For drinking water, the people of Bangladesh used to rely on surface water, which was often contaminated with bacteria causing diarrhea, cholera, typhoid, and other life-threatening diseases To reduce the incidences of these diseases, millions of tubewells were installed in Bangladesh since independence in 1971 This recent transition from surface water to groundwater has significantly reduced deaths from waterborne pathogens; however, new evidence suggests disease and death from arsenic (As) and other toxic elements in groundwater are affecting large areas of Bangladesh In this evaluation, the areal and vertical distribution of As and 29 other inorganic chemicals in groundwater were determined throughout Bangladesh This study of 30 analytes per sample and 112 samples suggests that the most significant health risk from drinking Bangladesh's tubewell water is chronic As poisoning The As concentration ranged from < 00007 to 064 mg/L, with 48% of samples above the 001 mg/L World Health Organization drinking water guideline Furthermore, this study reveals unsafe levels of manganese (Mn), lead (Pb), nickel (Ni), and chromium (Cr) Our survey also suggests that groundwater with unsafe levels of As, Mn, Pb, Ni, and Cr may extend beyond Bangladesh's border into the four adjacent and densely populated states in India In addition to the health risks from individual toxins, possible multimetal synergistic and inhibitory effects are discussed Antimony was detected in 98% of the samples from this study and magnifies the toxic effects of As In contrast, Se and Zn were below our detection limits in large parts of Bangladesh and prevent the toxic effects of As

http://www.betterlifelabs.org/EHP110p1147PDF.pdf

The concentrations of arsenic and other toxic elements in Bangladesh's drinking water.

We report on a comparative study by Transmission Electron Microscopy (HRTEM) and Scanning Transmission Ion Microscopy (STIM) combined with Rutherford Backscattering Spectrometry (RBS) and Particle Induced X-Ray Emission (PIXE) on ultra-thin and thin cross-sections, respectively, of various skin samples (porcine skin, healthy human skin, human skin grafted on a severe combined immuno-deficient mouse model) to which we applied topically various formulations containing titanium dioxide (TiO2) nanoparticles with primary particle sizes in the range from 20-100 nm. Whereas the HRTEM and STIM/PIXE images reveal clear differences - mainly related to the different thickness of the cross-sections - they unambiguously show that penetration of TiO2 nanoparticles is restricted to the topmost 3-5 corneocyte layers of the stratum corneum (SC).

Is there penetration of titania nanoparticles in sunscreens through skin? A comparative electron and ion microscopy study

The use of SEM-EDS, PIXE and EDXRF for obsidian provenance studies in the Near East: a case study from Neolithic Çatalhöyük (central Anatolia)☆

Elemental microanalysis of biological material in the frozen-hydrated state using in-vacuum proton induced X-ray emission is described for the first time. For this purpose, a com- mercially available cryotransfer system was modified and coupled to the experimental chamber of the nuclear microprobe (NMP). The analyzed material was frozen in propane cooled by liquid nitrogen, fractured, carbon coated, and transferred onto the cold stage (100 K) of the nuclear microprobe chamber. Micro-PIXE and simultaneous proton backscattering was performed using a 3 MeV proton beam. Quantitative results were obtained by the standardless method, and tested using 20% gelatin standards. Monitoring of the gas composition inside the system by means of mass spectrometry performed before, during, and after proton bombardment showed good stability of the analyzed material for proton currents not exceeding 150 pA. Average concentrations of light elements (C, N, O, and indirectly H) were also obtained by the proton backscattering technique. No losses of elements measurable by particle-induced X-ray emission (PIXE) during proton irradi- ation were found during repetitive, short analyses of the same micro areas of gelatin standards. Measurements of thick sections of selected plant and animal material in the frozen-hydrated state-leaf sections of the plant Senecio anomalochrous Hilliard (Asteraceae) and larvae of Chyso- lina pardalina Fabricius (Chrysomelidae)-showed very good preservation of morphology and elemental distribution. Limits of detection of the order of a few l gg � 1 were obtained for most ele-

X-ray microanalysis of biological material in the frozen-hydrated state by PIXE.

Multiple origins of Bondi Cave and Ortvale Klde (NW Georgia) obsidians and human mobility in Transcaucasia during the Middle and Upper Palaeolithic

The damage caused by the impact of a high energy focused ion beam on biological targets can lead, in a number of cases, to erroneous analytical results. Some of the observed modifications result from cummulative radiolytic effects and cannot be avoided. However, those alterations, induced by a local increase of the sample temperature can be minimized by high speed scanning. We present here the first comparative results achieved by irradiation of organic samples by the CENBG Nuclear Microprobe for different scan frequencies.

P.-H. Moretto

Papers

Advantages of high speed scanning for microprobe analysis of biological samples