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ENVI Committee Report

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Transportation and Dispersion of Pesticides in Soil, Air and Water

4.1    Pesticides are released into the environment through human activities. They may contribute to point source pollution and area source pollution. A point source of pollution is a source such as an urban water collection system outfall which discharges pesticide-contaminated water at a specific location. An area source, for example, is one which discharges earth contaminated by pesticides into the aquatic environment. Agricultural area pollution is the greatest and most problematic source of pollution in aquatic environments in Canada. Once in the environment, certain pesticides break down relatively quickly, whereas others persist over longer periods of time and can accumulate or transform into contaminant by-products. In addition to movement through soil, pesticides can be mobilized by precipitation and wind.

4.2    Committee members learned from the testimony of Dr. Bernard Hill25 a scientist with Agriculture and Agri-Food Canada's Lethbridge Research Centre, that precipitation helps pesticides disperse far from their source through the natural phenomena of water evaporation and condensation. A study conducted in Alberta in 1998 showed that large quantities of the herbicide 2,4-D were found in precipitation in that region, even though that product breaks down quickly in the presence of oxygen. Researchers developed a number of hypotheses to explain this phenomenon which is specific to the Lethbridge area. They believe that the presence of pesticides in rain reflects the fact that Lethbridge farmers are among the greatest 2,4-D users in Alberta (more than 20,000 kg of 2,4-D is applied for grain production annually).26 These findings also suggest that, apart from the abundance and duration of rain, pesticide concentrations in rain vary with factors such as land use, time of year and a region's economic profile.

4.3    Some pesticides are carried by wind in the form of vapour, particles or droplets, which enable them to be transported long distances from their source. Precipitation deposits these contaminants on the ground or in waterways where they may accumulate and/or transform. Figure 4.1 illustrates a typical path taken by certain pesticides in the environment. The contaminants are then absorbed by plant life and enter the food chain where they become concentrated in animal fat.


Source: Indian and Northern Affairs Canada, Canadian Arctic Contaminants Assessment Report, Northern Contaminants Program, 1997.

Long-Range Transportation of Pesticides: Persistent Organic Pollutants (POPs)

4.4    According to information provided by the Inuit Circumpolar Conference and the Inuit Tapirisat of Canada, 80% of pollutants detected in the Arctic (the territory north of the 60th parallel, which in fact covers the arctic and subarctic regions) appears to come from countries other than Canada.27 Through a cycle of long-range transportation, combined with specific physical and chemical characteristics, the wind carries some pesticides and POPs28 as far as the Arctic.29 The Committee learned that POPs -- chemicals found in the environment as a result of human activities -- have three characteristics: they are semi-volatile, persistent and fat-soluble. They are semi-volatile, readily moving from the solid to the gaseous state at high temperatures and back to the solid state at cold temperatures. These pesticides, used in more southerly regions, partially evaporate, are carried by winds, then condense under the effect of cold Arctic air and are deposited on the ground. When pollutants reach the North they tend to accumulate; cool temperatures prevent them from evaporating again. POPs can repeat this cycle a number of times and over long distances in a series of "hops," which led to the process being termed the "grasshopper effect" (Figure 4.2). POPs are persistent because they resist degradation under normal environmental conditions.

4.5    POPs are fat-soluble but are nearly water-insoluble and therefore living organisms cannot excrete them, hence, they accumulate them in their tissues. Bioaccumulation is the term to describe this process whereby toxic substances collect in the living tissues of an organism over a period of time. As organisms continue to eat plants or animals that are contaminated, contaminants continue to accumulate, and the concentration of contaminants increases as materials pass up the trophic levels of the food chain. This is known as biomagnification (Figure 4.3). POPs are known to biomagnify. As Dr. David Stone, Director, Northern Science and Contaminants Research Directorate, of Indian and Northern Affairs Canada explained to the Committee:

First of all, the organochlorine pesticides that we're worried about are called persistent organic pollutants because they share the characteristic of being persistent. They resist degradation in normal environmental conditions. They are semi-volatile, and this is a very important characteristic. It means that they cannot basically decide whether they want to be a solid, a fluid, or a gas. As you'll remember from your chemistry, that is always temperature dependent. So at warm temperatures these substances will enter the atmosphere; at cold temperatures they'll come down to the ground.
Finally, they are fat soluble and have a very low water-solubility. Our bodies are designed to get rid of pollutants that they don't like by converting them into water-soluble substances that we excrete in our urine. For fat-soluble substances, that mechanism doesn't work and they tend to build up over a lifetime. In the food chain, that means you can get quite extraordinary concentrations at high levels in the food chain.30


Source: J. Jensen, K. Adare and R. Shearer, Canadian Arctic Contaminants Assessment Report, Northern Contaminants Program, Indian and Northern Affairs, 508 p., 1997; Draft report, 1999 EcoSummit.

4.6    POPs detected in samples in the Arctic from 1991 to 199731 included the pesticides listed in Table 4.1, all of which are organochlorines. It should also be noted that all the pesticides listed as "Discontinued" have been classified under Track 1 of the federal Toxic Substances Management Policy (TSMP), which means that they are persistent, bioaccumulative, toxic and primarily the result of human activity, and will thus be targeted for virtual elimination from the environment.32 It has also been observed that three pesticides detected in samples are still registered in Canada: endosulfan, methoxychlor and trifiuralin. Lindane, a hexachlorocyclohexane, is still registered in Canada but for limited use.

Table 4.1: Pesticides Detected in Arctic Samples under the Northern Contaminants Program*


Pesticide Discontinued Not
Registered Track 1,
Aldrine x     x
Chlordane x     x
DDT x     x
Dieldrin x     x
Endrin x     x
Heptachlor x     x
Hexachlorobenzene x     x
Hexachlorocyclohexane     Some
still in use
Mirex   x   x
Toxaphene x     x
Endosulfan     x  
Methoxychlor     x  
Trifluralin     x  


Discontinued: The company has voluntarily taken the product off the market. Although a company may subsequently try to re-register a product in accordance with present requirements, according to the Pest Management Regulatory Agency (PMRA) the chances of a discontinued product becoming re-registered are small.
Registered: Registered by the PMRA
Not registered: Because of the Access to Information Act, it is impossible to tell whether "Not Registered'' means that a product did not pass the tests, or that no application was made for it.
Personal communications with the PMRA; and Indian and Northern Affairs Canada presentation on pesticide residue in the Canadian Arctic and the TSMP, December 9, 1999.

As Table 4.1 indicates, some highly persistent organochlorines are no longer used in Canada, but they are still detected in the arctic environment. Although use of these pesticides is prohibited or limited in Canada, they are manufactured and used in a number of other countries, and the fact that they are readily volatilized leaves the entire Canadian Arctic vulnerable to contamination through long range atmospheric transport.34 POPs are detected not only in the Arctic, but also in high concentrations in the Great Lakes basin and the St. Lawrence River.

Increasing Levels of Pesticides in the Urban Environment

U.S. Numbers

In the United States, at least 80% of the population uses pesticides at home: 57% use them to control weeds; 50% to eliminate pet parasites; 12% retain the services of lawn maintenance companies and 20% use pesticides inside their homes. (Sierra Club of Canada, Brief to the Committee).

4.7    Although most pesticides in Canada are used by the agricultural sector, which is the primary source of pollution in most aquatic ecosystems, urban populations contribute significantly to the presence of pollutants in the environment. The Committee heard from a number of groups familiar with pesticide use in cities, such as the Campaign for Pesticide Reduction, the Working Group on the Health Dangers of the Urban Use of Pesticides, Nature-Action Québec and the Federation of Canadian Municipalities. It would appear from the testimony of one of these groups, the Canadian Water and Wastewater Association, that pesticides are sometimes used to a greater degree in cities than in farming operations. The Association reported the findings of an American survey which revealed that lawn treatment with pesticides in Chicago averaged 9 kilograms per hectare per year compared to 2 kilograms per hectare per year for soya bean farmers.35 According to the Federation of Canadian Municipalities, the situation is no better in Canada where, it appears, two-thirds of Canadian households use pesticides. Half of these homeowners apply the products themselves, often without protection, an average of three times a year.36

4.8    The Federation of Canadian Municipalities reported to the Committee that 1.3 million kilograms of pesticides had been used in urban areas in Ontario in 1993. This figure, which does not even reflect quantities used by citizens, is equal to one-quarter of the total amount used for agricultural purposes.37 Nature-Action Québec reported that pesticide sales are still increasing in Quebec (15.2% since 1995).38 Apart from pesticide use on public lands and by individuals, the maintenance of golf courses and of rights-of-ways for electrical power lines, water and gas lines and railways also contribute to urban pollution.

4.9    Witnesses expressed serious doubt about the appropriateness of using such large quantities of pesticides in the urban environment. In their view, urban pesticide use to improve the appearance of lawns, gardens and public parks is non-essential. Nature-Action Québec explained the phenomenon as follows:

Enormous amounts of pesticides are used on lawns in an attempt to maintain this kind of monoculture which creates conditions that attract pests. In addition, consumers are massively influenced by pesticide sellers who have large budgets to convince people they need to have perfect lawns.39

A recent Environment Canada study on pesticides in the urban environment clearly illustrates the problem of urban pesticide contamination. In 1998, a team from the Ecosystem Health Division took samples from two streams in Toronto and three stormwater holding ponds in Guelph in order to determine the degree of water pollution from pesticides used in the urban environment. On the basis of the study, the researchers reached the following conclusions about heavy urban pesticide use: herbicides (2,4-D, MCPP) and insecticides (diazinon, chlorpyrifos) are often found immediately after periods of rain; similar pollution patterns can be observed in the Toronto, Hamilton and Guelph urban areas and detected quantities of diazinon and chlorpyrifos exceed established water quality objectives.40

4.10    Witnesses emphasized that pesticides are a constant threat to people. Pest control products used near houses filter into homes and likely persist longer than they do outdoors, where they are broken down more quickly by environmental media.

4.11    Based on this testimony, the Committee feels that urban pesticide use is as important an issue as agricultural utilization. Consequently, urban areas must form an integral part of a proper pesticide management system in Canada.

Pesticides in the Aquatic Environment

4.12    During the Committee's hearings, the issue of water contamination in natural and urban areas emerged as one of the major current issues. A number of groups, in particular the Canadian Water and Wastewater Association, the Learning Disabilities Association of Canada, the Canadian Public Health Association, the World Wildlife Fund, and the Sierra Club of Canada, testified that drinking water is subject to extensive pesticide exposure through contact with the air, water run-off and precipitation. These problems add to the increasing pressures brought to bear on the water resource in recent decades by pollution growth, agricultural, industrial and commercial development and growing water demand.

4.13    According to the Canadian Water and Wastewater Association, pesticide contamination of drinking water is a real problem. Although concentrations did not exceed recommended Canadian standards, pesticide residues were detected in wells by government monitoring teams across the country.41 Samples taken in Quebec have shown that 30% of Quebec drinking water systems inspected between 1989 and 1994 contained residues of the herbicide atrazine or its metabolites.42 Atrazine is one of the pesticides most frequently found in surface and groundwater in Quebec, Ontario, British Columbia, Nova Scotia and Saskatchewan. In Prince Edward Island, where agriculture is intensive, Health Canada observed in 1985 and 1986 that the pesticide aldicarb was present in 80% of samples and that certain concentrations exceeded recommended standards for drinking water. Aldicarb and its metabolites are highly persistent in groundwater. Also in P.E.I., evidence of water contamination was observed on eight separate occasions in 1999.43

4.14    The Canadian Water and Wastewater Association is particularly concerned about the impact of pesticides on municipal water and wastewater treatment. Although current technologies can lower pesticide concentrations in water to acceptable levels, the increased presence of contaminants could eventually require a change in water treatment processes, which would entail high costs and, according to the Association, would produce not particularly satisfactory results. The Association believes that Canada's drinking water protection system must be reassessed in view of the increasingly strong pressures placed on the resource. The Association advocates the development of government pesticide reduction initiatives.

4.15    In its testimony, the Learning Disabilities Association of Canada deplored the fact that unlike in the United States, there is no systematic control of water quality in this country. It is, therefore, impossible to study the population's total exposure to pesticides although evidence of their presence in water exists:

A number of pesticides have been shown to be present in well water. There is a U.S. pesticides and groundwater database, and it reviews data from over 68,000 wells in 45 states. Pesticides were found in more than 16,000 of these wells in 42 states. Nearly 10,000 of these wells had concentrations greater than EPA drinking water standards.
The only survey Mr. Shantora [Director General, Toxics Pollution Prevention Directorate, Environment Canada] knew of -- the Ontario Well Water Survey in 1998 -- found atrazine in one sample to be at 210 parts per billion which is 40 times the Canadian guideline of 5 parts per billion for atrazine. And atrazine is again being found in 30% of samples of rainwater in Europe.44

4.16    Committee members are seriously concerned about the impact of pesticides on the quality of ground and surface water in Canada, and feel that the issue of water safety and management must be addressed by government. The reduction of pesticide use appears to be an increasingly important objective based on the evidence presented to the Committee.

4.17    In addition to urban environments and aquatic systems, the Committee heard varying figures for pesticide application in Canada's forest. These figures range from 200,000 hectares sprayed with insecticides in 1998,45 to 12 million hectares sprayed with pesticides (Bt) during the last spruce budworm outbreak46. Given the dependence of Aboriginal peoples on hunting, gathering and fishing for their subsistence, a precautionary approach to pesticide applications in the environment on which these people rely is necessary.

Selected Pesticide Uses

Pentachlorophenol is exclusively used as a preservative on telephone poles. This pesticide contains small quantities of dioxins and furans, which Environment Canada considers toxic.

Acrolein is a herbicide approved for use in irrigation ditches. Although acrolein use might constitute the discharge of a toxic substance in a fish habitat, the application of this product in irrigation ditches is permitted even though the Fisheries Act prohibits the discharge of substances harmful to fish unless authorized by regulation.

Environmental Research Programs

4.18    The federal departments with research programs on pesticides in the environment (Agriculture and Agri-food, Environment, Natural Resources, Health, and Fisheries and Oceans) have established various research initiatives. Environment Canada concentrates its research on surface water and contaminants affecting wildlife, while Agriculture and Agri-Food Canada analyzes groundwater and waterways in agricultural areas.47

Agriculture and Agri-Food Canada (AAFC) also carries out major research projects using agro-environmental indicators. These indicators make it possible to evaluate trends and environmental changes caused by agricultural activities. Two studies, on soil and air, have been produced since 1993; the study on water should be available shortly.48

Natural Resources Canada carries out research mainly on integrated forest pest management. (See Chapter 11, "Alternatives to Pesticides''.)

4.19    The research work done by Fisheries and Oceans Canada (DFO) supplements that of Environment Canada, which is responsible for administering and enforcing the pollution prevention provisions under section 36 of the Fisheries Act. DFO has a national environmental sciences program and thus takes part in research on the impact of pesticides on fish and fish habitats. As part of this work, Environment Canada and Fisheries and Oceans Canada have established a link between pesticides used in forest environments and their impact on fisheries. Dr. Ron Pierce of the Environmental Science Branch, DFO, stated:

The studies we have done so far have demonstrated that there is a linkage between the use of the material in the pesticide formulations and reductions in Atlantic salmon populations, particularly in the sports fisheries. We are continuing that study. The results of this stage are relatively preliminary. We are just funding a new three-year study to look at the actual causal relationships between the carrying agents in the pesticides formulations and possible effects on juvenile Atlantic salmon.49

4.20    Future studies will help to assess more thoroughly the causal relationships between pesticides and aquatic environments. However, Dr. Pierce informed the Committee that budget cuts and the departure of experienced researchers had undermined the department's scientific resources and that this situation affected all scientific departments.50 The Committee is aware of this problem and feels it must be resolved in view of the need for sound scientific information as a tool for good pesticide management. Chapter 17 presents a detailed look at the inadequacy of funding for environmental research in a discussion of the budget of the Pest Management Regulatory Agency.

4.21    These research projects are a vital source of information on the presence and effects of pesticides in the environment. The Committee feels that government research projects provide an invaluable tool for sound pesticide management, and that it is important to ensure that this information is used effectively. The organizations responsible for conducting research cannot work in isolation, but must co-operate and exchange information harmoniously and effectively. Committee members deplore the budget cuts made to the research programs in scientific departments and ask the government to make the necessary resources available to them.

The Committee urges the government to substantially increase funding for research on and monitoring of the effects of pesticides in the environment, in order to protect human health and the environment.

25 Dr. Bernard Hill et al., Phenoxy Herbicides in Alberta Rainfall: Cause for Concern? Poster, unpub. Agriculture and Agri-Food Canada.

26 Ibid.

27 Inuit Circumpolar Conference and Inuit Tapirisat of Canada, Brief to the Committee.

28 In 1998, Canada signed international agreements on 16 POPs, 11 of which are pesticides. The 16 POPs now subject to international action are: Pesticides: chlordane, DDT, aldrine, dieldrine, endrine, heptachlore, hexachlorobenzene, mirex, chlordecone, lindane, toxaphene; Industrial Chemicals: PCBs, hexabromobiphenyl; Contaminants (by-products): dioxins, furans, polycyclic aromatic hydrocarbons (PAHs).

29 J. Jensen, K. Adare and R. Shearer, Canadian Arctic Contaminants Assessment Report, Northern Contaminants Program, Indian and Northern Affairs Canada, 508 p., 1997.

30 Evidence, Meeting No. 16, December 14, 1999.

31 The Northern Contaminants Program, which made this study possible, is described in Chapter 7, "Other Vulnerable Population Groups.'' In addition to the pesticides listed here, the following POPs have been detected in the Arctic: hexabromobiphenyl, PAHs, PCBs, dioxins, and furans.

32 Chapter 9 entitled "Risk Management'' describes the TSMP.

33 As of May 2000, the following substances, although not pesticides, are also found under Track 1: polychlorinated dibenzo-p-dioxins, polychlorinated dibenzofurans, PCBs.

34 J. Eetoolook, Acting President, Nunavut Tunngavik Inc., Brief to the Committee.

35 Canadian Water and Wastewater Association, Brief to the Committee.

36 Federation of Canadian Municipalities, Brief to the Committee.

37 Ibid., Brief to the Committee.

38 Nature-Action Québec, Brief to the Committee.

39 Ibid.

40 J. Struger and B. Ripley, Pesticide Concentrations in Urban Aquatic Environments, Poster presentation, Ecosystem Health Division, Environment Canada; Laboratory Services Division, University of Guelph; Industrial Waste and Stormwater Quality Unit, Toronto Works and Emergency Services, 1999.

41 Canadian Water and Wastewater Association, Brief to the Committee.

42 Government of Quebec, Water Quality Report for the period from 1989 to 1994. Cited in the Canadian Water and Wastewater Association, Brief to the Committee.

43 Dead fish in rivers believed to have been contaminated by pesticides such as the insecticide azinphos-methyl have been observed, among other places, in the Valleyfield and Souris rivers according to the Canadian Water and Wastewater Association.

44 Evidence, Meeting No. 4, November 16, 1999.

45 Evidence, Meeting No. 127, June 2, 1999.

46 Ibid.

47 Evidence, Meeting No. 128, June 8, 1999.

48 Ibid.

49 Ibid.

50 Ibid.