Uranium exposure of the Swiss population based on 24-hour urinary excretion.

AIM OF THE STUDY: Important regional differences in uranium exposure exist because of varying uranium concentrations in soil, water and food. Comprehensive data on the exposure of the general population to uranium is, however, scarce. Based on the 24-hour urinary excretion, the uranium exposure of the adult Swiss population was assessed in relation to age, sex, place of residence, body mass index (BMI), smoking habit and type of drinking water, as well as risk factors in relation to kidney impairment and indicators of a possible renal dysfunction. METHODS: Uranium was quantified in 24-hour urine from a nationwide population-based sample (n = 1393). The ratio 238U/233U was measured for isotope dilution calibration with a sector field inductively coupled plasma mass spectrometer (HR-ICP-MS). RESULTS: Overall median and 95th percentile were 15 and 67 ng/24 h, respectively. The place of residence significantly influenced urinary uranium excretion. However, most of the highest urinary uranium excretion levels could not be associated to areas known for their elevated uranium concentrations in the drinking water. Sources other than the local drinking water (e.g., bottled water) might be important, too. Gender as well as albumin excretion also had a significant effect on uranium excretion. The latter was, however, strongly dependent on the presence of diabetes mellitus. No association was found for age, BMI, smoking habit or the other examined kidney related variables. CONCLUSIONS: On the basis of uranium exposure, assessed via 24-hour urinary uranium excretion, and current knowledge of the toxicity of naturally occurring uranium, a substantial corresponding health risk for the general adult population is unlikely. However, as long as no specific sensitive biomarker for the biological impact of low-dose chronic uranium exposure has been identified and validated, assessing subtle health impact of such exposure will remain difficult.

Study design and baseline characteristics of a combined educational and environmental intervention trial to lower sodium intake in Swiss employees.

BACKGROUND: Blood pressure is a primary cardiovascular disease risk factor. Population-wide governmental strategies aim to reduce lifestyle and dietary risk factors for hypertension, one of which is an unbalanced diet with high sodium and low potassium intakes. Nutrition interventions in the workplace are considered a promising approach in encouraging health-promoting behaviors. We developed and conducted the health promoting sodium reduction trial "Healthful & Tasty: Sure!" in worksites in the German-speaking part of Switzerland from May 2015 to Nov 2016, for which we present the study protocol and baseline characteristics. METHODS: Healthful & Tasty, a cluster nonrandomized single-arm trial with calibration arm, aimed to demonstrate the effectiveness of a combined educational and environmental intervention in the workplace in reducing employees' average daily sodium/salt intake by 15%. To this end, health and food literacy of employees and guideline compliance among the catering facility team needed to be improved. The primary outcome measure was sodium/salt intake estimated from sodium excretion in a 24-h urine sample. Secondary outcome measures included changes in the overall qualitative diet composition, blood pressure, anthropometric indices, and health and food literacy. Of eight organizations with catering facilities, seven organizations took part in the nutrition education and catering salt reduction interventions, and one organization participated as a control. Overall, 145 consenting employees were included in the staggered, one-year four-phase trial, of which 132 participated in the intervention group. In addition to catering surveys and food sampling, the trial included five follow-up health assessments including questionnaires, blood pressure measurements, anthropometrics, and sodium, potassium, and iodine intake measurements obtained from 24-h and spot urine samples, and a food record checklist. Exploratory and hypothesis generating baseline statistical analysis included 141 participants with adequate 24-h urine samples. DISCUSSION: Despite practice-driven limitations to the study design and small cluster and participant numbers, this trial has methodological strength and will provide important insights into the effectiveness of a combined educational and environmental intervention to reduce salt intake among female and male Swiss employees. TRIAL REGISTRATION: German Clinical Trials Register, DRKS00006790 . Registered 23 September 2014.