[en] The Canadian National Calibration Reference Center for Bioassay and in-vivo Monitoring is part of the Radiation Protection Bureau, Department of Health. The Reference Center operates a variety of different intercomparison programs that are designed to confirm that workplace monitoring results are accurate and provide the necessary external verification required by the Canadian regulators. The programs administered by the Reference Center currently include urinalysis intercomparisons for tritium, natural uranium, and ¹⁴C, and in-vivo programs for whole-body, thorax, and thyroid monitoring. The benefits of the intercomparison programs to the participants are discussed by example. Future programs that are planned include dual spiked urine sample which contain both tritium and ¹⁴C and the in-vivo measurement of ^99mTc. 18 refs., 1 fig., 2 tabs

[en] 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 μg/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 to 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. (author)

[en] A study was conducted in two Canadian towns to determine the feasibility of using urinalysis data to estimate uranium uptake where exposure is through the chronic ingestion of soluble natural uranium in drinking water. Forty-three subjects participated in the study. Uranium levels in drinking water varied from 5 to 376 μg/L, and intakes ranged from 3 to 628 μd/day. Urinary excretion varied from 1 to 10 μg/day. Variation of the gut absorption factor (f₁) correlated poorly with gender, years of residence, and age, while significant negative correlation was obtained with intakes greater than 9.5 μg/day. (author)