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EC number: 203-678-8 | CAS number: 109-53-5
Long-term toxicity to aquatic invertebrates
Administrative data
Link to relevant study record(s)
Description of key information
Long-term effect on aquatic invertebrates are not to be expected.
Key value for chemical safety assessment
Additional information
QSAR-Disclaimer:
In Article 13 of Regulation (EC) No 1907/2006, it is laid down that information on intrinsic properties of substances may be generated by means other than tests, provided that the conditions set out in Annex XI (of the same Regulation) are met.
According to Annex XI of Regulation (EC) No 1907/2006 (Q)SAR results can be used if (1) the scientific validity of the (Q)SAR model has been established, (2) the substance falls within the applicability domain of the (Q)SAR model, (3) the results are adequate for the purpose of classification and labeling and/or risk assessment and (4) adequate and reliable documentation of the applied method is provided.
For the assessment of the substance, (Q)SAR results were used for the estimation of the long-term toxicity to aquatic invertebrates. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint is sufficiently covered and suitable for risk assessment.
Therefore, further experimental studies are not provided.
Assessment:
The long-term toxicity of isobutyl vinyl ether (CAS 109-53-5) was assessed using ECOSAR v2.2 and the OECD Toolbox v4.5. The typical test for the assessment of the long-term toxicity to aquatic invertebrates is a reproduction test with Daphnia magna. According to the relevant OECD TG 211 (OECD, 2012), the total number of living offspring is assessed at the end of the test. Additional parameters to characterize the reproductive output of the parent animals can be reported in addition to the total number. However, the Toolbox mainly provides data for the endpoint "reproduction". Additional endpoints deliver in most approaches an insignificantly low number of datapoints (n <= 10). Therefore, the data gap filling process with the Toolbox focuses on the endpoint "reproduction" as such. In case of ECOSAR, the QSAR model predicts long-term toxicity based on a chronic value (ChV), which is the geometric mean of the NOEC and the LOEC. The endpoint is not further specified.
Toolbox: The substances used to build the regression are substances with the classification as class 1 of the modified Verhaar acute aquatic toxicity classification scheme, which describes substances with narcosis or baseline toxicity. This MOA was further strengthened by using the acute aquatic MOA by OASIS (basesurface narcotics) and substances without an alert for protein binding by OECD and by OASIS.
Although the effect value EC10 should be preferred over the NOEC for the assessment of long-term toxicity, this trend analysis is based on the NOEC as the number of datapoints was by far higher for the approach using the NOEC (number of data/chemicals after subcategorizing: EC10: n = 27/17; NOEC: n = 138/81). The 21‑d NOEC for isobutyl vinyl ether (CAS 109-53-5) was estimated to be 3.78 mg/L.
ECOSAR v2.2 classifies the substance primarily as "Vinyl/Allyl/Propargyl Ethers". However, the QSAR models for this ECOSAR class are not reliable as they are derived from a very low number of substances (n <= 10). In addition, the results for the chronic effect values for fish and daphnids were derived using an acute to chronic ratio, which is also not reliable, especially as documentation of the database is lacking.
Therefore, the prediction for the neutral organic SAR was used to assess the long-term toxicity for aquatic invertebrates. This classification is justified as isobutyl vinyl ether is classified as basesurface narcotics (and narcosis/baseline toxicity) by the modified acute aquatic toxicity scheme of Verhaar and the acute aquatic toxicity MOA scheme of OASIS. No alert for protein binding was found (OASIS, OECD). It can be concluded that there are no indications for excess toxicity above the baseline.
ECOSAR v2.2 predicted a ChV of 0.742 mg/L for isobutyl vinyl ether. The substance is in the applicability domain of the model.
In a conservative approach, the lowest chronic effect level of ethyl vinyl ether is used for the assessment of long-term toxicity to aquatic invertebrates (ChV = 0.724 mg/L).
It can be concluded that long-term effects on aquatic invertebrates are expected.
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