Risk minimisation versus regulation
M Drikas, R Fabris
Publication Date (Web): 27 April 2018
DOI: https://doi.org/10.21139/wej.2018.017

Chemical disinfection of drinking water has been the single most important reason for improved public health by preventing disease caused by pathogenic microorganisms. However, potential chronic health impacts that may be associated with the consumption of disinfected water require health regulators and water utilities to consider the overall safety of drinking water. Throughout regulated jurisdictions worldwide, control of disinfection by-products (DBPs) in drinking water guidelines is currently managed by setting guidelines for (or regulating) specific compounds. This is based on, and limited by, identification of formed compounds, development of analytical capability and available toxicological data. For most DBPs all this information is not available, leading to extrapolation of potential health impacts from incomplete data. This lack of data delays guideline development and implementation and can potentially result in DBPs with greater health impact not having guidelines. Currently regulated DBPs do not adequately account for the potential health impacts and identification of the responsible compounds is difficult. Therefore alternative approaches to disinfection management are warranted. 

A possible approach to address the total risk would be to include a more comprehensive measure of the DBPs that are being formed. One such technique is total or adsorbable organic halogen concentration, referred to as TOX or AOX. More information on the extent of total DBP formation would be of value both in terms of informing utilities regarding their overall DBP production and as a potential regulatory/compliance approach. 

However introduction of additional DBP guidelines may not necessarily be the best approach in terms of encouraging proactive and effective management of water treatment processes and distribution systems. As has been seen from establishing THM guidelines in the ADWG, this can encourage operational practices, which may achieve compliance with the regulations, but that do not necessarily improve overall water quality or reduce health risk. A more effective approach would be to establish regulations that encourage changes to operational practice to reduce overall risk. This could occur by selecting regulations that target water quality prior to disinfection.

This paper discusses potential alternative approaches that could be implemented, in the short and longer term, to reduce DBP formation and improve overall public health associated with disinfected drinking water.

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