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Background The cause of amyotrophic lateral sclerosis (ALS) is unknown, but occupations have been explored as a potential proxy measure of risk. There is a substantial body of literature connecting military service to ALS. We aimed to summarize and assess the quality of this evidence. Methods Systematic review of the literature, including observational studies which explored one of the following exposures: general military service (army, air force, marines, or navy); or specific exposures associated with military service measured among military personnel. The outcome of interest was ALS incidence, which could include onset, diagnosis, or death from ALS. Results A total of 2642 articles were screened. Following exclusion, 19 articles remained for inclusion in the systematic review, including 1 meta-analysis and 18 original observational studies. Most studies were of moderate quality. In general, the relationship between military service was suggestive of an increased risk, particularly among Gulf War and WWII veterans. Exposure to pesticides (including Agent Orange) certain chemicals (exhaust, burning agents), heavy metals, and head trauma appeared to increase the risk of ALS among military personnel. Conclusions There is a possible association between military service and the subsequent development of ALS; however, the evidence was limited. Studies were generally hindered by small sample sizes and inadequate follow-up time. Future studies should endeavor to objectively measure specific exposures, or combinations thereof, associated with military service, as this will be of vital importance in implementing preventative strategies into military organizations.

Elemental analysis of dental hard tissues is of importance. The aim of this study is to evaluate X-ray microanalysis (XRMA) of bovine enamel in a scanning electron microscope (SEM) with different coatings. The buccal surface of bovine incisors was polished flat, one-third was coated with carbon, one-third with gold, leaving one-third uncoated for XRMA in an SEM equipped with an energy-dispersive microanalysis system. The elements oxygen, sodium, magnesium, phosphorous, chlorine, potassium, and calcium were analyzed using their respective characteristic K X-ray series. Comparisons were made with analyses of glass produced by fusion of the bovine enamel, showing that oxygen analyses using the K X-ray series are reliable and preferable to calculating oxygen by stoichiometry for natural enamel. For the gold-coated and uncoated analyses, carbon was also measured using the K X-ray series. Small area Analyses in small areas (80 × 80 μm) in variable pressure-SEM mode with low vacuum (20 Pa), without any coating, midway between 40 μm wide gold lines 140 μm apart to avoid build-up of electrostatic charge is the preferred method, especially if carbon is included in the analysis. The analyses of bovine enamel are sufficiently reproducible to be regarded as quantitative for all elements except carbon.

Background: many full-time welders experience some sort of respiratory disorder e.g., asthma, bronchitis and metal fume fever. Thus, welding aerosols are thought to cause airway inflammation. There is a need for markers of welding aerosols in exposure assessments, and as most welding aerosols contain manganese and iron, these metals may possibly be used as an indicator. We have previously developed a novel non-invasive technique to collect endogenous particles in exhaled air (PEx). This study is designed to (i) develop a method for analysis of manganese and iron in PEx and (ii) investigate whether the manganese and/or iron content of PEx changes after exposure to welding aerosols. Methods: nine individuals were experimentally exposed to welding fumes. PEx was collected at three time points for each individual; before, after and 24 hours after exposure. Analyses of PEx samples were performed using Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Results: four out of nine individuals showed an increase in manganese and iron levels after exposure to welding aerosols. The mean manganese and iron concentration increased from

Objectives: In this study, morphological and chemical changes in teeth enamel exposed to alkaline agents, with or without surfactants, have been investigated. In addition, chemical effects of the organic surface layer, i.e. plaque and pellicle, were also investigated. Methods: The present study was conducted using several techniques: Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results: From XPS-measurements, it was found that exposure to alkaline solutions resulted in a massive removal of carbon from the tooth surface, and that the addition of surfactants increased the rate under present conditions. Based on the results from the FTIR-analysis, no substitution reactions between phosphate, carbonate and hydroxide ions in the enamel apatite could be detected. From a minor SEM-analysis, degradation and loss of substance of the enamel surface was found for the exposed samples. From XRD-analysis, no changes in crystallinity of the enamel apatite could be found between the samples. Conclusions: The findings in this study show that exposure to alkaline solutions results in a degradation of enamel surfaces very dissimilar from acidic erosion. No significant erosion or chemical substitution of the apatite crystals themselves could be discerned. However, significant loss of organic carbon at the enamel surface was found in all exposed samples. The degradation of the protective organic layer at the enamel surface may profoundly increase the risk for caries and dental erosion from acidic foods and beverages.

Spectroscopic (XRD, XPS, ICP-MS and AAS) and microscopic (ESEM) techniques have been used in order to study the chemical effects with emphasis on mercury speciation, during thermal treatment of a mercury contaminated soil. In the untreated soil, mercury was found concentrated in spherical particles, which were successively broken down upon thermal treatment. Hg0 and inorganic mercury compounds (presumably HgO(s) and HgSO4(s)) could be detected. No (CH3)2Hg and only traces of CH3Hg+ could be found. The dependence on temperature and heating time indicated that the evaporation of mercury from the soil was partly controlled by diffusion mechanisms. Mercury volatilized in two separate stages during heating; initial elemental vaporization, and subsequent volatilization of the oxide or sulfate phase at higher temperatures (>230°C). By thermal treatment at 470°C and 20 min, a removal of >99% of the mercury could be achieved.

The equilibrium speciation in the pH+ + qMoO42− + rH2O2 + sH2PO4− + tSO42− ⇌ (H+)p(MoO42−)q(H2O2)r(H2PO4−)s(SO42−)tp−2q−s−2t system in 0.300 M Na2(SO4) medium at 25 °C and [H2O2]tot/[Mo]tot > 2 has been determined from potentiometric data and 31P NMR integral and chemical shift data in the range 1.0 ≤ pH ≤ 9.0, 2.0 ≤ [MoO42−]tot/mM ≤ 293, 32 ≤ [H2O2]tot/mM ≤ 640, 2 ≤ [H2PO4−]tot/mM ≤ 60 and 200 ≤ [SO42−]tot/mM ≤ 380. Species with the following compositions were obtained: MoX2P3− (0,1,2,1,0), MoX2P2− (1,1,2,1,0), MoX2P− (2,1,2,1,0), Mo2X4P3− (2,2,4,1,0), Mo2X4P2− (3,2,4,1,0), Mo3X6P3− (4,3,6,1,0), Mo3X6P2− (5,3,6,1,0) and Mo4X8P3− (6,4,8,1,0). The numbers and charges of molybdenum (Mo), peroxide (X), phosphate (P) and sulfate (S) in each species are given in the abbreviated formula MoqXrPsStp−2q−s−2t. The numbers in parentheses refer to the values of p, q, r, s and t in the formula above. The following formation constants with 3σ were obtained; log β0,1,2,1,0 = 5.16 ± 0.09, log β1,1,2,1,0 = 12.73 ± 0.02 (pKa = 7.63), log β2,1,2,1,0 = 16.14 ± 0.03 (pKa = 3.42), log β2,2,4,1,0 = 25.03 (± 0.04), log β3,2,4,1,0 = 29.54 ± 0.02 (pKa = 4.51), log β4,3,6,1,0 = 42.30 ± 0.03, log β5,3,6,1,0 = 44.06 ± 0.08 (pKa = 1.76), log β6,4,8,1,0 = 57.30 ± 0.07. pKa values for H3PO4 and H2PO4− were determined to 2.00 and 6.48, respectively. Chemical exchange processes were detected by 31P NMR 2D EXSY and selective magnetisation transfer experiments between the complexes. An averaged lifetime, τ(X2Mo–OP) ∼ 30 ms, can be estimated for the MoX2P and Mo2X4P species at pH = 5.5 and 5 °C.

Aqueous peroxomolybdates have been studied using 17O NMR together with equilibrium measurements and calculations, over a wide range of conditions. Ten peroxo species are identified, mostly in more than one state of protonation. Some are already known in the solid state, or from equilibrium analysis, but structural information is also obtained for MoO3(HO2)− and the new or previously tentative species Mo2O5(O2)22−, HpMo7O23(O2)2p−6 and HpMo7O23(O2)p−6 (p = 0–2). Sites of protonation are identified, as are 17O resonances from both bidentate and monodentate peroxide. Several oxygen exchange processes are also seen, including a probable dimer–tetramer exchange.

The equilibrium speciation at 278 K and the dynamics in the systems pH++qMoO42–+rH2O2+sL (H+)p(MoO42–)q(H2O2)r Ls(L = SO42– or Cl–) in 0.3 M Na2(SO4) and 0.6 M Na(Cl) medium has been determined fro ...

The equilibrium speciation in the system pH++qMoO42–+rH2O2+sSO42– (H+)p(MoO42–)q(H2O2)r(SO42–)s in 0.300 M Na2(SO4) medium at 25 °C has been determined from potentiometric titration data in the ran ...

Physicochemical properties, such as particle sizes, composition, and solubility of welding fumes are decisive for the bioaccessibility of manganese and thereby for the manganese cytotoxic and neurotoxic effects arising from various welding fumes. Because of the diverse results within the research on welding fume solubility, this article aims to review and discuss recent literature on physicochemical properties of gas metal arc welding, shielded metal arc welding, and flux-cored arc welding fumes, with focus on solubility properties. This article also presents a short introduction to the literature on arc welding techniques, health effects from manganese, and occupational exposure to manganese among welders.

Peroxomolybdates have shown to be efficient selective agents in the degradation of lignin in non-chlorine based bleach processes of kraft pulp. Furthermore, the process can be improved when anions such as phosphate are present. To clarify the chemistry in aqueous solution, fundamental speciation studies of relevant systems have been made under conditions similar to those in the bleaching step.