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

Long-term toxicity to fish

Description of key information

(33-d) NOELR ≥100 mg/l P. promelas (read-across, reliability 2).

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

100 mg/L

Additional information

A Fish Early Life Stage study has been conducted for with GTL Gasoil using the freshwater speciesPimephales promelas(Fathead minnow) for GTL Gasoil (Priestly, 2010a). The test was conducted in accordance with OECD 210 and was compliant with GLP.

Newly laid eggs 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 33 days at a temperature of 25°C ± 2°C under semi-static test conditions. The test was conducted using completely full test vessels which were covered to minimise any potential for volatile losses of the test substance.

There were no significant mortalities or sub-lethal effects at any loading rate. The mean hatching rate ranged from 92 to 95% and the mean survival rate ranged from 93 to 98%. There were no statistically significant reductions in mean fish length or dry weight at any loading rate when compared with controls. The report concluded that there were no effects on survival or growth of newly laid eggs of fathead minnows when exposure to loading rates up to 100 mg/l GTL Gasoil. The No Observed Adverse Loading Rate (NOELR) was therefore determined to be at least 100 mg/l.

A Fish Early Life Stage study has been conducted with GTL Base Oil Distillates using the freshwater speciesPimephales promelas(fathead minnow) (Priestly, 2010a). The test was conducted in accordance with OECD 201 and was compliant with GLP. TOC content was analysed in the test media for stability and exposure concentration.

Newly laid eggs 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 33 days at a temperature of 25°C ± 2°C under semi-static test conditions. 

There were no significant mortalities or sub-lethal effects at any loading rate. The mean hatching rate ranged from 87 to 92% and the mean survival rate ranged from 81 to 98%. There were no statistically significant reductions in mean fish length or dry weight between the control group and the 32 and 100 mg/l WAFs loading rate. However the observations at the 10 mg/l loading rate WAF were significantly different from the control. This was considered by the authors to be due to normal biological varation. The report concluded that there were no effects on survival or growth of newly laid eggs of fathead minnows when exposure to loading rates up to 100 mg/l GTL Distillates. The No Observed Effect Loading Rate (NOELR) was therefore determined to be at least 100 mg/l.

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 11.64 mg C/l. TOC analysis of the old test media showed amount of carbon present to range from less than the LOQ to 2.75 mg C/l There was no significant difference in TOC content between control and exposure vessels. This was expected due to the low water solubility of the test substance. 

Conclusion

Long-term fish toxicity tests are available for two GTL-derived substances in the relevant carbon number range for the registration substance. In the absence of adverse effects in these studies it can be concluded that, based on weight of evidence, the NOELR(freshwater fish) for Hydrocarbons, C16-C22, n-alkanes, isoalkanes, <2% aromatics is ≥100 mg/l