An investigation of the mechanism of detoxification in asbestos

⁵⁷Fe Mössbauer effect spectroscopy studies were conducted on native crocidolite and on a sample which had been detoxified by means of a chemical treatment with ferric salts. This allows for a comparison between the crystal chemistry of the untreated and treated samples. Significant chemical changes in the treated sample have been inferred from the Fe site-population analysis after conducting a temperature-dependent study of both samples in the range 300 K down to 90 K. These results, together with the results from complementary Electron Spin Resonance (ESR) studies, may help to elucidate the mechanism of toxicity in these asbetiforms.     

Effect of microwave radiation on surface charge, surface sites and ionic state of iron, and the activity of crocidolite asbestos fibres

Surface charge, surface sites, and the content of ferrous ions of crocidolite asbestos fibres are some of the properties which are considered to play a role in determining their activity in biological systems. Any treatment which changes these properties may therefore change their activity and subsequently increase or decrease their toxicity in biological surroundings. Surfaces of crocidolite fibres are shown to be negatively charged. In the present study, microwave radiation at 300^°C was able to increase the number of positive charges within the bulk of the crocidolite fibres. In the presence of atmospheric oxygen, this increase could simultaneously reduce the hydroxyl groups on the surface of the fibres. The increase in positive charge was monitored by: (i) Mössbauer spectroscopy, where a change in the oxidation state of iron from ferrous to ferric was observed, (ii) visual microscopic observations of the irradiated fibres where there was an increase in their aggregation, and (iii) the difficulty to suspend these radiated fibres in solution. A decrease in the number of the surface hydroxyl groups on the other hand, was monitored by infrared spectroscopy. The reduction in the activity of the radiated crocidolite fibres was investigated by studying their ability to peroxidize lipids. Results have shown that changes in their surface charge, surface site and a reduction of the content of ferrous ions produce a concomitant decrease in their ability to initiate lipid peroxidation.     

Using the Isalos platform to develop a (Q)SAR model that predicts metal oxide toxicity utilizing facet-based electronic,image analysis-based,and periodic table derived properties as descriptors

Structural Chemistry - Engineered nanoparticles (NPs) are being studied for their potential to harm humans and the environment. Biological activity, toxicity, physicochemical properties, fate, and...