Publications

Canadian Radiological Monitoring Network

1. Ahier BA, Tracy BL. 1995. Radionuclides in the Great Lakes Basin. Environmental Health Perspectives 103 Supplement 9):89-101.
   
   The Great Lakes basin is of radiologic interest due to the large population within its boundaries that may be exposed to various sources of ionizing radiation. Specific radionuclides of interest in the basin arising from natural and artificial sources include ³H, ¹⁴C, ⁹⁰Sr, ¹²⁹I, ¹³¹I, ¹³⁷Cs, ²²²Rn, ²²⁶Ra, ²³⁵U, ²³⁸U, ²³⁹Pu and ²⁴¹Am. The greatest contribution to radiation exposure is the natural background radiation that provides an average dose of 2.6 mSv/year to all basin residents. Global fallout from atmospheric nuclear weapons tests conducted before 1963 has resulted in the largest input of anthropogenic radioactivity into the lakes. Of increasing importance is the radionuclide input from the various components of the nuclear fuel cycle. Although the dose from these activities is currently very low, it is expected to increase if there is continued growth of the nu clear industry. In spite of strict regulations on design an operation of nuclear power facilities, the potential exists for a serious accident as a result of the large inventories of radionuclides contained in the reactor cores; however, these risks are several orders of magnitude less than the risks from natural and man-made hazards. An area of major priority over the next few decades will be the management of the substantial amounts of radioactive waste generated by nuclear fuel cycle activities. Based on derived risk coefficients, the theoretical incidence of fatal and weighted nonfatal cancers and hereditary defects in the basin's population, attributable to 50 years exposure to natural background radiation, is conservatively estimated to be of the order of 3.4x10⁵ cases. The total number of attributable health effects to the year 2050 from fallout radionuclides in the Great Lakes basin is of the order of 5.0x10³. In contrast, estimates of attributable health effects from 50 years of exposure to current nuclear fuel cycle effluent in the basin are of the order of 2x10². Although these are hypothetical risks, they show that the radiological impact of man-made sources is very small compared to the effects of normal background radiation.
   
   
2. Létourneau EG, Meyerhof DP, Ahier B. 1994. A retrospective of fallout monitoring in Canada. Environment International 20:665-73.
   
   From 1945 to 1980, 520 nuclear weapons were exploded in the atmosphere resulting in fallout mostly in the northern hemisphere. From 1959 to the present, Canada has operated a national radioactivity network involving stations from coast to coast and in the high Artic to determine the distribution of fallout across the country. The information from almost 40 years of operation of this network and data from the Ottawa Valley including ³H and ¹⁴C measurements are summarized. Some spatial and temporal trends are discussed. The results of these years of observation demonstrate the relatively rapid removal of radioactivity from the environment following cessation of the contaminating event.
   
   
3. Tracy BL, Letourneau EG, McGregor RG, Walker WB. 1996. Variations in natural background radiation across Canada. Environment International 22(Suppl. 1):S55 - S60.
   
   This paper describes gamma radiation levels from across Canada obtained with a network of thermoluminescent dosimeters (TLDs) at 28 environmental monitoring sites and 5 nuclear generating stations. The results showed clear trends with geographical location. Generally, readings from the prairie provinces (Alberta, Saskatchewan, and Manitoba) were higher than the average, whereas readings from central Canada (Ontario and Quebec) were lower. There were no significant seasonal variations. The levels around the nuclear generating stations were not significantly different from those at the environmental monitoring sites. Then national average of gamma dose rate was 76 nGy/h, with a standard deviation of 10 nGy/h. This variablility has implications for the de minimis radiation dose and for possible epidemiological studies of the effects of low level radiation.
   
   
4. Tracy BL, Walker WB, McGregor RG. 1989. Transfer to milk of ¹³¹I and ¹³⁷Cs released during the Chernobyl reactor accident. Health Physics 56(2):239-43.
   
   For the transfer of radionuclides from air to pasture grass and subsequently to milk observed in this study, it appears that dry deposition was more siginificant for I and wet deposition for Cs. Concentrations of ¹³¹I in milk measured in Bq/L were 1,000 to 2,000 times the concentrations of particulate ¹³¹I in air measured in Bq/m³. The transfer of I from grass to milk was consistent with the predictions of conventional models. About 10% of deposited Cs was intercepted by the edible portion of the grass. Transfer of Cs from grass to milk was an order of magnitude lower than predicted by conventional models.