Alkanes, C16-47, branched and linear

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

A discussion and report on the read across strategy is given as an attachment in IUCLID Section 13.

Reason / purpose for cross-reference:

read-across source

Duration:

21 d

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

immobilisation

Remarks on result:

other: 95 % CL not reported.

Duration:

21 d

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks:

There were no statistically significant differences (P≥ 0.05) between the control and the 32 and 100 mg/l loading rate WAF groups in terms of length of daphnids.

Remarks on result:

other: 95 % CL not reported.

Duration:

21 d

Dose descriptor:

other: Lowest Observed Effect Loading rate" (LOEL)

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks:

at this loading rate no significant mortalities (immobilisation) were observed in the parental generation (P1) and that there were no significant differences (P ≥0.05) between the control and the 100 mg/l loading rate WAF test group in terms of numbers of

Remarks on result:

other: 95 % CL not reported

Details on results:

Validation of Mixing Period
Pre-study investigational work (see Appendix 2) indicated that there was no significant increase in the amount of total organic carbon in the WAF when the preparation period was extended for longer than 24 hours. Therefore the test was conducted using a
23-Hour stirring period followed by a 1-Hour settlement period.

Definitive Test
The observations for each test and control group are summarised in Tables 1 to 5. The total cumulative production of live young is given in Table 6 and the number of live young produced per adult is shown in Table 7. The total number of offspring per parent daphnia (for each replicate) alive at the end of the test is shown in Figure 1. Data for each individual replicate flask are given in Appendices 5 to 8.

Vortex depth measurements
The vortex depth was recorded at the start and end of the mixing period and was observed to be a dimple at the water surface on each occasion (see Table 8).

Observations on Test Material Solubility
Observations on the test media were carried out during the mixing and testing of the WAFs.
At the start of the mixing period the 10, 32 and 100 mg/l loading rates were observed to be clear, colourless water columns with oily globules of test item floating at the surface. After 23 hours stirring and a 1-Hour standing period the 10, 32 and 100 mg/l loading rates were observed to remain clear, colourless water columns with oily globules of test item floating at the surface. Microscopic inspection of the WAFs showed no micro-dispersions or globules of test item to be present. After siphoning and for the duration of the test, the 10, 32 and 100 mg/l loading rates were observed to be clear, colourless solutions.

Lethal Effects on the Parental Generation (P1)
Mortality was observed at the 10 mg/l loading rate WAF on Day 20. However, statistical analysis of the mortality data using the corrected chi-squared statistic (Breslow and Day 1980) showed that the observed mortalities in the 10 mg/l loading rate WAF test group were not significant (P0.05) when compared to the control group.
No further mortality occurred throughout the test and, hence, no prolonged effects attributable to exposure of Daphnia magna to the test item were observed.
The following EL*50 (immobilisation) values based on nominal loading rates were estimated throughout the test:
Time EL*50
(mg/l)
24 hours >100
48 hours >100
96 hours >100
7 days >100
14 days >100
21 days >100
The daphnids in the 10, 32 and 100 mg/l loading rate WAF test groups were observed to be the same size and colour as the control animals.
Sub-lethal Effects on the Parental Generation (P1)
After 21 days there were no statistically significant differences between the control and all the test groups in terms of the number of live young produced per adult (see Appendix 4).


The EL*50 (reproduction) value, based on nominal loading rates was estimated to be greater than 100 mg/l loading rate WAF.
After 21 days the length of each surviving adult was determined, the results of which are given in Appendix 12. The results showed that there were no statistically significant differences (P 0.05) between the control and the 32 and 100 mg/l loading rate WAF test groups in terms of length of the daphnids after 21 days exposure to the test item (see Appendix 4). The daphnids from the 10 mg/l loading rate WAF test group were shown to be statistically smaller (P<0.05) compared to the control group. A review of the data indicated that this was due to a few larger daphnids in the control group compared to the test groups. Given that no significant differences were observed between the control and remaining loading rate WAF test groups in terms of daphnia lengths, and that no significant differences were observed in terms of the number of live young produced between the control and all the test groups, it was considered that the difference observed was due to natural variation within the daphnia population rather than an effect of the test item.
* EL = Effective loading rate

Effects on the Filial Generation (F1)
Information on the effects of the test item on the F1 generation is limited, since, by study design, the young are removed soon after liberation from the brood pouch. However, an assessment made at each media renewal showed the "filial" daphnids produced by all the test groups were in the same general condition as the young produced by the controls over the duration of the test.
Young were first produced in the control test group on Day 8 of the test.
Numbers of unhatched eggs and dead young were low in all control and treatment groups surviving to maturation.

Lowest Observed Effect Loading Rate
The "Lowest Observed Effect Loading rate" (LOEL) was considered to be greater than 100 mg/l loading rate WAF on the basis that at this loading rate no significant mortalities (immobilisation) were observed in the parental generation (P1) and that there were no significant differences (P0.05) between the control and the 100 mg/l loading rate WAF test group in terms of numbers of live young produced per adult by Day 21.

No Observed Effect Loading Rate
The "No Observed Effect Loading rate" (NOEL) was 100 mg/l loading rate WAF as there were no significant mortalities (immobilisation) observed in the parental generation (P1) and there were no significant differences (P0.05) in terms of the number of live young produced per adult when compared to the control after 21 days.

Total organic carbon analysis
Total Organic Carbon (TOC) analysis of the freshly prepared test preparations (see Appendix 3) showed amount of carbon present within the 10, 32 and 100 mg/l loading rate WAF test vessels to range from less than the limit of quantitation (LOQ) for the method (1.0 mg carbon C/l) to 1.60 mg C/l. TOC analysis of the old test media showed the amount of carbon present to range from less than the LOQ to 1.20 mg C/l.
Given the background level of carbon in the control vessels and also the low level of carbon in the test vessels, it was considered that all the results were around the limit of quantitation of the analytical methodand hence did not provide definitive evidence of stability of the test preparations.
The dissolved test item may have been one or several components of the test item. Given that toxicity cannot be attributed to a single component or mixture of components but to the test item as a whole, the results were based on nominal loading rates only.

Validation Criteria

The following validation criteria were achieved during the test:

	Required	Actual
a       Control mortality	≤20%	0%
b       Dissolved oxygen	> 3 mg O2/l	> 8.2mg O2/l
c       pH (control group)	deviation ≤ 1.5	0.9
d       Mean number of live young per surviving adult (control group)	≥ 60 after 21 days	64
e       Coefficient of variation for control group	≤ 25 %	13%

Please see attached table 1 to table 8.

Validity criteria fulfilled:

yes

Conclusions:

CONCLUSION
Exposure of Daphnia magna to the read across substance Distillates (FT), heavy, C18-50-branched, cyclic and linear resulted in no significant mortalities at all the loading rates employed during the test.
The 21-Day EL50 (immobilisation) values, based on nominal loading rates, for the parental Daphnia generation (P1) were estimated to be greater than 100 mg/l loading rate WAF.
No significant impairment of reproduction was observed at the loading rates employed during the test.
The 21-Day EL*50 (reproduction) based on nominal loading rates was greater than 100 mg/l loading rate WAF.
The "Lowest Observed Effect Loading rate" (LOEL) based on nominal loading rates was considered to be greater than 100 mg/l loading rate WAF and the "No Observed Effect Loading rate" (NOEL) was considered to be 100 mg/l loading rate WAF.

Executive summary:

Introduction.

A study was performed to assess the effect of the read across substance 'Distillates (Fischer-Tropsch), heavy, C18-50 - branched, cyclic and linear’ on the reproduction of Daphnia magna over a 21-day period. The method followed that described in the OECD Guidelines for Testing of Chemicals No 211 (1998) "Daphnia magna, Reproduction Test", referenced as Method C.20 of Commission Regulation (EC) No. 440/2008.

Methods.

Based on data supplied by the Sponsor, Daphnia magna were exposed (10 replicates of a single daphnid per group) to Water Accommodated Fractions (WAFs) of the test item over a range of nominal loading rates of 10, 32 and 100 mg/l for a period of 21 days. The WAFs were renewed 3 times per week. The numbers of live and dead adult Daphnia and young daphnids (live and dead) were determined daily. The Daphnia were fed daily with an algal suspension. 

Results.

The 21-Day EL*₅₀(immobilisation) values, based on nominal loading rates, for the parental Daphnia generation (P₁) was estimated to be greater than 100 mg/l loading rate WAF.

The 21-Day EL*₅₀(reproduction) value based on nominal loading rates was estimated to be greater than 100 mg/l loading rate WAF.

The "Lowest Observed Effect Loading rate" was considered to be greater than 100 mg/l loading rate WAF on the basis that at this loading rate no significant mortalities (immobilisation) were observed in the parental generation (P₁) and that there were no significant differences (P ≥0.05) between the control and the 100 mg/l loading rate WAF test group in terms of numbers of live young produced per adult by Day 21.

The "No Observed Effect Loading rate" was considered to be 100 mg/l loading rate WAF on the basis that at this loading rate there were no significant mortalities (immobilisation) observed in the parental generation (P₁) and that there were no significant differences (P ≥0.05) between the control and the 100 mg/l loading rate WAF test group in terms of numbers of live young produced per adult by Day 21.

Total Organic Carbon (TOC) analysis of the freshly prepared test preparations showed the amount of carbon present within the 10, 32 and 100 mg/l loading rate WAF test vessels to range from less than the limit of quantitation (LOQ) for the method (1.0 mg carbon C/l) to 1.60 mg C/l. TOC analysis of the old test media showed amount of carbon present to range from less than the LOQ to 1.20 mg C/l. 

Given the background level of carbon in the control vessels and also the low level of carbon in the test vessels, it was considered that all the results were around the limit of quantitation of the analytical method and hence did not provide definitive evidence of stability of the test preparations.

The dissolved test item may have been one or several components of the test item. Given that toxicity cannot be attributed to a single component or mixture of components but to the test item as a whole, the results were based on nominal loading rates only.

CONCLUSION

Exposure of Daphnia magna to the test item resulted in no significant mortalities at all the loading rates employed during the test.

The 21-Day EL^*₅₀(immobilisation) values, based on nominal loading rates, for the parental Daphnia generation (P₁) were estimated to be greater than 100 mg/l loading rate WAF.

No significant impairment of reproduction was observed at the loading rates employed during the test.

The 21-Day EL*₅₀(reproduction) based on nominal loading rates was greater than 100 mg/l loading rate WAF.

The "Lowest Observed Effect Loading rate" (LOEL) based on nominal loading rates was considered to be greater than 100 mg/l loading rate WAF and the "No Observed Effect Loading rate" (NOEL) was considered to be 100 mg/l loading rate WAF.

*EL = Effective loading rate

Description of key information

(21d) NOELR ≥100 mg/L  (D. magna) 

Additional information

An invertebrate reproduction study has been conducted with the read across substance GTL Base Oil Distillates using the freshwater species Daphnia magna (Goodband, 2010). The test was conducted in accordance with OECD 211 and was compliant with GLP.

Daphnia magna were exposed to water accommodated fractions (WAFs) of the test material over a range of nominal loading rates of 10, 32 and 100 mg/l for a period of 21 days under semi-static test conditions. The WAFs were prepared by stirring for 23 hour and then leaving to stand for 1 hour.

The Lowest Observed Effect Loading Rate was considered to be greater than 100 mg/l on the basis that at this loading rate, no significant differences (P³0.05) were observed between the control and the 100 mg/l WAF loading rate in terms of numbers of live young produced per adult by Day 21.

The No Observed Effect Loading Rate (NOELR) was considered to be 100 mg/l on the basis that at this loading rate there were no significant mortalities (immobilisation) observed in the parental generation (P₁) and that there were no significant differences (P³0.05) between the control and the 100 mg/l loading rate WAF test group in terms of numbers of live young produced per adult by Day 21.

Total Organic Carbon (TOC) analysis of the freshly prepared test preparations showed amount of carbon present within the 10, 32 and 100 mg/l loading rate WAF test vessels to range from less than the limit of quantitation (LOQ) for the method (1.0 mg C/l) to 1.60 mg C/l. TOC analysis of the old test media showed amount of carbon present to range from less than the LOQ to 1.20 mg C/l.