Chlorinated paraffins: chapter 4

4. Risk assessment of ecological impacts

4.1 Environmental fate

4.1.1 Short-chain chlorinated paraffins

Level III fugacity modelling of short-chain chlorinated paraffins (SCCPs) has shown that they would achieve their highest concentrations in sediment and soil (Muir et al. 2001).

4.1.2 Medium-chain chlorinated paraffins/long-chain chlorinated paraffins

The environmental distribution of three medium-chain chlorinated paraffins (MCCPs) (C14-17) and a liquid C18 long-chain chlorinated paraffins (LCCPs) was estimated using the equilibrium criterion (EQC) Level III fugacity model of Trent University’s Canadian Environmental Modelling Centre (Mackay et al. 1996). Level III represents a steady-state, non-equilibrium system comprised of soil, sediment, air and water compartments, with the chemical undergoing reactions or inputs and removal processes (advection, volatilization, deposition, photolysis, hydrolysis and biodegradation). Inputs of 100 kg/hour to soil, 1.6-6.4 kg/hour to air and 2.2-8.8 kg/hour to surface water were designed to reflect potential emissions of chlorinated paraffins (CPs) mainly associated with landfills, land application of sewage sludge and consumer uses. Results from the Level III EQC model suggest that these CPs would achieve their highest concentrations in sediment and soil. Concentrations in water and air were extremely low for all compounds. The environmental residence time of the three C16-18 CPs were estimated to be greater than 500 days compared with 250 days for the C14 CP. However, these results should be viewed with caution because the degradations rates, used as input parameters for the CPs, were highly uncertain. Similar results were obtained using a Level III fugacity calculation with a C14-17 MCCPs (U.K. Environment Agency 2003).

4.2 Persistence and bioaccumulation potential

When evaluating persistence in this section, the focus is on sediment as results of fugacity modelling indicate that this is an important compartment for all CPs. Persistence in air is also evaluated, because of the potential for long-range transport in this medium. Although soil is potentially an important compartment for CPs, there are too few data available to permit meaningful evaluation of persistence in soil.

4.2.1 SCCPs

Table 2 summarizes persistence and bioaccumulation information for SCCPs in comparison with criteria of the Persistence and Bioaccumulation Regulations of Canadian Environmental Protection Act, 1999 CEPA 1999 (Government of Canada 2000).

Table 2: Summary of persistence and bioaccumulation information on SCCPs
Medium or parameter CEPA criteria
(Government of Canada 2000)
SCCPs information
Air t1/2 ≥ 2 days or it is subject to atmospheric transport from its source to a remote area Estimated t1/2 of many SCCPs are ≥ 2 days

SCCPs have been detected in air, sediment and biota in the Arctic in the absence of significant sources, indicating long range transport
Sediment t1/2 ≥ 1 year Back calculation using concentrations from sediment cores shows half-life >1 year. Biodegradation test following the Organisation for Economic Co-operation and Development (OECD) standard methods indicates half-lives >1 year in aerobic and anaerobic freshwater and marine sediments.
Soil t1/2 ≥ 6 months Limited evidence for rapid biodegradation or removal following sludge applications
BAF ≥5000 Field BAFs >5000 in sculpin, smelt and trout; BMF values approaching or >1; Modified Gobas Model predicts BAF >5000 for some SCCPs
BCF ≥5000 BCFs>5000 in trout and mussels.
Log KOW ≥5 4.39 - 8.69 (measured and modeled)
A- Persistence
Air and long-range transport

Estimated atmospheric half-lives for SCCPs based on reaction with hydroxyl radicals range from 0.81 to 10.5 days, using the default atmospheric hydroxyl radical concentration of 1.5 × 106 molecules/cm³ during sunlight hours in AOPWIN (v. 1.86) computer program (Meylan and Howard, 1993; Atkinson 1986, 1987). Using a lower hydroxyl radical concentration of 5 × 105 molecules/cm³, which is generally used as a daily (24-hour) average in relatively unpolluted air in the EU, atmospheric half-lives ranged from 1.2 to 15.7 days. Tomy (1997) also estimated atmospheric half-lives of greater than 2 days for the major SCCPs detected in the Great Lakes and Arctic air and biota.

SCCPs have vapour pressures (VPs) (2.8 × 10-7 to 0.028 Pa) and Henry’s Law Constants (HLCs) (0.68-17.7 Pa•m³/mol for C10-12 congeners) that are in the range of VPs and HLCs for some persistent organic pollutants that are known to undergo long-range atmospheric transport under the 1979 UNECE Convention on Long Range Transboundary Air Pollution (e.g., hexachlorocyclohexane [lindane], heptachlor, mirex)Footnote 1. The HLC values imply partitioning from water to air or from moist soils to air, depending on environmental conditions and prevailing concentrations in each compartment.

SCCPs were detected in four air samples collected at Alert at the northern tip of Ellesmere Island in the high Arctic. Concentrations ranged from <1 to 8.5 pg/m³ in gas-phase samples. Borgen et al. (2000) measured SCCPs in Arctic air samples taken at Mt. Zeppelin, Svalbard, Norway, in 1999. Concentrations ranging from 9.0 to 57 pg/m³ were detected. Borgen et al. (2002) found much higher SCCPs concentrations in air at Bear Island, a small isolated island between Svalbard and mainland Norway. Total SCCPs concentrations ranged from 1 800 to 10 600 pg/m³. SCCPs residues were found in the surficial sediments in three remote Arctic lakes including Yaya Lake, Hazen Lake and Lake DV-09. Concentrations ranged from 0.0016 to 0.0176 mg/kg dry wt. (Tomy et al. 1998a; Stern and Evans 2003).

SCCPs have been found at concentrations ranging from 0.095 to 0.626 mg/kg wet wt. in the blubber of marine mammals, including beluga (Delphinapterus leucas), ringed seal (Phoca hispida) and walrus (Odobenus rosmarus) from several locations in the Arctic (Tomy et al. 1998b;2000). Tomy et al. (2000) observed that the concentration profiles for the Arctic marine mammals show a predominance of the shorter carbon chain length congeners, i.e., the C10 and C11 formula groups. Drouillard et al. (1998a) showed that these congeners are the more volatile components of SCCPs mixtures, which show a trend of decreasing VPs with increasing carbon chain length and degree of chlorination. Reth et al. (2006) measured SCCPs in liver and muscle from seabirds (little auk and kittiwake) collected at Bear Island (European Arctic). Concentrations ranged from 0.005 to 0.088 mg/kg wet weight.

Estimated atmospheric half-lives of many SCCPs are greater than 2 days for a large percentage (61% using hydroxyl radical concentration of 1.5 × 106 molecules/cm³ and 83% using hydroxyl radical concentration of 5 × 105 molecules/cm³) of example structures. Therefore, SCCPs meet the CEPA 1999 half-life criterion for persistence in air specified in the Persistence and Bioaccumulation Regulations (Government of Canada 2000). The detection of the more volatile shorter carbon chain length congeners of SCCPs in Arctic biota and in Arctic lake sediments in the absence of significant sources of SCCPs in this region suggests that these residues are present due to long-range atmospheric transport.

On the basis of the available information, it is concluded that estimated atmospheric half-lives of SCCPs exceed the criterion of 2 days and SCCPs are subject to long-range atmospheric transport. Hence, SCCPs are persistent in air according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

Sediments and soils

There is limited evidence for the biodegradation or removal of SCCPs from soil following sewage sludge application. Nicholls et al. (2001) did not detect SCCPs/MCCPs in farm soils amended with sludges containing mg/kg concentrations of CPs. However, worms living in these same soils did contain low mg/kg wet wt. levels of CPs.

Using 25-day biochemical oxygen demand (BOD) tests, Madeley and Birtley (1980) found that SCCPs composed of 49% chlorine appeared to be rapidly and completely degraded by acclimatized micro-organisms after 25 days. However, no significant oxygen uptake was observed in tests using the highly chlorinated CPs, which included two SCCPs (60% and 70% chlorine). On the other hand, Fisk et al. (1998a) found that two 14C-labelled C12 chloro-n-alkanes (56% and 69% chlorine) were degraded at 12°C in aerobic sediments used for a study of the bioavailability of SCCPs to oligochaetes. Half-lives in sediment were 12 ± 3.6 days and 30 ± 2.6 days for the 56% and 69% chlorine products, respectively.

A study on the aerobic and anaerobic biodegradation of SCCPs in both freshwater and marine sediments was undertaken by Thompson and Noble (2007). Using 14C-labelled n-decane and n-tridecane 65% chlorine by weight products and basing their experiments on the OECD 308 Test Guideline (aerobic and anaerobic transformation in aquatic sediment systems), mineralization (as measured by carbon dioxide or methane production) over 98 days was determined. The mean half-lives for mineralization for a C10-13, 65% chlorine by weight product, calculated as the average for the two individual products, were estimated to be 1630 days in freshwater sediments and 450 days in marine sediments under aerobic conditions. Little or no mineralization was noted in anaerobic sediments. It should be noted that these half-lives were calculated based on degradation observed after the 40-50 day lag phase, and that the half-lives were extrapolated beyond the available data.

SCCPs residues were found in the surficial sediments of the following remote Arctic lakes (reported in mg/kg dry wt.): Yaya Lake (0.0016), Hazen Lake (0.0045) and Lake DV09 (0.0176). The profile from Lake DV09 generally follows the pattern of historical usage of SCCPs (Stern and Evans 2003). Concentration profiles of SCCPs in sediments from Lake Winnipeg (Manitoba), Fox Lake (Yukon Territory), the west basin of Lake Ontario (Ontario) and Lake DV09 (Devon Island, Nunavut) indicate that SCCPs residues were present in the 1940s (Muir et al. 1999a; Tomy et al. 1999). The highest concentration in Lake Ontario (800 ng/g dry wt.) was observed in the slice dated at 1971 (Muir et al. 1999a).

In the absence of information on loading for any of the years at any of these locations, it is not possible to calculate discrete half-life values from these data for comparison with the criteria for persistence in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000). However, the fact that SCCPs residues were detected in sediment cores dating back to the 1940s at these locations is evidence that SCCPs can persist for more than 50 years in subsurface anaerobic sediments. Environment Canada (2008) used first order decay equations in a back calculation method to determine that SCCPs have a half-life in sediments longer than 1 year. The equation used for these calculations are standard first order decay equations.

Several government assessments and published reviews have concluded that only slow biodegradation in sediment may be expected to occur, even in the presence of adapted micro-organisms (Government of Canada 1993a,b; Tomy et al. 1998a; European Commission, 2000). On the basis of the available information, it is thus concluded that SCCPs are persistent in sediments according to the criterion stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

B- Bioaccumulation

Bioaccumulation factors (BAFs) for SCCPs chain length groups in Lake Ontario plankton, alewife (Alosa pseudoharengus), slimy sculpin (Cottus cognatus), rainbow smelt (Osmerus mordax) and lake trout (Salvelinus namaycush) were determined based on a whole organism (wet weight) and filtered water concentrations using data from Houde et al. (2006). SCCPs were found in all components of the food chain and BAFs ranged from 9 900 to 51 200 (wet weight). SCCPs bioaccumulated to the greatest extent in fish, with the highest BAFs (51 200) in sculpin, smelt and trout. Assuming no metabolism, the Modified Gobas BAF model for fish estimated BAF values greater than 5000 for all possible SCCPs (Arnot and Gobas 2003).

Bioconcentration factors (BCFs) calculated from laboratory studies for SCCPs have been reviewed in Government of Canada (1993b) and were found to vary dramatically among different species. Relatively low BCF values have been determined in freshwater and marine algae (<1-7.6). BCF values of up to 7 816 wet wt. have been measured in rainbow trout (Oncorhynchus mykiss) (Madeley and Maddock 1983a,b) and 5 785-138 000 wet wt. in the common mussel (Mytilus edulis) (Madeley et al. 1983b, Madeley and Thompson 1983d, Renberg et al. 1986).

Other evidence that SCCPs are bioaccumulative is as follows:

  • Reported log Kow values for SCCPs range from 4.39 - 8.69 (Table 1).
  • Lipid normalized biomagnification factors (BMFs) were also determined by Houde et al. (2006) for pelagic food webs in both Lakes Ontario and Michigan. BMFs ranged from 0.3 to 3.2. While BMFs are not a parameter considered in the Persistence and Bioaccumulation Regulations (Government of Canada 2000), BMFs are important supplemental information. If a substance has a BMF greater than one, it is more likely to have high BCF/BAF values.
  • Concentrations of SCCPs in fish collected around the Great Lakes between 1996 and 2001 ranged from 0.0046 to 2.63 mg/kg wet weight (Muir et al. 2001; and Houde et al. 2006). SCCPs have also been detected in the blubber of belugas from the St. Lawrence River at an average concentration of 0.785 mg/kg wet wt. (Tomy et al. 1998b; 2000) and blubber of ringed seal from several Arctic locations. Concentrations in these mammals from the Arctic and the St. Lawrence River ranged from 0.095 to 0.626 mg/kg wet wt. (Jansson et al. 1993; Tomy et al. 1998b; 2000). These relatively high concentrations suggest that SCCPs have the potential to bioaccumulate in aquatic organisms.
  • Tomy (1997) found that SCCPs (around 60-70% chlorine by weight) were present at a concentration of 0.011-0.017 mg/kg lipid (mean concentration 0.013 mg/kg lipid) in human breast milk from Inuit women living on the Hudson Strait in northern Quebec, Canada. These findings are indicative of bioaccumulation through the food chain since food would be the major or only source of environmental exposure for the Inuit.

On the basis of the available information, it is concluded that SCCPs are bioaccumulative substances according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

4.2.2 MCCPs

Table 3 summarizes persistence and bioaccumulation information for MCCPs in comparison with criteria in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

Table 3: Summary of persistence and bioaccumulation information on MCCPs
Medium or parameter CEPA criteria
(Government of Canada 2000)
MCCPs Information
Air t1/2 ≥ 2 days Estimated to be 2.7-7.1 days for vapor phase, but it should be noted that the extent of partitioning for MCCPs to air is low Degradation rate on airborne particles likely to be much slower
Sediment t1/2 ≥ 1 year Back calculation using concentrations from sediment cores shows half-life >1 year
Soil t1/2 ≥ 6 months Limited evidence for rapid biodegradation or removal following sludge applications
BAF ≥5000 Field BAFs for fish >5000 in Lake Ontario; high BMFs found in laboratory studies and a food web study in Lake Ontario and Lake Michigan; Modified Gobas Model predicts BAF>5000 for all congeners
BCF ≥5000 Laboratory BCFs <5000; however, the BCF was probably underestimated due to CP concentrations exceeding solubility
Log KOW ≥5 5.47-8.21 (measured and modeled)
A- Persistence
Air

Atmospheric half-lives for MCCPs were calculated using the Syracuse Research Corporation AOPWIN (v. 1.91) program using a hydroxyl radical concentration of 5 × 105 molecules/cm³. Half-lives for vapour phase MCCPs ranged from 2.7 to 7.1 days, with the longest half-lives for MCCPs with the highest chlorine contents and also with the shorter chain lengths. However, MCCPs have very low partitioning to air.

MCCPs have estimated VP (4.5 × 10-8 to 2.27 × 10-3 to Pa at 20-25°C) and HLC (0.014 - 51.3 Pa•m³/mol for C14-17 congeners) values that are in the range of VPs and HLCs for some persistent organic pollutants that are known to undergo long-range atmospheric transport under the 1979 UNECE Convention on Long Range Transboundary Air Pollution, such as lindane, heptachlor and mirex.

On the basis of the available information, it is concluded that estimated atmospheric half-lives of MCCPs exceed the criterion of 2 days and hence are persistent in air according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

Sediment and soil

There is limited evidence for the biodegradation or removal of MCCPs from soil following sewage sludge application. Nicholls et al. (2001) did not detect SCCPs/MCCPs in farm soils amended with sludges containing mg/kg concentrations of CPs. However, worms living in these same soils did contain low mg/kg wet wt. levels of CPs.

Concentrations of total MCCPs in a sediment core from Lake St. Francis, downstream of Cornwall, Ontario, ranged from 0.75 to 1.2 mg/kg dry wt, with the highest concentrations estimated to have been deposited in 1972 (Muir et al. 2002). Environment Canada (2008) used first order decay equations in a back calculation method to determine that MCCPs have a half-life in sediments longer than 1 year. The equation used for these calculations are standard first order decay equations. Moreover, the fact that MCCPs residues were detected in sediment cores dating back to the 1970s at these locations is evidence that SCCPs can persist for more than 30 years in subsurface anaerobic sediments. Persistence in sediment is particularly important as Level III fugacity calculations show that MCCPs are expected to partition primarily to sediment and soil.

On the basis of the available information, it is concluded that MCCPs are persistent in sediments according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

B- Bioaccumulation

Bioaccumulation factors (BAFs) for MCCPs chain length groups in Lake Ontario alewife (Alosa pseudoharengus), slimy sculpin (Cottus cognatus), rainbow smelt (Osmerus mordax) and lake trout (Salvelinus namaycush) were determined based on a whole organism (wet weight) and filtered water concentrations collected in 2001 using data in Houde et al. (2006). C14-15 MCCPs were found in all components of this food chain and BAFs ranged from 9.99 x 106 to 7.15 x 108. In addition, bioaccumulation factors (BAF) for 21 MCCPs congeners using the Modified Gobas BAF Model (assuming no metabolism) were all above the bioaccumulative criteria (≥5000 BAF) (Arnot and Gobas 2003).

Most of the laboratory-based BCF studies conducted on aquatic organisms may underestimate the true BCF, because the studies were performed at MCCPs concentrations above the water solubility limit, using acetone as the co-solvent in the test solutions, and hence are not in compliance with OECD guideline requirements. Estimated BCF values for common mussel, bleak and rainbow trout (32-2856) are all below the BCF criterion of 5000 (Madeley et al. 1983b; Madeley and Maddock 1983a; Bengtsson et al. 1979; Madeley and Thompson 1983a), except for one common mussel study which reported a BCF of 6920 (Renberg et al. 1986). The only BCF study that did not use acetone reported BCFs values of 349 to 1087 for rainbow trout following the OECD test method 305 (Thompson et al. 2000).

Other evidence that MCCPs are bioaccumulative is as follows:

  • Reported log Kow values for MCCPs range from 5.47 - 8.21 (Table 1).
  • Lipid normalized biomagnification factors (BMFs) were also determined by Houde et al. (2006) between Diporeia and sculpin in Lake Ontario and Lake Michigan. BMFs ranged from 1 to 15. Large BMFs were observed for these species for all chain lengths in Lake Ontario, and for C14 in Lake Michigan, indicating biomagnification. BMFs (2.4 - 7.7) were also above 1 for smelt and lake trout in Lake Michigan. In laboratory studies with rainbow trout and oligochaetes, lipid-normalized equilibrium BMFs estimated from a first-order bioaccumulation model for constant dietary exposure (Bruggeman et al. 1981) ranged from 0.4-5.0 (Fisk et al. 1996; 1998b;2000). While biomagnifications factors (BMF) are not a criterion considered in the Persistence and Bioaccumulation Regulations (Government of Canada 2000), BMFs are important supplemental information. If a substance has a BMF greater than one, it is more likely to have high BCF/BAF values.
  • Oligochaetes were found to have biota-sediment accumulation factors (BASFs) ranging from 0.6 to 4.4 (Fisk et al. 1998a). These BASFs, reflecting bioaccumulation from sediment at levels above that expected at equilibrium, imply significant food chain transfer.
  • Elevated levels of MCCPs were found in catfish from the Detroit River (0.904 mg/kg wet wt.), and in crab and mussel (up to 38.7 mg/kg lipid wt.) located near a CPs manufacturing plant in Australia (Tomy and Stern 1999; Kemmlein et al. 2002). Kemmlein et al. (2002) stated: "Bioaccumulation is clearly evident, the mussel meat containing around double and crab meat around six times the amount of chloroparaffins found in the most contaminated sediment sample."
  • MCCPs have been found in a breast milk sample (0.061 mg/kg lipid) from the United Kingdom (Thomas and Jones 2002), and C10-20 CPs were detected in liver, adipose and kidney tissues from human cadavers at up to 1.5 mg/kg wet wt. (Campbell and McConnell 1980a). These findings qualitatively indicate potential for bioaccumulation of MCCPs through the human food chain.

On the basis of the available information, and in particular the field BAF estimates, it is concluded that MCCPs are bioaccumulative substances according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

4.2.3 LCCPs

4.2.3.1 C18-20 liquid LCCPs

Table 4 summarizes persistence and bioaccumulation information for C18-20 liquid LCCPs in comparison with criteria in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

Table 4: Summary of persistence and bioaccumulation information on C 18-20 LCCPs
Medium or parameter

CEPA criteria
(Government of Canada 2000)

C18-20 LCCPs information
Air t1/2 ≥ 2 days Estimated to be 2.4-10.5 days but it should be noted that the extent of partitioning to air for LCCPs is low
Sediment t1/2 ≥ 1 year Unknown, but half-life likely > 1 year
Soil t1/2 ≥ 6 months Unknown
BAF ≥5000 Laboratory diet studies suggest highly chlorinated C18 has high BMF from food; insufficient information on field BAFs; Modified Gobas Model finds nearly half of the C18-20 congeners examined have BAF≥5000 (see section 4.4.3.3.)
BCF ≥5000 Laboratory BCFs <5000; BCF probably underestimated due to CP concentrations exceeding solubility
Log KOW ≥5 7.34 - 7.57 (modeled)
A- Persistence
Air

Atmospheric half-lives for liquid LCCPs were calculated using the Syracuse Research Corporation AOPWIN (v. 1.91) program using a hydroxyl radical concentration of 5 × 105 molecules/cm³. Half-lives for liquid LCCPs ranged from 2.4 to 10.5 days, with many example structures having half-lives greater than 2 days. However, C18-20 liquid LCCPs have very low partitioning to air.

C18-20 liquid LCCPs have estimated VP (5 × 10-4 to 2 × 10-8 Pa at 25 °C) values that are in the range of VPs for some persistent organic pollutants that are known to undergo long-range atmospheric transport under the 1979 UNECE Convention on Long Range Transboundary Air Pollution, such as lindane, heptachlor and mirex.

On the basis of the available information, it is concluded that estimated atmospheric half-lives of C18-20 liquid LCCPs exceed the criterion of 2 days and hence are persistent in air according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

Sediment and Soil

There is no empirical information available on the fate (i.e., half-lives) of LCCPs in soil or sediment with which to compare with the CEPA criteria. However, given that both SCCPs and MCCPs are expected to be persistent in sediment (half lives > 1 year), and that resistance to microbial degradation has been observed to generally increase with increases in carbon chain length (Allpress and Gowland 1999; Omori et al. 1987), it is likely that LCCPs also have half lives of more than 1 year in sediment.

On the basis of the available information, it is concluded that C18-20 liquid LCCPs are persistent in sediments according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

B- Bioaccumulation

Assuming no metabolism the Modified Gobas BAF Model predicts that 12 out of 27 (44%) C18-20 congeners meet the bioaccumulation criteria of BAF ≥5000 (Arnot and Gobas 2003). As confirmed by personal communication with Frank Gobas (Simon Fraser University, Burnaby, BC), the model is applicable for LCCPs, as they are simple hydrophobic and persistent chemicals.

On the other hand, BCF values for C18-26 liquid LCCPs were estimated by U.K. Environmental Agency (2001), using the data of Bengtsson et al. (1979) and were found to range from 8 to 16 in bleak; these values are below the BCF criterion of 5000 (Government of Canada 2000). However, this study may underestimate the true BCF values, because the study was performed at LCCPs concentrations above the solubility limit for water and hence was not in compliance with OECD guidelines. As well, the study did not indicate if steady state was reached during the uptake phase of the test.

Other evidence that LCCPs are bioaccumulative is as follows:

  • Reported log Kow values for C18-20 liquid LCCPs range from 7.34 - 7.57 (Table 1).
  • Biomagnification factors (BMFs) were determined by Fisk et al. (2000) in a dietary accumulation study involving juvenile rainbow trout exposed to C18H31Cl7. Lipid normalized BMFs ranged from 2.1 to 2.8. While biomagnifications factors (BMF) are not a criterion considered in the Persistence and Bioaccumulation Regulations (Government of Canada 2000), BMFs are important supplemental information. If a substance has a BMF greater than one, it is more likely to have high BCF/BAF values.
  • Fisk et al. (2000) also found that C18H31Cl7 has similar biotransformation half-lives in rainbow trout compared to half-lives of recalcitrant organochlorines (Fisk et al. 1998c). This suggests limited biotransformation or metabolism.
  • Limited biotransformation of LCCPs was also observed during an uptake/elimination study with bleak. Bengtsson and Baumann-Ofstad (1982) found that a C18-26 LCCPs had a low uptake efficiency, but 50% of this compound remained in the fish tissues after a 316-day elimination period, which suggests that some of the LCCPs isomers in this formulation are bioaccumulative (Bengtsson and Baumann-Ofstad 1982).
  • Elevated levels of C18-29 LCCPs were found in crab and mussel (9.3 and 14.3 mg/kg lipid wt., respectively) located near a CPs manufacturing plant in Australia (Kemmlein et al. 2002). Kemmlein et al. (2002) stated: "Bioaccumulation is clearly evident, the mussel meat containing around double and crab meat around six times the amount of chloroparaffins found in the most contaminated sediment sample." However it is unclear if bioaccumulation of C18-20 or C>20congeners was responsible for the elevated concentrations.

On the basis of the available information, and in particular the BAF model and empirical BMF estimates, it is concluded that C18-20 liquid LCCPs are bioaccumulative substances according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

4.2.3.2 C>20 liquid LCCPs

Table 5 summarizes persistence and bioaccumulation information for C>20 liquid LCCPs in comparison with criteria in the CEPA 1999 Persistence and Bioaccumulation Regulations (Government of Canada 2000).

Table 5: Summary of persistence and bioaccumulation information on C >20 liquid LCCPs
Medium or parameter CEPA criteria
(Government of Canada 2000)
C>20 liquid LCCPs information
Air t1/2 ≥ 2 days Estimated to be 1.8-8.4 days but it should be noted that the extent of partitioning to air for LCCPs is low
Sediment t1/2 ≥ 1 year Unknown, but half life likely > 1 year
Soil t1/2 ≥ 6 months Unknown
BAF ≥5000 Insufficient information on field BAFs; Modified Gobas Model finds none of the C>20 congeners examined have BAF≥5000
BCF ≥5000 Laboratory BCFs <5000; BCF probably underestimated due to CP concentrations exceeding solubility
Log KOW ≥5 >7.46 - 12.83 (estimated)
A- Persistence
Air

Atmospheric half-lives for liquid LCCPs were calculated using the Syracuse Research Corporation AOPWIN (v. 1.91) program using a hydroxyl radical concentration of 5 × 105 molecules/cm³. Half-lives for liquid LCCPs ranged from 1.8 to 8.4 days, with many example structures having half-lives greater than 2 days. However, LCCPs have very low partitioning to air.

C>20 liquid LCCPs have estimated VPs (5 × 10-5 to 3 × 10-15 Pa at 25 °C) that are in the range of VPs for some persistent organic pollutants that are known to undergo long-range atmospheric transport under the 1979 UNECE Convention on Long Range Transboundary Air Pollution, such as heptachlor and mirex.

On the basis of the available information, it is concluded that estimated atmospheric half-lives of C>20 liquid LCCPs exceed the criterion of 2 days and hence are persistent in air according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

Sediment and Soil

There is no empirical information available on the fate (i.e., half-lives) of LCCPs in soil or sediment with which to compare with the CEPA criteria. However, given that both SCCPs and MCCPs are expected to be persistent in sediment (half lives > 1 year), and that resistance to microbial degradation has been observed to generally increase with increases in carbon chain length (Allpress and Gowland 1999; Omori et al. 1987), it is likely that LCCPs also have half lives of more than 1 year in sediment.

On the basis of the available information, it is concluded that C>20 liquid LCCPs are persistent in sediments according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

B- Bioaccumulation

Although C>20 liquid LCCPs may have some potential to bioaccumulate, the Modified Gobas BAF Model predicts that none of the C>20 congeners meet the bioaccumulation criteria of BAF ≥5000. Thus, these very high molecular weight LCCPs are not expected to be bioaccumulative.

BCF values were found to range from 8-16 for C18-26 liquid LCCPs in bleak, and 18-1158 for liquid C>20 LCCPs in rainbow trout and common mussel (Madeley and Maddock 1983b; Bengtsson et al. 1979; Madeley and Thompson 1983b; U.K. Environment Agency 2001). However, these values may underestimate the true BCF values, because the studies were performed at LCCPs concentrations above the solubility limit for water and hence were not in compliance with OECD guidelines. As well, the studies did not indicate if steady state was reached during the uptake phase of the tests. BCF values for these species were below the BCF criterion of 5000.

On the other hand there is some evidence to suggest that C>20 LCCPs may be bioaccumulative:

  • Reported log Kow values for C>20 liquid LCCPs range from 7.46 - 12.83 (Table 1).
  • Limited biotransformation of LCCPs was also observed during an uptake/elimination study with bleak. Bengtsson and Baumann-Ofstad (1982) found that a C18-26 LCCPs had a low uptake efficiency, but 50% of this compound remained in the fish tissues after a 316-day elimination period, which suggests that some of the LCCPs isomers in this formulation are bioaccumulative (Bengtsson and Baumann-Ofstad 1982).
  • Elevated levels of C18-29 LCCPs were found in crab and mussel (9.3 and 14.3 mg/kg lipid wt., respectively) located near a CPs manufacturing plant in Australia (Kemmlein et al. 2002). Kemmlein et al. (2002) stated: "Bioaccumulation is clearly evident, the mussel meat containing around double and crab meat around six times the amount of chloroparaffins found in the most contaminated sediment sample." However it is unclear if bioaccumulation of C18-20 or C>20 congeners was responsible for the elevated concentrations.
  • C20-30 CPs were detected in fat and liver of some postmortem human tissues from the United Kingdom at concentrations between 0.080 and 3.5 mg/kg wet wt. These findings qualitatively indicate the potential for bioaccumulation of LCCPs in the human food chain.

Although there are noteable uncertainties, based mainly on the available BAF information, it is concluded that C>20 liquid LCCPs are not bioaccumulative substances according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

4.2.3.3 C>20 solid LCCPs

Table 6 summarizes persistence and bioaccumulation information for C>20 solid LCCPs in comparison with criteria in the CEPA 1999 Persistence and Bioaccumulation Regulations (Government of Canada 2000).

Table 6: Summary of persistence and bioaccumulation information on C >20 solid LCCPs
Medium or parameter CEPA criteria
(Government of Canada 2000)
C>20 solid LCCPs information
Air t1/2 ≥ 2 days Estimated to be =7.8 days but it should be noted that the extent of partitioning to air for LCCPs is low
Sediment t1/2 ≥ 1 year Unknown, but half life likely > 1 year
Soil t1/2 ≥ 6 months Unknown
BAF ≥5000 Low accumulation by salmon; poor absorption and high excretion via feces by rats; Modified Gobas Model predicts BAF <5000
BCF ≥5000 Laboratory BCFs <5000; BCF probably underestimated due to CP concentrations exceeding solubility
Log KOW ≥5 Unknown
A- Persistence
Air

Atmospheric half-lives for solid LCCPs were calculated using the Syracuse Research Corporation AOPWIN (v. 1.91) program using a hydroxyl radical concentration of 5 × 105 molecules/cm³. Half-lives for solid C18-25 LCCPs ranged from 7.8 to 15.5 days. However, LCCPs have very low partitioning to air.

On the basis of the available information, it is concluded that estimated atmospheric half-lives of C>20 solid exceed the criterion of 2 days and hence are persistent in air according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

Sediment and Soil

No soil or sediment half-life data exist for the C>20 solid LCCPs. However, given that both SCCPs and MCCPs are expected to be persistent in sediment (half lives > 1 year), and that resistance to microbial degradation has been observed to generally increase with increases in carbon chain length (Allpress and Gowland 1999; Omori et al. 1987), it is likely that LCCPs also have half lives of more than 1 year in sediment.

On the basis of the available information, it is concluded that C>20 solid LCCPs are persistent in sediments according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

B- Bioaccumulation

Although C>20 LCCPs may have some potential to bioaccumulate, the Modified Gobas BAF Model predicts that none of the C>20 congeners meet the bioaccumulation criterion of BAF ≥ 5000. Thus, these very high molecular weight LCCPs are not expected to be bioaccumulative.

Measured BCF values for solid LCCPs were found to range from 5.7 to 341 in fish and common mussels (Madeley and Maddock 1983c, Madeley and Thompson 1983c). However, these studies may underestimate the true BCF values, because the studies were performed at LCCPs concentrations above the solubility limit for water and hence were not in compliance with OECD guidelines. As well, the studies did not indicate if steady state was reached during the uptake phase of the tests. Estimated BCF values for these species were below the BCF criterion of 5000 (Madeley and Maddock 1983b,c; Bengtsson et al. 1979; Madeley and Thompson 1983b,c).

Log Kow values are not available for C>20 solid LCCPs.

Other evidence that C>20 LCCPs may not be bioaccumulative is as follows:

  • One aquatic BAF study was identified for C>20 solid LCCPs. Zitko (1974) observed very low accumulation of a 70% chlorine LCCPs by juvenile Atlantic salmon fed a diet that had high CP concentrations (10 and 100 µg/g) during a 181-day exposure period.
  • Two rat bioaccumulation studies with LCCPs, including C>20 solid LCCPs, showed high rates of excretion via feces and poor absorption of the LCCPs, Section 4.4.3.2, supporting document (Environment Canada, 2008). No BMF data exist for C>20 solid LCCPs.

Although there are noteable uncertainties, based on the available information it is concluded that C>20 solid LCCPs are not bioaccumulative substances according to the criteria stipulated in the Persistence and Bioaccumulation Regulations of CEPA 1999 (Government of Canada 2000).

4.3 Environmental Concentrations

This section describes the results of recent monitoring of CPs in environmental samples using analytical techniques having higher specificity for SCCPsS. Data on environmental levels of MCCPs and LCCPs are very limited. Due to the non-volatile and hydrophobic characteristics of these CP groups, the majority of results are for sediments and sewage sludges.

Data presented in this section focus on Canadian concentrations. In situations where Canadian data are lacking or are few, concentrations measured in other countries are presented. Additional information on ambient concentrations may be found in the supporting document (Environment Canada, 2008).

4.3.1 Atmospheric concentrations

SCCPs were detected in air in Canada, United Kingdon and Norway. They have also been detected in arctic air and in air of other remote areas (Section 4.2.1). Concentrations of SCCPs in air samples collected at Egbert, Ontario, Canada, in 1990 ranged from 65 to 924 pg/m³ (Tomy 1997; Tomy et al. 1998a). Concentrations of SCCPs over Lake Ontario in 1999 and 2000 ranged from 120 to 1510 pg/m³ (Muir et al. 2001).

No atmospheric concentration data are available for MCCPs and LCCPs, either in Canada or elsewhere.

4.3.2 Wastewater treatment effluents, sewage sludge and soils

SCCPs were detected in wastewater effluents in Canada, the United States and Germany. SCCPs were detected in all eight sewage treatment plant final effluents from southern Ontario, Canada, sampled in 1996. Total SCCPs (dissolved and particulate C10-13) ranged from 59 to 448 ng/L. The highest concentrations were found in samples from treatment plants in industrialized areas, including Hamilton, St. Catharine’s and Galt. No wastewater treatment effluent concentration data are available for MCCPs and LCCPs, either in Canada or elsewhere.

Concentrations of CPs have also been detected in sewage sludge in several European countries and the United States. Nicholls et al. (2001) found total CPs (SCCPs + MCCPs) concentrations in digested sewage sludge ranging from 1.8 to 93.1 mg/kg dry wt. in England and Wales. Similarly, Stevens et al. (2002) found SCCPs concentrations ranging from 6.9 to 200 mg/kg dry wt. in sewage sludge from 14 WWTPs in the United Kingdom. Highest concentrations of SCCPs were in sludge from industrial catchments. However, a rural catchment with zero industrial effluent had significant levels (590 mg/kg) of total SCCPs/MCCPs in sludge (Stevens et al. 2002). Total concentrations of MCCPs in sewage sludges from 15 WWTPs in the United Kingdom ranged from 30 to 9700 mg/kg dry wt. (Stevens et al. 2002). Agricultural soils may also be a potentially major reservoir of CPs due to sewage sludge application (Stevens et al. 2002; Nicholls et al. 2001). No values in sewage sludge or soil were identified for LCCPs. Concentrations of CPs in sewage sludge in Canada are not available.

4.3.3 Surface Waters

SCCPs were detected in surface waters in Canada and the United Kingdom. Low levels of dissolved total (C10-13) SCCPs were measured in western Lake Ontario between 1999 and 2004 (Muir et al. 2001, Houde et al. 2006). The concentration of total SCCPs was 1.75 ng/L in 1999. Concentrations of total SCCPs ranged from 0.606 - 1.935 ng/L over the 2000 - 2004 sampling period. Concentrations were generally greater in western Lake Ontario, likely due to the proximity of large urban areas (Houde et al. 2006). SCCPs concentrations of 30 ± 14 ng/L were measured in the Red River in Selkirk, Manitoba, over a 6-month period in 1995 (Tomy 1997).

MCCPs were detected in surface waters in Canada, the United States, the United Kingdom and Germany. Metcalfe-Smith et al. (1995) reported C14-17 MCCPs concentrations in a 24-hour composite sample of effluent from the only manufacturing plant in Canada, ICI Canada (now PCI Canada), on the St. Lawrence River at Cornwall, Ontario, to be 12 700 ng/L. This plant is not currently manufacturing CPs. Houde et al. (2006) collected water samples from various sites in Lake Ontario in 2002 and 2004. Total MCCPs concentrations ranged from <0.0005 to 0.0026 ng/L in filtered samples. Concentrations of MCCPs in an impoundment ditch that received effluent from a CP production plant in Dover, Ohio, were <150 - 3800 ng/L (Murray et al. 1988). MCCPs were found in all the samples taken in 16 rivers, canals and reservoirs in the United Kingdom (ICI 1992). Concentrations ranged from 620 to 3750 ng/L. The majority of the samples appear to have been collected in urban/industrial areas. Levels of MCCPs have been measured at several sites in Germany (Hoechst AG 1987; Ballschmiter 1994). The levels measured in 1987 ranged from 4 000 to 20 000 ng/L while those of 1994 were substantially lower and ranged from < 50 to 185 ng/L. 

There are no Canadian measured water concentrations of LCCPs and very few measurements of LCCPs in surface waters from other countries. Nicholls et al. (2001) reported <100 ng/L of any CP group in all sites near sewage treatment works in the United Kingdom except for one (Darwen, U.K.). Only one study was identified measuring surface water concentrations of LCCPs. Murray et al. (1988) conducted a study near a CPs production plant in Dover, Ohio, reporting total concentrations of C20-30, 40-50% chlorine LCCPs of 8300 ng/L in the middle of the impoundment lagoon at this site. In a drainage ditch leading from the impoundment lagoon, a concentration of 4200 ng/L total LCCPs (3700 ng/L particulate, 500 ng/L dissolved) was measured just above its discharge to Sugar Creek. A concentration of 620 ng/L particulates (<50 ng/L dissolved) was found in water from Sugar Creek, just downstream of the outlet of the drainage ditch.

4.3.4 Sediments

SCCPs were detected in sediments around the Great Lakes, St. Lawrence River, and other lakes in Canada, as well as in Germany, Czech Republic and the United Kingdom. They have also been detected in arctic sediment (Section 4.2.1). Concentrations of SCCPs in Lake Winnipeg and Lake Nippigon ranged from 0.008 to 0.176 mg/kg dry wt. (Tomy et al. 1999; Stern and Evans 2003). Tomy et al. (1997) measured SCCPs at concentrations around 0.245 mg/kg dry wt. in sediment from the mouth of the Detroit River at Lake Erie and Middle Sister Island in western Lake Erie, in 1995. SCCPs were also detected in all surface sediment samples from harbour areas along Lake Ontario at concentrations ranging from 0.0059 to 0.290 mg/kg dry wt. in 1996 (Muir et al. 2001). The highest concentrations were found at the most industrialized site (Windermere Basin, Hamilton Harbour), which has well-documented heavy metal, PAH and PCB contamination. Similarly, Marvin et al. (2003) reported a SCCPs concentration of 0.410 mg/kg dry wt. in Lake Ontario sediments near an industrialized area. SCCPs were detected in all 26 samples from Lake Ontario, and the average SCCPs concentration was 0.049 mg/kg dry wt., which is much higher than sediment concentrations reported for lakes (Yaya, DV09, Hazen, Nipigon) influenced primarily by atmospheric sources (Tomy et al. 1999; Stern and Evans 2003).

MCCPs were detected in sediments around the Great Lakes in Canada, as well as in the United States, Germany, Wales, Switzerland, Australia and the United Kingdom. Metcalfe-Smith et al. (1995) were unable to detect (<3.5 mg/kg dry wt.) SCCPs + MCCPs in sediments from the St. Lawrence River downstream of a CP manufacturing plant. Tomy and Stern (1999) reported concentrations of C14-17 MCCPs of 0.068 mg/kg dry wt. in sediment samples collected near the mouth of the Detroit River in western Lake Erie. Muir et al. (2002) reported concentrations of total MCCPs in a sediment core from Lake St. Francis downstream of Cornwall, Ontario, of 0.75 -1.2 mg/kg dry wt. The highest concentrations of MCCPs detected in sediments were found downstream from sewage treatment works in the United Kingdom. Concentrations of MCCPs ranged from <0.2 to 65.1 mg/kg dry wt. (Nicholls et al. 2001). Similar concentrations were found at several other locations downstream from sewage treatment plants in the United Kingdom (Nicholls et al. 2001).

No LCCPs were measured in sediments in Canada, but they have been detected in the United States, Australia and Germany near CP manufacturing plants. Concentrations of LCCPs in these countries ranged from 0.0081 to 170 mg/kg dry wt. (Rotard et al. 1998; Murray et al. 1988; Kemmlein et al. 2002).

4.3.5 Biota

A- Aquatic biota

SCCPs were detected in biota in Canada, England, Norway, Chile, Greece, Germany, Iceland, France, the United States, and the North and Baltic Seas. Muir et al. (2001) and Houde et al. (2006) measured SCCPs in fish collected from Lake Ontario and Lake Michigan, between 1996 and 2001. Concentrations of total SCCPs ranged from 0.0046 to 2.63 mg/kg wet wt. The highest concentration was measured in carp collected at Hamilton harbour (Muir et al. 2001). Houde et al. (2006) determined the concentration of SCCPs in plankton, Diporeia sp. and Mysis sp. from Lakes Ontario and Michigan. In Lake Ontario, total SCCPs concentrations in plankton, Diporeia and Mysis were 0.0055, 0.0063, and 0.0028 mg/kg wet wt., respectively, and in Lake Michigan they were 0.023, 0.024, and 0.0075 mg/kg wet wt., respectively. 

MCCPs have been measured in fish in Canada, the United Kingdon, Norway, Chile, Greece and Germany amongst others. Houde et al. (2006) also measured the concentrations of MCCPs in fish in Lake Ontario and Lake Michigan in 1999 and 2001. Concentrations of total MCCPs ranged from 0.0028 to 0.109 mg/kg weight wt. MCCPs were also detected in Diporeia at concentrations ranging from 0.0024 to 0.0041 mg/kg (Houde et al. 2006). The highest concentration in fish measured in Canada was 0.904 mg/kg weight wt. for catfish in the Detroit River (Tomy and Stern 1999).

Murray et al. (1988) measured concentrations of C20-30, 42% chlorine LCCPs in zebra mussels from Sugar Creek, Ohio, near a CPs manufacturing plant. Concentrations ranged from <0.007 upstream to 0.18 mg/kg downstream of where the drainage ditch from the plant emptied into Sugar Creek. Kemmlein et al. (2002) found high levels of C18-29 LCCPs in marine mussels and crabs (9.3 and 14.3 mg/kg lipid wt., respectively) near a CPs manufacturing plant in Australia.

B- Marine mammals

SCCPs have been detected in the blubber of belugas from the St. Lawrence River at an average concentration of 0.785 mg/kg weight wt. SCCPs have also been detected in the blubber of ringed seal from southwest Ellesmere Island (Eureka), Pangnirtung (Cumberland Sound) and Svalbard; in beluga whales from northwest Greenland, Sanikiluaq (Hudson Bay), Pangnirtung (Cumberland Sound), Kimmirut and the Mackenzie Delta; and in walrus from northwest Greenland. Concentrations of SCCPs from these areas ranged from 0.095 to 0.626 mg/kg weight wt. (Jansson et al. 1993; Tomy et al. 1998b; 2000).

Concentrations of MCCPs in beluga blubber in the St-Lawrence ranged from 1.8 - 80.0 mg/kg weight wt. (Bennie et al. 2000). However, results obtained by Bennie et al. (2000) may not be reliable due to interferences in the analytical method.

C- Terrestrial and avian wildlife

Very limited information is available on SCCPs concentrations in tissues of terrestrial wildlife. In Sweden, Jansson et al. (1993) reported CP concentrations (unspecified chain length) in rabbit (Revingeshed, Skåne), moose (Grismsö, Västmanland), reindeer (Ottsjö, Jaämtland) and osprey (from various regions in Sweden) to be 2.9, 4.4, 0.14 and 0.53 mg/kg lipid wt., respectively. Nicholls et al. (2001) reported the concentrations of SCCPs and MCCPs in earthworms residing in fields on which sludge had been applied ranging from <0.1 to 0.7 mg/kg dry wt. in the United Kingdom in the summer of 1998. Campbell and McConnell (1980a) determined levels of C10-20 CPs in birds in the United Kingdom. The C10-20 levels were likely to be dominated by contributions from the SCCPs and MCCPs. Concentrations of C10-20 CPs ranged from 0.1 to 1.2 mg/kg weight wt. in liver of birds and from <0.05 to >6 mg/kg in seabird eggs. Concentrations of C20-30 CPs ranged from not detected to 1.5 mg/kg weight wt. in liver of birds and from <0.05 to 1 mg/kg in seabird eggs. Reth et al. (2006) quantified SCCPs in liver and muscle from the seabirds, little auk (Alle alle) and kittiwake (Rissa tridactyla) collected at Bear Island (European Arctic). Concentrations between 0.005 and 0.088 mg/kg wet weight were measured. Reth et al. (2006) determined the concentration of C14-15 MCCPs in seabirds from the European Arctic. Concentrations ranged from 0.005 to 0.370 mg/kg wet wt.

4.4 Environmental effects

Overall, toxicity studies are few for effects of SCCPs to pelagic biota and mammals. Lowest-observed-effect concentrations (LOECs) (survival, reproduction and growth) ranged from 8 900 to 10 000 ng/L for pelagic biota. Effects of SCCPs to benthic and soil-dwelling organisms are not available. More toxicological data are available for MCCPs. In particular, the acute and chronic toxicity of MCCPs has been studied in algae, invertebrates and several species of fish. The range of acute effects is 5 900 ng/L to > 10g/L (10 000 000 000 ng/L). LOECs for pelagic biota ranged from 18 000 to 31 000 ng/L. Contrary to SCCPs, toxicity studies, albeit few, are available for benthic and soil-dwelling organisms. LOECs for sediment-dwelling biota ranged from 270 to 410 mg/kg dry weight. A reproductive LOEC for earthworm was reported to be 383 mg/kg dry weight. Few studies are available for effects of MCCPs to mammals; lowest-observed-adverse-effect levels (LOAELs) ranged from 4.2 to 5.7 mg/kg bw/day for effects to rats. Similarly, limited number of studies is available for effects to pelagic biota. Acute effects were observed at greater than 3 800 000 ng/L. Very few toxicological data are available for the three types of LCCPs. These data are presented below.

This section will focus on the most sensitive toxicological information used to derive the critical toxicity values (CTV) only. Additional toxicity information is available in the supporting document.

4.4.1 SCCPs

A- Pelagic aquatic organisms

The lowest toxic effect level identified for a pelagic freshwater aquatic species is 8900 ng/L, which is the 21-day chronic LOEC for Daphnia magna (Thompson and Madeley 1983a). The effect was for mortality of the offspring. The no-observed-effect concentration (NOEC) is 5000 ng/L.

B- Benthic organisms

A valid measurement endpoint was not available for a sediment-dwelling invertebrate. As a result, an equilibrium partitioning approach (Di Toro et al. 1991) using the most sensitive chronic measurement endpoint identified for a pelagic freshwater invertebrate aquatic species (8900 ng/L) was used to estimate the toxicity to benthic organisms. The LOEC benthic was estimated to be 35.5 mg/kg dry wt. for sediment containing 2% organic carbon (Environment Canada, 2008).

C- Soil-dwelling organisms

Bezchlebová et al. (2007) investigated the effects of SCCPs on the survival and reproduction of five species of soil organisms (Fosomia candida, Eisenia fetida, Enchytraeus albidus, Enchytraeus crypticus, and Caenorhabditis elegans). All tests were preformed following international methods, using an OECD artificial soil (70% sand, 20% clay, 10% peat) with an organic carbon content of approximately 2.7%. Folsomia candida (collembola) was identified as the most sensitive organism, with an LC50 value for adult survival and EC50 and EC10 values for reproduction of 5733, 1230, and 660 mg/kg dry wt. (nominal), respectively. The soil CTV for SCCPs is 660 mg/kg dry wt.

D- Mammals

In a 13-week oral (gavage) rat study by IRDC (1984), increases in liver and kidney weight and hypertrophy of the liver and thyroid occurred at doses of 100 mg/kg-bw per day. This value was the most sensitive LOAEL for mammals. Interspecies scaling using data for a typical adult otter was used to extrapolate to a food concentration for this species. This resulted in a CTV of 1000 mg/kg food. See Table 7 of this report and Appendix 2 of supporting document for additional information (Environment Canada, 2008).

4.4.2 MCCPs

A- Pelagic aquatic organisms

In a 21-day chronic study with Daphnia, Thompson et al. (1997) reported a LOEC of 18 000 ng/L and a NOEC of 10 000 ng/L for a decrease in the number of live offspring and the length of the parent organisms. This LOEC is the most sensitive toxicity value for aquatic organisms.

B- Benthic organisms

The most sensitive value for sediment toxicity of MCCPs is the LOEC for growth from a 28-day study with the amphipod Hyalella azteca using sediment that contained 5% organic carbon (Thompson et al. 2003). A statistically significant (p = 0.05) reduction in the mean dry weights of survivors in the treatment groups was seen at exposure concentrations of 270 mg/kg dry wt. and above when compared with the solvent control.

C- Soil-dwelling organisms

The most sensitive toxicity value for terrestrial organisms is the chronic (28-day) LOEC of 383 mg/kg dry wt. in soil with an organic carbon content of 2%, for reproduction in earthworms (Thompson et al. 2001a).

D- Mammals

The lowest effect level observed for mammals is the LOAEL of 4.2 mg/kg-bw per day for mild effects on the kidney and thyroid of female rats during a 13-week feeding study (Poon et al. 1995). Interspecies scaling using data for a typical adult otter was used to extrapolate to a food concentration for this species. This resulted in a CTV of 42 mg/kg food. See Table 7 of this report and Appendix 2 of supporting document for additional information.

4.4.3 LCCPs

4.4.3.1 LCCPs (C18-20 liquid)
A- Pelagic aquatic organisms

A chronic 21-day Daphnia magna study was carried out by Frank (1993) and Frank and Steinhäuser (1994). The most sensitive aquatic toxicity value for liquid C18-20 LCCPs is the 21-day (chronic) LOEC of 68 000 ng/L.

B- Soil-dwelling organisms

There are no studies available on the toxicity of either liquid or solid LCCPs to terrestrial plants, earthworms or other soil-dwelling organisms. Therefore, an equilibrium partitioning approach (Di Toro et al. 1991) using the most sensitive measurement endpoint identified for a pelagic freshwater species (68 000 ng/L) was used to estimate the toxicity of liquid C18-20 LCCPs to soil-dwelling organisms . The LOECsoil for C18-20 LCCPs was estimated to be 2035 mg/kg dry wt. for a soil containg 2% organic carbon (Environment Canada, 2008). 

4.4.3.2 LCCPs (C>20 liquid)

There is no relevant exposure or toxicity data available for C>20 liquid LCCPs in pelagic organisms, benthic organisms, or soil dwelling organisms.

A- Mammals

In 90-day and 2-year feeding studies with rats with C>20 (43% chlorine by weight) LCCPs, the lowest LOAEL in the studies was 100 mg/kg-bw per day (Serrone et al. 1987; Bucher et al. 1987; NTP 1986). This LOAEL was the most sensitive toxicity value. The main effects were seen on the liver, and in both studies effects were seen at the lowest concentrations. Interspecies scaling using data for a typical adult otter will be used to extrapolate to a food concentration for this species. This resulted in a CTV of 1000 mg/kg food. See Table 7 of this report and Appendix 2 of supporting document for additional information.

4.4.3.3 LCCPs (C>20 solid)

There is no relevant exposure or toxicity data available for C>20 solid LCCPs in pelagic organisms, benthic organisms, or soil dwelling organisms.

A- Mammals

Serrone et al. (1987) reported a LOAEL for hepatic lesions in female rats following administration by gavage of another long-chain CP (C20-30, 43% chlorine) during a 90-day study. In addition, mild nephrosis was observed in the kidneys of male rats, as was mineralization in the kidneys of female rats administered 3750 mg/kg-bw per day. A NOEL could not be established for the females (LOEL = 100 mg/kg- food). Interspecies scaling using data for a typical adult otter will be used to extrapolate to a food concentration for this species. This resulted in a CTV of 100 mg/kg food. See Table 7 of this report and Appendix 2 of supporting document for additional information.

4.5 Potential to Cause Ecological Harm

Potential to cause environmental harm may be estimated quantitatively using risk quotients (RQs). When RQs exceed 1 (in this case when estimated exposure values (EEVs) exceed estimated no-effect values (ENEVs)) this is an indication of potential for risk.

It is acknowledged, however, that when risks for persistent and bioaccumulative substances - such as SCCPs, MCCPs, and C18-20 LCCPs - are determined using standard methods, the risks may be underestimated. For example, since it can take decades for persistentsubstances to achieve maximum steady state concentrations in sediment and soil, EEVs based on monitoring data will be too low if steady state concentrations have not been achieved in these media. Similarly, since it can take a long time for persistent and bioaccumulative substances to reach maximum steady state concentrations in the tissues of laboratory organisms, ENEVs based on standard toxicity tests may underestimate effect thresholds if test durations are insufficient to achieve maximum internal organism concentrations. Furthermore, since food consumption is usually the primary route of exposure to persistent and bioaccumulative substances in the field -- especially for top predators -- ENEVs may underestimate effect thresholds if the food pathway is not considered in key toxicity studies. These factors are exacerbated when available effects and exposure data are limited, as is the case for the chlorinated paraffins.

Risk quotients were calculated for SCCPs, MCCPs, C18-20 LCCPs and C>20 LCCPs (Table 7). For each identified class of risk receptors (for example, pelagic organisms, benthic organisms), an EEV was selected based on empirical data. The maximum reported field concentration which is relevant to the Canadian environment was used as the EEV. Chemical concentrations from the Canadian environment were preferably used for EEVs; however, data from other regions in the world were used in the absence of suitable Canadian data. Section 8.2 of the supporting document (Environment Canada, 2008) further discusses this point. An ENEV was determined by dividing a critical toxicity value (CTV) by an assessment factor. CTVs, a detailed description is provide in Section 8.0 of the supporting document (Environment Canada, 2008), typically represent the lowest chronic ecotoxicity value from an available and acceptable data set. Assessment factors were used to reduce the CTV to account for extrapolation from a sometimes limited set of effects data for laboratory organisms, to estimates of effect thresholds for sensitive species in the field. Note that an extra assessment factor was not used to account for the tendency for conventional RQs to underestimate potential for harm for persistent and bioaccumulative substances. Results are summarized in Table 7.

Concentrations of C18-20 liquid LCCPs in sediments representative of Canadian environments are not available. In addition, no toxicity data were available for the effects of C18-20 liquid LCCPs on secondary consumers. Therefore, risk quotients could not be calculated for exposure of benthic organisms and secondary consumers to C18-20 liquid LCCPs. Furthermore there are no relevant exposure and toxicity data available for C>20 liquid and C>20 solid LCCPs in pelagic organisms, benthic organisms, or soil dwelling organisms. As such, risk quotients were not calculated for these groups.

Table 7 (SCCPs): List of estimated exposure values (EEV), critical toxicity values (CTV), assessment factors (AF), and estimated no exposure values (ENEV) used in the calculation of risk quotients (RQ)
Organism EEV CTV AF ENEV RQ
(EEV/ENEV)
Pelagic 44.8Footnote a ng/L 8 900Footnote b ng/L 10 (lab/field) 890 ng/L 0.05
Benthic 0.41Footnote c mg/kg 35.5Footnote d mg/kg 10 (lab/field) 3.55 mg/kg 0.12
Soil-dwelling 0.64Footnote emg/kg 660Footnote d mg/kg 10 (lab/field) 66.0 mg/kg 0.01
Secondary consumer 2.63Footnote f mg/kg 1 000Footnote g mg/kg food 100 (lab/field & species variations) 10 mg/kg 0.26
Table 7 (MCCPs): List of estimated exposure values (EEV), critical toxicity values (CTV), assessment factors (AF), and estimated no exposure values (ENEV) used in the calculation of risk quotients (RQ)
Organism EEV CTV AF ENEV RQ
(EEV/ENEV)
Pelagic 0.0026Footnote h ng/L 18 000Footnote i ng/L 10 (lab/field) 1 800 ng/L 0.0000014
Benthic 65.1Footnote j mg/kg 270Footnote k mg/kg 10 (lab/field) 27 mg/kg 2.40
Soil-dwelling 31.0Footnote l mg/kg 383Footnote m mg/kg 10 (lab/field) 38.3 mg/kg 0.81
Secondary Consumer 0.904Footnote n mg/kg 42Footnote o mg/kg food 100 (lab/field & species variations) 0.42 mg/kg 2.15
Table 7 (C 18-20 liquid LCCPs): List of estimated exposure values (EEV), critical toxicity values (CTV), assessment factors (AF), and estimated no exposure values (ENEV) used in the calculation of risk quotients (RQ)
Organism EEV CTV AF ENEV RQ
(EEV/ENEV)
Pelagic 100Footnote p ng/L 68 000Footnote q ng/L 10 (lab/field) 6 800 ng/L 0.02
Soil-dwelling 3.1Footnote r mg/kg 2 035Footnote s mg/kg 10 (lab/field) 203.5 mg/kg 0.02
Table 7 (C >20 liquid LCCPs): List of estimated exposure values (EEV), critical toxicity values (CTV), assessment factors (AF), and estimated no exposure values (ENEV) used in the calculation of risk quotients (RQ)
Organism EEV CTV AF ENEV RQ
(EEV/ENEV)
Secondary Consumer 0.0465Footnote t mg/kg 1 000Footnote u mg/kg 10 (lab/field) 100 mg/kg 0.0005
Table 7 (C >20 solid LCCPs): List of estimated exposure values (EEV), critical toxicity values (CTV), assessment factors (AF), and estimated no exposure values (ENEV) used in the calculation of risk quotients (RQ)
Organism EEV CTV AF ENEV RQ
(EEV/ENEV)
Secondary Consumer 0.0465Footnote v mg/kg 100Footnote w mg/kg 10 (lab/field) 100 mg/kg 0.000465

Only two of the 12 calculated risk quotients are larger than 1. The MCCPs risk quotient for benthic organisms (RQ=2.40) and the MCCPs risk quotient for secondary consumers (RQ=2.15) both suggest that MCCPs pose a risk to these receptors. However, because of limitations in available exposure and effects data mentioned above and explained in more detail in Section 8.2 of the supporting document, the absence of RQs above 1 for SCCPs and C18-20 LCCPs cannot be considered proof that these persistent and bioaccumulative substances do not cause ecological harm.

Because data available for C>20 LCCPs are very limited, only one RQ could be calculated for each of the solid and liquid subgroups. Although the resulting RQs are very low, this too is likely an underestimate of possible high-end risks, in part because of limitations in information on environmental concentrations close to relevant point sources (Section 8.2 of the supporting document).

Evidence that a substance is very persistent and bioaccumulative as defined in the Persistence and Bioaccumulation Regulations of CEPA 1999, when taken together with potential for environmental release and potential for toxicity to organisms, provides a significant indication of its potential to cause harmful long term ecological effects. Substances that are persistent remain in the environment for a long time, increasing the magnitude and duration of exposure. Releases of small amounts of bioaccumulative substances may lead to high internal concentrations in exposed organisms. Highly bioaccumulative and persistent substances are of special concern, since they may biomagnify in food webs, resulting in very high internal exposures, especially for top predators.

SCCPs, MCCPs and C18-20 LCCPs are considered to be both highly persistent and bioaccumulative. The limited available evidence suggests that although C>20 LCCPs are persistent, they are not bioaccumulative.

In addition, there is evidence (including some monitoring data), that SCCPs, MCCPs and C18-20 LCCPs are released into the Canadian environment and have the potential to cause harm to sensitive aquatic organisms at relatively low concentrations (i.e., chronic NOECs for pelagic organisms < 100 ng/L).

In light of this evidence, it is concluded that SCCPs, MCCPs and LCCPs up to C20 may be causing long term ecological harm in Canada.

4.6 Uncertainties on the ecological risk assessment

This risk assessment contains several sources of uncertainty. Uncertainties in the exposure and effects assessment can influence the characterization of risks. Below is a brief discussion of these uncertainties. Additonal details can be found in Section 8.2 of the supporting document.

4.6.1 Exposure, effects and risk quotient calculations

When Canadian exposure data were lacking, data from other countries were used as EEVs and assumed to be representative of Canadian conditions. Concentrations of CPs in various media were often only available for certain areas, and were only representative of a short time period, in Canada and other countries. As a result, it is unkown how concentrations of CPs vary temporally and spatially. Moreover, concentrations were often not available near potential point sources such as metalworking operations (primary source of CPs) and other formulating/manufacturing sites that use CPs.

Uncertainties with the toxicity information used to drive ENEVs in this assessment include:

  • The use of an equilibrium partitioning approach to estimate toxicity to benthic and soil organisms for SCCPs and LCCPs. 
  • The lack of aquatic toxicity tests for C>20 solid LCCPs, particularly with daphnids, a species that was found to be the most sensitive to SCCPs, MCCPs and liquid LCCPs.
  • The use of test substance concentrations in excess of their water solubility for all fish toxicity tests.

Additional assessment factors were not used to account for these limitations when deriving ENEVs from CTVs.

Because of the above-mentioned limitations - and the fact that in general risks of persistent and bioaccumulative substances are likely to be underestimated using standard assessment approaches - ecological risks from exposure to SCCPs, MCCPs, C18-20 LCCPs in Canada have likely been underestimated by risk quotient calculations, especially close to industrial sources. In the case of C>20 LCCPs, limitations in the available exposure and effects data mean that risks to secondary consumers have likely been underestimated, and that risks to other types of organisms cannot be estimated at all.

4.6.2 Persistence and Bioaccumulation Status and Risk Implications

Information on physical properties of MCCPs, and especially LCCPs, is limited. Values used in this assessment are based on extrapolations mainly from SCCPs or quantitative structure-activity relationships (QSARs). The analysis of SCCPs and MCCPs in sediment cores and associated calculations provide strong evidence for the persistence of these substances in the environment. Even though there are no data for persistence of LCCPs in sediment, based on biodegradation data which indicate increasing stability with increasing carbon chain length, it is reasonable to conclude that LCCPs are persistent in sediment.

The empirical and modelled bioaccumulation data for SCCPs and MCCPs are very robust and indicate the substances are bioaccumulative. While there is a lack of empirical bioaccumulation data for LCCPs, the modelling results provided by the Modified Gobas BAF Model - which suggest that of all the LCCPs congeners only liquid C18-20 LCCPs have significant bioaccumulation potential -- are considered credible.

Lastly, there are uncertainties associated with extrapolating from evidence that a substance is both persistent and bioaccumulative to a conclusion that it may be causing ecological harm. However, given that persistent and bioaccumulative substances have the potential to cause widespread harm that is difficult to reverse, a precautionary assessment approach is justified.

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