Alkanes, C10-13, chloro

Ecotoxicological Summary

Hazard for aquatic organisms

Freshwater

Hazard assessment conclusion:

PNEC aqua (freshwater)

PNEC value:

0.5 µg/L

Assessment factor:

10

Extrapolation method:

assessment factor

Marine water

Hazard assessment conclusion:

PNEC aqua (marine water)

PNEC value:

0.15 µg/L

Assessment factor:

50

Extrapolation method:

assessment factor

STP

Hazard assessment conclusion:

PNEC STP

PNEC value:

6 mg/L

Assessment factor:

100

Extrapolation method:

assessment factor

Sediment (freshwater)

Hazard assessment conclusion:

PNEC sediment (freshwater)

PNEC value:

6.5 mg/kg sediment dw

Assessment factor:

20

Extrapolation method:

assessment factor

Sediment (marine water)

Hazard assessment conclusion:

PNEC sediment (marine water)

PNEC value:

1.3 mg/kg sediment dw

Assessment factor:

100

Extrapolation method:

assessment factor

Hazard for terrestrial organisms

Soil

Hazard assessment conclusion:

PNEC soil

PNEC value:

5.95 mg/kg soil dw

Assessment factor:

20

Extrapolation method:

assessment factor

Hazard for predators

Secondary poisoning

Hazard assessment conclusion:

PNEC oral

PNEC value:

5.5 mg/kg food

Assessment factor:

30

Additional information

PNEC aqua (freshwater)

For SCCPs, there are reliable short-and long-term toxicity tests with freshwater fish, invertebrates, and algae, covering three trophic levels (predators, plant-eating animals, and primary producers, respectively), and NOECs have been reported for each trophic level. The most sensitive NOEC was from the freshwater crustacean, Daphnia magna.

 

In a well-conducted GLP study, no significant effects on survival, reproduction and growth were seen in Daphnia magna exposed to a mean measured concentration of Chlorowax 500C (a C10-12 chlorinated paraffin; 58% chlorination) at up to 5 µg/L for 21 days. Therefore, the 21-day NOEC for Chlorowax 500C under these conditions was considered to be 5 µg/L and the LOEC was 8.9 µg/L (Thompson and Madeley, 1983a).

 

Indeed, data on MCCPs also indicate that Daphnia are the most sensitive species. Therefore, it can be presumed with a high probability that the most sensitive species has been examined (i.e. a further long-term toxicity test from a different taxonomic group would not result in a NOEC lower than the 5 µg/L already available). The 21-day NOEC of 5 µg/L determined for Daphnia in the Thompson and Madeley (1983a) study will be used in the PNEC determination and an AF of 10 is considered to be protective of other aquatic freshwater species.

 

PNECaqua (freshwater) = 5 µg/L / 10 = 0.5 µg/L

 

 

PNEC aqua (marine water)

For SCCPs, there are reliable short-and long-term toxicity tests with marine/estuarine fish, invertebrates, and algae, covering three trophic levels (predators, plant-eating animals, and primary producers, respectively), and NOECs have been reported for each. The most sensitive NOEC was from the marine mysid shrimp (Mysidopsis bahia).

 

In a well-conducted GLP study, the chronic toxicity of Chlorowax 500C (a C10-12 chlorinated paraffin; 58% chlorination) to the mysid shrimp was investigated in a saltwater flow-through system. Replicate samples of 20 shrimp/group, aged <48 h, were exposed to nominal concentrations of 0, 1.0, 1.8, 3.2, 5.6 and 10 µg/L (mean measured concentrations of 0, 0.6, 1.2, 2.4, 3.8 and 7.3 µg/L) for 28 days. There were no significant treatment-related effects on survival, sexual maturation, reproduction or final body length. The 28-day NOEC for Chlorowax 500C to the marine mysid shrimp was, therefore, determined to be 7.3 µg/L, the highest mean measured concentration tested (Thompson and Madeley, 1983d).

 

According to the TGD (Chapter R.10), where at least two long-term results (e.g. NOECs) from freshwater or saltwater species representing two trophic levels and one long-term result from an additional marine taxonomic group are available, an assessment factor of 50 can be used. For SCCPs, there are reliable long-term toxicity tests for freshwater and brackish/salt water fish and invertebrates, and an additional marine taxonomic group (molluscs), therefore an AF of 50 will be applied to the most sensitive NOEC of 7.3 µg/L obtained from the 28-day toxicity study on the marine mysid shrimp (Thompson and Madeley, 1983d).

 

PNECsaltwater (marine) = 7.3 µg/L / 50 = 0.15 µg/L

 

 

PNEC aqua (intermittent releases)

REACH TGD (R.16) states that “Intermittent releases are defined as occurring infrequently, i.e. less than once per month and for no more than 24 hours”. It is not anticipated that such releases will occur, therefore, a PNEC aqua for intermittent release has not been derived. If, however, such releases do occur in the future, the PNECs derived for continuous exposure are considered protective of intermittent releases, and can therefore be used.

 

PNEC STP (sewage treatment plant)

Toxicity data available for the effects of C10-13 chlorinated paraffins (52-70% chlorination) on bacteria suggest that SCCPs are of low toxicity to microorganisms.

According to the final RAR (EU, 2000), C10-13 chlorinated paraffins were of low acute toxicity to anaerobic bacteria from a domestic wastewater treatment plant, with toxicity seen at 5000, 1700, 2500 and 2000 mg/L for 52, 56, 58 and 62% chlorinated products, respectively (Hoechst AG, 1977) and the lowest reported toxic effect concentration of 600 mg/L reported for a 70% chlorinated product (Hoechst AG, 1976). This is the lowest threshold concentration reported to cause effects, and therefore considered the most sensitive test system available. The TGD suggests that an assessment factor of 10 can be applied to the NOEC from a test using mixed bacterial populations. Unfortunately, due to the limited information cited in the RAR (EU, 2000) for this study, no NOEC is given or can be deduced. Therefore, a precautionary AF of 100 will be added to this LOEC.

 

PNECmicroorganisms = 600 mg/L / 100 = 6 mg/L

PNEC sediment (freshwater)

There are no studies currently available on the effects of exposure to SCCPs on sediment-dwelling organisms (information is available on the midge Chironomus tentans, but exposure was via water only). In view of the similarities in structure and physicochemical properties [between SCCPs and MCCPs], it can reasonably be predicted that SCCPs would have similar effects to MCCPs on sediment-dwelling organisms. Indeed aquatic invertebrates (Daphnia) have been shown to be the most sensitive species following exposure to both SCCPs and MCCPs, therefore further testing of sediment-dwelling organisms is not considered necessary. [However, to account for the additional uncertainty of using read-across for derivation of the PNECsediment, an additional AF of 2 is included; see below].

 

For MCCPs, three prolonged toxicity studies, based on OECD Guideline 218, have been performed with freshwater amphipods, oligochaete worms and midges exposed to artificial sediment spiked with Cereclor S52 (a C14-17 chlorinated paraffin; 52% chlorination) for 28 days. Mortality and a range of sub-lethal toxicity endpoints such as reproduction, growth and emergence were assessed, and these are regarded as the most relevant. For Chironomus riparius, a 28-day NOEC of 3800 mg/kg sediment dry wt was determined based on the number of emerged adult midges (Thompson et al. 2001b). However, a lower 28-day NOEC of 130 mg/kg sediment dry wt has been reported based on the reduced growth seen in female amphipods (Hyalella azteca) and effects on mortality/reproduction in the oligochaete worm (Lumbriculus variegates) (Thompson et al. 2001a, 2002). Therefore, the lowest NOEC from these three reliable prolonged toxicity tests is 130 mg/kg sediment dry wt for both the freshwater amphipod and oligochaete worm (equivalent to about 50 mg/kg wet wt).

 

The TGD suggests that an assessment factor of 10 can be applied to the lowest NOEC from three long-term sediment tests with species representing different living and feeding conditions (which is the case with these amphipods, worms and midges). To account for the additional uncertainty of using read-across from MCCPs for derivation of the PNECsediment, an additional AF of 2 is included.

 

 

PNECsediment (freshwater): 130 mg/kg sediment dry wt / 10 = 13 mg/kg dry wt / 2 = 6.5 mg/kg sediment dry wt. Based on the default sediment wet:dry ratio of 2.6, this equates to 2.5 mg/kg wet wt. This value will be considered in the risk characterisation.

 

PNEC sediment (marine water)

No toxicity data with SCCPs (or MCCPs) are available for sediment-dwelling organisms in the marine environment. As described above, three reliable prolonged toxicity studies on MCCPs, based on OECD Guideline 218, have been performed with freshwater amphipods (Thompson et al. 2002), oligochaete worms (Thompson et al. 2001a) and midges (Thompson et al. 2001b) exposed to artificial sediment spiked with Cereclor S52 for 28 days. The lowest NOEC from these studies was 130 mg/kg sediment dry wt for both a freshwater amphipod and oligochaete worm. In view of the similarities in structure and physicochemical properties [between SCCPs and MCCPs], it can reasonably be predicted that SCCPs would have similar effects to MCCPs on sediment-dwelling organisms.

 

The TGD suggests that an assessment factor of 50 can be applied to the lowest NOEC from three long-term sediment tests with species representing different living and feeding conditions (which is the case with these amphipods, worms and midges). To account for the additional uncertainty of using read-across from MCCPs for derivation of the PNECsediment, an additional AF of 2 is included.

 

PNECsediment (marine water): 130 mg/kg sediment dry wt / 50 = 2.6 mg/kg dry wt / 2 = 1.3 mg/kg sediment dry wt. Based on the default sediment wet:dry ratio of 2.6, this equates to a value of 0.5 mg/kg wet wt. This value will be considered in the risk characterisation.

PNEC soil (terrestrial)

There are no studies currently available on the effects of exposure to SCCPs on soil organisms exposed directly via pore water and/or soil. For MCCPs, there are prolonged toxicity tests with plants [see note below], microorganisms and earthworms, covering primary producers, decomposers and consumers respectively. In view of the similarities in structure and physiochemical properties [between SCCPs and MCCPs], it can reasonably be predicted that SCCPs would have similar effects to MCCPs on sediment-dwelling organisms.

In GLP studies on MCCPs conducted according to OECD Guideline 208, no significant effects were seen on seedling emergence at 14 days and growth up to 28 days in wheat (Triticum aestivum), oilseed rape (Brassica napus) and mungbean (Phaseolus aureus) exposed to soil containing Cereclor S52 at up to nominal concentrations of 5000 mg/kg dry wt soil (the highest tested concentration; considered the NOEC for these studies) (Thompson et al. 2001d). [Please note, studies conducted according to the updated OECD Guideline 208 are designed to assess the potential effects of substances on seedling emergence and growth. Therefore, it is specific to a part of the plant's life-cycle and does not cover chronic effects or effects on reproduction. However, it is assumed to cover a sensitive stage in the life-cycle of a plant and therefore data obtained from this study can be used to estimate chronic toxicity.] In a GLP study conducted according to OECD Guideline 216, the effect of Cereclor S52 at up to 400 mg/kg dry wt soil (nominal concentration) on the transformation by soil microorganisms of an organic nitrogen source (lucerne) to nitrate over a period of 28 days has been assessed. No statistically significant decrease in nitrate formation was seen at any concentration, giving a NOEC of 400 mg/kg dry wt of soil (Thompson, 2002). In a GLP study conducted according to OECD Guideline 216 (draft 2000 version), exposure of earthworms (Eisenia fetida) to Cereclor S52 resulted in adverse effects on survival, growth and reproduction at measured concentrations of 9300, 2800 and 900 mg/kg dry wt soil, respectively, but none at 280 mg/kg dry wt soil (Thompson et al. 2001c).

Therefore, the overall lowest NOEC from these three studies was 280 mg/kg dry wt soil for effects on reproduction of earthworms (equivalent to about 248 mg/kg wet wt). As the majority of MCCP exposure to worms occurs via the pore water, this value has been converted to a standard soil, which is defined in the TGD as a soil with an organic matter content of 3.4% and organic carbon of 2% (the organic carbon content of the soil used in the worm study was 4.7%). Therefore, the normalised NOEC is calculated as follows:

NOECstandard = NOECexp xFomsoil(standard) = 119 mg/kg soil dry wt

                                                         Fomsoil(exp)

Where,

NOECexp = experimental NOEC = 280 mg/kg dry wt soil

NOECstandard = NOEC in standard soil

Fomsoil(standard) = fraction organic carbon in standard soil = 0.02

Fomsoil(exp) = fraction organic carbon in experimental soil = 0.047

 

Based on the default soil wet/dry ratio of 1.13, this equates to a value of 119 mg/kg soil dry wt / 1.13 = 105 mg/kg wet wt

 

The TGD suggests that an assessment factor of 10 can be applied to the lowest NOEC from three long-term tests with species representing three trophic levels (which is the case here). To account for the additional uncertainty of using read-across from MCCPs for derivation of the PNECsoil, an additional AF of 2 is included.

 

PNECsoil: 105 mg/kg wet wt / 10 =10.5 mg/kg wet wt/ 2 = 5.25mg/kg wet wt (or about 5.95 mg/kg soil dry wt)

 

PNEC oral (secondary poisoning; birds/mammals)

The reproductive toxicity of a C10-12 chlorinated paraffin (58% chlorination) was assessed in a GLP study performed using a protocol similar to OECD Guideline 206, in which Mallard ducks were fed the SCCP in the diet for 22 weeks at a concentration of up to 1000 mg/kg diet. A decrease in 14-day embryo viability was seen at the top dose, but no effects (including egg shell cracking, egg weight, egg shell thickness, and hatchability) were seen at 166 or 28 mg/kg diet. Therefore, the reproduction NOEC is considered to be 166 mg/kg diet and the parental NOEC 1000 mg/kg diet (Shults et al. 1984). The TGD suggests that an assessment factor of 30 could be applied to the NOEC from a chronic avian study.

 

PNECoral(bird) of 166 mg/kg diet /30 = 5.5 mg/kg food

 

However, the TGD suggests that “if a chronic NOEC for both birds and mammals is available, the lower of the resulting PNECs is used in the secondary poisoning assessment to represent all predatory organisms”.

 

A NOEC of about 1000 mg/kg food (using a conversion factor of 10 from a human relevant NOAEL of about 100 mg/kg bw/day) was reported in a good-quality GLP study (IRDC, 1984a) in which reductions in body weight and increases in kidney weights were seen at higher doses in rats fed a C10-12 chlorinated paraffin (58% chlorinated) for 13 weeks in the diet. According to the TGD an AF of 90 is appropriate for extrapolation from a 90-d study, which takes into account both species variation and lab-to-field extrapolation.

 

PNECoral(mammal); 1000 mg/kg diet / 90 = 11.1 mg/kg food

 

Overall, therefore, as it is the lower (and more health precautionary value) a PNECoral(bird) of 5.5 mg/kg food will be used in the risk characterisation.

 

             

Atmospheric compartment

No data are available on possible effects of SCCPs on the atmosphere. However, given their low volatility, neither biotic nor abiotic effects (e.g. global warming, ozone depleting, acidification) are likely.

 

Conclusion on classification

Based on the available data (48 h EC50 < 1 mg/L and a BCF>500), MCCPs should be classified as R50/53 (very toxic to aquatic organisms, may cause long-term adverse effects in the aquatic environment) according to the EU DSD and as H410 (Very toxic to aquatic life with long lasting effects) according to the EU CLP.