Alkanes, C16-47, branched and linear

Sediment toxicity

Link to relevant study record(s)

Reference

Endpoint:

sediment toxicity: long-term

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

Key result

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: Not stated

Key result

Duration:

28 d

Dose descriptor:

NOEC

Effect conc.:

560 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

emergence rate

Remarks on result:

other: Not stated

Key result

Duration:

28 d

Dose descriptor:

EC50

Effect conc.:

> 1 000 mg/kg sediment dw

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

development rate

Remarks on result:

other: Not stated

Details on results:

See any other information on results incl. tables section.

RESULTS

Range-findingTest

Emergence data (number of adult midges emerging from the test vessels) from the exposure of Chironomus riparius larvae to the test item during the range finding test are given in Table 1 - in attached section

Inspection of the data indicated that whilst the 10 and 100 mg/kg test concentrations showed similar emergence to the control, fewer midges emerged in the 1000 mg/kg test concentration compared to the control.

Based on this information test concentrations of 100, 180, 320, 560 and 1000 mg/kg were selected for the definitive test.

DefinitiveTest

Day 10 larval survival and growth

The Day 10 larval survival and growth data during the definitive test are given in Tables 2 and 3 - in attached section

Inspection of the data showed no differences in larval survival between the control and each test group. No significant differences (P≥0.05) were observed in larval growth, in terms of mean larval dry weight, between the control and each test group.

Mortality data

Emergence data (number of adult midges emerging from the test vessels) from the exposure of Chironomus riparius larvae to the test item during the definitive test are given in Table 4 - see in attached section.

Inspection of the emergence data showed similar numbers of emerged adult midges in the control and 100, 180, 320 and 560 mg/kg test concentrations. However, fewer adult midges were observed to have emerged from the 1000 mg/kg test concentration compared to the control. Following normalisation against the control the observed effect at 1000 mg/kg was determined to be less than 50% therefore an EC₅₀value could not be calculated.

Inspection of the emergence data gave the following results based on nominal test concentrations of spiked sediment:

Time (days)	EC50(emergence) mg/kg
28	>1000

The No Observed Effect Concentration after 28 days was 560 mg/kg. The No Observed Effect Concentration was based on no significant reduction in emergence.

There were no observed sub-lethal effects of exposure observed in the definitive test.

The sediment was sieved at the end of the study and the number of visible pupae that failed to emerge were counted (see Table 5 in attached section).

Emergence ratio data

Statistical analysis of the emergence ratio data, transformed by the square root arcsin function in order to obtain an approximate normal distribution and to equalise the variance, using Dunnett’s multiple comparison procedure (Dunnett 1955) (see Appendix 3 in attached section) showed no significant differences (P³0.05) between the control and 100, 180, 320 and 560 mg/kg test groups. However, significant differences were observed between the control and 1000 mg/kg test group.

Development site

The mean development rate per vessel was calculated for each test concentration (see Table 6 in attached section). The overall mean development rates for the control and each test concentration were calculated and an EC₅₀(development rate) estimated by inspection of the data.

The EC₅₀(development) rate based on nominal concentration was estimated to be greater than 1000 mg/kg.

No observed effect concentration

The No Observed Effect Concentration was 560 mg/kg on the basis that no biologically significant reduction in emergence was observed after 28 days and additionally no sub-lethal effects were observed at 560 mg/kg.

Validity criteria fulfilled:

yes

Conclusions:

The toxicity of the read across substance GTL Base Oil Distillates to the sediment-dwelling larvae of Chironomus riparius has been investigated and gave a 28-Day EC50 (emergence) of greater than 1000 mg/kg. The No Observed Effect Concentration was 560 mg/kg. The EC50 (development rate) based on nominal test concentrations was greater than 1000 mg/kg.

Executive summary:

Introduction.

A study was performed to assess the toxicity of the read across substance ‘Distillates (Fischer-Tropsch), heavy, C18-50 - branched, cyclic and linear' to the sediment-dwelling larvae ofChironomus riparius. The method followed was designed to be compatible with the OECD Guidelines for Testing of Chemicals No. 218 (April 2004) “Sediment-Water Chironomid Toxicity Test using Spiked Sediment”.

Methods.

Following a preliminary range-finding test 80 larvae of Chironomus riparius were exposed in groups of twenty (four replicates of 20 larvae per concentration) to formulated sediment spiked with test item over a range of concentrations of 100, 180, 320, 560 and 1000 mg/kg for a period of 28 days. The numbers of emerged adult midges were recorded daily.

A further 40 larvae (two replicates of 20 larvae) of each test group were prepared and sacrificed on Day 10 of the exposure period to determine the 10-Day larval survival and growth data.

Results.

The 28-Day EC₅₀(reduction in emergence) based on nominal test concentrations was greater than 1000 mg/kg. 

The No Observed Effect Concentration was 560 mg/kg.

The EC₅₀(development rate) based on nominal test concentrations was greater than 1000 mg/kg.

Analytical work indicated that extraction of the test item from the prepared ‘wet’ sediment was problematic, possibly due to an interaction between the water, calcium carbonate and solvents during extraction. Analysis was therefore also conducted on the ‘dry’ sediment following mixing with the test item but prior to the addition of the water.

Analysis of the ‘dry’ sediment on the day of preparation (Day -7) showed measured concentrations to range from 92% to 111% of nominal with the exception of the 180 mg/kg test concentration which showed a measured concentration of 73% of nominal value. Analysis of the corresponding duplicate sample stored frozen prior to analysis, showed a measured concentration of 90% of nominal value indicating that the initial analysis was erroneous. The results from the ‘dry’ sediment analysis indicated that the test item had been correctly prepared.

Analysis of the ‘wet’ sediment on Days -7, 0 and 28 showed measured concentrations to range from less than the limit of quantitation to 48% of nominal value. Analysis was also conducted on the ‘wet’ sediment after pre-drying the sediment at approximately 60°C. Analysis of these pre-dried samples on Days -7, 0 and 28 showed measured concentrations to range from 63% to 89% of nominal value.

Analysis of the overlying and interstitial ‘pore’ water on Days 0 and 28 showed measured concentrations of less than the limit of quantitation of the analytical method.

Description of key information

- NOEC (28 d): ≥1000 mg/kg sediment dw test mat. (nominal) based on: development rate
- EC50 (28 d): >1000 mg/kg sediment dw test mat. (nominal) based on: development rate
- NOEC (28 d): 560 mg/kg sediment dw test mat. (meas. (arithm. mean)) based on: mortality and emergence ratio
- EC50 (28 d): >1000 mg/kg sediment dw test mat. (nominal) based on: mortality and emergence ratio

Additional information

The toxicity of the read across substance GTL Base Oil Distillates has been determined in a test with the sediment organism Chironomus tentans. The test was conducted in accordance with OECD Test Guideline 218.

Chironomus tentans were exposed to formulated spiked sediment nominal loading rates of 100, 180, 320, 560 and 1000 mg/kg of test material over a period of 28 days. The study was carried out according to GLP and analytical monitoring took place. Analytical work on the ‘wet’ sediment was problematic, therefore analysis on the ‘dry’ sediment was also carried out.

The test results, expressed as the EC₅₀ and NOEC values, showed that the sample was not toxic to sediment organisms at 1000 mg/kg over the time period tested.

Analysis of the ‘dry’ sediment on the day of preparation (Day -7) showed measured concentrations to range from 90% to 111% of nominal. Analysis of the overlying and interstitial pore water on Days 0 and 28 showed measured concentrations to be <LOQ.