| 1. |
- Ellingsen, D. G., et al.
(författare)
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The variability of arsenic in blood and urine of humans
- 2023
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Ingår i: Journal of Trace Elements in Medicine and Biology. - 0946-672X. ; 78
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Tidskriftsartikel (refereegranskat)abstract
- Background: Humans are exposed to inorganic and organic arsenic. The total arsenic (As) concentration in urine is a commonly used biomarker of exposure. However, little is known about variability of As in biological fluids and the diurnal variation of As excretion.Objectives: Main objectives were to assess the variability of As in urine, plasma (P-As), whole blood (B-As), and the blood cell fraction (C-As), and to assess diurnal variation of As excretion. Methods: Six urine samples were collected at fixed times during 24 h on two different days around one week apart among 29 men and 31 women. Blood samples were collected when the morning urine samples were delivered. The intra-class correlation coefficient (ICC) was calculated as the ratio of the between-individuals variance to the total observed variance.Results: Geometric mean (GM) 24 h urinary excretions of As (U-As24 h) were 41 and 39 mu g/24 h on the two days of sampling. Concentrations of B-As, P-As and C-As were highly correlated with U-As24 h and As in first void morning urine. No statistically significant differences were observed for the urinary As excretion rate between the different sampling times. A high ICC was observed for As in the cellular blood fraction (0.803), while ICC for first morning urine corrected for creatine was low (0.316).Conclusions: The study suggests that C-As is the most reliable biomarker for use in exposure assessment of individual exposure. Morning urine samples have low reliability for such use. No apparent diurnal variation was observed in the urinary As excretion rate.
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| 2. |
- Eriksson, Janna, 1992, et al.
(författare)
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Urinary iodine excretion and optimal time point for sampling when estimating 24-h urinary iodine
- 2023
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Ingår i: British Journal of Nutrition. - : Cambridge University Press (CUP). - 0007-1145 .- 1475-2662. ; 130:8, s. 1289-97
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Tidskriftsartikel (refereegranskat)abstract
- Iodine deficiency may cause thyroid dysfunction. The iodine intake in a population is measured by urinary iodine concentration (UIC) in spot samples or 24-h urinary iodine excretion (24UIE). 24UIE is considered the gold standard and may be estimated using an equation including UIC, urinary creatinine concentration, sex and age (e24UIE). The aims of this study were to evaluate the preferable timing of UIC when using this equation and assess the variability of UIE. Sixty healthy non-smoking women (n 31) and men (n 29) were included in Gothenburg, Sweden. Twelve urine samples were collected at six fixed times on two separate days. Variability was calculated for UIC, 24UIE, e24UIE, iodine excretion per hour (iHr) and UIC adjusted for creatinine and specific gravity. Median 24UIE was 156 mu g/24 h and the median UIC (all spot samples) was 104 mu g/l. UIC (P < 0 center dot 001), 24UIE (P = 0 center dot 001) and e24UIE (P < 0 center dot 001) were significantly higher in men. e24UIE was relatively similar to 24UIE. However, when e24UIE was calculated from UIC in the first void, it was about 15 % lower than 24UIE (P < 0 center dot 001). iHr was lowest in the morning and highest in the afternoon. Median iHr was higher in men (7 center dot 4 v. 5 center dot 3 mu g/h, P < 0 center dot 001). The variability of UIE was higher within individuals than between individuals. This study suggests that most time points for estimation of individual 24UIE are appropriate, but they should preferably not be collected in the first void.
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| 3. |
- Nguyen Ngoc, Hung, et al.
(författare)
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Chemical composition and morphology of individual aerosol particles from a CARIBIC flight at 10 km altitude between 50 degrees N and 30 degrees S
- 2008
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Ingår i: Journal of Geophysical Research. - 2156-2202. ; 113:D23
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Tidskriftsartikel (refereegranskat)abstract
- Analysis of individual particles by analytical electron microscopy as well as quantitative analysis using particle-induced X-ray emission (PIXE) and particle elastic scattering analysis (PESA) were carried out on samples collected from a flight at 10 km altitude between 50 degrees N and 30 degrees S as part of the Civil Aircraft for Regular Investigation of the atmosphere Based on an Instrument Container (CARIBIC) project (http://www.caribic-atmospheric.com). Particle morphology showed large variability with sampling latitude. Complicated branched structures dominated the large particles of the extratropical northern and southern hemisphere and the northern tropics. Particles in the tropics of the southern hemisphere were small in size and large in number concentration, whereas particles in or close to the intertropical convergence zone were few and small in size. Particles in the lowermost stratosphere were found to have similar structures but more branched than the ones found in the upper troposphere of the extratropics. Quantitative analysis revealed that the sulfur concentration varied by a factor of 50 in the nine samples analyzed in this study. The carbon-to-sulfur mass concentration ratio was lowest in the lowermost stratosphere (0.5) and highest in the tropics of the southern hemisphere (3.5). The elemental distribution of carbon and sulfur in individual particles was mapped by energy-filtered transmission electron microscopy (EFTEM). Almost all particles analyzed contained a mixture of carbonaceous and sulfurous matter. Particles with satellites were found by EFTEM to contain both carbon and sulfur in the central particle, whereas in the satellite particles only carbonaceous material was detected.
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| 4. |
- Sällsten, Gerd, 1952, et al.
(författare)
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Variability of lead in urine and blood in healthy individuals
- 2022
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Ingår i: Environmental Research. - : Elsevier BV. - 0013-9351. ; 212
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Tidskriftsartikel (refereegranskat)abstract
- Background: Lead is a non-essential toxic trace element. Lead in blood (BPb) is the most common biomarker of lead exposure but lead in urine (UPb) has also been used. There is, however, limited data on the variability of UPb in the general population and the association with BPb. Objectives: Our aims were to assess variability of lead in repeated blood and urine samples. The diurnal variation of UPb was also examined as well as associations with BPb. Methods: We established an openly available biobank including 60 healthy non-smoking individuals, 29 men and 31 women, 21–64 years of age (median 31 years), with repeated sampling of blood and urine. Timed urine samples were collected at six fixed time points in two 24 h periods, about one week apart, and adjusted for creatinine and specific gravity (SG). BPb and UPb were analyzed by inductively coupled plasma mass spectrometry. The within- and between-individual variabilities and intra-class correlation coefficients (ICCs; ratios of the between-individual to total observed variances) were calculated using mixed-effects models. Results: The ICCs for UPb samples were mostly above 0.5, when adjusted for creatinine or SG, and higher for overnight samples compared with daytime samples. The highest ICCs were obtained for BPb (ICC = 0.97) and for urine samples corrected for dilution by SG or creatinine. The ICC was 0.66 for overnight samples adjusted for creatinine. High correlations with BPb were found for 24 h UPb (rs = 0.77) and overnight samples, e.g. rs = 0.74 when adjusted for SG. There was diurnal variation of UPb with lowest excretion rate in overnight samples. There was also a significant association between the Pb excretion rate and urinary flow rate. Conclusions: In addition to BPb, UPb adjusted for creatinine or SG seems to be a useful biomarker for exposure assessment in epidemiological studies.
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