Biomedical subjects

Mats Tysklind

Publications and source records attributed to Mats Tysklind.

36 records · Page 2Linked to original sources

PubMed2004

Investigations into the vertical distribution of PCDDs and mineralogy in three ball clay cores from the United States exhibiting the natural formation pattern.

In this study, we report the PCDD and mineralogical results from the analyses of 27 different samples from three ball clay cores from different locations in Kentucky and Tennessee. One goal of this study was to determine if there is a correlation between the mineralogy of the ball clay samples and the PCDD concentrations and/or homologue profiles in each sample. Samples from each of the three cores exhibited the natural formation profile with extremely high PCDD concentrations with low and mostly undetectable levels of polychlorinated dibenzofurans (PCDFs). The maximum toxic equivalents (TEQs) for Cores C-E were 2500, 440, and 15,000 pg WHO-TEQ/g, respectively. Although there does not seem to be a direct correlation between mineralogy and PCDD concentrations or homologue profiles, the mineralogy of Core C is substantially different than that of Cores D and E, which may in part explain the differences in congener patterns we observed among the three cores.

Aluminum Silicates↗

PubMed2004

Photolytic debromination of decabromodiphenyl ether (BDE 209).

Polybrominated diphenyl ethers (PBDE) are commonly used flame retardants. During the past years, concerns have increased due to their occurrence in the environment and humans. In general, the concentrations of lower brominated (tetra-penta) diphenyl ethers in biota exceed those of the most heavily used product, decabromodiphenyl ether (DecaBDE). In this study, the photolytic debromination of DecaBDE has been investigated in order to study the formation of lower brominated diphenyl ethers. The time course of photolysis of DecaBDE was studied in toluene, on silica gel, sand, sediment and soil using artificial sunlight and on the natural matrices (sediment, soil, sand) also using natural sunlight. DecaBDE was photolytically labile and formed debromination products in all matrices studied. Nona- to tetraBDEs were formed as well as some PBDFs. The half-lives in toluene and on silica gel were less than 15 min, and half-lives on other matrices ranged between 40 and 200 h. No differences were seen in the debromination pattern of BDE congeners sequentially formed in the different matrices or under different light conditions. However, the debromination rates were strongly dependent on the matrix with longer half-lives on natural matrices than artificial ones.

Bromine↗

PubMed2004

Low-resolution mass spectrometric relative response factors (RRFs) and relative retention times (RRTs) on two common gas chromatographic stationary phases for 87 polychlorinated dibenzofurans.

All 87 tetra- to octa-chlorinated dibenzofurans (PCDFs) were analysed using high-resolution gas chromatography/low-resolution mass spectrometry (HRGC-LRMS). The mass spectrometer was operated in two different modes: electron ionisation (EI), and negative ion chemical ionisation (NCI) with methane as a reagent gas. Baseline separation and identification of all PCDF congeners was carried out using one non-polar (DB-5) and one polar (RT-2330) capillary GC column. Relative retention times (RRTs) on both columns, and relative response factors (RRFs) in both EI- and NCI-modes, were calculated for all 87 of the PCDFs. Comparison of the EI-RRFs and NCI-RRFs showed that the mass spectrometric NCI-responses varied to a higher degree than the EI-responses. The level of NCI-response was dependent on the substitution positions of the chlorine atoms on the dibenzofuran molecule skeleton. The ratio between the highest and lowest RRFs was 26 in the NCI-mode, but only 2.3 in the EI-mode. Thus, quantification of tetra- to octa-CDFs in environmental samples using the NCI-mode will result in incorrect estimates of PCDF concentrations unless 13C-labelled internal standards are used for each congener, or RRFs are taken into consideration. In contrast, the quantification of PCDFs in the EI-mode using a single internal 13C-labelled PCDF standard for each PCDF homologue is accurate according to the findings in this investigation. A flue gas sample from a municipal solid waste incinerator (MSWI) analysed in the NCI-mode was quantified with and without NCI-RRFs. When using NCI-RRFs the reported concentration of SigmaPCDFs in the flue gas sample increased by 40%. Furthermore, TCDF analysis was compared using two mass spectrometers (a VG 12-250 and a Finnigan 4500) operating in EI-mode. These quadrupole instruments performed equally well, giving similar EI-RRFs for the tested compounds.

Benzofurans↗

PubMed2004

Determination of antibiotic substances in hospital sewage water using solid phase extraction and liquid chromatography/mass spectrometry and group analogue internal standards.

A method for determination of antibiotics in hospital sewage water has been developed and validated. Analogue internal standards for fluoroquinolones, sulfonamides, trimethoprim, beta-lactams (penicillins and cephalosporins), nitroimidazoles and tetracyclines were successfully used for calibration and shown to generally improve precision compared to external calibration. Matrix components caused ion suppression/enhancement effects during the MS detection for all analytes studied. Two effects were observed: general suppression and short-term variations in the MS response. In the hospital sewage water large temporal variations in the analyte concentration were observed during the course of the sampling period (seven grab samples in 13 h). Analyte concentrations varied within the following ranges (in microg l(-1)): ciprofloxacin, 3.6-101.0; metronidazole, 0.1-90.2; sulfamethoxazole, 0.4-12.8; ofloxacin, 0.2-7.6; trimethoprim, 0.6-7.6; and doxycycline, 0.6-6.7.

Anti-Bacterial Agents↗

PubMed2004

Fluoroquinolone antibiotics in a hospital sewage line; occurrence, distribution and impact on bacterial resistance.

In hospital sewage lines, human faecal bacteria are exposed to antibiotics, posing a risk for selection of antibiotic resistant microorganisms. We constructed a system for continuous sampling in a hospital sewage line that allowed us to study longitudinal establishment of bacteria, concentrations of antibiotics, and selection of bacterial resistance in waste water, sediment and biofilm. The focus in this study was on fluoroquinolones, a widely used group of antibiotics with increasing resistance problems. We found low levels of ciprofloxacin and ofloxacin in waste water but high concentrations in sediment. Despite the high levels of fluoroquinolones bound to sediment, we did not find any development of resistance against fluoroquinolones in Enterobacteriacae spp. and faecal enterococci isolated from sediment.

Drug Resistance, Bacterial↗

PubMed2004

Assessment of the availability of polycyclic aromatic hydrocarbons from gasworks soil using different extraction solvents and techniques.

This study was designed to assess the availability of polycyclic aromatic hydrocarbons (PAHs) present at a gasworks site to different soil remediation techniques. The study examined the effect on PAH availability of using different organic solvents, the degree of pretreatment, and the extraction time. In total, 25 PAHs (with two to six fused rings) and five carbonyl derivatives were measured. The results indicated that the PAHs and their derivatives were bound loosely to the surface of the studied soil and that there were no significant kinetic boundaries associated with the extraction of the PAHs. Furthermore, it was concluded that the studied soil was not suitable for bioremediation, as the concentration of PAHs with low molecular weight were limited. However, pressurized liquid extraction (PLE) with methanol as the solvent extracted 97% of all PAHs and PAH-derivatives, indicating that extraction may be effective as part of a soil remediation technique for old gasworks soils.

Biological Availability↗

PubMed2003

Time trends of selected persistent organic pollutants in lake sediments from Greenland.

Sediments from seven lakes in West Greenland were used as natural archives to study past and present levels of PCBs (polychlorinated biphenyls, tri- to decachlorinated), tetra-BDE #47 (2,2',4,4'-bromodiphenyl ether), chlordane (cis- and trans-octachlordane) and HxCBz (hexachlorobenzene). The concentrations found are lower than or comparable to concentrations found in sediments from other Arctic regions and one to 2 orders of magnitude lower than concentrations typically found in sediments at lower latitudes. The observed temporal trends (direct and indirect dating) show a decreasing total PCB concentration. Even though local contamination sources exist, the POP deposition in the studied area is most likely a result from long-range transport. The hypothesis about "cold condensation" suggests a latitudinal fractionation to occur between different volatile compounds during the transport toward the pole. In this study a time delay in the deposition for the low-chlorinated PCBs (tri- and tetrachlorinated), compared to their emission histories and compared to higher chlorinated PCBs, was indicated. Although very low tetra-BDE #47 concentrations are observed in this study, there are indications for an increasing concentration in recent sediment layers that may reflect increasing environmental concentrations at lower latitudes. The investigated pesticides are still in use at lower latitudes, however neither chlordane nor HxCBz show any distinct temporal trend of increasing or decreasing concentration toward the sediment surface.

Chlordan↗

PubMed2003

Multivariate characterization of polycyclic aromatic hydrocarbons using semi-empirical molecule orbital calculations and physical data.

Multivariate characterization of 60 polycyclic aromatic hydrocarbons (PAHs) was performed using data from literature and semi-empirical molecular orbital calculations. This dataset was analyzed by principal component analysis and projections to latent structures by means of partial least square. The PAHs were found to distribute in the chemical domain in several groups mainly governed by the number of aromatic rings and the number of five-membered rings. The multivariate model and training set was used to predict GC retention times on a non-polar column (DB-5). Using a 2(4) experimental design on the principal components of the chemical characterization model, a test set of PAHs was selected dependent on the distribution in the chemical domain of the PAHs. Such a test set is expected to improve selection of PAHs for future testing and modeling of both biological and chemical responses. Although the model of GC retention times was good, the precision was however not good enough for practical use.

Environmental Pollutants↗

PubMed2003

Contaminant exposure and effects in Baltic ringed and grey seals as assessed by biomarkers.

The Baltic Sea ecosystem has suffered from a heavy pollutant load for more than three decades. Persistent organic pollutants (POPs) and heavy metals have been of most concern due to their persistence and toxic properties. Ringed seals (Phoca hispida baltica) and grey seals (Halichoerus grypus) living in the Baltic Sea have been suffering from pathological impairments, including reproductive disturbances, which have resulted in a depressed reproductive capacity. We investigated several biochemical parameters as potential biomarkers for exposure to and effects of the contaminant load in the Baltic seals. Seals from less polluted areas were used as reference material in terms of the pollution load. In both Baltic seal populations, the levels of some biochemical parameters diverged from those in the reference seals, and some of these showed a clear correlation with the individual contaminant load. Of the potential bioindicators, we propose cytochrome P4501A activity and vitamin E levels, in blubber or plasma, as exposure biomarkers for polychlorinated biphenyls (PCBs) and dichlorodiphenyltrichloroethane (DDT) in both species. The arylhydrocarbon receptor-mediated chemical-activated luciferase gene expression (CALUX) response reflects the whole PCB and DDT burden in ringed seals. Retinyl palmitate (vitamin A) levels showed a negative correlation with the individual POP load, and is proposed as potential effect biomarkers for the depletion of the vitamin A stores. As the nutritional levels of both vitamin A and E have an impact on the vitamin levels in the seals, more information on the dietary vitamin levels is needed before any conclusions can be drawn. As the relationship between biochemical parameters and contaminants varied between the two species, species-specific characteristics has to be considered when monitoring the health status and possible toxic effects of the contaminant load in ringed and grey seals.

Animals↗

PubMed2003

Flux estimates and sedimentation of polychlorinated naphthalenes in the northern part of the Baltic Sea.

The concentrations and fluxes of polychlorinated naphthalenes (PCNs) were measured in surface sediments, and settling particulate matter collected in sediment traps, at two coastal and two offshore sampling stations in the Gulf of Bothnia, northern Baltic Sea, Sweden. The PCN concentrations (of tetra- to hepta-chloro congeners) in the surface sediments ranged from 0.27 to 2.8 ng/g dry weight and were of the same order of magnitude as background concentrations reported previously in Europe. The PCN fluxes in the southern basin (0.93 and 0.86 microg/m2/year) of the Gulf of Bothnia were higher than those in the northern basin (0.58 and 0.49 microg/m2/year); they were also higher near the coast than in the open sea. These PCN fluxes are similar to the pre-industrial levels determined from lake sediments in northwest England. The PCN homologue distribution changed from a relatively even distribution in samples collected near the coast, to TeCNs dominating in the samples from the open sea. This indicates that higher chlorinated PCNs are deposited and retained in sediments to a higher degree near the coast. The total annual deposition of PCNs in sediments in the Gulf of Bothnia was estimated to be 91 kg/year.

Geologic Sediments↗

PubMed2002

Polychlorinated naphthalene levels, distribution, and biomagnification in a benthic food chain in the Baltic Sea.

The scientific literature contains little information regarding bioaccumulation and biomagnification of polychlorinated naphthalenes (PCNs) in food webs. Here we present new information on the food chain transfer of PCNs within a food chain in a subarctic environment PCNs (tetra- to hepta-chloro congeners) were measured in surface sediments and in a marine benthic food chain, comprising amphipods, isopods, and fourhorned sculpins. Samples were collected from five locations in the Gulf of Bothnia, northern Baltic Sea. PCN concentrations in the sediments were similar to background levels determined previously in sediments from the northern hemisphere. Measurement of the carbon content of the sediments allowed the calculation of biota to sediment accumulation factors (BSAFs). Tetra- and penta-CNs exhibited BSAF values greater than one, while BSAFs for the more chlorinated PCNs were less than one. This suggests more efficient assimilation, by amphipods, of the less chlorinated PCNs. A decrease in sigmaPCN concentrations from the lowest to the highest trophic level was demonstrated (amphipods: 10-69 ng/g lw, isopods: 3.9-16 ng/g lw; fourhorned sculpins: 0.54-1.5 ng/g lw). Biomagnification factors (BMFs) were calculated based on the concentrations of the congeners. These indicated that a few congeners biomagnified significantly: the highest BMFs (0.09-1.4) were found for 2,3,6,7-substituted congeners and those lacking adjacent hydrogen-substituted carbon atoms.

Amphipoda↗

PubMed2002

Development of a high-performance liquid chromatography carbon column based method for the fractionation of dioxin-like polychlorinated biphenyls.

A method to separate polychlorinated biphenyls (PCBs) by using high-performance liquid chromatography (HPLC) was developed. The HPLC column was packed with Amoco PX-21 activated carbon dispersed on octadecylsilane (ODS). The separation was carried out by gradient elution with n-hexane-dichloromethane and toluene in the forward direction followed by reversed elution with toluene. The results show that this HPLC method is useful for the separation of PCBs according to the number of substituted ortho chlorine atoms attached to the biphenyl structure. Average recoveries for a number of individual di-ortho PCBs, mono-ortho PCBs, and non-ortho PCBs in three selected elution windows were 97, 92, and 96%, respectively. Clophen A50, a herring sample, and a cod liver oil sample were fractionated on the column and the analytical results are compared with data from the literature. The method presented here is useful for quantitative separations of mono-ortho PCBs as well as non-ortho PCBs which have been assigned toxic equivalency factors by the World Health Organisation.

Carbon↗

PubMed2002

Selection of a representative set of chemical accidents from a complex data matrix for the development of environment-accident index.

Chemical accidents often lead to negative consequences for the environment. Preparedness and proper actions are, therefore, essential components in order to minimise environmental effects. To assist and facilitate this work, a proposed planning tool, the environment-accident index (EAI), was formulated by Scott [J. Hazard. Mater. 61 (1998) 305]. As a result of a first validation of the index, based on 21 chemical accidents, the database was complemented with 42 additional accidents covering a broader spectrum of chemicals. The additional accidents were collected by means of an inquiry and their environmental consequences are, so far, unknown. The collected data had an overrepresentation of accidents involving petroleum products (69%). Because of the overrepresentation of this group of chemicals in the material, the data was skewed with respect to chemical properties. Since the model should be valid for a variety of chemical accidents, a method was needed which enabled a proper and unbiased selection of a representative subset of accidents to be used in development and validation of the model. For this purpose, the possibility to use multivariate data analysis in combination with statistical design was investigated. The result showed the feasibility of this method in the selection of a representative subset from a complex and skewed large dataset. Within the new dataset, 53% were accidents involving petroleum products and 47% involved other chemicals. The selected accidents will be used in further work to evaluate the environmental consequences, for model development and model validation.

Accidents↗

PubMed2002

Multivariate physicochemical characterisation and quantitative structure-property relationship modelling of polybrominated diphenyl ethers.

Levels of polybrominated diphenyl ethers (PBDEs) are increasing in the environment and may cause long-term environmental problems. Developing a model describing the chemical variation among the 209 possible congeners would be a useful step in any systematic approach for assessing the fate and risk posed by the PBDEs. Therefore, 40 physicochemical descriptors were derived for all PBDEs using a semi-empirical method (AM1), molecular mechanics, and empirically estimated parameters. Descriptors included heats of formation, frontier molecular orbital energies, atomic charges, dipole moments, logP values, and molecular surface areas. Principal component analysis (PCA) was used to evaluate the descriptors. The first four PCs, explaining 76% of the variation in the data, described the size, charge distribution and symmetric elements of the congeners. A quantitative structure-activity relationship model was constructed based on data for dioxin-like activity (using the luciferase bioassay) for 17 PBDEs with the partial least squares method. In addition, quantitative structure-property relationship models for gas chromatographic relative retention times on four capillary columns were developed. These models proved suitable to assist in the identification of untested PBDEs. Based on the results of the PCA, a factorial design was applied for selecting 21 representative congeners. PBDEs 11, 13, 17, 32, 35, 47, 53, 77, 85, 99, 119, 135, 153, 155, 156, 169, 176, 181, 190, 192, and 209. The spacing of these congeners in the physicochemical domain maximises the coverage of key factors such as molecular size and substitution pattern. Consideration of the selected congeners should be useful for guiding the synthesis of new compounds for use in future studies of the fate and biological effects of PBDEs.

Biological Assay↗

PubMed2002

Assessing the environmental fate of chemicals of emerging concern: a case study of the polybrominated diphenyl ethers.

It is suggested that assessments of chemicals of emerging concern can be rationally structured around a multistage process in which fate and risk are evaluated with increasing accuracy as new data become available. An initial tentative and approximate assessment of fate and risk can identify key data gaps and justify and direct further investigations, which progressively improve the reliability of the assessment. This approach is demonstrated for a class of chemicals, the polybrominated diphenyl ethers (PBDEs), which is of increasing concern, but about which there is presently a lack of comprehensive data on properties, sources, fate and effects. Specifically, 20 PBDE congeners are investigated using the suggested approach and research needs are identified.

Environmental Monitoring↗

PubMed2002

Biological and chemical determination of dioxin-like compounds in sediments by means of a sediment triad approach in the catchment area of the river Neckar.

To evaluate the sediment quality of selected sites in the catchment area of the River Neckar, an integrative assessment approach was used to assess the ecological hazard potential of dioxin-like sediment compounds. The approach is based on 7-ethoxyresorufin-O-deethylase (EROD) induction in embryonic chicken liver culture and comprehensive chemical analyses of polycyclic aromatic hydrocarbons (priority PAHs according to the US Environmental Protection Agency). The majority of the sediment extracts exhibited high potencies as EROD-inducers. In one sediment sample, which was influenced by a sewage treatment plant, a very high concentration of 930 ng bioassay 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) equivalents (bio-TEQs )/g organic carbon could be determined. However, in none of the samples, more than 6% of the EROD-inducing potency could be explained by the PAHs analyzed chemically. Thus, non-analyzed compounds with EROD-inducing potency were present in the extracts. A fractionation of sediment samples according to pH allowed to localize the major part of EROD-inducing compounds in the neutral fractions. However, a significant portion of the EROD induction could also be explained by the acidic fractions. Following the concept of the Sediment Quality Triad according to Chapman, in situ alterations of macrozoobenthos were examined. A comparison of the results predicted by the EROD assay and chemical analyses with alterations in situ, as measured by means of the saprobic index and the ecotoxicological index according to Carmargo, revealed a high ecological relevance of the results of bioassays and chemical analyses for major sites.

Animals↗

PubMed2002

Accumulation and elimination of 16 polycyclic aromatic compounds in the earthworm (Eisenia fetida).

Accumulation and elimination of different polycyclic aromatic compounds (PACs) were studied in earthworms (Eisenia fetida) exposed to contaminated soil from an old gasworks site. In total, 12 polycyclic aromatic hydrocarbons (PAHs), two N- and S-heterocyclic PACs, and two PAC-quinones were included in the study. Peak-shaped accumulation curves were found for many of the compounds. After 19 d of exposure, the ratio between concentrations in worm lipids and soil organic matter was 0.02 on average. The half-lives of the PACs were relatively long, between 2 and 11 d. The elimination rate constants, k2, correlated both with literature-derived octanol-water partition coefficients (Kow) for PAHs (r2 = 0.93) and the computed polarizability (r2 = 0.88) of all the compounds. The elimination rate constants of PAHs are comparable to those of PCBs found in earlier studies, and the linear regression coefficient, r2, of k2 against Kow for PAHs and PCBs together was 0.93.

Animals↗

PubMed2002

Application of sewage sludge to arable land-soil concentrations of polybrominated diphenyl ethers and polychorinated dibenzo-p-dioxins, dibenzofurans, and biphenyls, and their accumulation in earthworms.

Soils from five agricultural sites, three research sites, and two privately owned farms were analyzed for polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), polychlorinated biphenyls (PCBs), and polybronimated diphenylethers (PBDEs). In soils that had not been treated with sludge (reference soils), the international toxic equivalents (I-TEQs) were 0.6 to 1.5 pg/g dry matter (D.M) for the PCDD/Fs. which are low compared to generally reported background soil levels in Europe. The concentrations of sum of six penta- and hexa-PCBs were 450 to 1,400 pg/g DM. The PBDEs 47 and 99 dominated among the tri- to hepta-PBDEs analyzed (8-80 pg/g DM). The impact of adding 1 to 3 tonnes of sludge (DM) per hectare per year on the concentrations was studied at the three research sites by calculating ratios of the compounds in sludge-treated soil to reference soil (S/R ratio). The concentrations of I-TEQs did not increase in the sludge-treated soil, whereas the S/R ratios for PBDEs were greater than one. Also, although the PCB contents were higher in the sludge-treated soils, the background sources were more important for the concentrations of PCBs than of PBDEs. The largest increase in the S/R ratios was found at a private farm where large amounts of sludge had been used in the past. Accumulation of the compounds in earthworms from the sites also was investigated. The biota-soil accumulation factors (BSAFs) of the tested compounds declined in the following order: ortho-PCBs approximately PBDEs > non-ortho-PCBs > 2.3,7,8-substituted PCDD/Fs. The average BSAF for ortho-PCBs was five (organic matter/lipids), and the lowest BSAFs (0.1-0.8) found were for octachlorodibenzo-p-dioxin. To our knowledge, accumulation of PBDEs in earthworms has not been published previously.

Agriculture↗