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​​​​​A photo of a sofa fire.
Flame Retardants​

Flame retardants are chemicals that can be applied to an object in order to make it resistant to catching fire. They are very important for the protection of products and people from fire, but their use has also caused contamination to the environment.

There are many different chemicals used as flame retardants, some emerging more recently as a concern for the environment. Others have been long known as contaminants, such as PCBs (polychlorinated biphenyls) that were banned in the late 1970s but can still be found in the environment.  

Some of these chemicals have had industrial uses while others have been added to manufactured products including plastics, textiles and surface coating formulas (that are used on furniture, for example), with the purpose of inhibiting or delaying the spread of fire. These chemicals can pollute the environment from industrial waste and leaks, atmospheric transport and through the usage and disposal of consumer products.

Owing to their chemical structures, flame retardants can be persistent in the environment meaning they last for long periods of time, sometimes decades, without breaking down. Because of their longevity there is a greater potential that living things, including fish and birds, will be exposed to them. Unfortunately they can absorb these chemicals faster than they can naturally break them down or expel them, a process known as bioaccumulation, where the contaminant builds up in their body over time.

With the prominence of fire safety regulations there is a growing market for flame retardants, but some of the chemicals have faced scrutiny and government regulations because of environmental issues. Action to reduce flame retardants in the environment has taken place. PCBs were listed in the Stockholm Convention that recognized its adverse ecological effects and its need for elimination from use worldwide.

The presence of some flame retardant chemicals in sediment and fish has been documented in recent studies of the Lake Simcoe watershed.

  1. ​What are flame retardants?
  2. Mobility and fate of flame retardants in the environment
  3. Environmental impacts
  4. Flame retardants in the Lake Simcoe watershed
  5. Additional Ontario studies and resources
  6. Actions to reduce flame retardants in the environment
  7. References

​What are flame retardants?

Flame retardants are a class of contaminants that comprises a diverse group of chemicals with both legacy and emerging concerns for the environment.  Various flame retardant chemicals have been used industrially or have been added to manufactured materials including plastics and textiles, and to surface finish and coating formulas, for the purpose of inhibiting or delaying the spread of fire. Many flame retardants have chlorinated or brominated chemical structures making them persistent in the environment and bioaccumulative in organisms such as fish. With the prominence of fire safety regulations there is a growing market for flame retardants, but some flame retardants have faced scrutiny and government regulations because of frequent detection in the environment and the occurrence or potential of adverse ecological effects (Green, 1995; Hoh et al., 2006).

Polychlorinated compounds

Polychlorinated biphenyls(PCBs) are a group of synthetic chlorinated organic compounds used historically for hundreds of industrial and commercial purposes. A number of complex mixtures were produced for commercial use and were marketed under the trade name Aroclor. PCBs are essentially resistant to catching fire (due to their high flashpoint), have low electrical conductivity, high thermal conductivity and are highly resistant to thermal degradation, excellent properties for their use in dielectric and coolant fluids in electrical equipment. PCBs have also been used as plasticizers in paint and in dyes and carbonless copy paper. PCBs were not manufactured in Canada but were imported and used widely.

Dechloranes are another set of polychlorinated compounds used for their flame retardant properties in plastics, rubber and other products, but also as an insecticide for fire ants and termites. The insecticide and flame retardant, Mirex (the original dechlorane compound), was used mainly in the 1960s and 1970s but was never registered for use as a pesticide in Canada. Once Mirex was banned, other less toxic dechlorane compounds came into use. Products containing other dechlorane compounds, including Dechlorane Plus (DP), were imported to Canada [Environment and Climate Change Canada (ECCC) and Health Canada, 2016] and DP is currently used in Canada as a flame retardant in automobile manufacturing.

Polybrominated compounds

Polybrominated diphenyl ethers (PBDEs) are brominated organic compounds with flame retardant function that are used in many different products. The chemicals are not manufactured in Canada but are imported as commercial mixtures and then added to products including computers casings, home appliances, furniture, interiors of vehicles and aircrafts and a number of electrical and electronic parts (ECCC, 2016). There are a number of types of PBDEs, with increasing number of bromine atoms in their chemical structure, tetra- and penta-BDEs, for example. PBDEs used commercially are mixtures of these.

Hexabromocyclododecane (HBCD) is a more recently produced brominated flame retardant, used in polystyrene foam for insulation in the building industry.

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Mobility and fate of flame retardants in the environment

​Polychlorinated compounds

PCBs were the first contaminant of this class to be introduced to the environment from extensive industrial use starting in 1929 [Mahanty and John, 1986 (as cited in Sauve and Desrosiers, 2014)]. Bans were placed on PCBs in the late 1970s in North America but environmental problems continued because of their persistent and toxic nature and their capacity to biomagnify through trophic food webs and to be transported long-distances in the atmosphere (Corsolini et al, 2011; Sauve and Desrosiers, 2014). PCBs can still potentially enter the environment from leaks, spills, leachate from landfills, effluent from municipal and industrial operations, runoff and volatilization from contaminated areas and surfaces and from atmospheric deposition {Strachan, 1988 [as cited in Canadian Council of Ministers of the Environment (CCME), 2001]; World Health Organization (WHO), 1993; Hu and Hornbuckle, 2010}.

Mirex, the most toxic and bioaccumulative dechlorane compound, entered the Canadian environment from manufacturing plants in the U.S. near shared water bodies and from long-range atmospheric transport.  Dechlorane Plus may enter the environment from processing facilities or in lower amounts from consumer or commercial products (ECCC and Health Canada, 2016).

Polybrominated compounds

In more recent decades, polybrominated compounds have replaced the polychlorinated compounds and are also appearing in regions distant from the source (Sormo et al., 2009; Borghesi  et al., 2009; Sauve and Desrosiers, 2014; ECCC, 2016). PBDEs are entering the environment through industrial operations, and during the service lifetime and disposal of consumer products (ECCC, 2016). Despite reduction of industrial use of PBDEs due to federal regulation, they are persisting in the environment especially in sediments that act as a sink.

Industries have produced other novel brominated flame retardants (e.g., HBCDs) and these are also appearing in the environment (Guerra et al., 2010) and in various organisms (La Guardia et al., 2012). Their harmful effects to the environment are becoming more realized. Furthermore, some of these brominated organic compounds degrade or transform in the environment into other persistent and bioaccumulative compounds.

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​​Environmental impacts

Polychlorinated compounds

Most PCBs that enter into the aquatic environment eventually end up in the sediment, where aquatic biota can be exposed to them.  Adverse biological effects most commonly observed included change in species richness and abundance of benthic invertebrates [Environment Canada (EC), 1998]. Toxic effects of PCBs in birds and animals have been well documented, including reproductive failure and compromised immune systems.

Polybrominated compounds

According to a screening assessment under Canadian Environmental Protection Act (CEPA; 1999), it was determined that commercial mixtures of PBDEs can have immediate or long-term harmful effects to the environment and its biological diversity (EC, 2006). Many PBDEs were phased out but high levels of PBDEs have since been observed in top predators, including raptors, and these exposures can lead to disrupted behaviours including courtship and reproduction (see citations in Guigueno and Fernie, 2017).

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Flame retardants in the Lake Simcoe watershed

Polychlorinated compounds


In a 2008 study of persistent organic pollutants (POPs) in Lake Simcoe, Helm et al. (2011) collected surface sediments,  approximately 1-2 cm of top which would represent approximately three decades of sediment accumulation (Hawryshyn et al. 2012).  The study found that total PCB concentrations (the sum of PCB compounds) were highest in Kempenfelt Bay as compared to lower levels observed in Cook's Bay and the Main Basin. One sample (of the six taken from the deeper parts of Kempenfelt Bay) had a total PCB concentration [36 ng/g dry weight (dw)] that exceeded the Canadian interim sediment quality guideline (ISQG; 34.1 ng/g dw, 5 cm of top sediment; CCME, 2001). Helm et al. compared the results from Lake Simcoe to levels in the Great Lakes from previous studies, and found that Lake Erie and Lake Ontario had higher levels whereas Lake Superior, Lake Huron and Georgian Bay were not significantly different than Lake Simcoe.

In a study by LSRCA in 2015, samples were collected in Kempenfelt Bay from approximately 15cm of sediment, approximately 70 to more than 100 years of accumulation (Hawryshyn et al. 2012), essentially the entire period of PCB use.  With inclusion of values below the detection limit, the total PCB content at each site exceeded the ISQG (CCME, 2001). One of these sites was in the nearshore (littoral zone) in proximity to tributary outlets from Barrie and had a concentration of 200 ng/g dw, much higher than the PCB levels observed by Helm et al. (2011) in the deeper zones of the bay (See Sources below).

In this LSRCA study in 2015, PCBs were observed only at one other site (out of 21 sampling sites in the lake and tributaries), the Beaver River. LSRCA sampled surface sediment from several tributaries in 2004 but PCBs were not detected (LSRCA, 2005).

Chaudhuri et al. (2017) collected surface sediment (ca. 10 cm of top sediment) from several tributaries around the Lake Simcoe watershed in 2008/2009 for PCB analysis. Total PCBs exceeded the ISQG at Tannery Creek (40.3 ng/g dw), a tributary of the East Holland River that drains parts of the urban centre of Aurora [Chaudhuri et al., 2017; Southern Ontario stream sediment project (SOSSP), unpublished data].


Gewurtz et al. (2011) observed declines in concentrations of total PCB in two predatory sport fish species (lake whitefish and lake trout) of Lake Simcoe. However the largest size class (>60 cm) of lake trout tested in this study had concentrations that approached or exceeded the “complete restriction" consumption guideline of PCBs for the general population (MECP, 2018b). According to the results of the study, eating larger-sized whitefish (>55 cm) and lake trout (>50 cm) poses the risk of PCB toxicity to sensitive members of the population (women of childbearing age and children under 15 years old) as a number of the fish tested in these size classes exceeded the consumption guidelines for partial and complete restriction for this population group (Gewurtz et al., 2011).


The elevated levels of PCBs found in Kempenfelt Bay sediment are indicative of historical sources of these chemicals in the Barrie area. According to timelines derived from a sediment core collected in Kempenfelt Bay by Helm et al. (2011), PCB levels peaked in the late 1960s, consistent with historical use and emissions. PCB concentrations in other parts of the lake (the Main Basin and Cook's Bay) were lower and relatively uniform, suggesting atmospheric deposition from the regional air mass that moves through large urban and industrial areas southwest of Lake Simcoe including the midwestern U.S. and southern Ontario (Helm et al., 2011). Higher levels of PCBs in some of the Great Lakes (Erie and Ontario) are due to past point sources there that were not present in Lake Simcoe (Helm et al., 2011).

The highest level of PCB observed in Lake Simcoe and its watershed was in the nearshore of Kempenfelt Bay. It may be that legacy PCBs became mobile and were newly deposited into the bay from tributaries in Barrie or that there were historical deposits in that location that have persisted. Helm et al. (2011) noted that historical contaminants, including PCBs, in the nearshore and tributaries of the Great Lakes had increased levels from past localized inputs. Further investigation would be required to understand more about this phenomenon of elevated PCB levels in the nearshore area of Lake Simcoe, but presumably it indicates legacy contamination within the watershed from historic usage as opposed to any current uses.

Polybrominated compounds


In 2008, PBDE levels were investigated in the surface sediments of Lake Simcoe by Helm et al. (2011). The highest measured concentrations of total PBDEs were found in Kempenfelt Bay and Cook's Bay.  Otherwise total PBDE concentrations varied throughout the lake and bays with levels between 5 to 38 ng/g dw (guidelines for total PBDEs are not available for comparison).

Chaudhuri et al. (2017) reported that total PBDEs from samples in the tributaries of Lake Simcoe were relatively low (< 5.5 ng/g dw) compared to higher values reported at some sites in other parts of Ontario (e.g., 301 ng/g dw near Windsor; Chaudhuri et al., 2017). Mirex did not occur above the detection limit at any lake and tributary sites sampled by LSRCA (LSRCA, in prep.) or tributary sites sampled by Chaudhuri et al. (2017).


PBDEs did not exceed any fish consumption guidelines, for lake whitefish and lake trout (Gewurtz et al., 2011; MECP, 2018b). Regardless, the authors note that continued monitoring is important due to potential additional PBDE loadings to the system. Monitoring for newer flame retardants would be important as well.


PBDE emissions occur from the use of consumer goods in the urban areas of the watershed, including Barrie (as detected in Kempenfelt Bay) and Newmarket and Aurora (as detected in Cook's Bay).Inputs from outside of the watershed can occur from atmospheric deposition originating from large urban areas southwest of the lake (Helm et al., 2011).

According to a sediment core collected from Kempenfelt Bay, PBDEs were first detected in the mid-1970s. Levels increased fairly steadily since then with the highest level found in the most recent core slice (ca. 2010; 21 n/g dw; Helm et al., 2011).

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​​​Additional Ontario studies and resources

Polychlorinated compounds

As a result of actions to clean-up contaminants, declines of PCBs in fish between two time periods (1975-1985 and 2005-2013) were observed in several Areas of Concern (AOCs) of Lake Ontario, including the Hamilton Harbour, Toronto waterfront, Bay of Quinte and the Niagara River (MOECC, 2016). Despite these declines, there are still contaminant concentrations above the fish consumption guidelines especially for larger sizes of fatty fish species in the Canadian waters of the Great Lakes. Another AOC, Peninsula Harbour on the north shore of Lake Superior, underwent a management technique called “capping" in 2012 where PCB-contaminated sediment was covered with clean sand in an effort to accelerate natural recovery and reduce exposure of PCB to biota (MECP, 2018a). This contamination, which originated from operation of a pulp mill in the area that closed in 2009, will be monitored overtime. Investigative and targeted monitoring using multiple sampling techniques concurrently has been used in several locations in the Great Lakes basin to track the source(s) of PCB contamination. These efforts lead to remediation action for sediments of the affected streams and rivers (for example, Sinister Creek near Lindsay, Ontario; MOE, 2013).

A number of dechlorane compounds and their degradation products are present in the sediment and fish of the Great Lakes (MECP, 2018a), including the occurrence of Dechlorane Plus (DP) near the Niagara River and in Lake Ontario, downstream of an American DP manufacturing facility (ECCC and Health Canada, 2016).

Polybrominated compounds

Due to increased use of PBDEs in the 1980s and 1990s, their concentrations increased rapidly in the sediments of Lake Ontario [Ministry of the Environment (MOE), 2009]. A study of sediment of the Great Lakes highlighted that the highest concentrations were found near urban areas, due to some quantities coming from leaching of PBDEs into the air from products or being washed from products into wastewater treatment facilities (MOE, 2011). Monitoring will continue to ensure that levels in the environment decline, as precipitated from regulatory actions on PBDEs (as described below) in Canada and around the world (MECP, 2018a).

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Actions to reduce flame retardants in the environment

Polychlorinated compounds

PCBs were one of the twelve original persistent organic pollutants (POPs) listed in the Stockholm Convention that recognized its adverse ecological effects and its need for elimination from use worldwide. The manufacturing, processing, importing and selling of PCBs became illegal in 1977 in Canada and release to the environment became illegal in 1985 (ECCC, 2017). However, Canadian legislation allows owners to use PCB-containing equipment for the duration of its service life. The dechlorane, Mirex, was also listed as an original POP under the Stockholm Convention and all uses were banned in the late 1970s in the U.S. In Canada, its regulation is outlined in the Mirex Regulations, 1989 and Mirex appears on the List of Toxic Substances (Schedule 1) of CEPA, 1999 (EC, 2013).

Polybrominated compounds

There have been voluntary initiatives undertaken to decrease the usage of PBDEs since 2001. More recently, PBDEs and HBCDs have been assessed and regulated under the Stockholm Convention and by the Canadian government for phase-out and elimination. Canada started regulations for the elimination of penta-BDE and octa-BDE homologues of PBDE in 2006 and deca-BDE in 2013 (EC, 2010; Sauve and Desrosiers, 2014). Some flame retardants are still in use and the toxicity of these and other new flame retardants still need to be established (Guigueno and Fernie, 2017).

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Borghesi N, Corsolini S, Leonards P, Brandsma S, de Boer J and Focardi S. 2009. Polybrominated diphenyl ether contamination levels in fish from the Antarctic and the Mediterranean Sea. Chemosphere 77: 693–698.

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La Guardia MJ, Hale RC, Harvey E, Mainor TM and Ciparis S. 2012. In situ accumulation of HBCD, PBDEs, and several alternative flame-retardants in the bivalve (Corbicula fluminea) and gastropod (Elimia proxima). Environ. Sci. Technol. 46: 5798–5805.

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