Around this time of year – late summer and early fall – forest management turns chemical. The work of preparing clearcuts for the next crop of timber is done by the weed-killer glyphosate. Glyphosate is sprayed from helicopters and drifts as a chemical fog over recently harvested areas, settling on the young maples, aspens, birches, raspberries, wildflowers, leaf litter, and a mesh of small streams and wetlands. This year alone up to 1,550 hectares scattered throughout 16 townships in Robinson-Huron treaty territory are slated to be sprayed. (1)
The TEK Elders of the North Shore of Lake Huron are working to put a stop to the aerial spraying of glyphosate, because of the harm it does to wildlife, plants, insects, amphibians, and the water. Hunters from Anishinabek communities along the north shore regularly report that the internal organs of moose contain tumours and other abnormalities. The hunters connect these observations to a spray program they say has far-reaching ecological and health effects. People consider moose from areas that have been sprayed as unsafe to eat and avoid gathering berries and medicinal plants from areas they know have been sprayed.
Glyphosate is a non-selective herbicide that targets deciduous plants. It is not effective on conifers, which is why it is used in “conifer-release” treatments to suppress the growth of hardwood species that compete with the commercially valuable softwoods, like jack pine. Also known as Roundup (or Vision, in its silvicultural formulation), glyphosate has made possible the development of numerous “Roundup ready” transgenic crop varieties, and it is one of the most heavily used herbicides in the world. Glyphosate is celebrated as a “once-in-a-century” herbicide for compared with some other herbicides it is thought to have lower acute toxicity to terrestrial animals and does not appear to bio-accumulate.(2) Health Canada’s Pest Management Regulatory Agency is currently re-evaluating glyphosate for use in Canada and has concluded (in a preliminary decision) that glyphosate poses no undue risk to the environment as long as it is used according to label instructions.
The risk assessment for mammals – a brief overview
Health Canada’s assessment of the environmental risk is detailed in a proposed re-evaluation decision, though moose, one of the species of concern to First Nations, is mentioned not once in the 300-page document.(3) The evaluation of the effects of glyphosate formulations on mammals is based on laboratory experiments with rats, mice, and rabbits, representing “small mammals” (15g), “medium mammals” (35g), and “large mammals” (1kg).(4) Reviews of existing toxicology studies provide regulators with two endpoints (least and most sensitive) bracketing a range of “acute” exposure concentrations. These values are further legitimated by the fact that the majority of studies indicated LD50 values greater than the highest dose tested (LD50 stands for lethal dose 50, or the dose, estimated by fitting the available data to a dose response curve, at which 50% of test animals would be killed).(5)
These toxicity levels are then compared to the estimated dietary exposure (EDE) of mammals, and the result is represented as a risk quotient (RQ). Exposure levels are calculated as concentration of glyphosate acid ingested per unit body weight. If the RQ is larger than 1.0 (dietary exposure exceeds toxicity level) then exposure is above the level of concern (LOC). Estimated dietary exposure is determined for different “guilds” of animals – insectivores, frugivores, granivores, and herbivores -- using (1) data from agricultural settings of post-treatment residues on seeds, fruits, grasses, and broadleaf plants, and (2) a standardized food ingestion rate that is derived from an equation based on animal body weight. The estimated dietary exposure is therefore calculated simply as the food ingestion rate, divided by the body weight, multiplied by the estimated environmental concentration: EDE= (FIR/BW) × EEC.(6)
Some of the calculated risk quotients (RQ) presented in Health Canada’s assessment for terrestrial mammals fall above the safety benchmark of 1.0, and therefore exceed the level of concern. However, the assessment concludes that
“Overall, available data indicate that risks to mammals following acute oral exposure to glyphosate and its formulations are low. If any, acute risks to mammals would be restricted to on-field exposure of only a few guilds (herbivores and perhaps insectivores). No reproductive risks to mammals are expected from the use of glyphosate. This conclusion is supported by the absence of incident reports for mammals related to the use of glyphosate. Mammalian hazard statements are not required on glyphosate product labels.”(7)
Indigenous knowledge and the scientific production of ignorance
Pesticide regulators ground their decisions in toxicology – a field of knowledge that makes use of standards of evidence such as LD50 and NOEL (no observed effect level), and that measures single-factor causal relationships. Toxicology has enabled regulators to test, and ultimately approve for use, the myriad of synthetic pesticides that have been developed since the 1950s. The science of toxicology lends credibility to those who draw on it.(8) In shying away from the precautionary regulation of chemicals and by making claims of certainty about chemical effects, toxicology has tended to serve the interests of the agrochemical and forest industries rather than the interests of Indigenous peoples concerned about the land, water, and the safety of their traditional foods.
The toxicological approach to risk assessment creates specialized knowledge, but it also creates areas of scientific “non-knowledge” or ignorance.(9) Toxicology has trouble dealing with causes that may operate indirectly and through the multiple, intersecting, and non-linear pathways that keep the land alive over an extended period of time. It does not consider sublethal effects that occur slowly or that are not observable in laboratory settings. This gap in knowledge is the result of how unknowns are neutralized within toxicology’s technical but highly simplified risk assessment protocols.
Left unasked (and unanswerable, from within the framework of toxicology) are questions that take into account ecological complexity and change, variation among species and individual animals, and the histories of sprayed and unsprayed areas. For example, how does glyphosate affect moose moving through a mosaic of regenerating, logged and sprayed habitats, browsing on glyphosate-damaged vegetation over a lifetime? What are the interactive effects of exposure to glyphosate and other forms of contamination, such as the toxic metals seeping into land and water from mine tailings sites? How do glyphosate and its breakdown products affect moose health where moose have lost both habitat and access to particular plants? How does glyphosate spraying change feeding and movement, and hence exposure, of moose to glyphosate? How can exposure scenarios be made more realistic for Indigenous peoples eating moose meat and other country foods on a regular basis?
Health Canada promises to use a “science-based approach” in making its final re-evaluation decision on glyphosate, but it is difficult to see how a toxicological focus will further useful understanding about glyphosate.(10) The renowned Lakota scholar Vine Deloria, Jr. explained that there is no cleverness in “artificially forcing nature to tell us about herself.” “Any damn fool,” he wrote, “can treat a living thing as if it were a machine and establish conditions under which it is required to perform certain functions – all that is required is a sufficient application of brute force.”(11)
The TEK Elders of the North Shore of Lake Huron are calling for a consultation process in which their knowledge is understood on its own terms, in the context of the oral histories and place-based knowledge of Anishinabek land users.(12) Indigenous experts are constantly evaluating the relevance and meaning of different forms of knowledge. They do so in order to protect the land, water, and sacred covenants with the non-human. Taking traditional knowledge seriously would be an opportunity to renew the Treaty relationship, by applying Indigenous law and the ecological principles contained therein.
(1) Letter from Wayne Fiset, District Manager Sault Ste. Marie, Ontario Ministry of Natural Resources and Forestry to Willie Pine, TEK Elders Group. 12 July 2016.
(2) Stephen O. Duke and Stephen B. Powles, “Glyphosate: A Once in a Century Herbicide.” Pest Management Science 64 (2008): 319-325.
(3) Health Canada, “Proposed Re-evaluation Decision, Glyphosate,” Publication PRVD2015-01.
(4) Health Canada, “Proposed Re-evaluation Decision, Glyphosate,” p. 216-217.
(5) Health Canada, “Proposed Re-evaluation Decision, Glyphosate,” p. 36.
(6) Health Canada, “Proposed Re-evaluation Decision, Glyphosate,” p. 217.
(7) Health Canada, “Proposed Re-evaluation Decision, Glyphosate,” p. 36.
(8) Sainath Suryanarayanan and Daniel Lee Kleinman, “Be(e)coming Experts: The Controversy Over Insecticides in the Honey Bee Collapse Disorder,” Social Studies of Science 43 (2013): 215-240. P. 219.
(9) Daniel Lee Kleinman and Sainath Suryanarayanan, “Dying Bees and the Social Production of Ignorance,” Science Technology & Human Values 38 (2012): 492-517.