Brominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) are increasingly reported at significant levels in various matrices, including consumer goods that are manufactured from plastics containing certain brominated flame retardants. PBDD/Fs are known ligands for the aryl hydrocarbon receptor (AhR) but are not yet considered in the hazard assessment of dioxin mixtures. The aim of the present study was to determine if PBDD/Fs levels present in plastic constituents of toys could pose a threat to children's health. PBDD/Fs, unlike their chlorinated counterparts (PCDD/Fs), have not been officially assigned toxic equivalence factors (TEFs) by the WHO therefore, we determined their relative potency towards AhR activation in both human and rodent cell-based DR CALUX® bioassays. This allowed us to compare GC-HRMS PBDD/F congener levels, converted to total Toxic Equivalents (TEQ) by using the PCDD/F TEFs, to CALUX Bioanalytical Equivalents (BEQ) levels present in contaminated plastic constituents from children's toys. Finally, an estimate was made of the daily ingestion of TEQs from PBDD/Fs-contaminated plastic toys by child mouthing habits. It is observed that the daily ingestion of PBDD/Fs from contaminated plastic toys may significantly contribute to the total dioxin daily intake of young children.
- MeSH
- Biological Assay MeSH
- Cell Line MeSH
- Child MeSH
- Play and Playthings * MeSH
- Rats MeSH
- Environmental Pollutants analysis toxicity MeSH
- Humans MeSH
- Luciferases genetics MeSH
- Environmental Monitoring methods MeSH
- Plastics chemistry standards MeSH
- Gas Chromatography-Mass Spectrometry MeSH
- Polychlorinated Dibenzodioxins analysis toxicity MeSH
- Dibenzofurans, Polychlorinated analysis toxicity MeSH
- Child, Preschool MeSH
- Receptors, Aryl Hydrocarbon genetics MeSH
- Genes, Reporter MeSH
- Flame Retardants analysis toxicity MeSH
- Transfection MeSH
- Animals MeSH
- Check Tag
- Child MeSH
- Rats MeSH
- Humans MeSH
- Child, Preschool MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
The Exradin W1 plastic scintillator (Standard Imaging) was examined for measurement suitability in high-energy photon beams, high-energy electron beams and tomotherapy in terms of dose to water for reference fields. For photon beams, pulse repetition rate dependence, calibration stability, noise from the photodiode enclosure, detector motion during treatment, output factors, off-axis doses and percentage depth doses were tested. For electron and tomotherapy beams, energy non-dependence was verified. All features make the detector suitable in small and non-standards fields, and for electron beams.
- MeSH
- Humans MeSH
- Radiation Monitoring instrumentation methods standards MeSH
- Plastics chemistry MeSH
- Radiotherapy instrumentation MeSH
- Scintillation Counting instrumentation MeSH
- Check Tag
- Humans MeSH
- Publication type
- Journal Article MeSH
Methods for analysis of microplastic in soils are still being developed. In this study, we evaluated the potential of a soil universal model method (SUMM) based on thermogravimetry (TGA) for the identification and quantification of microplastics in standard loamy sand. Blank and spiked soils (with amounts of one of four microplastic types) were analyzed by TGA. For each sample, thermal mass losses (TML) in 10 °C intervals were extracted and used for further analysis. To explain and demonstrate the principles of SUMM, two scenarios were discussed. The first refers to a rare situation in which an uncontaminated blank of investigated soil is available and TML of spiked and blank soils are subtracted. The results showed that the investigated microplastics degraded in characteristic temperature areas and differences between spiked and blank soils were proportional to the microplastics concentrations. The second scenario reflects the more common situation where the blank is not available and needs to be replaced by the previously developed interrelationships representing soil universal models. The models were consequently subtracted from measured TML. Sparse principal component analysis (sPCA) identified 8 of 14 modeled differences between measured TMLs and the universal model as meaningful for microplastics discrimination. Calibrating various microplastics concentrations with the first principal component extracted from sPCA resulted in linear fits and limits of detection in between environmentally relevant microplastics concentrations. Even if such an approach using calculated standards still has limitations, the SUMM shows a certain potential for a fast pre-screening method for analysis of microplastics in soils.
- MeSH
- Principal Component Analysis MeSH
- Models, Chemical * MeSH
- Soil Pollutants analysis MeSH
- Plastics analysis chemistry MeSH
- Polyethylene analysis MeSH
- Polyethylene Terephthalates analysis MeSH
- Polystyrenes analysis MeSH
- Polyvinyl Chloride analysis MeSH
- Soil chemistry MeSH
- Temperature MeSH
- Publication type
- Journal Article MeSH
Three biodegradable plastics materials, namely pure poly(l-lactide) (PLA), PLA with plasticizer triacetine (TAC) and the mixture PLA/polyhydroxybutyrate (PHB) and TAC were investigated concerning changes of physical properties due to biodegradation in compost at 58°C up to 16days. With rising time of degradation in compost, both number and weight molecular masses were decreasing progressively, but only marginal change of the polydispersity index was observed which indicates that biodegradation is not random process. FTIR spectroscopy revealed that in spite of the extensive decrease of molecular weight, no substantial change in chemical composition was found. The most significant modification of the spectra consisted in an appearing of the broad band in region 3100-3300cm-1, which was assigned to a formation of biofilm on the sample surfaces. This effect appeared for all three materials, however, it was much more pronounced for samples containing also triacetine. Measurement of changes in crystalline portion confirmed that amorphous phase degrades substantially faster compared to crystalline part. The plasticizer triacetine is disappearing also rather fast from the sample resulting besides other effect also in a temporary increase of Tg, which at the beginning grows almost to the value typical for PLA without plasticizer but later the Tg is decreasing due to substantial changes in molecular weight. Generally during composting, the samples keep shape for up to 8days, after that time the material disintegrates to rough powder.
Composites of thermoplastic starch (TPS) with titanium dioxide particles (mTiO2; average size 0.1μm) with very homogeneous matrix and well-dispersed filler were prepared by a two-step method, including solution casting (SC) followed by melt mixing (MM). Light and scanning electron microscopy confirmed that only the two-step procedure (SC+MM) resulted in ideally homogeneous TPS/mTiO2systems. The composites prepared by single-step MM contained non-plasticized starch granules and the composites prepared by single-step SC suffered from mTiO2agglomeration. Dynamic mechanical measurements showed an increase modulus with increasing filler concentration. In TPS containing 3wt.% of mTiO2the stiffness was enhanced by >40%. Further experiments revealed that the recommended addition of chitosan or the exchange of mTiO2for anisometric titanate nanotubes with high aspect ratio did not improve the properties of the composites.
- MeSH
- Mechanical Phenomena * MeSH
- Plastics chemistry MeSH
- Rheology * MeSH
- Starch chemistry MeSH
- Temperature * MeSH
- Titanium chemistry MeSH
- Publication type
- Journal Article MeSH
This review provides a brief survey of the biological effects of selected endocrine-disrupting compounds that are formed after internal exposure of organisms. Further, the present analytical methods available for the determination of these compounds in foodstuffs are critically evaluated. The attention is primarily devoted to the methods for sample pretreatment, which are the main source of errors and are usually the most time-consuming step of the whole analysis. This review is focused on selected natural and synthetic estrogens, estrogen conjugates, and chemical additives used in the plastic industry that can act as estrogen mimics.
The evolution of damage to building materials has been estimated for the 21st century, with a particular focus on aluminum, zinc, copper, plastic, paint, and rubber in urban areas. We set idealized air pollution and climates to represent London and Prague across the period 1950-2100. Environmental parameters were used to estimate future recession, corrosion, and loss of properties through published damage or dose-response functions. The 21st century seems to provide a less aggressive environment for stone and metals than recent times. Improvements in air quality are the most relevant drivers for this amelioration. Changes in climate predicted for the 21st century do not alter this picture. On the other hand, polymeric materials, plastic, paint, and rubber might show slightly increased rates of degradation, to some extent the result of enhanced oxidant concentrations, but also the possibility of contributions from more solar radiation.
- MeSH
- Algorithms MeSH
- Photolysis drug effects MeSH
- Rubber chemistry MeSH
- Aluminum chemistry MeSH
- Risk Assessment methods trends MeSH
- Construction Materials analysis standards MeSH
- Copper chemistry MeSH
- Environmental Monitoring methods MeSH
- Paint analysis standards MeSH
- Oxidants pharmacology MeSH
- Plastics chemistry MeSH
- Forecasting MeSH
- Risk Factors MeSH
- Light MeSH
- Zinc chemistry MeSH
- Air Pollution analysis MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Geographicals
- Czech Republic MeSH
- London MeSH
- MeSH
- Adult MeSH
- Research Support as Topic MeSH
- Ankle Joint MeSH
- Middle Aged MeSH
- Humans MeSH
- Bandages MeSH
- Plastics chemistry therapeutic use MeSH
- Ankle Injuries MeSH
- Aged MeSH
- Thromboembolism prevention & control MeSH
- Check Tag
- Adult MeSH
- Middle Aged MeSH
- Humans MeSH
- Male MeSH
- Aged MeSH
- Publication type
- Review MeSH
- Comparative Study MeSH
- MeSH
- Cartilage cytology metabolism drug effects MeSH
- Enzyme-Linked Immunosorbent Assay MeSH
- Collagen biosynthesis MeSH
- Chick Embryo MeSH
- Oligopeptides pharmacology MeSH
- Plastics chemistry metabolism MeSH
- Prostheses and Implants standards MeSH
- Growth Substances pharmacology MeSH
- Animals MeSH
- Check Tag
- Chick Embryo MeSH
- Animals MeSH
