Managing health risks in urban agriculture: The effect of vegetable washing for reducing exposure to metal contaminants.

A common, yet poorly evaluated, advice to remove contaminants from urban vegetables is to wash the produce before consumption. This study is based on 63 samples of chard, kale, lettuce and parsley that have grown near a heavily trafficked road in the third largest city in Sweden, with one portion of each sample being analysed without first being washed, and the other portion being subjected to common household washing. Concentrations of 71 elements were analysed by ICP-SFMS after a sample digestion that dissolves both the plant tissues and all potentially adhering particles. The results show that the washing effect, or the fraction removed upon washing, varies significantly between elements: from approximately 0 % for K to 68 % for the ∑REEs. Considering traditional metal contaminants, the efficiency decreased from Pb (on average 56 % lost) to Co (56 %) > Cr (55 %) > As (45 %) > Sb (35 %) > Ni (33 %) > Cu (13 %) > Zn (7 %) > Cd (7 %), and Ba (5 %). A clear negative correlation between the washing effect and the different elements' bioconcentration factors shows that the elements' accessibility for plant uptake is a key controlling factor for the degree to which they are removed upon washing. Based on the average washing efficiencies seen in this study, the average daily intake of Pb would increase by 130 % if vegetables are not washed prior to consumption. For the other contaminant metals this increase corresponds to 126 % (Co), 121 % (Cr), 82 % (As), 55 % (Sb), 50 % (Ni), 16 % (Cu), 8 % (Zn), 7 % (Cd) and 5 % (Ba). The advice to wash vegetables is therefore, for many elements, highly motivated for reducing exposure and health risks. For elements which are only slightly reduced when the vegetables are washed, however, advising should rather focus on reducing levels of contamination in the soil itself.

Early diagenesis of anthropogenic uranium in lakes receiving deep groundwater from the Kiruna mine, northern Sweden.

The uranium (U) concentrations and isotopic composition of waters and sediment cores were used to investigate the transport and accumulation of U in a water system (tailings pond, two lakes, and the Kalix River) receiving mine waters from the Kiruna mine. Concentrations of dissolved U decrease two orders of magnitude between the inflow of mine waters and in the Kalix River, while the concentration of the element bound to particulate matter increases, most likely due to sorption on iron­manganese hydroxides and organic matter. The vertical distribution of U in the water column differs between two polluted lakes with a potential indication of dissolved U supply from sediment's pore waters at anoxic conditions. Since the beginning of exposure in the 1950s, U concentrations in lake sediments have increased >20-fold, reaching concentrations above 50 µg g-1. The distribution of anthropogenic U between the lakes does not follow the distribution of other mine water contaminants, with a higher relative proportion of U accumulating in the sediments of the second lake. Concentrations of redox-sensitive elements in the sediment core as well as Fe isotopic composition were used to re-construct past redox-conditions potentially controlling early diagenesis of U in surface sediments. Two analytical techniques (ICP-SFMS and MC-ICP-MS) were used for the determination of U isotopic composition, providing an extra dimension in the understanding of processes in the system. The (234 U)/(238 U) activity ratio (AR) is rather uniform in the tailings pond but varies considerably in water and lake sediments providing a potential tracer for U transport from the Kiruna mine through the water system, and U immobilization in sediments. The U mass balance in the Rakkurijoki system as well as the amount of anthropogenic U accumulated in lake sediments were evaluated, indicating the immobilization in the two lakes of 170 kg and 285 kg U, respectively.

Spatio-temporal variation of metals and organic contaminants in bank voles (Myodes glareolus).

Environmental contamination with metals and organic compounds is of increasing concern for ecosystem and human health. Still, our knowledge about spatial distribution, temporal changes and ecotoxicological fate of metals and organic contaminants in wildlife is limited. We studied concentrations of 69 elements and 50 organic compounds in 300 bank voles (Myodes glareolus), Europe's most common mammal, sampled in spring and autumn 2017-2018 in five monitoring areas, representing three biogeographic regions. In addition, we compared measured concentrations with previous results from bank voles sampled within the same areas in 1995-1997 and 2001. In general, our results show regional differences, but no consistent patterns among contaminants and study areas. The exception was for the lowest concentrations of organic contaminants (e.g. perfluorooctane sulfonate, PFOS), which were generally found in the northern Swedish mountain area. Concentrations of metals and organic contaminants in adults varied seasonally with most organic contaminants being higher in spring; likely induced by diet shifts but potentially also related to age differences. In addition, metal concentrations varied between organs (liver vs. kidney), age classes (juveniles vs. adults; generally higher in adults) as well as between males and females. Concentrations of chromium and nickel in kidney and liver in the northernmost mountain area were lower in 2017-2018 than in 1995-1997 and in three of four areas, lead concentrations were lower in 2017-2018 than in 2001. Current metal concentrations (except mercury) are not expected to negatively affect the voles. Concentrations of hexachlorobenzene displayed highest concentrations in 2001 in the mountains, while it was close to detection limit in 2017-2018. Likewise, PFOS concentrations decreased in the mountains and in south-central lowland forests between 2001 and 2017-2018. Our results suggest that season, age class and sex need to be considered when designing and interpreting results from monitoring programs targeting inorganic and organic contaminants in wildlife.

The potential of vehicle and road infrastructure interventions in fatal bicyclist accidents on Swedish roads-What can in-depth studies tell us?

Objective: The objective of this article is to describe the characteristics of fatal crashes with bicyclists on Swedish roads in rural and urban areas and to investigate the potential of bicycle helmets and different vehicle and road infrastructure interventions to prevent them. The study has a comprehensive approach to provide road authorities and vehicle manufacturers with recommendations for future priorities. Methods: The Swedish Transport Administration's (STA) in-depth database of fatal crashes was used for case-by-case analysis of fatal cycling accidents (2006-2016) on rural (n = 82) and urban (n = 102) roads. The database consists of information from the police, medical journals, autopsy reports, accident analyses performed by STA, and witness statements. The potential of helmet use and various vehicle and road infrastructure safety interventions was determined retrospectively for each case by analyzing the chain of events leading to the fatality. The potential of vehicle safety countermeasures was analyzed based on prognoses on their implementation rates in the Swedish vehicle fleet. Results: The most common accident scenario on rural roads was that the bicyclist was struck while cycling along the side of the road. On urban roads, the majority of accidents occurred in intersections. Most accidents involved a passenger car, but heavy trucks were also common, especially in urban areas. Most accidents occurred in daylight conditions (73%). Almost half (46%) of nonhelmeted bicyclists would have survived with a helmet. It was assessed that nearly 60% of the fatal accidents could be addressed by advanced vehicle safety technologies, especially autonomous emergency braking with the ability to detect bicyclists. With regard to interventions in the road infrastructure, separated paths for bicyclists and bicycle crossings with speed calming measures were found to have the greatest safety potential. Results indicated that 91% of fatally injured bicyclists could potentially be saved with known techniques. However, it will take a long time for such technologies to be widespread. Conclusions: The majority of fatally injured bicyclists studied could potentially be saved with known techniques. A speedy implementation of important vehicle safety systems is recommended. A fast introduction of effective interventions in the road infrastructure is also necessary, preferably with a plan for prioritization.

Seasonal shift of diet in bank voles explains trophic fate of anthropogenic osmium?

Diet shifts are common in mammals and birds, but little is known about how such shifts along the food web affect contaminant exposure. Voles are staple food for many mammalian and avian predators. There is therefore a risk of transfer of contaminants accumulated in voles within the food chain. Osmium is one of the rarest earth elements with osmium tetroxide (OsO4) as the most toxic vapor-phase airborne contaminant. Anthropogenic OsO4 accumulates in fruticose lichens that are important winter food of bank voles (Myodes glareolus). Here, we test if a) anthropogenic osmium accumulates in bank voles in winter, and b) accumulation rates and concentrations are lower in autumn when the species is mainly herbivorous. Our study, performed in a boreal forest impacted by anthropogenic osmium, supported the hypotheses for all studied tissues (kidney, liver, lung, muscle and spleen) in 50 studied bank voles. In autumn, osmium concentrations in bank voles were even partly similar to those in the graminivorous field vole (Microtus agrestis; n=14). In autumn but not in late winter/early spring, osmium concentrations were generally negatively correlated with body weight and root length of the first mandible molar, i.e. proxies of bank vole age. Identified negative correlations between organ-to-body weight ratios and osmium concentrations in late winter/early spring indicate intoxication. Our results suggest unequal accumulation risk for predators feeding on different cohorts of bank voles.

Application of double-focusing sector field ICP-MS for determination of ultratrace constituents in samples characterized by complex composition of the matrix.

The performance of double focusing, sector field mass spectrometry (ICP-SFMS) for determination of analytes, including technology critical elements (TCE), at ultra-trace levels in environmental and clinical matrices was critically evaluated. Different configurations of the ICP-SFMS introduction system as well as various sample preparations, pre-concentration and matrix separation methods were employed and compared. Factors affecting detection capabilities and accuracy of data produced (instrumental sensitivity, contamination risks, purity of reagents, spectral interferences, matrix effects, analyte recovery and losses) were discussed. Optimized matrix-specific methods were applied to a range of reference and control materials (riverine, brackish and seawaters; whole blood, serum and urine) as well as tap water and snow samples collected in the area of Luleå city, northern Sweden; brackish and seawater from the Laptev Sea; venous blood samples with a special emphasis on determination of Au, Ag, Ir, Os, Pd, Pt, Re, Rh, Ru, Sb and Te. Even though these low abundant elements are relatively under-documented, the results produced were compared with published data, where available.

Prevalence of microbiological contaminants in groundwater sources and risk factor assessment in Juba, South Sudan.

In low-income regions, drinking water is often derived from groundwater sources, which might spread diarrheal disease if they are microbiologically polluted. This study aimed to investigate the occurrence of fecal contamination in 147 improved groundwater sources in Juba, South Sudan and to assess potential contributing risk factors, based on bivariate statistical analysis. Thermotolerant coliforms (TTCs) were detected in 66% of the investigated sources, including 95 boreholes, breaching the health-based recommendations for drinking water. A significant association (p<0.05) was determined between the presence of TTCs and the depth of cumulative, long-term prior precipitation (both within the previous five days and within the past month). No such link was found to short-term rainfall, the presence of latrines or damages in the borehole apron. However, the risk factor analysis further suggested, to a lesser degree, that the local topography and on-site hygiene were additionally significant. In summary, the analysis indicated that an important contamination mechanism was fecal pollution of the contributing groundwater, which was unlikely due to the presence of latrines; instead, infiltration from contaminated surface water was more probable. The reduction in fecal sources in the environment in Juba is thus recommended, for example, through constructing latrines or designating protection areas near water sources. The study results contribute to the understanding of microbiological contamination of groundwater sources in areas with low incomes and high population densities, tropical climates and weathered basement complex environments, which are common in urban sub-Saharan Africa.

The role of bacterial consortium and organic amendment in Cu and Fe isotope fractionation in plants on a polluted mine site.

Copper and iron isotope fractionation by plant uptake and translocation is a matter of current research. As a way to apply the use of Cu and Fe stable isotopes in the phytoremediation of contaminated sites, the effects of organic amendment and microbial addition in a mine-spoiled soil seeded with Helianthus annuus in pot experiments and field trials were studied. Results show that the addition of a microbial consortium of ten bacterial strains has an influence on Cu and Fe isotope fractionation by the uptake and translocation in pot experiments, with an increase in average of 0.99 ‰ for the δ(65)Cu values from soil to roots. In the field trial, the amendment with the addition of bacteria and mycorrhiza as single and double inoculation enriches the leaves in (65)Cu compared to the soil. As a result of the same trial, the δ(56)Fe values in the leaves are lower than those from the bulk soil, although some differences are seen according to the amendment used. Siderophores, possibly released by the bacterial consortium, can be responsible for this change in the Cu and Fe fractionation. The overall isotopic fractionation trend for Cu and Fe does not vary for pot and field experiments with or without bacteria. However, variations in specific metabolic pathways related to metal-organic complexation and weathering can modify particular isotopic signatures.

Isotopic analyses by ICP-MS in clinical samples.

This critical review focuses on inductively coupled plasma mass spectrometry (ICP-MS) based applications for isotope abundance ratio measurements in various clinical samples relevant to monitoring occupational or environmental exposure, human provenancing and reconstruction of migration pathways as well as metabolic research. It starts with a brief overview of recent advances in ICP-MS instrumentation, followed by selected examples that cover the fields of accurate analyte quantification using isotope dilution, tracer studies in nutrition and toxicology, and areas relying upon natural or man-made variations in isotope abundance ratios (Pb, Sr, actinides and stable heavy elements). Finally, some suggestions on future developments in the field are provided.

Sources of contamination and remedial strategies in the multi-elemental trace analysis laboratory.

In theory, state of the art inductively coupled plasma mass spectrometry (ICP-MS) instrumentation has the prerequisite sensitivity to carry out multi-elemental trace analyses at sub-ng L-1 to sub-pg L-1 levels in solution. In practice, constraints mainly imposed by various sources of contamination in the laboratory and the instrument itself, and the need to dilute sample solutions prior to analysis ultimately limit detection capabilities. Here we review these sources of contamination and, wherever possible, propose remedial strategies that we have found efficacious for ameliorating their impact on the results of multi-elemental trace analyses by ICP-MS. We conclude by providing a list of key points to consider when developing methods and preparing the laboratory to routinely meet the demands of multi-elemental analyses at trace analytical levels by ICP-MS.

Comparison of power spectra for tomosynthesis projections and reconstructed images.

Burgess et al. [Med. Phys. 28, 419-437 (2001)] showed that the power spectrum of mammographic breast background follows a power law and that lesion detectability is affected by the power-law exponent beta which measures the amount of structure in the background. Following the study of Burgess et al., the authors measured and compared the power-law exponent of mammographic backgrounds in tomosynthesis projections and reconstructed slices to investigate the effect of tomosynthesis imaging on background structure. Our data set consisted of 55 patient cases. For each case, regions of interest (ROIs) were extracted from both projection images and reconstructed slices. The periodogram of each ROI was computed by taking the squared modulus of the Fourier transform of the ROI. The power-law exponent was determined for each periodogram and averaged across all ROIs extracted from all projections or reconstructed slices for each patient data set. For the projections, the mean beta averaged across the 55 cases was 3.06 (standard deviation of 0.21), while it was 2.87 (0.24) for the corresponding reconstructions. The difference in beta for a given patient between the projection ROIs and the reconstructed ROIs averaged across the 55 cases was 0.194, which was statistically significant (p < 0.001). The 95% CI for the difference between the mean value of beta for the projections and reconstructions was [0.170, 0.218]. The results are consistent with the observation that the amount of breast structure in the tomosynthesis slice is reduced compared to projection mammography and that this may lead to improved lesion detectability.

Osmium in environmental samples from Northeast Sweden. Part II. Identification of anthropogenic sources.

Osmium (Os) concentrations and (187)Os/(188)Os isotope abundance ratios measured in epiphytic lichens from Northeast Sweden have been used for the identification of anthropogenic emission sources of this element. Based on isotope abundance ratios and similarities in spatial distributions between Os and chromium, smelters operated on chromium ores from Kemi deposits have shown to be the most important factor affecting the airborne Os burden in the region. The extent of the exposure is reflected by lichen concentrations near the source exceeding those from remote areas by a factor of 1000. Contributions from metal foundries processing iron, copper, lead and zinc ores can also be seen, though, because of lower Os concentrations in the feedstock, on a considerably lower scale. Masked by these industrial emissions in the studied area, the impact of Os originating from automotive catalytic converters cannot be resolved at present.

Osmium in environmental samples from Northeast Sweden. Part I. Evaluation of background status.

Osmium (Os) concentrations and (187)Os/(188)Os isotope abundance ratios are presented for sedimentary materials, soils, humus, plants, mushrooms, mosses and lichens collected in the vicinity of the town of Luleå, Northeast Sweden, the data for biological specimens being the first reported. Contributions from sampling and varying exposure time to the observed environmental variability were evaluated. Sedimentary materials (from both fresh and brackish water) are most elevated in radiogenic (187)Os, followed by inorganic soil horizons, mushrooms and humus. The Os isotopic compositions of plants, mosses and lichens are much less radiogenic, with mean (187)Os/(188)Os lying within a relatively narrow 0.3-0.6 range. Significant temporal variations in Os concentrations and isotopic compositions of plant samples are attributed to integrative uptake of airborne Os with non-radiogenic composition. Measured Os concentrations in biological matrices increase in the order: small shrub leaves (blueberry and lingonberry)< or =spruce needles< or =mushrooms< or =tree leaves< or =pine needles

Methylmercury measurement in whole blood by isotope-dilution GC-ICPMS with 2 sample preparation methods.

BACKGROUND: Despite its known toxicity, methylmercury is rarely measured directly in clinical studies; instead, conclusions are based on total mercury measurements. We have developed isotope-dilution-based methods for methylmercury-specific analysis of whole blood by coupled gas chromatography-inductively coupled plasma mass spectrometry (GC-ICPMS). METHODS: We analyzed animal and human blood samples after alkaline digestion or extraction of methylmercury into dichloromethane and back extraction into water. Methylmercury was converted to the volatile ethyl derivative, purged, and trapped on a solid-phase collection medium, and then introduced into the GC-ICPMS system. RESULTS: Limits of quantification were 0.4 and 0.03 microg/L at a signal-to-noise ratio of 10 with the alkaline digestion and extraction methods, respectively. Extraction met our selected acceptable total error criterion, with an SD of 0.58 microg/L at the critical maternal blood concentration of 5.8 microg/L. Results obtained with alkaline digestion indicated the need for improved random analytical uncertainty, which was achieved by increasing the enrichment of the isotope dilution. For 37 blood samples, the mean (SD) proportion of total mercury present as methylmercury was 60 (27)%, range 6%-100%. CONCLUSIONS: The combination of extraction and isotope-dilution GC-ICPMS meets the requirements for use as a reference method for measuring methylmercury in whole blood.

Chromatographic purification for the determination of dissolved silicon isotopic compositions in natural waters by high-resolution multicollector inductively coupled plasma mass spectrometry.

A procedure is described for accurate Si isotope ratio measurements by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Dissolved silicon was preconcentrated and separated from other elements present in natural surface waters using anion-exchange chromatography. The optimized procedure provides virtually complete elimination of major inorganic constituents while maintaining Si recovery in excess of 97%. High-resolution capabilities of MC-ICPMS used in this study allow interference-free measurements of 28Si and 29Si isotopes using conventional solution nebulization sample introduction without aerosol desolvation. Owing to the magnitude of polyatomic ion contributions in the region of mass 30, mostly from 14N16O+, measurements of the 30Si isotope can be affected by tailing of the interference signals, making exact matching of analyte and nitric acid concentrations in all measurement solutions mandatory. Isotope abundance ratio measurements were performed using the bracketing standards approach and on-line correction for mass-bias variations using an internal standard (Mg). Uncertainties, expressed as 95% confidence intervals, for replication of the entire procedure are better than +/-0.18/1000 for delta29Si and +/-0.5/1000 for delta30Si. For the first time with MC-ICPMS, the quality of Si isotope abundance ratio measurements could be verified using a three-isotope plot. All samples studied were isotopically heavier than the IRMM-018 Si isotopic reference material.

Measurement of iron and zinc isotopes in human whole blood: preliminary application to the study of HFE genotypes.

Multi-collector inductively coupled plasma--sector field mass spectrometry was applied to the measurement of Fe and Zn isotopes in human whole blood samples. For the Fe present in the blood of healthy adults, enrichment of the lighter isotopes relative to a standard material was observed, in agreement with earlier studies. The level of fractionation was found to be lower in hemochromatosis patients exhibiting homozygous (C282Y/C282Y) mutation of the HFE gene. On the one hand, this reinforces the hypothesis that Fe fractionation in blood decreases with enhanced dietary absorption. On the other hand, this contradicts predictions made on the basis of determinations of Fe fractionation in blood samples collected from subjects characterized by milder HFE mutations. In healthy subjects, the Zn in blood is depleted in lighter isotopes, consistent with the limited number of prior observations. As for Fe, the Zn isotopic composition exhibited a tendency toward lower levels of fractionation in the blood of subjects with hereditary hemochromatosis with homozygous mutation (C282Y/C282Y) of the HFE gene. The results therefore suggest that both Fe and Zn isotopic signatures in whole blood, at least to some extent, reflect polymorphisms in the HFE gene.

Determination of low-abundance elements at ultra-trace levels in urine and serum by inductively coupled plasma-sector field mass spectrometry.

A procedure is described for the determination of Y, Zr, Nb, Ru, Rh, Pd, Ag, Sb, Te, Hf, Ta, W, Re, Os, Ir, Pt, Au, Tl, Bi, and U in human urine and serum at concentrations relevant to the occupationally unexposed population. Sample preparation was limited to tenfold dilution with 2% HCl. A combination of a sample-introduction system designed to provide enhanced sensitivity and the use of water and acids of high-purity has resulted in limits of quantification (LOQ) in the sub-nanogram per liter range for 13 analytes. Instrumental background caused by release of analytes (Y, Zr, Ag, Sb, Au, Tl, Bi, U) from different parts of the sample-introduction system was found to be the major limitation in obtaining even better LOQ. Nevertheless, detection capabilities of the proposed procedure were adequate for all elements except Ru, Pd, and Rh. Despite of the use of high-resolution mode for these analytes some unresolved spectral interferences might still be present. For 13 elements an external accuracy assessment was accomplished by participation in proficiency testing and inter-comparison programs. Results obtained for pooled urine and serum were compared with concentrations reported for occupationally unexposed populations in recent publications.

Isotopic variations of Zn in biological materials.

Variations in the isotopic composition of Zn present in various biological materials were determined using high-resolution multicollector inductively coupled plasma mass spectrometry (MC-ICPMS), following digestion and purification by anion exchange chromatography. To correct for differences in instrumental mass discrimination effects between samples and standards, Cu was employed as an elemental spike. Complementary analyses of Zn separates by sector field ICPMS instruments revealed that the concentrations of the majority of potentially interfering elements were reduced to negligible levels. Residual spectral interferences resulting from (35)Cl(16)O(2)(+), (40)Ar(14)N(2)(+), and (40)Ar(14)N(16)O(+) could be instrumentally resolved from the (67)Zn, (68)Zn, and (70)Zn ion beams, respectively, during measurement by MC-ICPMS. The only other observed interference in the Cu and Zn mass range that could not be effectively eliminated by high-resolution multicollection resulted from (35)Cl(2)(+), necessitating modification of the sample preparation procedure to allow accurate (70)Zn detection. Complete duplication of the entire analytical procedure for human whole blood and hair, as well as bovine liver and muscle, provided an external reproducibility of 0.05-0.12 per thousand (2sigma) for measured delta(66/64)Zn, delta(67/64)Zn, and delta(68/64)Zn values, demonstrating the utility of the method for the precise isotopic analysis of Zn in biological materials. Relative to the selected Zn isotopic standard, delta(66/64)Zn values for biological samples varied from -0.60 per thousand in human hair to +0.56 per thousand in human whole blood, identifying the former material as the isotopically lightest Zn source found in nature to date.