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[en] This article highlights the disagreement between 2 scientific commissions about the maximal acceptable concentration of radon. 1000 or 400 becquerels for each cubic-meter of air (Bq/m3). Information about the average concentration of radon in the different French departments is given by means of a map. (A.C.)
[en] In the assessment of the quality of surface waters, the typical procedure is that the concentration of contaminants in the surface water is monitored and subsequently compared with their respective Maximum Permissible Concentrations (MPCs). If the MPCs are not exceeded the water quality is considered to be safe. But can we be certain that this is true? We compared MPCs to observed and calculated effects of measured contaminants in Dutch surface waters and showed that effects of mixtures can cause a daphnid population to go extinct within 30 h of exposure even when MPCs are not exceeded. We conclude that there are shortcomings underlying the concepts of the MPCs. And that the MPCs aim to protect 95% of all species is not met. - Daphnid populations can go extinct rapidly in surface waters if exposed to mixtures even if environmental quality standards are not exceeded.
[en] Attention has been focused on the issue of radon in drinking water by a European Commission recommendation proposing that surveys should be undertaken in Member States to determine the scale and nature of exposures caused by radon in domestic drinking water supplies. The Commission recommends 1000 Bq/l as the radon activity concentration in private drinking water supplies above which remedial action to reduce the concentration should be taken. The logic behind the proposed action level is that it would broadly correspond to the risk posed to an individual from exposure to radon in the home at the current Reference Level of 200 Bq/m3 in air. A pilot study to assess the distribution and concentrations of radon in private ground water supplies was recently completed in Co. Wicklow. County Wicklow was selected for the study primarily on the basis that the underlying geology is predominantly granite with elevated uranium content. Furthermore, there is an estimated 1200 to 5000 private ground water supplies in use in the county and high radon activity concentrations in air in a significant number of dwellings have previously been predicted. As part of the pilot study, a number of scientific issues were addressed in order to underpin the results obtained and these are also discussed in the report. Radon activity concentrations were measured in the private ground water supplies of 166 houses in Co. Wicklow. In all cases the ground water was the principal source of drinking water for the house occupants. Four supplies had activity concentrations in excess of the Recommended EC action level of 1000 Bq/l, fifteen had activity concentrations between 500 and 1000 Bq/l, 51 were between 100 and 500 Bq/l and 96 had activity concentrations below 100 Bq/l. The doses estimated for the ingestion of radon bearing water varies significantly with the quantity of drinking water consumed and the degree to which the water has been processed prior to consumption. However dose estimates based on measurements made in this study demonstrate that radon in drinking water may pose a significant additional health risk, in the longer term, to some consumers who depend on private ground water supplies as their primary source of drinking water. (author)
[en] The Kuril Islands region is considered promising for development of salmon aquaculture. There are 41 salmon fish hatcheries in the Sakhalin Island and the Kuril Islands, 34 of them are hatcheries of the chum. Therefore, concentrations of six elements (Zn, Cu, Cd, Pb, As, and Hg) were determined in chum salmon were caught in this region. The contents of toxic elements (Cd, Pb, As, and Hg) don't exceed their maximum permissible concentrations (MPC) according to the Russian sanitary standards, but concentration of Pb are closely to MPC. Increased concentrations of Pb in wild chum have the natural origin. The unusual conditions of the Western Pacific are formed under the influence such factors as volcanism and upwelling. - Highlights: • High content of Pb, found in chum from the Kuril Islands, is caused by natural sources. • The content of elements do not exceed maximum permissible concentrations in Russia. • Kuril region is considered as promising zone for development of salmon aquaculture. - Kuril region is suitable for aquaculture development of Pacific salmon.
[en] Carbon nanotubes (CNT) can be chemically modified by doping or functionalization to change the chemical and surface properties. These characteristic makes to CNT candidates for multiple applications including medical field in cardiovascular area. A novel method to CNT functionalization by formation of two compounds: α-bromoacid and the organic compound 2-(methacryloyloxy) ethyl phosphorylcholine (MPC), will be discussed in this article. According to results, CNT are suggested like candidates to repel oxidized low-density lipoproteins (ox-LDL) to prevent restenosis. The electronegative character on surface of functionalized CNT (F-CNT) is shown by wettability analysis observing a repellent behaviour in contact with ox-LDL after functionalization route. Here we analyse the toxicity of CNT and F-CNT on HepG2 cell line and find no damage to the cell membrane of HepG2 cells in concentration at doses below 1 mg/ml. - Highlights: • Carbon nanotubes, materials suggested like candidates to repel ox-LDL causative of cardiovascular diseases. • MPC functionalized CNT, a new route to repel ox-LDL. • MPC functionalized CNT increased repulsive behaviour with angles up to 135 grades in contact with ox-LDL. • CNT could be considered to medical applications in concentrations < 1mg/ml and diameters up to 60 nm.
[en] Highlights: • The water-soluble Au13 clusters under the protection of binary thiolates are synthesized. • The formula and structure are determined via experimental and theoretical investigations. • Natural bond orbital (NBO) analysis reveals the origin of the Au13 MPCs stability. • The water-soluble Au13 MPCs are found to be a decent candidate for chemosensing and bioimaging. Here we report a successful synthesis of water-soluble 13-atoms gold clusters under the monolayer protection of binary thiolates, glutathione and penicillamine, under a molecular formula of Au13(SG)5(PA)7. This monolayer-protected cluster (MPC) finds decent stability and is demonstrated to possess an icosahedral geometry pertaining to structural accommodation in contrast to a planar bare Au13 of local minima energy. Natural bond orbital (NBO) analysis depicts the interaction patterns between gold and the ligands, enlightening to understand the origin of enhanced stability of the Au13 MPCs. Further, the water-soluble Au13 MPCs are found to be a decent candidate for chemosensing and bioimaging.
[en] Malaysian zircon contains higher level of NORM especially uranium and thorium than the permissible level set by many importing countries. These elements are present mainly on the mineral surface as well as in its crystal lattice. A study was conducted using selective leaching to reduce NORM content in the mineral. Various parameters such as temperature, time, concentration of leachants, particle size and heat treatment affect the rate of leaching. Optimum conditions for these parameters were determined in order for maximum reduction will be obtained. (Author)