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Long-term toxicity to aquatic invertebrates

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A long-term study on aquatic invertebrates with Oxooil LS9 is not available. In a first step, the PNEC for the aquatic environment is derived from short-term toxicity tests with a conservative assessment factor. The risk assessment according to Annex I of the REACh regulation (EC) No 1907/2006, based on the result from the short-term tests, reveals an acceptable risk (PEC/PNEC <1) of Oxooil LS9 on aquatic organisms. Therefore, the effect of Oxooil LS9 on aquatic organism does not need to be investigated further and a long-term test with invertebrates is not required. 

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Additional information

A long-term study on aquatic invertebrates with Oxooil LS9 is not required. In a first step, the PNEC for the aquatic environment is derived from short-term toxicity tests with a conservative assessment factor. Short-term aquatic toxicity was investigated for three trophic levels (fish, aquatic invertebrates and algae) using water accommodated fractions (WAFs). The most sensitive species for acute aquatic toxicity is Daphnia magna with an EC50 (48 h) of 12 mg/L nominal loading rate WAF and a NOEC of 5.6 mg/L nominal loading rate WAF (OECD TG 202). Oxooil LS 9 is therefore evaluated as acutely harmful to aquatic organisms. Oxooil LS9 is not harmful to fish or algae. The LC50 (96 h) for Oncorhynchus mykiss is >100 mg/L (OECD TG 203) and the EC 50 (72 h) for growth rate for the green algae Desmodesmus subspicatus is 120 mg/L (OECD TG 201).

In accordance with REACh Regulation Annex IX, 9.1, column II, long-term toxicity testing shall be proposed by the registrant if the chemical safety assessment indicates the need to investigate further the effects on aquatic organisms.

The risk assessment according to Annex I of the REACh regulation (EC) No 1907/2006, based on the result from the short-term tests, reveals an acceptable risk (PEC/PNEC <1) of Oxooil LS9 on aquatic organisms. Therefore, the effect of Oxooil LS9 on aquatic organism does not need to be investigated further and a long-term test with invertebrates is not required.

Supporting data are available of structurally similar substances from the C7-C9 Aliphatic Hydrocarbon Solvents Category (SIDS, 2010):

A 21-day Daphnia magna reproduction toxicity study is available for one member of the subcategory, hydrocarbons, C7-C9, n-alkanes, isoalkanes, cyclics (CAS RN 64742-49-0). All measured biological parameters (reproduction rate, survival of first generation daphnids, the time to first brood, and the length of first-generation daphnids at the conclusion of the test) were equally sensitive during this test. Exposure of daphnids to the test substance resulted in a NOELR value of 1.0 mg/L and a LOELR value of 2.0 mg/L, based on nominal loading rates.

Although the substance was not readily biodegradable in an OECD TG 310 study and hydrolysis is not considered to be a relevant pathway of degradation, the substance is not expected to be persistent. A fugacity model (Mackay level III model; EpiSuite v. 4.11) demonstrated that the constituents of the UVCB substance Oxooil LS9 will predominantly partition to water or volatilise into air to significant amounts. Volatilization from water is predicted to occur rapidly (hours to days), with Henry’s Law Constants (EpiSuite v4.11, US EPA, 2012; HENRYWIN v3.20; bond method) ranging from 3.14 Pa-m³/mole to 3.77E+005 Pa-m³/mole. Due to its volatility, photodegradation (EpiSuite v4.11, US EPA, 2012; AOP v1.92) is the major pathway of degradation with half-lives for hydroxyl radical reaction ranging from 1.14 h to 15.49 h; for olefins, additionally reaction with ozone is possible; half-lives ranged from 13.75 min to 22.92 h. Overall, these results indicate fast photodegradation of the substance. Consideration of these degradation processes supports the assessment that the substance will degrade relatively rapidly in the environment and does not persist. Therefore, based on the volatility of the substance, no long-term effects to aquatic organisms are expected.

The weighted mean log Kow of Oxooil LS9 was calculated to be 4.17. Based on this screening criterion (log Kow </=4.5) no relevant bioaccumulation would be expected. Additionally, the bioaccumulation potential of Oxooil LS9 was estimated by QSAR (EpiSuite v4.11, US EPA, 2012; BCFBAF v3.01).

The estimation of the bioaccumulation of the constituents of Oxooil LS9 by QSAR (EpiSuite v4.11, US EPA, 2012; BCFBAF v3.01) resulted in values ranging from 27.8 to 1220 L/kg for the single constituents and a weighted mean of 326.5 L/kg. The highest BCF value of 1220 L/kg was obtained for one constituent present at low quantity in Oxooil LS9– all other constituents have BCF values lower than 300 L/kg, which is below the cut-off of </=2000 L/kg. Therefore, the overall bioaccumulation potential of Oxooil LS9 is low.

Overall, results from a Daphnia reproduction study conducted with a structurally related substance show, that the extrapolation from the available short-term toxicity studies is sufficiently conservative to also cover long-term exposure. The PNEC derived from the short-term toxicity study in Daphnia magna with Oxooil LS9 was 12 µg/L. The PNEC derived from the Daphnia reproduction study with structurally related substance would be 20 µg/L applying an assessment factor of 50 in accordance with the Guidance on information requirements and chemical safety assessment. Chapter R.10: Characterisation of dose [concentration]-response for environment (2008). Therefore, no additional information would be expected from a chronic study.

Reference

SIDS, 2010. SIDS Dossier: C7-C9 ALIPHATIC HYDROCARBON SOLVENTS. OECD HPV Chemical Programme, SIDS Dossier, approved at SIAM 30 (20/04/2010)