Experimentelle Untersuchung zur Bisphenol-A-Migration aus Beruhigungssaugern und Bewertung des potenziellen Gesundheitsrisikos für Säuglinge und Kleinkinder

Bisphenol A (BPA) ist eine in Industrienationen ubiquitär verbreitete Substanz mit endokriner Wirksamkeit. BPA wird zur Herstellung von Alltagsgegenständen aus Polycarbonat-Kunststoffen und Epoxidharzen eingesetzt. Dazu zählen auch Produkte für Säuglinge und Kleinkinder wie Beruhigungssauger (umgangssprachlich Schnuller). Diese Altersgruppe gilt aufgrund ihrer eingeschränkten BPA-Metabolisierung und der ablaufenden physischen Entwicklungsprozesse als vulnerabel gegenüber einer Exposition mit endokrinen Disruptoren wie BPA. Ein Verbot von BPA bei der Herstellung von Beruhigungssaugern wurde trotz der Gefahr einer direkten oralen Exposition bislang nicht durch die Europäische Kommission beschlossen. Derzeit ist unklar, inwiefern der Gebrauch von Beruhigungssaugern eine Gefahr der BPA-Exposition und dem damit verbundenen Gesundheitsrisiko darstellt. Das Ziel der vorliegenden Studie war die qualitative und quantitative Erfassung der BPA-Freisetzung aus kommerziell verfügbaren Beruhigungssaugern unter Worst-Case-Bedingungen mittels Hochleistungsflüssigkeitschromatografie mit Fluoreszenzdetektion (HPLC-FLD). Auf Basis der HPLC-Daten wurde anschließend ein Risk-Assessment durchgeführt. Die Schild- und Saugeranteile von sieben Beruhigungssaugern der Hersteller NUK, Hevea, MMBABY, FUNNYBABY, Novatex und einem unbekannten Hersteller wurden getrennt analysiert. Die 42 Proben (n=3 je Schild- und Saugeranteil) wurden nach mechanischer Zerkleinerung bei 37 °C für 72 Stunden in Methanol extrahiert und mit einer HPLC-FLD analysiert. Als Validierungsparameter der HPLC-Analyse wurden eine Nachweisgrenze (LOD) von 0,22 µg/l und eine Bestimmungsgrenze (LOQ) von 0,66 µg/l bei einer Wiederfindungsrate (WFR) von 92,3 % auf Basis von Aufdotierungen bestimmt. Ein qualitativer BPA-Nachweis war in allen untersuchten Proben möglich. Bei zwei Proben, einem Schildanteil des Herstellers NUK und dem Saugeranteil des Herstellers FUNNYBABY, lagen die ermittelten Konzentrationen unterhalb der LOQ, sodass keine Quantifizierung erfolgen konnte. Der Schildanteil des Beruhigungssaugers von FUNNYBABY setzte die höchste BPA-Konzentration (288 µg/l) im Vergleich zu den anderen untersuchten Proben der Schild- und Saugeranteile (0,69 µg/l bis 9,40 µg/l) frei. Für die maximal freigesetzte BPA-Konzentration des Beruhigungssaugers von FUNNYBABY wurde eine BPA-Aufnahme von 0,38 µg/kg KG/Tag für Säuglinge und 0,18 µg/kg KG/Tag für Kleinkinder unter Worst-Case-Bedingungen berechnet. Die von der European Food Safety Authority (EFSA) 2015 veröffentlichte und aktuell gültige t-TDI (temporary Tolerable Daily Intake) von 4 µg/kg KG/Tag wurde somit deutlich unterschritten. Unter Einbeziehung der von der EFSA geschätzten maximalen BPA-Grundbelastung wird die t-TDI ebenfalls nicht ausgeschöpft. Nach derzeitigem Kenntnisstand trägt daher die Verwendung von Beruhigungssaugern mit hoher Wahrscheinlichkeit nicht wesentlich zum BPA-assoziierten Gesundheitsrisiko von Säuglingen und Kleinkindern bei. Zukünftig gilt es zu klären, inwiefern BPA-Ersatzstoffe und andere Substanzen mit potenziellem Gesundheitsrisiko bei der Produktion von Beruhigungssaugern und weiteren Verbraucherprodukten eingesetzt werden. Darüber hinaus sollte das toxikologische Gesundheitsrisiko solcher Alternativstoffe und deren Freisetzung aus Kunststoffen weitreichend untersucht werden.Bisphenol A (BPA) is a substance with endocrine activity that is ubiquitously used in industrialized nations. BPA is used in the manufacture of everyday items made from polycarbonate plastics and epoxy resins. These include products for infants and toddlers such as pacifiers (so called dummies). This age group is considered being vulnerable to the exposure to endocrine disruptors such as BPA due to their limited BPA metabolism and occurring physical development processes. A ban on BPA in the production of pacifiers has not yet been determined by the European Commission, despite the risk of direct oral exposure. Currently, it is unclear to what extent the use of pacifiers poses a risk of BPA exposure and the associated health risk. The aim of the present study was to evaluate BPA migration from commercially available pacifiers under worst-case conditions by qualitative and quantitative analysis using high-performance liquid chromatography with fluorescence detection (HPLC-FLD). Based on the resulting data a risk assessment was performed. Shield and teat fractions of seven different pacifiers of the manufacturers NUK, Hevea, MMBABY, FUNNYBABY, Novatex along with an unknown manufacturer were analyzed separately. After cutting the 42 samples (n=3 per each shield and teat) into small pieces, samples were extracted in methanol at 37 °C for 72 hours and analyzed by HPLC-FLD. As validation parameters of the HPLC analysis, a limit of detection (LOD; 0.22 µg/l) and a limit of quantitation (LOQ; 0.66 µg/l) were determined with a recovery rate (RR) of 92.3% based on spiking. BPA was detected qualitatively in all samples tested. BPA concentrations of two samples (a shield fraction of NUK and a teat fraction of FUNNYBABY) were below the LOQ, so that no quantification could be performed. The pacifier shield fraction of the manufacturer FUNNYBABY released the highest BPA concentration (288 µg/l) compared to the remaining investigated shield and teat fractions (0.69 µg/l to 9.40 µg/l). A potential BPA uptake under worst-case conditions of 0.38 µg/kg bw/day for infants and 0.18 µg/kg bw/day for toddlers was calculated from the FUNNYBABY pacifier. These concentrations are clearly lower in comparison to the recent t-TDI (temporary Tolerable Daily Intake) which was published and validated by the European Food Safety Authority (EF-SA) in 2015 with a value of 4 µg/kg bw/day. Summing up with estimated maximum environmental background concentration of BPA (EFSA), resulting BPA values are still not exceeding the t-TDI. Therefore, based on current knowledge, the use of pacifiers is highly unlikely to contribute to BPA-associated health risk towards infants and toddlers. Future investigations should clarify to which extent BPA substitutes and other sub-stances with potential health risks are used in the production of pacifiers and any other consumer products. In addition, the toxicological health risk of such alternative sub-stances and their release from plastics should be widely investigated

La cuantificación de los desplazamientos en contextos de desastres urbanos

Las actividades de reducción del riesgo de desastres y los programas humanitarios para ayudar a las poblaciones desplazadas son más efectivos cuando se basan en datos oportunos y precisos. Pero existe una importante deficiencia de datos en el contexto del desplazamiento urbano

Analysis of time‐lapse travel‐time and amplitude changes to assess reservoir compartmentalization

Fluid depletion within a compacting reservoir can lead to significant stress and strain changes and potentially severe geomechanical issues, both inside and outside the reservoir. We extend previous research of time-lapse seismic interpretation by incorporating synthetic near-offset and full-offset common-midpoint reflection data using anisotropic ray tracing to investigate uncertainties in time-lapse seismic observations. The time-lapse seismic simulations use dynamic elasticity models built from hydro-geomechanical simulation output and a stress-dependent rock physics model. The reservoir model is a conceptual two-fault graben reservoir, where we allow the fault fluid-flow transmissibility to vary from high to low to simulate non-compartmentalized and compartmentalized reservoirs, respectively. The results indicate time-lapse seismic amplitude changes and travel-time shifts can be used to qualitatively identify reservoir compartmentalization. Due to the high repeatability and good quality of the time-lapse synthetic dataset, the estimated travel-time shifts and amplitude changes for near-offset data match the true model subsurface changes with minimal errors. A 1D velocity–strain relation was used to estimate the vertical velocity change for the reservoir bottom interface by applying zero-offset time shifts from both the near-offset and full-offset measurements. For near-offset data, the estimated P-wave velocity changes were within 10% of the true value. However, for full-offset data, time-lapse attributes are quantitatively reliable using standard time-lapse seismic methods when an updated velocity model is used rather than the baseline model

Feasibility of time-lapse AVO and AVOA analysis to monitor compaction-induced seismic anisotropy

Hydrocarbon reservoir production generally results in observable time-lapse physical property changes, such as velocity increases within a compacting reservoir. However, the physical property changes that lead to velocity changes can be difficult to isolate uniquely. Thus, integrated hydro-mechanical simulation, stress-sensitive rock physics models and time-lapse seismic modelling workflows can be employed to study the influence of velocity changes and induced seismic anisotropy due to reservoir compaction. We study the influence of reservoir compaction and compartmentalization on time-lapse seismic signatures for reflection amplitude variation with offset (AVO) and azimuth (AVOA). Specifically, the time-lapse AVO and AVOA responses are predicted for two models: a laterally homogeneous four-layer dipping model and a laterally heterogeneous graben structure reservoir model. Seismic reflection coefficients for different offsets and azimuths are calculated for compressional (P–P) and converted shear (P–S) waves using an anisotropic ray tracer as well as using approximate equations for AVO and AVOA. The simulations help assess the feasibility of using time-lapse AVO and AVOA signatures to monitor reservoir compartmentalization as well as evaluate induced stress anisotropy due to changes in the effective stress field. The results of this study indicate that time-lapse AVO and AVOA analysis can be applied as a potential means for qualitatively and semi-quantitatively linking azimuthal anisotropy changes caused by reservoir production to pressure/stress changes

When do fractured media become seismically anisotropic? Some implications on quantifying fracture properties

Fractures are pervasive features within the Earth's crust and they have a significant influence on the multi-physical response of the subsurface. The presence of coherent fracture sets often leads to observable seismic anisotropy enabling seismic techniques to remotely locate and characterise fracture systems. In this study, we confirm the general scale-dependence of seismic anisotropy and provide new results specific to shear-wave splitting (SWS). We find that SWS develops under conditions when the ratio of wavelength to fracture size (λS/d) is greater than 3, where Rayleigh scattering from coherent fractures leads to an effective anisotropy such that effective medium model (EMM) theory is qualitatively valid. When 1<λS/d<3 there is a transition from Rayleigh to Mie scattering, where no effective anisotropy develops and hence the SWS measurements are unstable. When λS/d<1 we observe geometric scattering and begin to see behaviour similar to transverse isotropy. We find that seismic anisotropy is more sensitive to fracture density than fracture compliance ratio. More importantly, we observe that the transition from scattering to an effective anisotropic regime occurs over a propagation distance between 1 and 2 wavelengths depending on the fracture density and compliance ratio. The existence of a transition zone means that inversion of seismic anisotropy parameters based on EMM will be fundamentally biased. More importantly, we observe that linear slip EMM commonly used in inverting fracture properties is inconsistent with our results and leads to errors of approximately 400% in fracture spacing (equivalent to fracture density) and 60% in fracture compliance. Although EMM representations can yield reliable estimates of fracture orientation and spatial location, our results show that EMM representations will systematically fail in providing quantitatively accurate estimates of other physical fracture properties, such as fracture density and compliance. Thus more robust and accurate quantitative estimates of in situ fracture properties will require improvements to effective medium models as well as the incorporation of full-waveform inversion techniques

Reservoir stress path and induced seismic anisotropy: Results from linking coupled fluid-flow/geomechanical simulation with seismic modelling

We present a workflow linking coupled fluid-flow and geomechanical simulation with seismic modelling to predict seismic anisotropy induced by nonhydrostatic stress changes. We generate seismic models from coupled simulations to examine the relationship between reservoir geometry, stress path and seismic anisotropy. The results indicate that geometry influences the evolution of stress, which leads to stress-induced seismic anisotropy. Although stress anisotropy is high for the small reservoir, the effect of stress arching and the ability of the side-burden to support the excess load limit the overall change in effective stress and hence seismic anisotropy. For the extensive reservoir, stress anisotropy and induced seismic anisotropy are high. The extensive and elongate reservoirs experience significant compaction, where the inefficiency of the developed stress arching in the side-burden cannot support the excess load. The elongate reservoir displays significant stress asymmetry, with seismic anisotropy developing predominantly along the long-edge of the reservoir. We show that the link between stress path parameters and seismic anisotropy is complex, where the anisotropic symmetry is controlled not only by model geometry but also the nonlinear rock physics model used. Nevertheless, a workflow has been developed to model seismic anisotropy induced by non-hydrostatic stress changes, allowing field observations of anisotropy to be linked with geomechanical models

Seismic and electric crosshole tomography for fracture detection and characterization

Available from British Library Document Supply Centre-DSC:DXN046822 / BLDSC - British Library Document Supply CentreSIGLEGBUnited Kingdo

Quantifying displacement in urban disaster contexts

Disaster risk reduction and humanitarian programming activities to assist displaced populations are more effective when informed by timely, accurate data. There is, however, a significant data gap in the context of urban displacement