ConservationBytes.com

A few months ago I made a general call for submissions to ConservationBytes.com. I’m happy to say that the first person answering that call has come through with the goods. Please welcome Julie Pollock of Environment Canada and her post on environmental testing. Thanks, Julie.

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Environment Canada is often called upon to assess damage or the risk of damage to natural systems. Scientific and legal staff depend on the reliability of test methods and, in some cases, may require entirely new methods. Challenges federal government researchers face supporting these assessments include ensuring ecological relevance in subject selection, keeping up with industry to capture new substances, and understanding the cumulative nature of damaging pollutants.

The Biological Assessment and Standardization Section, led by Rick Scroggins, develops, validates and standardizes test methods for assessing contaminants in natural soil systems. Part of the Science & Technology Branch, they are located in the National Capital Region (Ottawa) where they work closely with the Enforcement Branch.

Their test methods support assessments of new and existing chemical substances and programs to clean up contaminated sites under federal jurisdiction. The group provides test method research to Natural Resources Canada’s Program of Energy Research and Development, which funds government R&D for sustainable energy. Another collaborator is Alberta, one of Canada’s largest provinces, which requires expertise in soil sampling and assessments associated with oil and gas extraction in the northern boreal and taiga ecozones.

Currently, the Section is developing soil test methods specific to Canada’s boreal forest. The boreal region is a major economic driver for Canada in mining, forestry, fisheries and agriculture. Yet no biological test methods designed for these northern soil ecosystems existed until 2004. Even today, soil toxicity tests do not use species relevant to boreal ecosystems.

To address this gap, they have acquired species from upland and wetland boreal soils such as deciduous and coniferous tree and understory species, and invertebrate species including earthworms, collembola (springtails) and mites. The last few years of progress in their laboratory have set the stage for use of the methods in contaminated soil assessment studies. They will publish standard test methods suited to Canada’s northern regions in the near future.

At the Pacific and Yukon Laboratory for Environmental Testing, Graham van Aggelen and his team lead the development of toxicogenomic capacity. The laboratory evaluates chemical substances for toxicological risk. They also apply toxicogenomic tools to assess potential gene-level effects of pesticides on amphibians and fish to identify deleterious effects in support of Canada’s Fisheries Act.

Some of this research takes place in the highly-populated farmland of the Okanagan Valley in western Canada. Fruit orchards and vineyards are the main agricultural activity. Legacy pesticides, including the persistent DDT metabolite known as DDE, have affected ecosystem health, particularly observed in birds.

The group, in collaboration with Christine Bishop, have conducted field assays and controlled laboratory exposures of amphibians to water collected from farm areas in the valley. The purpose is to determine whether there are molecular-level effects from legacy and in-use pesticides. The study includes the Great Basin spadefoot, a species at risk of extinction.

They examined amphibian egg survival in agricultural ponds where mortality of up to 100 % of the amphibian embryos correlated with pesticide and nutrient exposures. Laboratory follow-up explored which of the identified pesticides – atrazine, endosulfan, azinphosmethyl and diazinon – are most toxic to amphibians. They also assessed the potential chronic toxicity of pesticide compounds and resulting toxicogenomic effects on amphibians and fish.

These studies have helped validate test methods for determining molecular-level effects on amphibians and fish. Test methods increasingly take into account variability in species sensitivity when different species are exposed to single contaminants and “real-world” chemical mixtures, particularly in understanding the cumulative impact of pollutants on aquatic ecosystems.

Céline Boutin of the National Wildlife Research Centre in the National Capital Region (Ottawa) focuses on protecting biodiversity through studies of organic and conventional farming, and the role of adjacent wild habitats in agricultural landscapes. Her team develops methods to examine agriculture and pesticide risk assessment to native plants. She works at the national and international levels (e.g., OECD, USEPA, NAFTA) to develop test methods for phytotoxicity testing.

Tests assessing toxic impact on crop-type plants in laboratory conditions might not be adequate to assess the response of wild plants in nature. For this reason, toxicity evaluations under existing guidelines have underestimated the sensitivity of wild plants to agricultural herbicides. To demonstrate the importance of species selection in testing, Dr. Boutin has collaborated with Carleton University in Ottawa to conduct greenhouse and growth chamber experiments. These studies assess which species offer ecological relevance while also meeting regulatory testing needs.

Recent experiments measure the relevance of current guidelines for risk assessment from an ecological perspective, including interactions between species and test conditions. One study involving two herbicides – glyphosate and atrazine – required 4,500 individually growing plants to assess variation in seed characteristics, germination patterns and herbicide sensitivity.

The group’s work has included many crops and wild plant species chosen from recommendations in the amended guidelines (2006) prepared by the Organisation for Economic Co-operation and Development. The results emphasize the wide variability of wild plants’ sensitivity to herbicides, and recommend inclusion of an uncertainty factor in risk assessments.

Studies have also compared a community of plants (grown in microcosms) with the same species of terrestrial and wetland plants growing singly in pots, and found greenhouse microcosm communities were more sensitive. Another considered plant recovery following sublethal doses of herbicides sprayed into wild habitats, including effects at the plant reproduction stage versus the juvenile stage as recommended under current guidelines.

(all images © Environment Canada)