On 16 October 1996, a malfunction at the Swan Hills Special Waste Treatment Center (SHSWTC) in Alberta, Canada, released an undetermined quantity of persistent organic pollutants to the atmosphere. An ecologically based, staged health risk assessment was conducted to evaluate the human health risk, the findings of which are presented in Part 2, on Ecotoxicology and Human Health Risk. The incident resulted in the largest fine for an environmental infraction in Alberta history up to that time. Despite the incident, the province of Alberta has continued to subsidize the facility and has kept it in operation, with changes in management. The policy rationale is that if the facility were not available, accumulation and possible diversion of hazardous waste into illegal disposal alternatives would threaten the environment much more than operation of the plant. This case study illustrates an ecological approach to risk assessment and an attempted culturally sensitive approach to risk management. Incidents in which people are exposed to toxic substances do not occur in a social vacuum. Risk management strategies must be adapted to groups with different cultural values and expectations. Community and individual responses to such incidents, and the development of health advisory messages, may depend on presenting information on exposure and risk in terms consistent with cultural patterns among subpopulations in the community.


  • Incidents in which people are exposed to toxic substances do not occur in a social or cultural vacuum.

  • Risk communication messaging in such incidents, and the development of health advisory messages, depends on presenting information on exposure and risk in terms consistent with cultural patterns in the community.

  • Risk management strategies must be adapted to the needs of groups with different cultural values and expectations.

  • In the real world, decisions must be made in real time and with incomplete information.

  • Issues of siting, management, rapid access to maintenance and technological support, and regulatory oversight are as important as specifications of operation and monitoring in preventing health risks.

  • Markets, entrepreneurship, and private initiative are limited in the environmental management problems they can solve.

  • Policy may require acceptance of an imperfect solution in order to prevent greater harm.


Human health risks associated with environmental release of persistent organic pollutants (POPs) depend on the ecological behavior of the compounds and pathways by which the POPs reach human populations. Sometimes predicted consequences do not occur and other times they do.

In 1996, an incident at the Swan Hills Special Waste Treatment Center (SHSWTC, now called the “Swan Hills Treatment Facility”) in the town of Swan Hills, province of Alberta, resulted in uncontrolled emissions of polychlorinated biphenyls (PCBs), polychlorinated dibenzo-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and other organochlorines [1]. We report here the background to a human health hazard assessment that was based on contaminant levels in which ecological pathways of bioaccumulation and bioconcentration leading to human consumption were studied. The findings of this and related health assessments are presented in Part 2, on Ecotoxicology and Human Health Risk. By tracking the behavior of POPs through the ecosystem, educated judgments could be derived regarding potential future risk. Health advisories based on these judgments reflected a risk management strategy that took into account the movement of POPs through the ecosystem prior to widespread exposure of the resident population. We also discuss problems associated with modifying the risk management strategy for the population presumed to be at greatest risk. Names of provincial agencies are given as they were in 1997; most have been changed since, but their areas of responsibility are obvious.


The Swan Hills Special Waste Treatment Center (SHSWTC) in Swan Hills, Alberta, which is now called the Swan Hills Treatment Center, is a purpose-built facility owned by the provincial Government of Alberta. The SHSWTC is located approximately 12 km north-east of the Town of Swan Hills, in the north-central part of the province of Alberta (Figure 1). The facility began operation in 1987 to receive and dispose the potentially toxic waste safely. (Figures 2 and 3 provide views of the facility.) At the time of the incident, SHSWTC was owned by the Province of Alberta and operated by Chem-Security, Ltd. The facility was sited on a relatively remote plateau in northern central Alberta in part to isolate it from population centers and in part because the community of Swan Hills invited it, as a means of economic diversification. However, although sparsely populated by humans, the area is ecologically sensitive and rich in wildlife, which both the majority and the Aboriginal population harvest for food and exploit for recreation and commercial guided hunting.


Location of Swan Hills, Alberta (Modified from outline map of waterways of Alberta, Natural Resources Canada). The First Nations Communities are not identified in order to protect their interests, confidentiality, and cultural traditions. Edmonton is the capital city of Alberta and the nearest metropolitan centre. Lesser Slave Lake, the second-largest body of water in the province, receives waters from the Swan Hills watershed and drains into the Athabasca River.


Location of Swan Hills, Alberta (Modified from outline map of waterways of Alberta, Natural Resources Canada). The First Nations Communities are not identified in order to protect their interests, confidentiality, and cultural traditions. Edmonton is the capital city of Alberta and the nearest metropolitan centre. Lesser Slave Lake, the second-largest body of water in the province, receives waters from the Swan Hills watershed and drains into the Athabasca River.


Aerial View of the Swan Hills Special Waste Treatment Centre.


Aerial View of the Swan Hills Special Waste Treatment Centre.


The Swan Hills Special Waste Treatment Center in 2002. (Photo by Tee L. Guidotti.)


The Swan Hills Special Waste Treatment Center in 2002. (Photo by Tee L. Guidotti.)

Wild game, especially moose, and fish are abundant in the area and have been a traditional source of food for Aboriginal people as well as a source of food and recreation for other residents. In addition to the town of Swan Hills, there are several First Nations (Aboriginal and Métis) communities nearby. Wildlife is abundant and many residents harvest country foods, including deer, moose, fish, and berries. The area is popular among hunters and attracts enthusiasts from across North America for recreational hunting. Guided hunting was, together with the SHSWTC, one the major sources of cash employment in the area for the First Nations population. Economic activity in the area also includes oil and gas extraction and provincial highway maintenance.

The facility is the largest local employer after the provincial government. Central to the operation of the waste treatment process for organochlorines is a high-temperature incinerator complex designed to destroy organic material contained in the liquid, solid, and sludge waste received at the facility. This consisted, at the time, of a rotary kiln and two rocking kiln incinerators. Combustion by-products are scrubbed to remove particulate matter and acidic gases prior to being discharged to the ambient air through the stack. An essential component of the plant is a specially engineered incinerator designed to pyrolize, or thermally decompose, persistent organic compounds sent to the facility for disposal.

Concern that the release of these potentially toxic compounds might affect human health in the area arose immediately. An environmental monitoring program was undertaken to assess the impact of the release on local vegetation, wildlife, and human food sources.

On 16 October 1996, a malfunction in the incinerator at the SHSWTC resulted in a leak. The leak vented to the outside and released quantities of organochlorine compounds, including dioxins, furans, and PCBs. The plant had by then treated 27 million kg of hazardous waste, much of it contaminated with PCBs, during 1996 alone.

The malfunction of a transformer furnace was discovered when an unusual odor was detected in the plant. This malfunction had allowed some process gas (containing untreated waste chemicals) to bypass the scrubber and to pass directly into the stack gas (downstream from the incinerator and emitted directly to the atmosphere). This resulted in release of some process gases containing POPs, primarily PCBs, and PCDDs and PCDFs into the ambient air. It was not known how long the process gas had been escaping through the leak but the cause was determined to be a failed isolation flange, isolating process gases from flue gases, and an associated expansion joint. Stack emissions were then conducted the following day and confirmed the presence of an uncontrolled release, quantified at approximately 200 g/h, or 597 g/h under current operating conditions, compared to 19 g/h in a similar facility elsewhere.

In this event, the initial detection and quantification of the release rate was complicated by an error in emissions reporting when a dilution factor was miscalculated. The error was discovered by tracking down the reason for a discrepancy in the results and was corrected early.

A process was established to manage the investigations. The work group undertook data collection, laboratory analysis, data analysis, data interpretation, and data presentation. A specially constituted Science Advisory Committee, consisting of local, national, and international experts, the author included, provided advice on direction of the study and assistance in interpreting results. A Public Health Advisory Committee advised on issues of the human health risk and management options. The risk communication team at Alberta Health delivered the information to targeted audience and stakeholders through various channels including public media, local community meetings, direct mail, and telephone.


The SHSWTC was sited in Swan Hills because of favorable geology limiting the potential for groundwater contamination, road access, a small population placed at risk, community interest in hosting the facility, and the presence in the area already of oil producers [2]. The Aboriginal community living around Swan Hills and Lesser Slave Lake vehemently opposed the project from the beginning.

Although there are mobile hazardous-waste incineration units operating elsewhere in the country, SHSWTC remains the only fully integrated hazardous waste treatment facility in Canada, one that can dispose of all POPs.

This incident resulted in the prosecution of the SHSWTC (as a business) under the then-fairly new Alberta Environmental Protection Act of 1993, a relatively stringent legislation for the time [3]. After a rather lengthy trial, the operation was fined $625,000, the largest penalty in the provincial history for an environmental violation [3]. This, and the prolonged shutdown of the facility, guaranteed that there would be no future profit margin for the operator.

The SHSWTC has never operated at a profit. It has required an on-going subsidy by the Provincial Government of Alberta. The rationale has been that it is needed to prevent much worse environmental pollution [3]. Intake is currently around 18,000 tonnes (1000 kg) per year, sourced from throughout Canada. Most of the current waste stream consists of paint sludge. Very little consists of the special waste that could give rise to POPs, but illegal dumping or discharge into sewers or waterways would be very detrimental regardless.

The plant was built in 1985 by the Government of Alberta primarily to dispose of hazardous materials generated within the province from oil drilling and the chemical industry. At that time, and till today, there were no alternatives for the large-scale destruction of POPs and other hazardous wastes in western Canada, and the problem of disposal was acute. The town of Arlington, Oregon, which had previously imported waste from Alberta, was closing its doors. A planned hazardous waste treatment plant in Fort Saskatchewan, a medium-sized city near Edmonton, was rebuffed in 1979. In the 1970s, there were documented episodes of dumping in ditches, discharge into rivers or municipal sewers, disposal in municipal landfills. Much hazardous waste was stored in warehouses, awaiting a solution [1, 2].

The provincial government of the day decided that there had to be a public option. Two communities actively pursued the plant and Swan Hills was chosen. Ownership by the province and financial guarantees were considered essential as business conditions because no private sector company was likely to take the risk, especially with the close oversight and expected public scrutiny [2].

Originally, the plan was for the plant to receive oilfield waste in large quantities, mostly spent drilling fluid. In 1992, this waste stream was exempted because it was not sufficiently hazardous to merit the expensive treatment. Without routine oilfield waste, the province, despite its large oil and gas and petrochemical industrial base, did not generate enough hazardous waste to support such a massive facility with fees [1, 2]. The financial viability of the project required that it receive and treat waste from all parts of Canada in order to charge enough to cover costs. It was expected to break even by 2001, but that never happened and the plant runs deficits today in the order of Can$30 million per year. It employees 100 people [3].

The SHSWTC was initiated by the province, which built the plant at a cost of Can$60 million (1990) and retained a 40% ownership stake. The 60% co-owner and operator of the SHSWTC, Chem-Security, was unable to restart the plant with a profitable operation and so abandoned the business, essentially giving the plant to the Province of Alberta for nothing. The Province then contracted with a series of operators until 2011, when it chose AECOM to operate it on a long-term basis in partnership with SENA, a waste management firm [1, 3, 4].

The plant is notable for its fully integrated services, because in addition to pyrolysis of POPs, it has the capacity to inject liquid water waste into deep wells, to neutralize chemically reactive waste, to stabilize and solidify solid material, and to deposit in a secure landfill non-hazardous residual solid waste. Over time, the innovative “rocking kiln” technology, unique in the world, proved unsatisfactory and prone to damage. The incinerators have been replaced with more conventional rotary-kiln technology. The plant has never handled radioactive, explosive, or medical waste.

The decision to reopen the plant and to keep it operating was not arbitrary. By 1998, immediately following the incident, an estimate of the total cost to taxpayers of the SHSWTC had reached about Can$440 million. The province obtained an authoritative estimate that it would cost in the order of Can$20 million to decommission the SHSWTC safely. An estimate of the environmental legacy of the plant is that it will cost approximately Can$176 million to clean up and decommission the plant in 2025 [4, 5].

In 2013, the then-operator of SHSWTC was cited under the Alberta Environmental Protection Act for failing to maintain the barrier (liner) that prevented runoff from the plant and leachate from its landfill from entering groundwater. The company paid a fine. However, actual groundwater contamination was not alleged. Other than that and a similar previous episode, there have been few other environmental infractions cited at the plant.

Management of the plant was taken over by Suez, a French company, in 2001. In 2014, the license to operate the facility came up for renewal and the previous operating license expired in 2016. The plant was issued a temporary operating license in 2016 while the Government of Alberta completes an exhaustive review of the highly technical application. The licensed was strongly opposed by the Lesser Slave Lake Indian Regional Council [5].

The party in power during the key events described was the Progressive Conservative Party, which was center-right and oriented toward business development and especially, in the 1980s, economic diversification. The current party in power in Alberta, since 2015, has been the New Democratic Party, best described as center-left or social democratic in orientation. Although very different ideologically, the New Democrats have maintained the same policy toward keeping the SHSWTC open, despite the need for subsidy.

Pricing of chemical destruction services has been an issue. If the full cost of the plant’s operations were reflected in the fees charged, they would be prohibitive to many and perhaps most users, both inside and outside the province. The Government of Alberta has decided, as a matter of policy, that it is better to subsidize the operation of the plant and to destroy as much of the special waste that remains as possible over time, than to risk going back to the situation that existed before the plant where illegal dumping and diversion took place. Since the plant requires enough volume to operate efficiently, and since Alberta does not generate such a large quantity, which means accepting waste from outside the province and treating it below cost is one more reason for this is not an attractive business model. No entrepreneurial enterprise is going to buy a money-losing operation like this to operate it privately. If the province were to get out of the business, however, there would be no backup, no place for the waste to go, and Alberta, which generates a disproportionate share, would have no disposal alternatives. Thus, Alberta is resigned to continue the subsidy and operation of the plant.

The cost of the Swan Hills investigation and correction of the problems ran into many millions of dollars. (The cost has not been published and would be difficult to disentangle from the plant subsidy.) Few jurisdictions in western Canada could have afforded this expense on a single facility, but Alberta was wealthy in those days because of its revenue from the oil and gas industry.

From the policy point of view, the cost of operating the plant at a deficit is balanced against the benefits of environmental protection by diverting waste from illegal disposal (such as dumping or shallow well injection) and of economic protection by maintaining an affordable disposal option, so that the development and diversification of industry is not constrained. Eventually, the problem may (hopefully) disappear with universal conversion to sustainable chemistry, so that hazardous wastes are not produced in the first place. Swan Hills has already destroyed much and perhaps most of the legacy burden of chlorine chemistry and POPs in the province. For the moment, however, such waste still exists and as an integrated facility the SHSWTC still handles a large volume of liquid waste aside from chlorinated materials that can produce POPs. There are no alternatives in Canada and the SHSWTC remains an efficient and effective, if troubled, disposal facility, expensive and problematic as it is.

Aboriginal Concerns and the Canadian Constitution

The Constitution of Canada, unlike that of the United States but much like that of the United Kingdom (which, however, is unwritten), is based on a codification and integration of many acts passed over the history of the country, most importantly the British North America Act (BNAA) of 1867, which converted the several British colonies into provinces of a single country, albeit one with loose, confederation form of association. Critically important, the Government of Canada, not the individual provinces, took over responsibility from the British government, for negotiating and enforcing compliance (or lack thereof) with treaties with Aboriginal people. These treaties were negotiated in the name of the Queen, not by England or the United Kingdom as such, and responsibility to fulfill them passed to the Government of Canada with the BNAA (The British monarch is also the King or Queen of Canada).

Under the BNAA, the federal government of Canada regulates the relationship of provinces to the whole (for example, transfer payments of federal tax funds and formulating guidelines for consistency in health and environmental protection) but the provinces have near-total responsibility within their borders for managing health issues (including discretion in adopting standards) and for managing the environment.

Major exceptions include areas that fall under the constitutional authority of the federal government, including Aboriginal relations and protection, federal employees, and interprovincial transportation. There is no large, powerful federal agency to compare with US agencies such as the Environmental Protection Agency. Canada does have a counterpart to the Centers for Disease Control and Prevention (Public Health Agency of Canada), but it was not established until 2006.

Because of this division of responsibilities, Health Canada, in consultation with provincial Ministers of Health, recommends standards but does not enforce compliance except in areas of federal jurisdiction, which includes Aboriginal affairs. Application of the guidelines and translation into standards, if needed, is within the mandate of provincial governments. That is why Alberta Health conducted the risk analysis but used Health Canada guidelines. Health Canada entered the picture when the time came to do a focused study on the Aboriginal population of northern Alberta, which fell within its area of responsibility.

Confounding factors, such as lifestyle and cigarette smoking, complicate interpretation of human risk assessment. In the presentation of the findings of the Lesser Slave Lake Study to the Aboriginal community in 2002 (conducted by the author), distrust was evident and there was considerable skepticism that elevations in indicators of certain exposures (specifically, cadmium) was attributable to smoking rather than ecological disruption (cadmium was not one of the chemical contaminants released in the incident).

The Aboriginal point of view as articulated by elders in the Lesser Slave Lake community meetings is that the entire situation was unnecessary and hurtful because of greed and lack of respect. The feeling expressed was that the plant was one more intrusion and injury. However, it is best to let Aboriginal peoples speak for themselves, as they did in a four-part video entitled “Poisoning Paradise”, one segment of which is available on YouTube [6].


The SHSWTC represents a success in environmental management in that it was one of the first demonstrations of plant siting using a consensus approach with incentives and offsets for the benefit of the host community. However, the complexity and novelty of the technology in the facility made the decision arguable to place it in a problematic remote community. Furthermore, although the area is sparsely populated by people, it was in a key and potentially vulnerable part of the water-dominated ecosystem. The Aboriginal community carried a disproportionate burden of risk, although in the event this risk turned out to be quite different than expected. Conduct of the evaluation was thorough but measurement and reporting deficiencies were present and caused practical difficulties. (The analytical company responsible for the measurement error did not recover confidence in time to play a further role in the study.) Translating findings into policy could not wait for perfection, however, and in the end, a decision based on risk-benefit favored continued operation of the plant under close supervision.

The disruption of Aboriginal life was considerable but confidence in provincial and federal government institutions was probably minimally affected because it was already low, despite generally effective public health services provided under difficult conditions to remote communities. By comparison, the impact on the majority (almost entirely white) population of Swan Hills was relatively minor because of continued operation of the plant, economic diversification, and relatively less reliance on country foods.

Part 2 continues the case study with the technical details of risk assessment and risk management.

This case study was taught for several years as a case study in PubH 243 Public Health Practice at the George Washington University and Ms. Amy O’Connor developed the narrative further for her MPH research project in 2007.


Funding for Dr. Guidotti’s participation in this case study in the role of consultant was initially provided by Alberta Environment as the lead agency for the Government of Alberta, and subsequently by Health Canada for the Lesser Slave Lake Study (described in Part 2). Neither government had a role in supporting the preparation of this culminating case study, other than as a source of publicly accessible information, and have not reviewed, approved, or provided input into its development since approximately 2004.


The author has no competing interest to declare.


During the events described in this case study, the author served as a principal consultant in environmental health for Alberta Environment, Alberta Health, and Alberta Justice, and, later, Health Canada (agency names are given as they were in 1997). See Part 2 for acknowledgements of the work of colleagues, coworkers, and collaborators.


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