Polyurea, produced by reacting aryl isocyanate with alkyl amines

Endpoint summary

Additional information

On the basis of experimental ecotoxicity data, Diurea 8 is not acutely toxic to fish, invertebrates or inhibitory to algal growth as it has acute aquatic lethal loading (LL) or effect loading (EL)50 values of >100 mg/L.

Due to the initial lack of experimental ecotoxicity data for Diurea 8, a novel testing strategy was undertaken. Due to the low aqueous solubility, tests were conducted as Water Accommodated Fractions of Diurea 8 and Diurea 8 within base oil grease (base grease). Amounts of test item were added to the surface of the dilutent at the appropriate loading rates and the media was stirred by a magnetic stirrer using a stirring rate such that a vortex was formed to give a dimple at the water surface. The stirring was stopped after 23 hours and the mixtures allowed to stand for 1 hour. A wide bore glass tube, covered at one end with Nescofilm was submerged into the vessel, sealed end down, to a depth of approximately 5 cm from the bottom of the vessel. A length of Tygon tubing was inserted into the glass tube and pushed through the Nescofilm seal and the WAFs removed by mid-depth siphoning (the first approximate 75-100 mL discarded) to give the WAFs. 

Isolated Diurea 8, only tested for toxicity to algal growth, showed no effects at a water accommodated fraction (WAF) loading rate of 100 mg/L. Diurea 8 in base grease showed no acute aquatic toxicity effects at a water accommodated fraction (WAF) loading rate of 100 mg/L to fish, invertebrates (Daphnia) and algae. Therefore, for fish the 96 hour LL50 is > 100 mg/L WAF, forDaphniathe 48 hour EL50 is >100 mg/L and for algal growth inhibition the 72 hour EL50 is >100 mg/L. The acute aquatic toxicity of Diurea 8 in base oil to fish (Harlan 2011f), invertebrates (Harlan 2011g) and algae (Harlan 2012d) and the toxicity isolated Diurea 8 to algae (Harlan 2012c) were determined in GLP-compliant, limit tests following OECD guidelines 203, 202 and 201 respectively.

Discussion on isolated and base grease forms

The individual chemical constituents of Diurea 8 do not exist outside of the grease matrix, but are synthesized during the production of the grease by reacting the starting materials of Diurea 8 within a synthetic or mineral lubricating base oil to form an insoluble fibrous network structure within the grease. The Diurea 8 used in the ecotoxicity tests was prepared in base oil without other additives at a concentration of approximately 20%. The concentration of Diurea 8 in the base oil was higher than would be expected in the finished greases, which are diluted with additives, and therefore provide a worst-case scenario for the toxicity of Diurea 8 to the aquatic environment. Because the Diurea 8 thickener components are created within the grease matrix, their ecotoxicological properties and requirements to provide test data on these endpoints should be interpreted with this understanding.

Studies on the toxicity of Diurea 8 to algae are available for both its isolated form as well as in the base grease. Both studies show Diurea 8 exhibited no toxicity to algae at loading rates significantly above its limit of water solubility. In both tests, the results gave EL50 (effect loading rate) values of greater than 100 mg/L WAF for both growth rate and yield. Correspondingly the No Observed Effect Loading Rate (NOELR) was 100 mg/L WAF.

The results of the acute studies on algae indicate that the toxicity of Diurea 8 is not influenced by the presence or absence of the base grease. As the constituents of Diurea 8 do not exist outside of the grease matrix, the studies on the toxicity of Diurea 8 in base grease to algae, invertebrates and fish are therefore considered to be reliable, adequate and relevant to satisfy these endpoints.

Chronic aquatic toxicity

No data are available for the long-term toxicity to invertebrates or fish for Diurea 8. Algal studies report both acute and chronic endpoints and therefore the data collected from the algal growth inhibition studies will be used to provide chronic data for this trophic level. The toxicity of isolated Diurea 8 and Diurea 8 in base grease showed no effects at 100 mg/L WAF in the reliable studies. Therefore, the 72 hour NOELR was determined to be 100 mg/L WAF in both of these studies (Harlan 2012c, d).

REACH Chapter R5 (ECHA 2011a) states that chronic aquatic ecotoxicity testing may be triggered if the CSA indicates that there is a need to investigate further the effects on the environment. Testing may be triggered if additional testing could alter the conclusions on classification, PBT assessment or the level of concern. Diurea 8 has a low potential for bioaccumulation and shows no acute toxicity at up to 100 mg/L WAF loading rate. No chronic effects were observed in the algal toxicity tests at up to 100 mg/L WAF loading rate. Additional chronic toxicity tests would therefore not lead to changes in the classification or the conclusion that Diurea 8 is neither PBT nor vPvB. As Diurea 8 is not classified or considered to be PBT/vPvB, an exposure assessment is not required and so additional chronic testing is not required to refine this assessment (ECHA R7b 2012b). Further chronic testing of invertebrates and fish is therefore not triggered and these endpoint data requirements are waived.

Sediment toxicity

No data are available for the toxicity to sediment organisms. Sediment toxicity data is not a data requirement at the registered tonnage band.

References

ECHA (2011) Guidance on information requirements and chemical safety assessment – Chapter R.5: Adaptation of information requirements. European Chemicals Agency

ECHA (2012) Guidance on information requirements and chemical safety assessment – Chapter R.7b: Endpoint Specific Guidance. European Chemicals Agency