Applying toxicogenomics to new and emerging environmental issues

Understanding the environment is getting more and more complicated, according to Environment Canada scientist Dr. François Gagné. As an example, he points to municipal effluent, which can contain thousands of bacteria, viruses, pharmaceuticals and industrial chemicals. "It is very difficult to make sense of the environmental effects of such complex mixtures, and figure out what components are the major players in causing an environmental problem."

Gagné is among the many keen supporters of toxicogenomics, which is the study of how an organism’s genetic information responds to a toxin. He considers the tools available in this new field of science to be just what is needed to distinguish the fine detail in complex environmental questions. In the case of municipal effluent, he says, "Toxicogenomics could tell us, for example, whether it was antibiotics or some other therapeutic drug that was causing a particular toxic effect in the environment."

With funding from the Genomics Research and Development Initiative (GRDI), Gagné and his many collaborators have added a toxicogenomics component to existing research projects that are looking at high priority environmental issues. As well as getting finer-level insight into the toxicity questions they are tackling, Gagné’s other goal is to showcase to the risk assessment community the benefits to be gained by using the new tools, new approaches and new technologies of toxicogenomics.

His current GRDI-funded research is wide-ranging, looking at the effectiveness of municipal wastewater treatment systems, as well as environmental issues linked to both nanotechnology and the development of the oil sands. So far, Gagné and his research teams are having good success in finding practical applications and highlighting the added value that toxicogenomics bring to research into big environmental questions.

A good example is a research project that helped the City of Montréal select a new wastewater treatment system. Montréal is one of the world’s top three municipal effluent emitters, with its wastewater treatment plant at Rivière des Prairies pumping out 32 square meters of water every second. Solids and phosphorous are removed before the effluent is released into the Saint Lawrence, but the resulting plume of water flowing downriver contains a mixture of potentially harmful bacteria and chemicals.

With rising concerns about the potential health hazard this was creating both to humans and ecosystems downriver, city planners started investigating options to disinfect the effluent prior to release into the river. Ozonation was a promising candidate, but setting up a facility would cost about $200 million for an expected thirty-year working life. Before making such a large investment, city officials needed an ironclad guarantee that the ozone used to kill bacteria and viruses would not combine with any chemicals in wastewater to create new toxic environmental problems.

Rainbow trout in tub

Rainbow trout exposed to municipal effluent and the effects of ozone during the Montréal ozonator pilot study.Credit: Sophie Trépanier

Gagné’s contribution, during the pilot testing of the ozonator, was to expose freshwater mussels and fish to wastewater treated with ozone and, using toxicogenomics tools, detect whether there was any increase in the toxicity of the wastewater because of the disinfection treatment. His findings were clear. The ozone did not increase the toxicity of the municipal effluent. Rather, ozonation effectively reduced target levels of bacteria, while at the same time breaking down many of the other contaminants in the effluent. The city invested in the ozonator facility, with the disinfection treatment expected to start up in 2013.

Another project looked at urban effluent from a different perspective. Across Canada, there are several systems used to treat wastewater, and, with toxicogenomics, Gagné was able to calculate the levels of toxicity in the raw effluent and compare it to the treated water from twelve different municipalities. The results show the relative effectiveness of the various systems, and this will be a very useful guide to municipalities wanting to introduce new treatment systems.

Gagné is also applying toxicogenomics to research, started in 2011, that is looking at ways to discriminate the toxicity signature of oil sands industry activities from that of the natural levels of bitumen (the heavy, viscous oil in the oil sands) found there. This is an important distinction as bitumen has been leaching into the ecosystem for thousands of years.

The first results have just been published, and Gagné explains, "Because of the toxicogenomics testing, we were able to understand the toxic fingerprint of the oil sands extraction industry and distinguish it from the natural levels of toxicity in the environment." This will be especially important should there be a major breakdown in one of the large ponds used to hold the wastewater from the extraction process. The released wastewater and the extent to which it was impacting the environment could be effectively tracked using toxicogenomics approaches.

Since 2007, Gagné has been conducting research in support of Environment Canada’s risk assessment of various nanoparticles. Nanomaterials are now being used in hundreds of consumer goods ranging from toothbrushes to washing machines. The environmental impact and toxicity and, indeed, even the basic properties of these molecule-sized particles are not well understood. For example, one project compared the difference in the effects found in rainbow trout exposed to nanosilver particles as compared to dissolved silver. He is finding that the high diagnostic power of the toxicogenomics tools are helping discriminate finer detail at this miniscule scale, and that they are providing better understanding of what determines the toxicity of nanomaterials.

Gagné’s research is putting a big spotlight on the benefits a toxicogenomics approach brings to emerging and new environmental issues, and he is committed to building awareness of them in the risk assessment community. As he says, "Toxicogenomics are complex tools to address new, emerging and complex environmental questions that are only getting more and more complex."

Bøhn was referring to earlier STAGE-funded research in which Gagné and his team had used toxicogenomics to identify DNA from transgenic corn in freshwater mussels and to detect changes to their well being as a result of their exposure to it.


"We warmly welcome the engagement of this Canadian group on a most important question, the effects of land-based agricultural deployment of transgenic crops on downstream ecosystems. Without a doubt, this is an area of utmost ecological, social and economic consequence, and one that has received very little scientific and public attention."

Thomas Bøhn, Scientific Director, GenØk Centre for Biosafety, a non-profit foundation at the University of Tromsø, Norway.

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