A carregar...
Projeto de investigação
Sem título
Financiador
Autores
Publicações
Disinfection by-products of emerging concern in drinking water : monitoring and hazard assessment
Publication . Chaves, Raquel S.; Santos, Miguel Alberto Fernandes Machado e; Cardoso, Vítor Manuel do Vale; Guerreiro, Catarina Ferreira Murinello de Sousa
The access to safe drinking-water is essential to assure health. It is a basic human right and a component of effective policy for health protection. Due to the increase levels of environmental pollution in some systems, it is crucial to assess water quality applying an integrative approach, combining environmental and human risk assessments, attending to surface sources pressure and the consequent drinking water security. Water treatment plants (WTPs) represent an important instrument to promote the quality of drinking water. Disinfection of water system is an essential strategy to protect human health from pathogens and prevent their regrowth during water distribution, but the reaction of disinfectant agents with organic matter can lead to the formation of disinfection by-products (DBPs). Given their widespread occurrence, potential human health impacts and (eco)toxicity associated with exposure to DBPs are of particular interest due to their potential carcinogenicity and vary non-carcinogenic effects, such as endocrine disruption. The work developed in the frame of this thesis had the ultimate aim to improve water safety plans and produce new knowledge towards a more comprehensive risk assessment, considering the occurrence and toxicity of target DBPs. In chapter I, a general description of the subject is made, considering aspects such as water treatment, the DBPs formation, main analytical methodologies to measure these compounds in drinking water, and their reported toxicity. In chapter II, with the aim of better characterizing the EPAL- Empresa Portuguesa das Águas Livres, S.A water supply system, we assessed the water quality parameters, correlating several microbiological and chemical parameters, some regulated under Portuguese /UE legal framework and others still not regulated but with environmental and human health relevance, during a 6-year period (2014-2019). For that purpose, two conventional WTPs with a technology largely implemented in many different regions, were assessed by an integrative approach as a proxy to improve processes understanding, treatment efficiency and global water quality. The outcomes of this first study contributed to the establishment of a framework to evaluate the quality of the water supply system, identifying relevant occurrence relationships, and providing meaningful information that decision makers can use for more effective water safety plans. In chapter III, we aim to characterize EPAL water supply system attending to some target UR-DBPs and given the limited validated analytical methods to detect and quantify UR DBPs, a new multi-residue gas chromatography coupled with mass spectrometry methodologies for the detection and quantification of 15 UR-DBPs in drinking water matrices was validated. The target compounds included DBPs from 4 chemically different classes, namely nitrosamines, haloketones, aldehydes and alcohols. The selected sample preparation methods included solid phase extraction (SPE), applied for nitrosamines group, and solid phase micro extraction (SPME), for the remaining DBPs. The developed analytical methods were applied to drinking water samples from different points of EPAL water supply system, including two conventional WTPs, geographically different, with distinct production capacities, periodically collected during a 4-month period. From the 15 UR-DBPs analyzed, 8 of them were detected in the analyzed drinking water samples, being the most representative DBPs belonging to aldehydes class. To the best of our knowledge, this study represents the first insights on the measurement of some of the target DBPs in drinking water matrices, considering one of the biggest Portuguese public distribution systems. In chapter IV, we review the recent literature on the effects of DBPs present in water for human consumption, mainly focusing in unregulated compounds and the putative underlying mode of action (MoA), linking the available data with adverse health outcomes. The main knowledge gaps in this field were identified, and future research priorities discussed. In chapter V, in order to improve hazard and risk assessment, 7 of the most prevalent UR DBPs were selected to be included in a toxicological approach. In this study, the developmental toxicity of the chemically-different UR-DBPs was evaluated using zebrafish (Danio rerio) embryo bioassay as a proxy animal model, and considering morphological abnormalities, % mortality and behavior endpoints. We demonstrate here toxicological effects on D. rerio development, at environmentally relevant levels, of 7 UR-DBPs. To gain additional insights into the biological functions and potential pathways disrupted by the exposure to 2 of the most toxic DBPs studied, 2-EH and NDMA, a comprehensive transcriptome assembly was also produced, and an exploratory analysis of the transcriptomic profiles were made. Before this work, no information was available regarding % of occurrence and toxicological data for some of the target DBPs analyzed. At the national context, it represents the first insights regarding the presence and characterization of target UR-DBPs, considering one of the largest Portuguese public water supply systems. In addition, an integrative analysis of the main WTPs of EPAL was made, contributing to more effective water safety plans.
Unidades organizacionais
Descrição
Palavras-chave
Contribuidores
Financiadores
Entidade financiadora
Fundação para a Ciência e a Tecnologia
Programa de financiamento
OE
Número da atribuição
PDE/BDE/122649/2016