Innovation dans le secteur de l’eau, surveillance et outils d’évaluation de la toxicité pour la caractérisation et la priorisation des contaminants et sous-produits de désinfection de l’eau potable

Xing-Fang Li, professeur, Université de l’Alberta, 2008 - 2012
Enjeu

Bien que la désinfection de l’eau potable soit essentielle à la santé humaine, des réactions entre les produits désinfectants et la matière organique naturelle ou autres précurseurs présents dans l’eau peuvent donner lieu à la formation de sous-produits de désinfection (SPD). Des études ont relevé certaines preuves d’une possible association entre la consommation d’eau potable chlorée et un risque élevé de cancer de la vessie, ainsi que des preuves toutefois moins cohérentes d’autres effets néfastes pour la santé. Toutefois, la réglementation des SPD ne tient pas compte de l’ampleur du risque estimé de cancer chez l’humain, ce qui met en évidence le manque de données permettant de déterminer quels sont les SPD qui ont une importance sur le plan toxicologique. Il faut mettre au point de meilleures techniques d’analyse pour caractériser les SPD et leur toxicité, déterminer quels sont leurs précurseurs et fournir des méthodes pour réduire les SPD qui sont toxiques. 

L’équipe de projet, dirigée par Xing-Fang Li, a mis au point des techniques d’analyse d’une grande sensibilité qui permettent la détection de nouveaux SPD toxiques et des techniques pour retirer les précurseurs de ces SPD.

Projet

To uncover which DBPs may be of health concern, this team has developed highly sensitive analytical techniques which 1) enable the detection of new toxic DBPs, 2) characterize the formation of these compounds under water disinfection conditions, and 3) investigated the removal of natural organic matter precursors to reduce the toxic DBPs in treated water.

To detect and characterize the formation of DBPs, nine drinking water treatment plants were surveyed for novel, unregulated DBPs.  Each drinking water treatment plant used some form of chlorination or ozonation.  Researchers found one novel DBP in all treatment plants (2,6-dichlorobenzoquinone) and another novel DBP in 72% of treatment plants (2,6-dibromobenzoquinone).  Additionally, researchers found that DBP toxicity testing showed these novel DBPs can damage DNA and proteins.  

Natural organic matter can interact with treatment processes, such as chlorination, to form DBPs.  Therefore, natural organic matter is a precursor to DBP formation.  To find useful approaches for reducing DBP formation, researchers used liquid chromatography–organic carbon detection (LC-OCD) to separate and quantify natural organic matter into six fractions which are based on size, ionic character and water solubility. By providing coagulation (clumping) of natural organic matter, DBP precursors were reduced.  However, future studies will need to address means of  further reducing these precursors.

The common occurrence and relatively high toxicity of some novel DBPs indicate the importance of monitoring and understanding the mechanisms of toxicity, and assessment of human exposure and health effects. Further research is warranted for a comprehensive survey for risk assessment, identification of the factors controlling DBP formation, and feasible treatment for reducing DBP formation.

Produits
  • Development of new analytical tools for monitoring, new toxicity testing tools for prioritization of DBPs for monitoring, and regulatory consideration in the future.  This was made possible because of the effective dissemination of knowledge via publications, conferences, workshops, and seminars.  
  • This project has resulted in several partner and end-user oriented publications.  These include:
    • Book "Disinfection By-Products – Relevance to Human Health". Hrudey, S.E; Charrois, J.W.A. (Eds). IWA Publishing. 2012
    •  "Occurrence and formation of chloro- and bromo-benzoquinones during drinking water disinfection" Water Research, 46, 4351-4360 (2012)..
    • “Removal of halobenzoquinone (emerging disinfection by-product) precursor material from three surface waters using coagulation” Water Research 47, 1773 -1782 (2013).
    • Monograph "Analytical Methods for Predicted DBPs of Probable Toxicological Significance" Water Research Foundation. Denver, CO. 2011.
    • "Application of automated solid-phase microextraction to determine haloacetonitriles, haloketones and chloropicrin in Canadian drinking water" Water Quality Research Journal of Canada, 48.1, 85-98, 2013.

Publications in Academic journals such as Environmental Science and Technology, Analytical Chemistry, Trends in Analytical Chemistry.  Additionally, this research has developed new techniques in the field which are being taught at both conferences and academic institutions.

Résultats
  • Enhanced understanding of the likelihood of substantial human cancer risks being attributed to drinking water exposure to DBPs.  The improved perspective on human cancer risks from DBPs has allowed development of an over-arching perspective for addressing health risks from DBPs in relation to the more pervasive and certain health risks from microbial pathogens. 
  • Potential changes to practice and policy for regulatory agencies in Canada, the USA, and Australia.  The drinking water guidelines committee of the Australian National Health and Medical Research Council has established a working group to explore developing guidelines for disinfection by-products. 
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Équipe de Recherche et Partenaires:

Équipe de Recherche

Xing-Fang Li, Ph. D., professeur, Université de l’Alberta
Steve Hrudey, Ph. D., professeur, Université de l’Alberta
Susan Andrews, Ph. D., professeure, Université de Waterloo
Robert Andres, Ph. D., professeur, Université de Toronto
Patrick Levallois, Ph. D., professeur, Université Laval
Jeffrey Charrois, directeur, Curtin Water Quality Research Centre (Australie), et assistant professeur auxiliaire, Université de l’Alberta
Janusz Pawliszyn, Ph. D., professeur, Université de Waterloo

Partenaires

Alberta Health and Wellness
EPCOR
Ville de Camrose
Ville d’Ottawa
Alberta Environment
Environnement Canada
Ville de Québec
Trojan Technologies