| 1. |
- Jiang, Zheshun, et al.
(author)
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Hexavalent chromium still a concern in Sweden : Evidence from a cross-sectional study within the SafeChrom project
- 2024
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In: International journal of hygiene and environmental health. - : Elsevier. - 1438-4639 .- 1618-131X. ; 256
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Journal article (peer-reviewed)abstract
- ObjectivesHexavalent chromium (Cr(VI)) is classified as a human carcinogen. Occupational Cr(VI) exposure can occur during different work processes, but the current exposure to Cr(VI) at Swedish workplaces is unknown.MethodsThis cross-sectional study (SafeChrom) recruited non-smoking men and women from 14 companies with potential Cr(VI) exposure (n = 113) and controls from 6 companies without Cr(VI) exposure (n = 72). Inhalable Cr(VI) was measured by personal air sampling (outside of respiratory protection) in exposed workers. Total Cr was measured in urine (pre- and post-shift, density-adjusted) and red blood cells (RBC) (reflecting Cr(VI)) in exposed workers and controls. The Bayesian tool Expostats was used to assess risk and evaluate occupational exposure limit (OEL) compliance.ResultsThe exposed workers performed processing of metal products, steel production, welding, plating, and various chemical processes. The geometric mean concentration of inhalable Cr(VI) in exposed workers was 0.15 μg/m3 (95% confidence interval: 0.11–0.21). Eight of the 113 exposed workers (7%) exceeded the Swedish OEL of 5 μg/m3, and the Bayesian analysis estimated the share of OEL exceedances up to 19.6% for stainless steel welders. Median post-shift urinary (0.60 μg/L, 5th-95th percentile 0.10–3.20) and RBC concentrations (0.73 μg/L, 0.51–2.33) of Cr were significantly higher in the exposed group compared with the controls (urinary 0.10 μg/L, 0.06–0.56 and RBC 0.53 μg/L, 0.42–0.72). Inhalable Cr(VI) correlated with urinary Cr (rS = 0.64) and RBC-Cr (rS = 0.53). Workers within steel production showed the highest concentrations of inhalable, urinary and RBC Cr. Workers with inferred non-acceptable local exhaustion ventilation showed significantly higher inhalable Cr(VI), urinary and RBC Cr concentrations compared with those with inferred acceptable ventilation. Furthermore, workers with inferred correct use of respiratory protection were exposed to significantly higher concentrations of Cr(VI) in air and had higher levels of Cr in urine and RBC than those assessed with incorrect or no use. Based on the Swedish job-exposure-matrix, approximately 17 900 workers were estimated to be occupationally exposed to Cr(VI) today.ConclusionsOur study demonstrates that some workers in Sweden are exposed to high levels of the non-threshold carcinogen Cr(VI). Employers and workers seem aware of Cr(VI) exposure, but more efficient exposure control strategies are required. National strategies aligned with the European strategies are needed in order to eliminate this cause of occupational cancer.
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| 2. |
- Jiang, Zheshun, et al.
(author)
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P-205 THE SAFECHROM PROJECT - EVIDENCE FROM A CROSS-SECTIONAL STUDY SHOWS THAT HEXAVALENT CHROMIUM IS STILL A CONCERN IN SWEDEN
- 2024
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In: Occupational Medicine. - 0962-7480. ; 74:Suppl 1, s. 291-292
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Conference paper (other academic/artistic)abstract
- Hexavalent chromium Cr(VI) is a human carcinogen, but the current exposure to Cr(VI) at Swedish workplaces is unknown.Recruitment of 113 workers with potential Cr(VI) exposure and 72 controls was combined with measurements of inhalable Cr(VI) (only exposed workers) and total Cr in urine and red blood cells (RBC), Bayesian analysis of occupational exposure limit (OEL) compliance was used, as well as the Swedish job-exposure-matrix.Exposed workers performed processing of metal products, steel production, welding, and plating. The geometric mean concentration of inhalable Cr(VI) in exposed workers was 0.15 μg/m3. Eight workers (7\ exceeded the Swedish OEL (5 μg/m3), and the share of OEL exceedances was estimated to be up to 19.6\ and RBC-Cr were significantly higher in exposed workers compared with controls. Workers with inferred non-acceptable local exhaustion ventilation showed significantly higher inhalable Cr(VI), urine- and RBC-Cr than those with acceptable ventilation. Workers with inferred correct use of respiratory protection had higher inhalable Cr(VI), and, paradoxically, higher urine- and RBC-Cr concentrations than workers with incorrect use. We estimate that ~17 900 Swedish workers are occupationally exposed to Cr(VI) today.Our study showed that although most air measurements were relatively low, 7\ and particularly stainless steel workers are at risk for exceeding the OEL. The existing protective measures implemented at workplaces are still inadequate and insufficient.Some workers in Sweden are exposed to high levels of the non-threshold carcinogen Cr(VI). National strategies aligned with European strategies are needed to eliminate occupational cancer.
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| 3. |
- Andersson, Jonas E, 1964-
(author)
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Architecture and Ageing : On the Interaction between Frail Older People and the Built Environment
- 2011
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Doctoral thesis (other academic/artistic)abstract
- This doctoral thesis deals with the type of architecture that materializes when age-related problems become a long-term condition (LTC) and gradually restrain the individual’s ability to perform activities in daily life (ADL). Their life situation necessitates a support from relatives or municipal eldercare staff in order for them to continue to participate in everyday living. In addition, the architectural space requires a close adjustment to the personal panorama of cognitive or functional impairments. The habitat can be a flat appropriated many years previously or in a residential care home for dependent and frail seniors. Architecture for ageing with dependency demonstrates how space can be used either to affirm or oppress the older person’s attempts to maintain an independent life style. By use of design theory, case study methodology and a heterogeneous research strategy, this study uses a threefold approach—a retrospective, a contemporaneous, and a future-oriented approach—to explore frail older people’s interaction with the architectural space of residential care homes. This has resulted in seven papers that focus on aspects of these human interactions with the built environment. Based on twelve exemplary models, the research paper I concludes that national guidelines result in a homelike, a hotel-like or a hospital-like environment. Research paper II is a retrospective study that examines the use of architecture competitions as a socio-political instrument to define architectural guidelines. Research paper III focuses on dependent seniors’ spatial appropriation of the communally shared space of a ward in a residential care home. Research paper IV employs two environmental assessment methods from the architecture profession and gerontological research (TESS-NH) in order to evaluate the use of interior colouring when refurbishing two residential care homes while the residents remained in place. Research paper V displays a municipal organizer’s considerations to opt for an architecture competition as a means of renewing architecture for the ageing population. Research paper VI examines competition documentation of three municipal architecture competitions organized during the period of 2006 to 2009. Research paper VII, the final study, explores notions concerning the appropriate space for ageing found among a group of municipal representatives, and people from organizations defending older people’s right. It supplies a model for understanding the appropriate space for ageing. This study illustrates the absence of older people with frailties in the public discussion about appropriate architecture for ageing. During the 20th century, the multi-dimensional idea of an architectural space with a homelike appearance has been used to contrast the negatively charged opposite—the complete and austere institution. The overarching conclusion of this study is that architecture for dependent and frail seniors constitutes a particular type of built space that requires an extended dialogue involving dependent seniors, architects, building contractors and care planners in order to conceive appropriate architecture for the ageing society.
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| 4. |
- Christenson, Andreas, et al.
(author)
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Direct heterogeneous electron transfer of theophylline oxidase
- 2004
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In: Biosensors & Bioelectronics. - : Elsevier BV. - 1873-4235 .- 0956-5663. ; 20:2, s. 176-183
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Journal article (peer-reviewed)abstract
- Direct electron transfer (DET) was shown between the heme containing enzyme theophylline oxidase (ThO) and the surface of both graphite and gold electrodes. As proof on graphite a steady state current for theophylline was recorded using the electrode modified with adsorbed ThO. The electrode showed a Michaelis–Menten-like response to theophylline with a detection limit of 0.2 mM and a Michaelis–Menten constant equal to 3.2 mM. These initial results open up a possibility for the development of reagentless third generation biosensor based on heterogeneous DET between ThO and an electrode. On gold DET between ThO and the surface of aldrithiol modified gold was studied with spectroelectrochemical measurements. DET was observed for soluble ThO as a change of its spectrum in a gold capillary responding to a change in the applied potential. It was shown that the redox conversion of the heme domain of the enzyme is directly (mediatorlessly) driven by the potential applied at the gold electrode. The measurements enabled an estimation of the formal potential (E°′) of the redox process equal to −275±50 mV versus Ag|AgClsat at pH 7.0. The experimentally determined number of the electrons involved in this heterogeneous electron transfer process was estimated to be equal to 0.53. The low precision in determination of the E°′ and the value of the number of electrons lower than one indicate that kinetic restrictions disturbed the evaluation of the true thermodynamic values from relatively fast spectroelectrochemical measurements. . . . This is the final, accepted and revised manuscript of this article. Use alternative location to go to the published article. Requires subscription.
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| 5. |
- Czolkos, Ilja, et al.
(author)
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Prediction of wastewater quality using amperometric bioelectronic tongues
- 2016
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In: Biosensors & bioelectronics. - : Elsevier. - 0956-5663 .- 1873-4235. ; 75, s. 375-382
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Journal article (peer-reviewed)abstract
- Wastewater samples from a Swedish chemi-thermo-mechanical pulp (CTMP) mill collected at different purification stages in a wastewater treatment plant (WWTP) were analyzed with an amperometric enzyme-based biosensor array in a flow-injection system. In order to resolve the complex composition of the wastewater, the array consists of several sensing elements which yield a multidimensional response. We used principal component analysis (PCA) to decompose the array's responses, and found that wastewater with different degrees of pollution can be differentiated. With the help of partial least squares regression (PLS-R), we could link the sensor responses to the Microtox (R) toxicity parameter, as well as to global organic pollution parameters (COD, BOD, and TOC). From investigating the influences of individual sensors in the array, it was found that the best models were in most cases obtained when all sensors in the array were included in the PLS-R model. We find that fast simultaneous determination of several global environmental parameters characterizing wastewaters is possible with this kind of biosensor array, in particular because of the link between the sensor responses and the biological effect onto the ecosystem into which the wastewater would be released. In conjunction with multivariate data analysis tools, there is strong potential to reduce the total time until a result is yielded from days to a few minutes. (C) 2015 Elsevier B.V. All rights reserved.
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| 6. |
- Dock, Eva, et al.
(author)
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A steady-state and flow-through cell for screen-printed eight-electrode arrays
- 2005
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In: Analytica Chimica Acta. - : Elsevier BV. - 1873-4324 .- 0003-2670. ; 531:2, s. 165-172
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Journal article (peer-reviewed)abstract
- An electrochemical cell has been developed enabling amperometric steady-state- and flow-injection measurements with screen-printed arrays consisting of eight working electrodes (circle divide = 1 mm) arranged radially around a printed Ag/AgCl reference electrode in the centre. The cell contained a rotator, providing similar hydrodynamics over all the working electrodes in the array, which was manually centered under the rotator. The reproducibility of steady-state measurements with eight-electrode platinum or gold arrays in this cell was studied by measuring and comparing currents from ferricyanide reduction at each electrode in the array. It was found that the relative standard deviation (R.S.D.) for the currents at different electrodes on one array was below 5%. Similar R.S.D. was found if measurements were compared between several arrays. This indicates that manual insertion/positioning of the eight-electrode array in the cell and hydrodynamics at the electrodes provided measurement reproducibility similar to the reproducibility of manufacturing eight-electrode platinum or gold arrays by screen-printing. A comparative study was performed between screen-printed and through mask sprayed carbon arrays. It was found that the reproducibility of the sprayed arrays was similar to that of the platinum or gold screen-printed arrays, with R.S.D. values below 6% regarding the variation between electrodes within the same array and the variation between different arrays. To enable flow-injection measurements, a tube (0.4 mm inner diameter) was inserted into a hole drilled through the centre of the steady-state cell rotator. This construction made it possible to inject the solution into the cell through the tube (not rotating), while the rotator was spinning over the eight-electrode array. It was found that this combination of flow-injection and mixing by a rotator provided a uniform current response over the array electrodes and that, at optimum conditions, the R.S.D. values between the eight electrodes in the array were nearly the same as in case of the steady-state measurements, i.e., below 5%. (C) 2004 Elsevier B.V. All rights reserved.
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| 7. |
- Dock, Eva
(author)
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Development of a Bioelectronic Tongue -Applications for Wastewater Analysis
- 2006
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Doctoral thesis (other academic/artistic)abstract
- A bioelectronic tongue has been developed for applications in wastewater analysis. The development of a biosensor array with complex signal analysis started from the idea of using group-selective phenol biosensors (tyrosinase and horseradish peroxidase) with chemometric analysis for signal processing. In a first step the ability to simultaneously determine each analyte in synthetic binary phenol mixtures was evaluated using multivariate data analysis on the responses from a single tyrosinase-modified solid graphite electrode. The next step was to construct a suitable device where different biosensors could be used in an array for multi-parameter detection of samples. Screen-printed electrodes of carbon and noble metals were first evaluated with the purpose of identifying electrodes that could be used as a basis for immobilisation of phenol- and pesticide-sensitive enzymes (horseradish peroxidase, soybean peroxidase, cellobiose dehydrogenase, acetylcholinesterase and butyrylcholinesterase). These enzymes were then immobilised on an array of eight radially distributed electrodes. To host the array and to provide equal hydrodynamics at each electrode in the array, a special electrochemical cell was constructed to enable flow-injection and steady-state measurements. Together with multivariate data analysis has this array system been successfully used for qualitative discrimination of wastewater samples as well as for quantitative determination of their toxicity and other pollution parameters such as chemical oxygen demand and biological oxygen demand. Pre-processing of data before multivariate analysis was shown to be necessary for reducing the noise that otherwise can hide the desired structural information. Several strategies to overcome noise problems due to drift in biosensors have been developed.
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| 8. |
- Dock, Eva, et al.
(author)
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Effect of interfering substances on current response of recombinant peroxidase and glucose oxidase-recombinant peroxidase modified graphite electrodes
- 2001
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In: Analyst. - 1364-5528. ; 126:11, s. 35-1929
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Journal article (peer-reviewed)abstract
- Graphite electrodes have been modified with different forms of horseradish peroxidase (HRP). These included native HRP, wild-type recombinant HRP, and two single-point recombinant HRP mutants, N70V and N70D. The mediator-less response of these electrodes to H2O2 was studied indicating that electrodes modified with recombinant HRP forms are more stable than those modified with native HRP. Various interfering compounds were investigated for their effect on the current response to H2O2. It was found that interferences such as acetaminophen and dopamine affected the response by mediating the electron transfer (ET) between graphite and peroxidases. The mediating behaviour manifested itself as an increased current of the electrode to H2O2. The interfering effect was less pronounced for the electrodes modified with recombinant HRPs possessing better electronic coupling with the graphite surface. The interfering behaviour of acetaminophen on the response for glucose with the bienzyme electrode containing co-immobilised glucose oxidase and HRP was mainly ascribed to mediation of ET between graphite and HRP. It was experimentally proven that a high efficiency of direct ET between graphite and recombinant HRP substantially reduces the interfering effect of acetaminophen.
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| 9. |
- Dock, Eva, et al.
(author)
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Multivariate data analysis of dynamic amperometric biosensor responses from binary analyte mixtures - application of sensitivity correction algorithms
- 2005
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In: Talanta. - : Elsevier BV. - 1873-3573 .- 0039-9140. ; 65:2, s. 298-305
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Journal article (peer-reviewed)abstract
- In this paper, it is demonstrated that a single-receptor biosensor can be used to quantitatively determine each analyte in binary Mixtures LIS in multivariate data analysis tools based on the dynamic responses received from flow injection peaks. Mixtures with different concentrations of two phenolic compounds, catechol and 4-chlorophenol, were measured with a graphite electrode modified with tyrosinase enzyme at an applied potential of -50 mV versus Ag/AgCl. A correction algorithm based on measurements of references in-between samples was applied to compensate for biosensor ageing as well as differences caused by deviations between biosensor preparations. After correction, the relative prediction errors with partial least squares regression (PLS-R) for catechol and 4-chlorophenol were 7.4 and 5.5%, respectively, using an analysis sequence measured on one biosensor. Additional validation mixtures of the two phenols were measured with a new biosensor, prepared with the same procedure but with a different batch of tyrosinase enzyme. Using the mixture responses for the first sensor as a calibration set in PLS-R. the relative prediction errors of the validation mixtures, after applying correction procedures. were 7.0% for catechol and 16.0% for 4-chlorophenol. These preliminary results indicate that by applying correction algorithms it could be possible to use less stable biosensors in continuous on-line measurements together with multivariate data analysis without time-consuming calibration procedures. (C) 2004 Elsevier B.V. All rights reserved.
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| 10. |
- Dock, Eva, et al.
(author)
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Screen-printed carbon electrodes modified with cellobiose dehydrogenase: Amplification factor for catechol vs. reversibility of ferricyanide
- 2003
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In: Electroanalysis. - : Wiley. - 1040-0397 .- 1521-4109. ; 15:5-6, s. 492-498
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Journal article (peer-reviewed)abstract
- A number of screen-printed carbon electrodes (SPCEs) have been electrochemically studied revealing strong correlation between the reversibility of the Fe(CN)/Fe(CN) couple and the sensitivity for catechol at the same electrodes modified with cellobiose dehydrogenase (CDH). Pretreatment of the electrode surfaces increased both the heterogeneous ferricyanide reaction rate and the catechol sensitivity. From cyclic voltammetric and chronoamperometric measurements of Fe(CN) it was concluded that the tested SPCEs behave as microelectrode arrays. Using the pinhole model the fraction of electroactive area was determined to directly correlate to a faster heterogeneous electron transfer for ferricyanide and a higher CDH-modified biosensor sensitivity for catechol. An electroactive area of 50% and higher is sufficient to create a sufficiently good biosensor for catechol.
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