Studi su trasformazioni chimiche di xenobiotici in sistemi modello di impianti di trattamento di acque reflue
Pistillo, Paola (2009) Studi su trasformazioni chimiche di xenobiotici in sistemi modello di impianti di trattamento di acque reflue. [Tesi di dottorato] (Inedito)
Full text disponibile come:
Pharmaceuticals and Personal Care Products (PPCPs) include cosmetics, pharmacological products, products employed in food farming to improve livestock growth and/or health. PPCPs continuous and massive use justifies their finding in different aquatic ecosystems and due to the improvement of sensitivity and accuracy of the analytic techniques, the scientific community has been able to identify the contribution to pollution of this common usage substances. PPCPs compose a variegated collection of chemical substances among which drugs are of particular interest for the purposes of this study. They have been designed to be active at very low concentration, to pass through biological membranes and to persist in the organism sufficiently to carry out their therapeutic effect before being secreted through urines or faeces. Thus they can have a substantial impact on the environment and to serious consequences on human health. Drugs are released into the environment through several ways, from landfill disposal of drugs (unused or out of date), to sewage disposal of households, hospitals, factories and intensive cattle farming. A big amount of drugs and of their metabolic products reaches the STPs (Sewage Treatment Plants) where treatment processes are often not capable of inducing mineralization of xenobiotics, thus allowing their inlet into surface waters. It is therefore extremely important to evaluate to what extent a drug is removed during wastewater disposal. The percentage of removal of a certain drug from wastewater not only depends on its mineralization, but also on its capacity to be transformed into a different chemical substance during treatments, in particular during disinfection step. The most used disinfection processes are: UV irradiation, chlorination, ozone or peroxyacetic acid oxidation. Chlorination is the most used sterilization process in the world. Chlorine is normally added to wastewater as gas or as a sodium hypochlorite solution (NaOCl). Hypochlorite disinfection is the most commonly used disinfection treatment in Italy. The mixture HOCl/OCl-, known as free available chlorine (FAC), is a powerful non-specific oxidant, capable of inducing degradation of different micro-pollutants to products which are chlorinated, oxidized and to fragmentation by-products that are potentially more toxic than the parental compound. Many data on the possibility that chlorination could induce drug transformation are available in recent literature but data on the identification of eventual transformation product are limited to few cases. This thesis work has been focused on studying transformations induced by hypochlorite treatment on drugs belonging to different pharmaceutical classes, in STPs like-conditions. Selection has been based on the following parameters: • Presence in the molecular structure of potentially reactive groups; • High use and sale of drugs containing the selected active ingredient; • Literature data on the detection of drugs in STP effluents; • Environmental load. The drugs examinated in this study are: atenolol, ranitidine, naproxen, gemfibrozil, benzafibrate and fenofibrate, tamoxifen, lincomycin, sidenafil and tadalafil. The main degradation products were isolated and fully characterized employing NMR techniques (COSY, HSQC, HMBC, NOESY) and mass spectrometry experiments (ESI-MS, MALDI-MS, EI-MS). The formation pathways were also elucidated. The potential environmental impact of the parental compounds and of their products has been evaluated by phytotoxicological quantification assays or, in collaboration with the Life Science Department of the Second University of Naples, by acute and chronic toxicity, genotoxicity and mutagenicity assays on different aquatic organisms. This study combination is rare in literature but in the last years it is becoming of particular interest in Environmental Chemistry.
Solo per gli Amministratori dell'archivio: edita il record