Deposition and solubility of airborne metals to four plant species grown at varying distances from two heavily trafficked roads in London

In urban areas, a highly variable mixture of pollutants is deposited as particulate matter. The concentration and bioavailability of individual pollutants within particles need to be characterised to ascertain the risks to ecological receptors. This study, carried out at two urban parks, measured the deposition and water-solubility of metals to four species common to UK urban areas. Foliar Cd, Cr, Cu, Fe, Ni, Pb and Zn concentrations were elevated in at least one species compared with those from a rural control site. Concentrations were, however, only affected by distance to road in nettle and, to a lesser extent, birch leaves. Greater concentrations of metal were observed in these species compared to cypress and maple possibly due to differences in plant morphology and leaf surfaces. Solubility appeared to be linked to the size fraction and, therefore, origin of the metal with those present predominantly in the coarse fraction exhibiting low solubility. © 2009

Bioavailability in soils

The consumption of locally-produced vegetables by humans may be an important exposure pathway for soil contaminants in many urban settings and for agricultural land use. Hence, prediction of metal and metalloid uptake by vegetables from contaminated soils is an important part of the Human Health Risk Assessment procedure. The behaviour of metals (cadmium, chromium, cobalt, copper, mercury, molybdenum, nickel, lead and zinc) and metalloids (arsenic, boron and selenium) in contaminated soils depends to a large extent on the intrinsic charge, valence and speciation of the contaminant ion, and soil properties such as pH, redox status and contents of clay and/or organic matter. However, chemistry and behaviour of the contaminant in soil alone cannot predict soil-to-plant transfer. Root uptake, root selectivity, ion interactions, rhizosphere processes, leaf uptake from the atmosphere, and plant partitioning are important processes that ultimately govern the accumulation ofmetals and metalloids in edible vegetable tissues. Mechanistic models to accurately describe all these processes have not yet been developed, let alone validated under field conditions. Hence, to estimate risks by vegetable consumption, empirical models have been used to correlate concentrations of metals and metalloids in contaminated soils, soil physico-chemical characteristics, and concentrations of elements in vegetable tissues. These models should only be used within the bounds of their calibration, and often need to be re-calibrated or validated using local soil and environmental conditions on a regional or site-specific basis.Mike J. McLaughlin, Erik Smolders, Fien Degryse, and Rene Rietr

Release of bisphenol-A from a light-cured adhesive bonded to lingual fixed retainers

Introduction: Our aim was to quantitatively determine the bisphenol-A (BPA) released from a light-cured orthodontic adhesive used to bond lingual fixed retainers. Methods: Eighteen recently extracted premolars, divided into 3 groups of 6 teeth each, were embedded in plaster in an arch shape. A light-cured adhesive (Transbond XT, 3M Unitek, Monrovia, Calif) was bonded to a .0195-in, 3-strand heat-treated twist flex wire (Wildcat, GAC International, Bohemia, NY) adjusted to the lingual surface of the teeth, and the arches were immersed in doubled-distilled water for 10, 20, and 30 days. The concentration of BPA in the 3 eluents was investigated with gas chromatography-mass spectroscopy; all assays were performed in triplicate, and the results were averaged. Results: Measurable amounts of BPA were identified for all groups, with the highest found in the immersion media of the 1-month groups (2.9 μg/L), whereas the control (tooth storage solution) had 0.16 μg/L. Conclusions: The BPA released from a light-cured adhesive used to bond lingual fixed retainers might be assigned to the application mode of the material that differs from conventional use. Further testing including estrogenicity assays will assess the potential estrogenic action of this application. Composite restorative resins should replace orthodontic adhesives that were not intended to function with their surfaces in the oral cavity; alternatively, canine-bonded fixed retainers might reduce the amount of adhesive used. © 2011 by the American Association of Orthodontists

BPA qualtitative and quantitative assessment associated with orthodontic bonding in vivo

Objective To assess the in vivo amount of BPA released from a visible light-cured orthodontic adhesive, immediately after bracket bonding. Methods 20 orthodontic patients were recruited after obtaining informed consent. All patients received 24 orthodontic brackets in both dental arches. In Group A (11 patients), 25 ml of tap water were used for mouth rinsing, whereas in Group B (9 patients) a simulated mouth rinse formulation was used: a mixture of 20 ml de-ionized water plus 5 ml absolute ethanol. Rinsing solutions were collected before, immediately after placing the orthodontic appliances and after washing out the oral cavity and were then stored in glass tubes. Rinsing was performed in a single phase for 60 s with the entire volume of each liquid. The BPA analysis was performed by gas chromatography-mass spectrometry. Results An increase in BPA concentration immediately after the 1st post-bonding rinse was observed, for both rinsing media, which was reduced after the 2nd post-bonding rinse. Water exhibited higher levels of BPA concentration than water/ethanol after 1st and 2nd post-bonding rinses. Two-way mixed Repeated Measures ANOVA showed that the primary null hypothesis declaring mean BPA concentration to be equal across rinsing medium and rinsing status was rejected (p-value <0.001). The main effects of the rinsing medium and status, as well as their interaction were found to be statistically significant (p-values 0.048, <0.001 and 0.011 respectively). Significance A significant pattern of increase of BPA concentration, followed by a decrease that reached the initial values was observed. The amount of BPA was relatively low and far below the reference limits of tolerable daily intake. © 2015 Published by Elsevier Ltd on behalf of Academy of Dental Materials. All rights reserved

Boron contamination of Mediterranean Groundwater resources: Extent, sources and pathways elucidated by environmental isotopes.

none10noneKloppmann W.; Bianchini G.; Charalambides A.; Dotsika E.; Guerrot C.; Klose P.; Marei A.; Pennisi M.; Vengosh A.; Voutsa D.Kloppmann, W.; Bianchini, Gianluca; Charalambides, A.; Dotsika, E.; Guerrot, C.; Klose, P.; Marei, A.; Pennisi, M.; Vengosh, A.; Voutsa, D

A catastrophic change in a european protected wetland: From harmful phytoplankton blooms to fish and bird kill

Understanding the processes that underlay an ecological disaster represents a major scientific challenge. Here, we investigated phytoplankton and zooplankton community changes before and during a fauna mass kill in a European protected wetland. Evidence on gradual development and collapse of harmful phytoplankton blooms, allowed us to delineate the biotic and abiotic interactions that led to this ecological disaster. Before the mass fauna kill, mixed blooms of known harmful cyanobacteria and the killer alga Prymnesium parvum altered biomass flow and minimized zooplankton resource use efficiency. These blooms collapsed under high nutrient concentrations and inhibitory ammonia levels, with low phytoplankton biomass leading to a dramatic drop in photosynthetic oxygenation and a shift to a heterotrophic ecosystem phase. Along with the phytoplankton collapse, extremely high numbers of red planktonic crustaceans-Daphnia magna, visible through satellite images, indicated low oxygen conditions as well as a decrease or absence of fish predation pressure. Our findings provide clear evidence that the mass episode of fish and birds kill resulted through severe changes in phytoplankton and zooplankton dynamics, and the alternation on key abiotic conditions. Our study highlights that plankton-related ecosystem functions mirror the accumulated heavy anthropogenic impacts on freshwaters and could reflect a failure in conservation and restoration measures. © 2022 Elsevier Lt