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Ecotoxicological information

Toxicity to soil microorganisms

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Description of key information

- (28d) EC50 320 mg/kg dw soil micro-organisms [OECD 216; test mat. 'Distillates (Fischer-Tropsch), C8-26 - branched and linear']
- (28d) NOEC 100 mg/kg dw soil micro-organisms [OECD 216; test mat. 'Distillates (Fischer-Tropsch), C8-26 - branched and linear']

Key value for chemical safety assessment

Short-term EC50 for soil microorganisms:
320 mg/kg soil dw
Long-term EC10 or NOEC for soil microorganisms:
100 mg/kg soil dw

Additional information

A nitrogen transformation test is available for the closely related substance GTL Gasoil (“Distillates (Fischer-Tropsch), C8-26 - branched and linear”). The test was conducted in accordance with OECD 216 and GLP:

Soil microorganisms were exposed to the test material at concentrations of 100, 180, 320, 560 and 1000 mg/kg (dry weight) for 28 days at a temperature of 21°C, in the dark, with addition of Lucerne-green-grass meal as a respiratory substrate. The inhibitory effect of the test substance on nitrogen transformation was determined by measurement of nitrate concentrations in soil samples taken on Days 7, 14, 21 and 28, in comparison to control samples.

The effect of the test substance on nitrogen transformation gave an EC50of 320 mg/kg dw and a NOEC of 180 mg/kg dw.

A nitrogen transformation test is available for GTL Base Oil Distillates (“Distillates (Fischer-Tropsch), heavy, C18-50 - branched, cyclic and linear”) as well. The test was conducted in accordance with OECD 216 and GLP:

Soil microorganisms were exposed to the test material at concentrations of 1000 mg/kg (dry weight) for 28 days at a temperature of 21°C, in the dark, on natural soil with an organic carbon content of 0.97 ± 0.07% with addition of Lucerne-green-grass meal as a respiratory substrate. The inhibitory effect of the test substance on nitrogen transformation was determined by measurement of nitrate concentrations in soil samples taken on Days 7, 14, 21 and 28, in comparison to control samples.

The effect of the test substance on nitrogen transformation gave an EC50 greater than 1000 mg/kg dw.

Conclusion

Soil microorganism toxicity data are available for two related substances in the relevant carbon number range for members of the Category “Hydrocarbons, C14-C20, aliphatics, <2% aromatics”.

For GTL Base Oil Distillates (C18 -C50) there were no effects up to the highest dose level of 1000 mg/kg dw soil. For GTL Gasoil (C8-C26), the EC50 (28-d) was determined to be 320 mg/kg dw soil, and the corresponding NOEC was 100 mg/kg dw soil. It is likely that the effects observed in the study with GTL Gasoil are attributable to the lower carbon number constituents but in the absence of individual constituent data for the terrestrial compartment to support this, the worst-case EC50and NOEC are read across to the category.