Clearing of the Radioactive Liquid Waste from Oils and Oil Products by UV-Radiation at NPPs

The basic methods of concentration and purification of liquid radioactive waste on the nuclear power plant are distillation and ionic exchange. During vaporization of oil waste products and the fulfilled washing solutions the part of oil passes into a condensate. Clearing of such condensate on ion-exchanged filters results to oiling of ion-exchanged materials and to decrease number of filter cycles. Due to the often regeneration of ion-exchanged filters additional volumes of waste products as the fulfilled reclaiming solutions, washing and loosening waters are formed. The attention of scientists was involved with methods of clearing of water environments from the organic substances, based on deep oxidizing transformations of hydrocarbons into carbonic gas and water. From processes of oxidation of hydrocarbons up to CO2 and H2O, sold at moderate conditions, our attention has involved photochemical oxidation with the help of UV-radiation.

Simulation of Accelerated Ageing of UV-Radiation for Photodegradable Geotextiles/Geomembranes

Geosynthetics used as geotextiles/geomembranes lose their mechanical properties when exposed to outdoor solar radiation. The UV-component present in the solar radiation is main cause for such degradation of mechanical properties. The life of geosynthetics has to be predicted before the intended purpose by exposing the material under artificial UV-radiation in the laboratory. Simulation of UV-radiation has been set up for accelerated ageing condition of Mumbai climate.

The protective effect of zeaxanthin on human limbal and conjunctival epithelial cells against UV-induced cell death and oxidative stress

AIM: To explore the protective effect of zeaxanthin on human limbal and conjunctival epithelial cells against UVradiation and excessive oxidative stress.METHODS: Human limbal and conjunctival epithelial cells were isolated from cadaver and cultured in vitro. They were challenged with UVB radiation and H2 O2 with and without zeaxanthin pretreatment. Cell viability, p38 and c-JUN NH(2)-terminal kinase(JNK) phosphorylation, IL-6, IL-8 and MCP-1 secretion and malondialdehyde(MDA) content were measured.RESULTS: Zeaxanthin had no measurable cytotoxicity on limbal or conjunctival epithelial cells when used at concentrations of 5 μg/mL and below. At 30 mJ/cm2 UVB, the pretreatment of zeaxanthin increased the percentage of live cells from 50% to 69%(P=0.01) and from 66% to 75%(P=0.05) for limbal and conjunctival epithelial cells, respectively. The concentrations of IL-6, IL-8 and MCP-1 in the culture medium reduced to 66%(for IL-6 and MCP-1)and 56%(for IL-8) of the levels without zeaxanthin. This was accompanied by reduced p38 and JNK protein phosphorylation. Pretreatment of zeaxanthin also reduced intracellular MDA content caused by H2 O2 stimulation from 0.86 μmol/L to 0.52 μmol/L(P=0.02) in limbal epithelial cells and from 0.96 μmol/L to 0.56 μmol/L in conjunctival epithelial cells(P=0.03). However, zeaxanthin did nothave significant effect on H2 O2-induced cell death in limbal or conjunctival epithelial cells.CONCLUSION: Zeaxanthin is an effective reagent in reducing the detrimental effect of UV-radiation and oxidative stress on ocular surface epithelial cells.

Real Facts about Safety and Efficacy of Zinc Oxide and Titanium Dioxide in Solar Products

Background: Titanium dioxide and zinc oxide were often criticized over the last decade because of their supposed noxious effects on human health. Moreover, these compounds which are frequently introduced in sunscreen products as UV filter, are sometimes associated with poor UVA protection factors. So, in order to clarify the real efficacy and safety status of these products, we provide here some bibliographic and experimental data regarding 1) their “real” protective effect against UVA rays and 2) their real harmful effects on human skin notably by studying their capability to penetrate through the human cutaneous tissue. Materials and Methods: We studied here 4 sunscreen products containing titanium dioxide and zinc oxide for 3 of them. First, because the UVA-PF values obtained for these compounds by using the “classical” in vitro ISO 24443 procedure seem to be significantly different from to those obtained by using the in vivo method ISO 24442, we chose to develop a new in vitro methodology in order to more precisely define the UVA-PF of titanium and zinc oxides. This new methodology was then used to lead UVA-PF studies with the 4 selected solar products. We also provide here an evaluation of the toxicological effects of titanium and zinc oxides on human skin based on the SCCS reports and analysis of recent and relevant bibliographic studies. Moreover, as the harmful effects of this type of products are closely linked to their ability to penetrate cutaneous tissue, we tested 7 sunscreen products to precise the skin penetration profiles of titanium dioxide and zinc oxide by using human skin explants mounted on Franz cells. Results: We here demonstrated that our new in vitro methodology gave some UVA-PF values very close to those obtained with in vivo methods and we took advantage of it to define more realistic UVA-PF for titanium dioxide and zinc oxide. Additionally, we here evaluated the human skin permeation and resorption capacities of titanium dioxide and zinc oxide incorporated in the 7 tested products. As it was defined by World Health Organization (WHO) in 2005, permeation consists in the ability for a compound to penetrate into different layers of a tissue, and the resorption consists in the absorption of this compound into the vascular system. In our experimental conditions, we showed 1) that zinc oxide and titanium dioxide permeations did not exceed 8.5 and 5.5 μg/cm2 of skin respectively (i.e. 0.89% and 0.26% of the applied product, respectively), and 2) that their resorptions were not significantly different from zero. As a consequence, we can assume that the supposed harmful effects of titanium dioxide and zinc oxide on cutaneous tissue could not be observed following the use of the tested solar products. Conclusion: Regarding their efficacy, we here provide, by using a new in vitro methodology for UVA-PF measurements (which is also very efficient to determine SPF), new evidence showing that titanium dioxide and zinc oxide could constitute “good” UV filters. In addition, our work with Franz cells reinforces the fact these compounds can be safely used for human skin solar protection.