Hydrocarbons, C16-C22, n-alkanes, isoalkanes, <2% aromatics

Toxicity to aquatic algae and cyanobacteria

Description of key information

(72-h) ErL50 >100 mg/l WAFs D. subspicatus (read-across, reliability 2).

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L

Additional information

Measured toxicity data are available for Hydrocarbons, C18-C24, isoalkanes, <2% aromatics to the freshwater green alga Pseudokirchneriella subcapitata (Vryenhoef, 2014b). The test was conducted under static conditions (no renewal of the test media) in accordance with OECD Test Guideline 201. Appropriate modifications to the test and media preparation procedures were made to take account of the test substance containing multiple constituents, having low solubility in water and being potentially volatile. No effects on growth of P. subcapitata (expressed in terms of average specific growth rate (µ) and the area under the growth curve (A)) were determined after 72 hours of incubation in the test medium prepared as a water-accommodated fraction (WAF) at a loading rate of 100 mg/l; the EL50 values for both growth parameters were >100 mg/l and the NOELRs were >100 mg/l. Total Organic Carbon (TOC) analysis of the 100 mg/l loading rate WAF test preparation at 0 hours showed a measured concentration of 1.82 mg C/l. A decline in measured TOC was observed at 72 hours to 0.98 mg C/l. The results of the test are considered to be reliable.

Measured toxicity data are available for Shell GTL Solvent GS270 (Hydrocarbons, C15-C19, n-alkanes, isoalkanes, <2% aromatics) to the freshwater green alga Pseudokirchneriella subcapitata (Vryenhoef, 2014c). The test was conducted under static (no renewal of the test media) conditions in accordance with OECD Test Guideline 201 and method C3 of EC Regulation No. EC 761/2009. Appropriate modifications to the test and media preparation procedures were made to take account of the test substance containing multiple constituents, having low solubility in water and being potentially volatile. No effects on growth (expressed in terms of yield (y) and growth rate (r)) of P. subcapitata were observed after 72 hours exposure to the test medium prepared as a water-accommodated fraction (WAF) at a loading rate of 100 mg/l; 72-hour E_yL₅₀ and E_rL₅₀ values were >100 mg/l and NOELR values were ≥100 mg/l. Total Organic Carbon (TOC) analysis of the 100 mg/l loading rate WAF test preparation at 0 hours showed a measured concentration of 4.93 mg C/l. A decline in measured carbon concentration was observed at 72 hours to 0.79 mg C/l. The results of the test are considered to be reliable.

 

The acute toxicity of a sample of GTL Gasoil has been determined by Palmer (2001) in a test with the unicellular alga Raphidocelis subcapitata. The tests were conducted in accordance with OECD Test Guideline 201.

WAFs of the sample were prepared in sealed vessels with minimum headspace by stirring for approximately 72 hours. The contents of the vessels were left to stand for 1-2 hours before drawing off the aqueous phase – the WAF – for testing. Static exposures were then carried out in completely full, sealed vessels. The tests were not subject to GLP and the test media were not analysed for stability or for exposure concentration of the test substance. However in other respects they were considered to fulfil the requirements of current best practice.

The test results, expressed as the EL₅₀and NOEL values, showed that the sample was not acutely toxic to algae at a loading rate of 1000 mg/l.

Albertus and Phillips (2005) have reported results for anacute toxicity test carried out ona second sample of GTL Gasoilwith the freshwater alga Selenastrum capricornutum.

The test was carried out using a scaled-down version of the US EPA algal bottle test method. In all cases the test media were water-accommodated fractions of the test sample that were prepared in sealed vessels with a small headspace according to the CONCAWE methodology for the ecotoxicological testing of petroleum products (CONCAWE report, 1993).

The test results, expressed as the EL₅₀and NOEL values, showed that the sample was not acutely toxic to algae at a loading rate of 1000 mg/l.

The toxicity of a sample of GTL Base Oil Distillates has been determined by Harlan (Vryenhoef, 2009) in a test with the unicellular alga Desmodesmus subspicatus. The tests were conducted in accordance with OECD Test Guideline 201.

Desmodesmus subspicatus were exposed to water accommodated fractions (WAFs) of the test material over a single nominal loading rates of 100 mg/l for a period of 72 hours. The WAFs were prepared by stirring for 23 hour and left to stand for 1 hour before drawing off the aqueous phase – the WAF – for testing. Static exposures were then carried. The study was carried out according to GLP and analytical monitoring, TOC analysis, also took place. 

The test results, expressed as the EL₅₀and NOELR values, showed that the sample was not toxic to algae at a loading rate of 100 mg/l.

Total Organic Carbon (TOC) analysis of the freshly prepared test preparations showed amount of carbon present within the 100 mg/l loading rate WAF test vessels to be less than the limit of quantitation (LOQ) for the method (1.0 mg C/l) in fresh and old test media samples.

Conclusion

Algal growth inhibition tests are available for the registered substannce and for two GTL-derived substances in the relevant carbon number range for the registered substance. In the absence of adverse effects in these studies it can be concluded that, based on weight of evidence, the ELR₅₀(algae) for Hydrocarbons, C18 -C24, isoalkanes, <2% aromatics is >100 mg/l and the NOELR is ≥100 mg/l.