O,O'-dioctadecylpentaerythritol bis(phosphite)

Bioaccumulation: aquatic / sediment

Description of key information

Based on QSAR modelling, the BCF value for the test substance is estimated to be 3.162 L/kg ww.
In accordance with Column 2 (specific rules for adaptation from Column 1) of Annex IX of Regulation (EC) No. 1907/2006, the bioaccumulation in aquatic species study, required under information point 9.3.2, can be omitted if direct and indirect exposure of the aquatic compartment is unlikely. Exposure to the aquatic environment is predicted to be unlikely, therefore testing is not required.

Key value for chemical safety assessment

BCF (aquatic species):

3.162 L/kg ww

Additional information

The test substance was assessed for bioaccumulation potential using recognised QSAR derivation software as follows:

 

US EPA On-Line EPI Suite™v4.11 model BCFBAF

US EPA T.E.S.T. (version 4.1) (Toxicity Estimation Software Tool)

BCF model (CAESAR) (version 2.1.11)

BCF model (Meylan) (version 1.0.0)

BCF Read-Across (version 1.0.0)

The QSAR modelling was conducted using the SMILES codes for the three most abundant structures present in the substance (> 10% w/w).

 

It is understood that Annex XI, section 1.3 allows adaptation of the standard testing requirements by making use of (Q)SAR only if the following conditions are met:

(i) results are derived from a (Q)SAR model whose scientific validity has been established,

(ii) the substance falls within the applicability domain of the (Q)SAR model,

(iii) results are adequate for the purpose of classification and labelling and/or risk assessment, and

(iv) adequate and reliable documentation of the applied method is provided.

 

Within the five models used, the conditions (i) through (iv) are considered to be met for one of the models:

•      US EPA On-Line EPI Suite™v4.0 model BCFBAF

The structures assessed with this model were deemed to mainly fall within the applicability domain of the model, and this is demonstrated within the relevant QPRF. This study is assigned as a Klimisch 2 level study because it is a QSAR assessment.

 

Within the five models used, the conditions (i), (iii) and (iv) are considered to be met for four of the models:

•      BCF model (CAESAR) (version 2.1.11)

•      BCF model (Meylan) (version 1.0.0)

•      BCF Read-Across (version 1.0.0)

• US EPA T.E.S.T. (version 4.1) (Toxicity Estimation Software Tool) 

 

Within these models, condition (ii) was not fulfilled for various reasons including the following:

- no similar compounds with known experimental value in the training set have been found

- only moderately similar compounds with known experimental value in the training set have been found

- accuracy of prediction for similar molecules found in the training set is not optimal

- similar molecules found in the training set have experimental values that strongly disagree with the target compound predicted value

- the maximum error in prediction of similar molecules found in the training set has a high value, considering the experimental variability

- some atom centered fragments of the compound have not been found in the compounds of the training set or are rare fragments

- descriptors for this compound have values outside the descriptor range of the compounds of the training set

 

These studies were therefore assigned as Klimisch 3 level studies and the values obtained using these studies were not used to determine the estimated BCF value.

 

Overall

On the basis of a weight of evidence approach, there is sufficient information available to state that the substance is not bioaccumulative. Whilst it is not possible to provide a definitive BCF value for the substance due to the variation in the results, none of the values determined via QSAR are above the threshold value quoted in the REACH Regulation of 2000 or 5000 which indicates the potential to bioaccumulate.

The substance is predicted to have a high Kow value (16.4) and a value in excess of 4.5 is considered to be of concern as potential for bioaccumulation, according to screening criteria for bioaccummulation in ECHA guidance (Chapter R.11 PBT Assessment). The likely reliability of the log Kow is, however, considered to diminish above a value of 6, as noted in Appendix R.11-1 Annex 1 of ECHA guidance on PBT Assessment. Substances with log Kow between 4.5 and 6 are considered likely to be highly accumulating; however no substantial bioconcentration is assumed for compounds having log Kow values greater than 6. For compounds having log Kow greater than 6, a gradual decrease of the BCF is observed and it has been hypothesised within the published literature that a high log Kow is more an effect of solubility than a tendency of the substance to be lipophilic.