Applied Ecotoxicology - Research Activities

Toxicological Effects of Pollutants on Organisms and Development of Biomarkers

Development of New in vivo and in vitro Genotoxicity Bioassays

Environmental Risk Assessment Tools

Toxicity of Mixtures and Bioavailability of Contaminants

Toxicological Effects of Pollutants on Organisms and Development of Biomarkers

Contact: Sylvie Rocheleau
Tel.: (514) 283-6447
E-mail: sylvie.rocheleau@cnrc-nrc.gc.ca

Standard ecotoxicity tests measure important physiological and ecologically-relevant responses such as lethality, growth and reproduction. Sublethal responses to toxic pollutants can be measured at the cellular and molecular levels of the exposed organisms. The Applied Ecotoxicology group has developed several biomarkers of exposure and of toxicity for different plant and earthworm species, including enzymes of oxidative stress and lipid peroxidation. Biomarkers are used in the laboratory and, once validated, can be used in mesocosm studies under field condition exposure. The research team has also designed microcosm tests that assess the bioaccumulation of labelled [¹⁴C]-organic contaminants in plants and earthworms. This approach is being used to derive bioaccumulation factors for energetic chemicals. The effects of various organic contaminants on plants and earthworms are also being investigated. In addition, the group is undertaking research on Caenorhabditis elegans, a free-living nematode commonly found in soil ecosystems around the world. Now that its genome has been fully sequenced and that many of its genes have high similarity with other ecologically relevant receptors, C. elegans is considered to be an ideal model organism to assess the ecotoxicological effects of contaminated water, sediment and soil samples at the physiological and molecular levels.

Development of New in vivo and in vitro Genotoxicity Bioassays

Contact: Pierre Yves Robidoux
Tel.: (514) 496-8087
E-mail: pierre-yves.robidoux@cnrc-nrc.gc.ca

Bioassays are essential tools for the direct measurement of the toxic effects of substances on living organisms. The Applied Ecotoxicology group is using a number of bioassays, for the measurement of the adverse effects of chemicals on the DNA of bacteria, and mammalian cells, as well as plants ("phytogenotoxicity"). Over the past two decades, numerous studies have been undertaken using the micronuclei test of higher plants to detect the mutagenicity of water, air, and pure chemicals. Recent applications of this technique have been extended to sediment and soil by means of direct contact, where they can be used for in situ monitoring of the effect of water and soil contaminants on plant cells, at the DNA level. In addition to bacterial genotoxicity assays (SOS Chromotest, and fluctuation test), the group has evaluated a number of organic genotoxicants using higher plant genotoxicity assays, including the Tradescantia micronuclei (Trad-MCN) test, the Tradescantia stamen hair mutagenicity (Trad-SHM) test, and the Vicia faba (broad bean) root tip micronucleus test. The group also used the TK6 human lymphoblast cytotoxicity-genotoxicity assay to characterize and understand the cell-damaging or cell-killing mechanisms of polycyclic aromatic hydrocarbons and selected polynitro-compounds.

Environmental Risk Assessment Tools

Contact: Geoffrey Sunahara
Tel.: (514) 496-8030
E-mail: geoffrey.sunahara@cnrc-nrc.gc.ca

The Applied Ecotoxicology group undertakes research in environmental risk assessment. The "Multi-disciplinary Laboratory to Field" approach has generated >30 peer-reviewed scientific publications over the past 3 years, and has attracted much scientific interest from different international organizations. For example, energetic compounds such as nitroaromatics and polynitramines are environmental contaminants at sites related to production and handling, military training and demolition activities. In collaboration with the National Defense Department - Defense Research and Development Canada at Valcartier (DND-DRDC), BRI is developing ecotoxicologically based soil quality criteria for sites contaminated with energetic materials. Another research project conducted by the Applied Ecotoxicology group focuses on the ecotoxicological assessment of sludge and soil remediation processes, in order to evaluate the reduction and/or increase of toxicity associated with the process. Several biotests representing different trophic groups are considered, depending on the receptors at risk. These tests include microbial, freshwater algae, terrestrial plant, earthworm, and human and mammalian cell culture toxicity assays. Finally, given the central role that soil microorganisms play in the cycling of many essential plant nutrients, and in the decomposition of organic matter and pesticides, the group is conducting research in order to develop microbial activity toxicity tests that can be used to assess the ecotoxicological effects of organic pollutants as well as heavy metals (Cd, Zn, Cu, As and Cr). These tests include potential nitrification, basal respiration, substrate-induced respiration, heterotrophic nitrogen-fixation and dehydrogenase activity assays.

Toxicity of Mixtures and Bioavailability of Contaminants

Contact: Pierre Yves Robidoux
Tel.: (514) 496-8087
E-mail: pierre-yves.robidoux@cnrc-nrc.gc.ca

This research activity aims to understand a new challenge facing the field of environmental assessment: the simultaneous contamination of ecosystems by various substances. One aspect of this challenge is the bioavailability of pollutants - the extent to which they can be absorbed and degraded. Another aspect is that the interactions between metals and organic contaminants have lethal and sublethal effects. Environmental criteria and benchmarks are generally based on the toxicity of single substances. Moreover, few toxicity data and criteria consider soil characteristics and the bioavailability of contaminants. The research team is developing selected tools to assess bioavailability and the interactions of contaminants. It is investigating the way the physical and biochemical behaviour of pollutants depends on soil characteristics, and how it may change in the presence of other chemicals. The bioavailability of contaminants such as metals, in presence of other organic compounds, and the effects of interactions between metals and organic contaminants are being addressed in several research projects in this area.

Related Information

Institutes:

• NRC Biotechnology Research Institute