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- Arriola, Aline, et al.
(author)
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Dechloranes and chlorinated paraffins in sediments and biota of two subarctic lakes
- 2024
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In: Frontiers in Toxicology. - 2673-3080. ; 6
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Journal article (peer-reviewed)abstract
- Our understanding of the environmental behavior, bioaccumulation and concentrations of chlorinated paraffins (CPs) and Dechloranes (Dec) in the Arctic environment is still limited, particularly in freshwater ecosystems. In this descriptive study, short chain (SCCPs) and medium chain (MCCPs) CPs, Dechlorane Plus (DP) and analogues, and polychlorinated biphenyls (PCBs) were measured in sediments, benthic organisms, three-spined stickleback (Gasterosteus aculeatus), Arctic char (Salvelinus alpinus) and brown trout (Salmo trutta) in two Sub-Arctic lakes in Northern Norway. Takvannet (TA) is a remote lake, with no known local sources for organic contaminants, while Storvannet (ST) is situated in a populated area. SCCPs and MCCPs were detected in all sediment samples from ST with concentration of 42.26–115.29 ng/g dw and 66.18–136.69 ng/g dw for SCCPs and MCCPs, respectively. Only SCCPs were detected in TA sediments (0.4–5.28 ng/g dw). In biota samples, sticklebacks and benthic organisms showed the highest concentrations of CPs, while concentrations were low or below detection limits in both char and trout. The congener group patterns observed in both lakes showed SCCP profiles dominated by higher chlorinated congener groups while the MCCPs showed consistency in their profiles, with C14 being the most prevalent carbon chain length. Anti- and syn-DP isomers were detected in all sediment, benthic and stickleback samples with higher concentrations in ST than in TA. However, they were only present in a few char and trout samples from ST. Dec 601 and 604 were below detection limits in all samples in both lakes. Dec 603 was detected only in ST sediments, sticklebacks and 2 trout samples, while Dec 602 was the only DP analogue found in all samples from both lakes. While there were clear differences in sediment concentrations of DP and Dec 602 between ST and TA, differences between lakes decreased with increasing δ15N. This pattern was similar to the PCB behavior, suggesting the lake characteristics in ST are playing an important role in the lack of biomagnification of pollutants in this lake. Our results suggest that ST receives pollutants from local sources in addition to atmospheric transport.
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| 2. |
- Carlsson, Carina, et al.
(author)
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Olfactory mucosal toxicity screening and multivariate QSAR modeling for chlorinated benzene derivatives
- 2004
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In: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 78:12, s. 706-715
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Journal article (peer-reviewed)abstract
- The olfactory mucosa (OM) is an important target for metabolism-dependent toxicity of drugs and chemicals. Several OM toxicants share a 2,6-dichlorinated benzene structure. The herbicides dichlobenil (2,6-dichlorobenzonitrile) and chlorthiamide (2,6-dichlorothiobenzamide) and the environmental dichlobenil metabolite 2,6-dichlorobenzamide all induce toxicity in the OM following covalent binding in the Bowmans glands. In addition, we have shown that 2,6-dichlorophenyl methylsulfone targets the Bowmans glands and is probably the most potent OM toxicant so far described. These findings suggest that the 2,6-positioning of chlorines in combination with an electron-withdrawing group in the primary position of the benzene ring is an arrangement that facilitates OM toxicity. This study examined the physicochemical characteristics of the 2,6-dichlorinated OM toxicants. A number of 2,6-dichlorinated benzene derivatives with various types of substituents in primary position were tested for OM toxicity in mice. In addition, some other 2,6- and 2,5-substituted benzene derivatives were examined. Two novel OM toxicants, 2,6-dichlorobenzaldehyde oxime and 2,6-dichloronitrobenzene, were identified. By the use of partial least squares projection to latent structures with discriminant analysis (PLS-DA) a preliminary quantitative structure-activity relationship (QSAR) model was built also using reported OM toxicity data. Physicochemical properties positively correlated with olfactory mucosal toxicity were identified as molecular dipolar momentum and the electronic properties of the substituent. Inversely correlated descriptors were variables describing the hydrophobicity, electronic properties of the molecule such as electron affinity and the electronic charge on the primary carbon. In conclusion, this preliminary PLS-DA model shows that a 2,6-dichlorinated benzene derivative with a large, polar, and strong electron-withdrawing substituent in the primary position has the potential of being a potent OM toxicant in mice.
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| 4. |
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| 5. |
- Danielsson, Conny, et al.
(author)
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Comparison of Levels of PCDD/Fs and non-Ortho PCBs in PCB 153 from seven different suppliers
- 2008
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In: Organohalogen Compounds. ; 70, s. 001201-3
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Journal article (peer-reviewed)abstract
- Twelve PCBs with dioxin-like (DL) properties have been carefully studied through the years to facilitate risk assessment and they have been assigned WHO-TEF values [1] based on their relative toxicity and endocrine effects compared to 2,3,7,8-TCDD. From a toxicological point of view, the non-dioxin-like PCBs (NDL-PCBs) are less characterized but usually account for more than 90% of the total mass of PCBs in food samples [2]. Furthermore, over 90% of the NDL-PCB exposure in the general population is via food and the average daily intake can be estimated to be 10-45 ng/kg (bw)/day according to the European Food Safety Authority EFSA [3]. The EFSA committee concluded that a proper risk assessment of this abundant and environmentally significant class of compounds could not be accomplished. In 2006, the European Commission initiated a project which has as its aim to better examine the toxicity of NDL-PCBs: ATHON- "Assessing the toxicity and hazard of nondioxin-like PCBs present in food". The ATHON project will perform all in vivo and in vitro studies with ultra pure PCBs with known levels of DL-PCBs, PCDD/Fs and total TEQ-levels. As a first step in this study the major suppliers of PCB 153 were identified and the aim of the research was to investigate if there were any clear differences in the quality of their products based on possible impurities of PCDD/Fs and non-ortho PCBs. PCB 153 was selected because of its relatively high presence in environmental compartments and biota and since it has been the most frequently studied NDL-PCB in a few major in vivo studies [2]. Impurities of PCDD/Fs and DL-PCBs, even at trace levels, in PCB 153 may make a significant contribution to the effects seen in in vivo studies as the highest concentrations being studied are at mg/g (bw)/day during a period of time. These high daily exposure levels in combination with possible accumulation of toxic impurities may by time pose a threat to the significance of observed effects. Within the ATHON project all NDL-PCBs used for both in vitro and in vivo tests are analyzed and in many cases purified to remove possible traces of PCDD/Fs and non-ortho PCBs.
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| 6. |
- Haglund, Peter, et al.
(author)
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Effects of temperature and flow regulated carbon dioxide cooling in longitudinally modulated cryogenic systems for comprehensive two-dimensional gas chromatography
- 2002
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In: Journal of Chromatography A. ; 962:1-2, s. 127-34
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Journal article (peer-reviewed)abstract
- Two different modes of temperature regulation in longitudinally modulated cryogenic systems (LMCSs) for comprehensive two-dimensional gas chromatography (GC×GC) were compared. Carbon dioxide was used as coolant. In the first mode of operation, the temperature of the trap was regulated to a pre-set temperature using a digital temperature controller (“the constant temperature mode”). In the second, the temperature was regulated to a fixed negative offset to the oven temperature by using a constant flow of CO2 (“the constant flow mode”). A number of problems were occasionally observed using the constant temperature mode: (1) severe band broadening of high boiling analytes in the second dimension; (2) non-Gaussian reconstructed first-dimension peak profiles; (3) high background due to modulation of first-dimension column bleed. It was concluded that these problems were associated with inefficient solute remobilization at low LMCS trap temperatures (1 and 2) or large trap temperature fluctuations (3). These problems could be avoided or significantly reduced by using the constant flow mode. Best results were obtained as the trap temperature was kept about 70 °C below the oven temperature.
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| 7. |
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| 8. |
- Haglund, Peter, et al.
(author)
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Shape selectivity : A key factor in comprehensive two-dimensional gas chromatographic analysis of toxic PCBs
- 2001
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In: Journal of Microcolumn Separations. - : Wiley. - 1040-7685 .- 1520-667X. ; 13:7, s. 306-311
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Journal article (peer-reviewed)abstract
- A number of toxic planar PCBs, that is, PCB 77, 105, 118, 126, 156, and 169, were successfully separated from other PCB congeners present in technical PCB formulations using comprehensive GC×GC. The planar PCBs were selectively retained using a liquid crystal column, which was used as the first-dimension column. A short and narrow bore (0.25 m×0.1 mm) nonpolar 5%-phenyl-methylpoly-siloxane column was used as the second-dimension column. A longitudinally modulating cryogenic system (LMCS) was used to modulate the first-dimension signal. Since the planar PCBs elute from the first column at relatively high oven temperatures they were rapidly eluted from the second column. Altogether, this resulted in a significant peak sharpening, and a 20-fold increase in the signal-to-noise ratio, as compared to standard one-dimensional GC. This column set also seems to separate seven frequently measured congeners, that is, PCBs 28, 52, 101, 118, 138, 153, and 180, from other major PCB congeners.
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| 9. |
- Harju, Jorma, et al.
(author)
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Radio Interferometric Observation of an Asteroid Occultation
- 2018
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In: Astronomical Journal. - : University of Chicago Press. - 0004-6256 .- 1538-3881. ; 156:4, s. 1-10
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Journal article (peer-reviewed)abstract
- The occultation of the radio galaxy 0141+268 by the asteroid(372)Palma on 2017 May 15 was observed using sixantennas of the Very Long Baseline Array(VLBA). The shadow of Palma crossed the VLBA station at Brewster,Washington. Owing to the wavelength used, and the size and the distance of the asteroid, a diffraction pattern in theFraunhofer regime was observed. The measurement retrieves both the amplitude and the phase of the diffractedelectromagnetic wave. This is thefirst astronomical measurement of the phase shift caused by diffraction. Themaximum phase shift is sensitive to the effective diameter of the asteroid. The bright spot at the shadow’s center,the so called Arago–Poisson spot, is clearly detected in the amplitude time-series, and its strength is a goodindicator of the closest angular distance between the center of the asteroid and the radio source. A sample ofrandom shapes constructed using a Markov chain Monte Carlo algorithm suggests that the silhouette of Palmadeviates from a perfect circle by 26±13%. The best-fitting random shapes resemble each other, and we suggesttheir average approximates the shape of the silhouette at the time of the occultation. The effective diameterobtained for Palma, 192.1±4.8 km, is in excellent agreement with recent estimates from thermal modeling ofmid-infrared photometry. Finally, our computations show that because of the high positional accuracy, a singleradio interferometric occultation measurement can reduce the long-term ephemeris uncertainty by an order ofmagnitude.
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| 10. |
- Harju, Mikael, 1968-
(author)
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Analysis of PCBs with special emphasis on comprehensive two-dimensional gas chromatography of atropisomers
- 2003
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Doctoral thesis (other academic/artistic)abstract
- There are 209 PCB congeners, 136 of which have been found in technical PCB mixtures and hence may be found in the environment as a result of either intentional or unintentional release. The identification and quantification of the congeners are difficult due to analytical bias from coeluting PCBs and other persistent organic pollutants. Among the 209 possible PCB congeners, 19 tri- and tetra-ortho chlorinated congeners exist in stable atropisomeric conformations. The racemization barrier were determined for twelve of the nineteen atropisomers and was found to be between 176-185 kJ × mol-1 and ca. 250 kJ × mol-1 for tri- and tetra-ortho PCB, respectively. Further, a buttressing effect of 6.4 kJ × mol-1 was observed for congeners with vicinal ortho-meta chlorines. Comprehensive two-dimensional gas chromatography (GC×GC) was used to analyze the atropisomers and other PCBs. A Longitudinally Modulated Cryogenic System (LMCS) was used with liquid CO2 as cryogen. The LMCS was optimized for semi-volatile organic substances, primarily PCBs. The trap temperature was shown to be an important factor for the trapping and desorption efficiency, as was the thermal mass of the column used in the modulator region. A number of column sets were tested and the separation efficiency, congener resolution and analysis time was evaluated. Good separation of non- and mono-ortho PCBs and “bulk” PCBs (in a technical PCB) was obtained within 8 min using a smectic liquid crystal column (LC50) as the first and a nonpolar column as the second dimension column. Using a second column, an efficient nonpolar (DB-XLB) column, which separates many PCB congeners, were combined with a polar (cyanopropyl) or shape selective (LC50) second dimension column. As a maximum, 181 of the 209 congeners and 126 of the 136 Aroclor PCBs were resolved. The seven frequently measured PCBs (PCBs 28, 52, 101, 118, 138, 153 and 180) and all WHO-PCBs were separated from all other Aroclor PCBs. Chiral PCBs are released into the environment as racemic mixtures. However, organisms have been shown to enantiomerically enrich many of the atropisomers, suggesting that enantioselective biotransformations occur. Non-racemic PCB enrichment has also been seen in mammalians including humans, which is of particular concern because of the potential health risk. An analytical procedure were therefore developed and used to determine the levels of atropisomeric PCBs, planar-PCBs (WHO-PCBs) and total PCBs in seals with different health status. GC×GC was used to separate the target PCBs from other PCBs and potential interferences. A chiral column (permethylated â-cyclodextrin) was used in combination with a polar or shape selective column and enantiomeric fractions (EFs) were determined for five atropisomeric PCBs, i.e. CBs 91, 95, 132, 149 and 174. Some atropisomers had EF that deviated largely from racemic. The deviation was larger in liver than blubber, indicating enantioselective metabolism. However, there was no selective passage of the studied atropisomeric PCBs across placenta and no selective blood-brain barrier. Similarly, no correlation between EFs and health status was observed, although there was a correlation between total PCBs and health status.
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