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| 2. |
- Jansson, Stina, et al.
(författare)
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Effect of injection of di- and tricyclic aromatic compounds on post-combustion formation of polychlorinated dibenzo-p-dioxins and dibenzofurans
- 2011
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Ingår i: Science of the Total Environment. - Amsterdam : Elsevier. - 0048-9697 .- 1879-1026. ; 409:18, s. 3386-3393
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Tidskriftsartikel (refereegranskat)abstract
- The formation of mono- to octachlorinated dibenzo-p-dioxins (PC(1-8)DD) and dibenzofurans (PC(1-8)DF) was studied using a model waste in a laboratory-scale combustion reactor with simultaneous collection of flue gas at three different temperatures (450°C, 300°C, and 200°C) in the post-combustion zone. To investigate the influence of chlorination reactions and the effects of carbon backbone-containing compounds present in the flue gases, five aromatic compounds were injected into the flue gas, namely dibenzofuran (DF), biphenyl (BP), naphthalene, phenanthrene and fluorene. The injection of DF induced a reduction in the concentration of PC(3-5)DD, but did not significantly influence the concentration of PCDF. A reduction in the concentration of PC(3-5)DD was also observed during the injection of fluorene, which is structurally very similar to DF. The injection of biphenyl, naphthalene and phenanthrene had less pronounced effects on the formation of PCDD and PCDF. A possible explanation of the observed changes during injection of DF and fluorene, based on homologue profiles and affected congeners, involves formation of radical species from fluorene and/or dibenzofuran. The fluorene radical is stabilized by the delocalization of electrons across the aromatic ring structure and has the propensity to react with highly abundant hydrogen chloride, whereas the molecular species would require reaction with Cl(2) or chlorine radicals.
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| 3. |
- Lindberg, Richard H, et al.
(författare)
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Behavior of fluoroquinolones and trimethoprim during mechanical, chemical, and active sludge treatment of sewage water and digestion of sludge
- 2006
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Ingår i: Environmental Science and Technology. - Washington : American Chemical Society. - 0013-936X .- 1520-5851. ; 40:3, s. 1042-1048
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Tidskriftsartikel (refereegranskat)abstract
- The behavior and fate of three fluoroquinolones (norfloxacin, ofloxacin, and ciprofloxacin), one sulfonamide (sulfamethoxazole), and trimethoprim were investigated at a sewage treatment plant in Umeå, Sweden, in 2004. This plant uses conventional mechanical, chemical, and activated sludge methods to treat the sewage water and digest the sludge; the dewatered digested sludge is pelleted (dry weight > 90% of total weight). Raw sewage water and particles as well as effluents and sludge from specific treatment areas within the plant were sampled. In addition to quantifying the antibiotics within the plant, we characterized the sample matrixes to facilitate evaluation of the results. Of the five substances examined, only norfloxacin, ciprofloxacin, and trimethoprim were present in concentrations higher than their limits of quantification. Norfloxacin and ciprofloxacin sorbed to sludge in a manner that was independent of changes in pH during sewage treatment, and more than 70% of the total amount of these compounds passing through the plant was ultimately found in the digested sludge. The results suggest that fluoroquinolones undergo thermal degradation during pelleting, but more studies are needed to confirm this. Trimethoprim was found in the final effluent at approximately the same concentration and mass flow as in the raw sewage, and could not be quantified in any solid sample. Predicted environmental concentrations, based on consumption data for Umeå municipality, correlated well with the results obtained, especially when the predicted concentrations were corrected to account for the amount of each active substance excreted in urine. The results obtained were compared to those of previous studies of these three substances' behavior and fate and were found to be similar, although some of the other plants studied employed the various treatment steps in different orders.
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| 4. |
- Stenberg, Mia, 1979-, et al.
(författare)
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A multivariate chemical map of industrial chemicals : Assessment of various protocols for identification of chemicals of potential concern
- 2009
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Ingår i: Chemosphere. - : Elsevier. - 0045-6535 .- 1879-1298. ; 76:7, s. 878-884
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Tidskriftsartikel (refereegranskat)abstract
- In present study the Industrial chemical map was created, and investigated. Molecular descriptors were calculated for 56 072 organic substances from the European inventory of existing commercial chemical substances (EINECS). The resulting multivariate dataset was subjected to principal component analysis (PCA), giving five principal components, mainly reflecting size, hydrophobicity, flexibility, halogenation and electronical properties. It is these five PCs that form the basis of the map of organic, industrial chemicals, the Industrial chemical map. The similarities and diversity in chemical characteristics of the substances in relation to their persistence (P), bioaccumulation (B) and long-range transport potential were then examined, by superimposing five sets of entries obtained from other relevant databases onto the Industrial chemical map. These sets displayed very similar diversity patterns in the map, although with a spread in all five PC vectors. Substances listed by the United Nations Environment Program as persistent organic pollutants (UNEP POPs) were on the other hand clearly grouped with respect to each of the five PCs. Illustrating similarities and differences in chemical properties are one of the strengths of the multivariate data analysis method, and to be able to make predictions of, and investigate new chemicals. Further, the results demonstrate that non-testing methods as read-across, based on molecular similarities, can reduce the requirements to test industrial chemicals, provided that they are applied carefully, in combination with sound chemical knowledge.
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| 6. |
- Ågerstrand, Marlene, et al.
(författare)
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Improving Environmental Risk Assessment of Human Pharmaceuticals
- 2015
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Ingår i: Environmental Science & Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 49:9, s. 5336-5345
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents 10 recommendations for improving the European Medicines Agency's guidance for environmental risk assessment of human pharmaceutical products. The recommendations are based on up-to-date, available science in combination with experiences from other chemical frameworks such as the REACH-legislation for industrial chemicals. The recommendations concern: expanding the scope of the current guideline; requirements to assess the risk for development of antibiotic resistance; jointly performed assessments; refinement of the test proposal; mixture toxicity assessments on active pharmaceutical ingredients with similar modes of action; use of all available ecotoxicity studies; mandatory reviews; increased transparency; inclusion of emission data from production; and a risk management option. We believe that implementation of our recommendations would strengthen the protection of the environment and be beneficial to society. Legislation and guidance documents need to be updated at regular intervals in order to incorporate new knowledge from the scientific community. This is particularly important for regulatory documents concerning pharmaceuticals in the environment since this is a research field that has been growing substantially in the last decades.
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