ViewPoints
Many unknowns still remain regarding
organic micropollutants in the water environment

Anna Comerton, Ph.D., is a process designer with the Water Group in Associated Engineering's Toronto office. Anna's doctoral research, which she completed at the University of Toronto in the Fall 2008, focused on the removal of organic micropollutants by membrane filtration. She can be reached at comertona@ae.ca

Ian Wright, P.Eng. is Associated Engineering's Vice President, Water. He has over 30 years experience in design and management of water supply and treatment facility projects across Canada and internationally ranging from small systems serving remote communities to large plants in metropolitan areas. Ian is currently the Chair of the AWWA Water Treatment Plant Design Handbook, 5th edition, Subcommittee. He can be reached at wrighti@ae.ca

by Anna Comerton, Ph.D. and Ian Wright, P.Eng.

Recent improvements in analytical techniques allowing for the detection of trace levels (typically parts per trillion) of organic micropollutants in the water environment have led to concern about potential negative impacts on ecological and human health. These organic micropollutants have been detected in wastewater effluents, receiving waters, drinking water sources, and even some treated drinking waters. Although these compounds are not currently regulated, the public has expressed interest and concern about the potential presence of these contaminant's in water.

Although several terms have been used to describe this group of pollutants (e.g. organic micropollutants, emerging contaminant's of concern, PPCPs, etc.), they can generally be classified as endocrine disrupting compounds (EDCs), pharmaceutically active compounds (PhACs), and/or personal care products (PCPs). The term EDC is used to describe chemicals that are not produced by the body, but act by mimicking or antagonizing natural hormones, such as pesticides and synthetic hormones. PhACs consist of pharmaceuticals used by humans and animals, as well as pharmaceutical metabolites. Pharmaceuticals are prescribed to cure or prevent illnesses; therefore, they are designed to interfere with specific biological systems. PCPs are synthetic organic chemicals derived for use by individuals in soaps, lotions, sunscreens, toothpastes, and cosmetics.

Several studies have investigated the exposure of wildlife to organic micropollutants and observed detrimental effects, such as feminization, and reproductive and developmental problems. However, no conclusive evidence of a linkage between exposure to trace levels of these compounds and human health has been found. To put things in perspective, it would take a lifetime of drinking tap water to ingest the equivalent of approximately one ibuprofen tablet. A cup of coffee contains over one million times more caffeine than a glass of tap water. However, the risks associated with exposure to trace levels of many different types of organic micropollutants that could potentially interact are difficult to evaluate. More research by toxicologists is needed.

Associated Engineering's water treatment process staff have been monitoring the development of the organic micropollutant issue. As subscribers to the Water Research Foundation (formerly AWWARF), we have access to current research. There are some uncertainties such as the possible long-term health effects of consuming combinations of these chemicals, and it is recognized that drinking water is but one means of exposure to them. However, the bottom line from the research is that there is no evidence of human health risk from consumption of these organic micropollutants in drinking water at the trace amounts measured.

Trying to eliminate all organic micropollutants from drinking water is not a realistic treatment objective. Although some advanced treatment technologies, such as reverse osmosis membranes, can provide high levels of organic micropollutant removal, most are not capable of reducing the concentrations of all contaminant's to less than the detection limits of modern analytical techniques. This point was stressed in the Water Research Foundation's “Toxicological Relevance of EDCs and Pharmaceuticals in Drinking Water” (2008). This study also noted that analytical techniques are constantly improving and stated that, “A key point is that today's non-detects (i.e., results from tests) will likely be tomorrow's emerging contaminants.” So, the take home message is that just because we are able to measure a particular contaminant does not necessarily make it a treatment concern.

Although the topic of organic micropollutants in the environment has raised much interest from the media, public, water industry, and research community, there remain many unknowns. Improvements in establishing standard and reliable methods for organic micropollutant analysis are also needed if these compounds are to be routinely monitored or regulated in our waters in the future. While there is no evidence of significant risks to human health from the levels of these compounds in drinking water, questions still remain with respect to the potential human health risks associated with cumulative exposure to trace levels of these compounds in our environment and whether the potential risks justify regulation of these compounds.