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- Lyche, Jan L., et al.
(author)
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Reproductive and developmental toxicity of phthalates
- 2009
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In: Journal of toxicology and environmental health. Part B, Critical reviews. - : Informa UK Limited. - 1093-7404 .- 1521-6950. ; 12:4, s. 225-249
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Journal article (peer-reviewed)abstract
- The purposes of this review are to (1) evaluate human and experimental evidence for adverse effects on reproduction and development in humans, produced by exposure to phthalates, and (2) identify knowledge gaps as for future studies. The widespread use of phthalates in consumer products leads to ubiquitous and constant exposure of humans to these chemicals. Phthalates were postulated to produce endocrine-disrupting effects in rodents, where fetal exposure to these compounds was found to induce developmental and reproductive toxicity. The adverse effects observed in rodent models raised concerns as to whether exposure to phthalates represents a potential health risk to humans. At present, di(2-ethylhexyl) phthalate (DEHP), di-n-butyl phthalate (DBP), and butyl benzyl phthalate (BBP) have been demonstrated to produce reproductive and developmental toxicity; thus, this review focuses on these chemicals. For the general population, DEHP exposure is predominantly via food. The average concentrations of phthalates are highest in children and decrease with age. At present, DEHP exposures in the general population appear to be close to the tolerable daily intake (TDI), suggesting that at least some individuals exceed the TDI. In addition, specific high-risk groups exist with internal levels that are several orders of magnitude above average. Urinary metabolites used as biomarkers for the internal levels provide additional means to determine more specifically phthalate exposure levels in both general and high-risk populations. However, exposure data are not consistent and there are indications that secondary metabolites may be more accurate indicators of the internal exposure compared to primary metabolites. The present human toxicity data are not sufficient for evaluating the occurrence of reproductive effects following phthalate exposure in humans, based on existing relevant animal data. This is especially the case for data on female reproductive toxicity, which are scarce. Therefore, future research needs to focus on developmental and reproductive endpoints in humans. It should be noted that phthalates occur in mixtures but most toxicological information is based on single compounds. Thus, it is concluded that it is important to improve the knowledge of toxic interactions among the different chemicals and to develop measures for combined exposure to various groups of phthalates.
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- Rudén, Christina
(author)
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Science and transscience in carcinogen risk assessment - The European Union regulatory process for trichloroethylene
- 2003
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In: Journal of toxicology and environmental health. Part B, Critical reviews. - : Informa UK Limited. - 1093-7404 .- 1521-6950. ; 6:3, s. 257-277
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Research review (peer-reviewed)abstract
- This is a study of carcinogen risk assessment of the chlorinated solvent trichloroethylene within the European Union existing substances program and the classification and labeling process. The focus is on the most active and influential participants of this process, namely, those from the United Kingdom, Germany, and Sweden, and from industry. The member state and other experts have different opinions regarding the appropriate classification of trichloroethylene for mutagenicity (no classification or category 3) and carcinogenicity (category 3, 2, or 1). In this article these differences are described, as well as how the primary carcinogenicity and mutagenicity data have been interpreted and evaluated by these participants. It is concluded that underlying the different assessments are disagreements about issues that to some degree lie outside the scope of purely scientific considerations.
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- Mbairi, Felix D., et al.
(author)
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Microwave bandstop filters using novel artificial periodic substrate electromagnetic band gap structures
- 2009
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In: IEEE transactions on components and packaging technologies. - 1521-3331 .- 1557-9972. ; 32:2, s. 273-282
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Journal article (peer-reviewed)abstract
- Novel microwave and millimeterwave (mm-wave) bandstop filters using artificial periodic substrate electromagnetic bandgap (EBG) are investigated in this paper. Three types of microstrip structures using periodically modified trace width, patterned dielectric substrate, and periodically modified ground plane are treated, respectively. By periodically modifying either the width of the conductor trace, the substrate height, or the dielectric constant of a standard microstrip transmission line, it has been possible to design microwave bandstop filter functions with wide stopband characteristics and reduced size, compared to conventional microwave/RF filter structures. Commercial electronic design automation (EDA) and computational electromagnetic tools such as Agilent's advanced design system (ADS) and CST Microwave Studio are used in the design and simulations of these filter structures. The effects of the physical parameters of the structures on the filter characteristic are studied. The design procedure and simulation results are described and possible applications of these filter structures are discussed in this paper. A particularly wide stopband is achieved by the circuits presented in this paper, which use only a few cell elements. A significant performance improvement of microstrip patch antenna has been observed by implementing one of the presented EBG periodic substrate structures.
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