Strategies for Assessing and Mitigating the Impacts of Emerging Contaminants in Wastewaters

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An understanding of the sources and distribution of potentially harmful substances in surface waters is needed to protect human health and ecosystems. For this reason, in 2006, the Canadian Government implemented its Chemicals Management Plan to address the legacy of unassessed chemical substances with the goal of significantly reducing risks to human health and environment. Thousands of substances require evaluation including many classified as pharmaceutically active compounds (PhACs). Even though PhACs such as painkillers, antibiotics, and diagnostic agents are designed to be beneficial to human health, their ability to stimulate or block physiological responses at low doses can create potentially hazardous impacts when they enter the environment. However, data is lacking for many compounds in terms of their release rates, fates, concentrations and prevalence in the environment, and potential impacts. Exposure models are urgently needed for thousands of existing substances, as well as those to be manufactured or imported in Canada in the future. Specifically, simple and effective methods are required to evaluate the impacts of compounds released into the environment and to prioritize them for action through mitigation options such as upgrading of water and wastewater treatment systems or source control options (e.g. separation, treatment at source, compound elimination or substitution). Importantly, given the health benefits that motivate the use of these drugs, mitigation options must be evaluated in a manner that accounts not only for their environmental consequences but also their social and economic impacts. Therefore, the objective of the research is to develop an understanding of the consumption patterns in a community of a particular substance or group of substances and their surface water concentrations in order to assess their potential for human health or aquatic impacts. The research will be conducted by a group of 6 graduate and 10 undergraduate students and will comprise the following: (1) A database will be created of almost 500 PhACs based on their sources and rates of use and their potential for environmental and health impacts; (2) source models for substances will be developed using consumption data and human metabolism measures to predict contaminant loads to sewers, wastewater treatment plants and surface waters and surface water concentrations; (3) indicators will be developed to assess and rank chemicals according to their potential for impacts upon release into surface waters and, from this, priority chemicals for further study or mitigation will be identified; (4) the geographic distribution of impacts will be assessed using the demographic information and hydrological conditions for Ontario and Quebec; and (5) mitigation strategies will be explored for selected individual or classes PhACs in order to minimize environmental and health impacts.