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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

The test substance does not significantly accumulate in organisms.

Key value for chemical safety assessment

Additional information

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. Furthermore according to Article 25 of the same Regulation testing on vertebrate animals shall be undertaken only as a last resort.

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 test substance (Q)SAR results were used for bioaccumulation. The criteria listed in Annex XI of Regulation (EC) No 1907/2006 are considered to be adequately fulfilled and therefore the endpoint(s) sufficiently covered and suitable for risk assessment.

Therefore, and for reasons of animal welfare further experimental studies on bioaccumulation are not provided.

The bioaccumulation potential of the substance was tested in a guideline study following OECD 305 (Institute of Ecotoxicology 2002). Japanese carp (Cyprinus carpio) were exposed to the test substance for 28 days. The determined bioconcentration factor was <33 and the test item does not significantly accumulate in fish. Despite the use of an emulsifier the test is regarded as valid in a weight of evidence since the low exposure level (0.1 mg/L) was at the water solubility of the test item (0.1 mg/L).

 

However, the results are supported by the calculated logPow of 12.91 and the molecular weight of the test item (at least 756). According to the guidance on information requirements and chemical safety assessment Chapter R.11 - PBT Assessment - the aquatic BCF of a substance is probably lower than 2000 L/kg if the calculated logKow is higher than 10. A molecular weight higher than 1100 g/mol is an indicator that the aquatic BCF of the respective substance is lower than 2000 L/kg. If the substance has a molecular weight higher than 700 g/mol this is an indicator that the BCF is below 5000 L/kg.

Furthermore, the maximum diameter of the main components was calculated using CATALOGIC v5.11.5. It resulted in an average maximum diameter (Dmaxaver) of 2.14 nm. According to the guidance R. 11 another parameter that directly reflects the molecular size of a substance is the average maximum diameter (Dmaxaver). Very bulky molecules will less easily pass the cell membranes. This results in a reduced BCF of the substance. From a diverse set of chemicals it appeared that for compounds with a Dmaxaver larger than 1.7 nm the BCF value was less than 5000 L/kg. It can be assumed combining the maximum diameter of above 1.7 nm and the high molecular size of the test item that the test item will not easily pass the cell membranes, the uptake is reduced and bioaccumulation will not occur.

 

Additionally, four different calculations were conducted to support these results. US EPA EPISuite v4.10 (BCF BAF v3.01) revealed a BCF of 3.16 L/kg wet-wt (the test substance was within the applicability domain, except for the calculated logKow). VEGA version 1.0.8 resulted in a BCF of 2 L/kg. However, the test substance was out of the model applicability domain. Nevertheless, the value fits in the overall weight of evidence and can be used as an indication for the assessment of the bioaccumulation potential. CATALOGIC v5.11.5 (BCF base-line model v2.05) resulted in a BCF of 7.44 with all mitigating factors applied. Even though the structural domain was correct with only 73.47 % (26.53 % unknown) the results support the overall conclusion in the weight of evidence. US EPA T.E.S.T v4.0.1 was also calculated, however, the consensus prediction for this chemical is considered unreliable since only one prediction can only be made and no BCF could be determined.

 

In overall conclusion, regarding all available information the test item does not significantly accumulate in organisms and the BCF is below 100.