Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

No data are available for the toxicity to terrestrial organisms. Diurea 8 exhibits no measureable aquatic toxicity and direct and indirect emissions to the terrestrial environment are expected to be unlikely. Therefore no testing has been proposed for toxicity to terrestrial organisms and the endpoints have been waived on the basis that there is expected to be no exposure of the terrestrial environment.

Equilibrium partitioning

The ECHA guidance document Chapter R.10 – Dose [Concentration]-Response Regarding Environment guidance document (ECHA 2008) states that “when no toxicity data are available for soil organisms, the equilibrium partitioning method is applied to identify a potential risk to soil organisms”. Equilibrium partitioning is based on estimation of the toxicity to terrestrial organisms from the aquatic toxicity and the physico-chemical and environmental fate properties of the substance.

Based on the model outputs, the predicted water solubility values for Diurea 8 range from 1.83 E-11 to 0.38 mg/L, with a mean average of 0.0067 mg/L (Dawick 2012). Since the water solubility is less than 1 mg/L, Diurea 8 is considered to be poorly water soluble and is not expected to dissolve out of the grease matrix into the water phase.

Based on the model outputs, the predicted log octanol-water partition coefficient for Diurea 8 falls within a range of 6.6 to 17.2 (Dawick 2012). Since the log octanol-water partition coefficient values for Diurea 8 are all greater than 6, Diurea 8 is expected to reside within the grease base oil matrix and is not expected to partition to water and hence is not anticipated to be bioavailable.

Based on the model outputs, the predicted vapour pressures for Diurea 8 fall within a range of 4.02 E-20 to 2.82 E-11 Pa (Dawick 2012). Since the vapour pressures of all components of Diurea 8 are predicted to be substantially less than 1 Pa, Diurea 8 is expected to have very little to no tendency to partition to air.

The predicted physico-chemical properties of constituents of Diurea 8 indicate that their bioavailability to terrestrial organisms would be severely limited as the substance would be expected to remain entrained within the grease matrix. Furthermore as no effects were observed in any of the toxicity studies, it is not possible or appropriate to use the equilibrium partitioning method to estimate the toxicity to terrestrial organisms.

Exposure

The chemical constituents which make up Diurea 8 do not exist outside of the base oil grease matrix in which it is contained. Furthermore, chemical components of Diurea 8 are not expected to leach out or partition from the grease into water due to their poor water solubility and strong physical chemical interactions with the grease matrix. On the basis of the information provided, the terrestrial toxicity endpoints are therefore considered irrelevant for the assessment of the hazard of Diurea 8.

Conclusion for terrestrial toxicity

The isolated Diurea 8 is a solid with predicted negligible water solubility and very low vapour pressure. However, as Diurea 8 only occurs contained in a grease matrix designed to minimise leaching or partitioning to water, Diurea 8 is considered not to occur in its isolated form. On the basis of both the isolated properties and the form in which it is manufactured and used, Diurea 8 is expected not to be available in the aqueous environment or atmospheric compartment.

Based on the results of the QSPR models, the predicted log octanol-water partition coefficient values for Diurea 8 are all greater than 6 and therefore Diurea 8 is expected to reside within the grease base oil matrix. Diurea 8 is not expected to partition to water and hence is not anticipated to be bioavailable to terrestrial organisms.

Diurea 8 has extremely low predicted volatility (so aerial deposition is unlikely) and is not applied directly or expected to be exposed to soil during use. Thus, terrestrial exposure is considered to be unlikely and as the terrestrial toxicity would not be environmentally relevant, these tests have not been conducted.

 

References

Dawick J (2012) Diurea 8 Grease Thickener: In silico prediction of physicochemical properties. Shell International B.V., The Hague. Report number: HE.12.041

ECHA (2008) Guidance on information requirements and chemical safety assessment – Chapter R.10: Dose [Concentration]-Response Regarding Environment. European Chemicals Agency