidney function and markers for cell toxicity. In all, 54 individuals (12–73 years old) participated in the study. Correlation of uranium excreted in urine with bio-indicators at p ≤.05 indicated interference with the kidneys reabsorptive function. Because of the communitys concerns regarding cancer incidence, the authors also calculated cumulative radiation doses using uranium intake in drinking water over the preceding 15-year period. The highest total uranium intake over this period was 1,761 mg. The risk of cancer from the highest dose, 2.1 mSv, is 13 in 100,000, which would be difficult to detect in the community studied (population size = 1,480). This study indicates that at the observed levels of uranium intake, chemical toxicity would be a greater health concern than would radiation dose.

Preliminary results of simultaneous radon and thoron tests in Ottawa

Ottawa is the capital city of Canada. In the previous cross Canada radon survey, Ottawa was not included. There is great interest to know radon level as well as thoron concentration in Ottawa homes. Therefore, radon/thoron discrimination detectors developed at the National Institute of Radiological Sciences in Japan were deployed in 93 houses for a period of 3 months. As expected, thoron is present in Ottawa homes. Radon concentrations ranged from 8 to 1525 Bq m(-3) while thoron concentrations varied from 5 to 924 Bq m(-3). The arithmetic mean of radon and thoron concentrations were found to be 110 +/- 168 and 56 +/- 123 Bq m(-3), respectively.

Method intercomparison for the analysis of 239/240Pu in human urine

Following a radiological or nuclear emergency, medical intervention requires rapid assessment of the exposure of people usually through determination of internal dose. For the plutonium urine bioassay, besides thermal ionization mass spectrometry (TIMS) and alpha spectrometry methods, inductively coupled plasma mass spectrometry (ICP-MS) methods have been recently developed, which can provide much higher sample throughput. In this work, three ICP-MS methods were compared with one TIMS method and two alpha spectrometry methods for the measurement of 239Pu and 240Pu in human urine samples spiked at different concentration levels. The sample throughputs for all three ICP-MS methods are similar: each instrument measures about 80 samples in the first 24 hours and 200 samples in the first 48 hours following the emergency event, if the samples arrive at the laboratory 8 hours after the event occurs. Method accuracy and precision were determined using ANSI N13.30. Method detection limits and minimum detectable amounts (MDA) were determined to evaluate method sensitivities. The sensitivities of the three ICP-MS methods were also compared with the derived urine action level (24 h urine, 500 mSv committed effective dose equivalent, inhalation exposure, maximum dose conversion factor) to evaluate their applicability to exposure situations.

RESULTS OF SIMULTANEOUS RADON AND THORON MEASUREMENTS IN 33 METROPOLITAN AREAS OF CANADA

Radon has been identified as the second leading cause of lung cancer after tobacco smoking. 222Rn (radon gas) and 220Rn (thoron gas) are the most common isotopes of radon. In order to assess thoron contribution to indoor radon and thoron exposure, a survey of residential radon and thoron concentrations was initiated in 2012 with ∼4000 homes in the 33 census metropolitan areas of Canada. The survey confirmed that indoor radon and thoron concentrations are not correlated and that thoron concentrations cannot be predicted from widely available radon information. The results showed that thoron contribution to the radiation dose varied from 0.5 to 6 % geographically. The study indicated that, on average, thoron contributes ∼3 % of the radiation dose due to indoor radon and thoron exposure in Canada. Even though the estimated average thoron concentration of 9 Bq m−3 (population weighted) in Canada is low, the average radon concentration of 96 Bq m−3 (population weighted) is more than double the worldwide average indoor radon concentration. It is clear that continued efforts are needed to further reduce the exposure and effectively reduce the number of lung cancers caused by radon.

Correlation of soil radon and permeability with indoor radon potential in Ottawa.

Soil gas radon and soil gas permeability measurements were conducted at 32 sites across the five most populated communities in the city of Ottawa where indoor radon measurements were available for 167 houses. A soil radon index (SRI) determined from the soil radon concentration and the soil gas permeability was used to characterise radon availability from soil to air. This study demonstrated that the average SRI in a community area correlates with the indoor radon potential (the percentage of homes above 200 Bq m(-3)) in that community. Soil gas radon concentrations together with soil gas permeability measurements can be a useful tool for the prediction of the indoor radon potential in the development of a Canadian radon risk map.

Long-term monitoring of soil gas radon and permeability at two reference sites

The long-term monitoring of soil radon variations was conducted at two reference sites in Ottawa. The purpose of this study was to determine whether a single soil radon survey could provide a representative soil radon characteristic of the site. Results showed that during the normal field survey period from June to September in Canada, a single field survey with multiple measurements of soil gas radon concentrations at a depth of 80 cm can characterise the soil radon level of a site within a deviation of +/-30%. Direct in situ soil permeability measurements exhibited, however, large variations even within an area of only 10 x 10 m(2). Considering such large variations and the weight of the equipment, soil permeability can be determined by direct measurements whenever possible or by other qualitative evaluation methods for sites that are hard to access with heavy equipment.

An international cooperation by using an all-encompassing passive radon monitor

The recently developed radon film-badge makes it possible to measure radon indoors, in soil, in water and/or in aqueous media (e.g. mud). As a result of its wide response linearity, this monitor has been successfully used to measure radon in-water with concentrations from 10 to ~10 000 Bq/L. By exploiting the unique characteristics of this badge, a mini-survey has been carried out by Health Canada in which radon in water was measured from 12 private wells, as well as in tap water originating from the Ottawa River. Due to the widespread interest of different laboratories in using these passive monitors, laboratories were provided with plastic films to construct their own badges by using in-house CR-39 detectors. Monitors were then irradiated by a known radon concentration at the National Institute of Radiation Metrology (ENEA)s radon chamber and sent back to each laboratory for processing and counting. Even though these laboratories have been using different etching- and counting-procedures, the film-badge responses varied only within ~12%.

Residential radon mitigations at Kitigan Zibi Anishinabeg: comparison of above ground level (RIM JOIST) and above roof line discharge of radon mitigation SUB-SLAB depressurization systems.

AbstractRadon mitigations in nine houses were conducted by installing sub-slab depressurization systems (SSDS) with two types of discharge and fan locations: Ground level discharge with the fan located in the basement or roof-discharge with the fan located in the attic. This paper presents a detailed comparative analysis of the radon reduction efficiency, condensation problems, and the cost-effectiveness of both SSDS installation scenarios in nine houses. The mitigations from both SSDS scenarios were successful in reducing radon. The results of rim-joist installations discharging above ground level with the fans located in the basement show that a sealed radon fan with proper fittings and sealed piping were able to reduce the radon to acceptable levels in a cost-effective manner.

Radon mitigation in cold climates at Kitigan Zibi Anishinabeg.

Abstract Available radon mitigation results were gathered for 85 houses mainly by installing sub-slab depressurization systems (SSDS) with two types of discharge and fan locations: Above ground level discharge with the fan located in the basement (AGL) or above roof line discharge with the fan located in the attic (ARL). A comparative analysis was made of mitigation efficiency and of exhaust icing. Results show that both SSDS scenarios reduced radon levels similarly. The results of SSDS with AGL show that a sealed radon fan having proper fittings and sealed piping was able to reduce the radon to acceptable levels, and that these installations were less subject to obstructive icing of the exhaust in cold climates.