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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

The key value for bioaccumulation is derived from a bioaccumulation study conducted according to the method used in ‘Bioconcentration test of chemicals in fish and shellfish (Kanpogyo No. 5, Yakuhatsu No. 615, 49 Kikyoku No. 392’.

Key value for chemical safety assessment

BCF (aquatic species):
11 L/kg ww

Additional information

A bioaccumulation study was conducted in 1979 with the test substance in accordance with the method used in ‘Bioconcentration test of chemicals in fish and shellfish (Kanpogyo No. 5, Yakuhatsu No. 615, 49 Kikyoku No. 392’. A flow-through system was used and the fish tested were carp (mean body weight: 27.1 g and mean body length: 10.3 cm). Two concentrations of the substance were tested (30 and 300 ppb w/v) and a dispersant was used (hydrogenated castor oil). The condition of the test fish was considered to be normal throughout the study. At 30 ppb w/v, the BCF value ranged from 0.12 or below to 4.2. At 300 ppb w/v, the BCF value ranged from 1.3 to 11 . Based on these results, the test substance is not considered to be bioaccumulative.

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

 

BCF model (CAESAR) (version 2.1.11)

BCF model (Meylan) (version 1.0.0)

BCF Read-Across (version 1.0.0)

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

The QSAR modelling was conducted using the SMILES codes for the substance.

 

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 four models used, the conditions (i) through (iv) are considered to be met for two of the models:

 

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

•      BCF Read-Across (version 1.0.0)

The structures assessed with these models were deemed to mainly fall within the applicability domain of the model, and this is demonstrated within the relevant QPRF's. Due to the fact that QSAR is utilised, these were assigned as Klimisch 2 level studies.

 

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

 

•      BCF model (CAESAR) (version 2.1.11)

•      BCF model (Meylan) (version 1.0.0)

 

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

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

- similar molecules found in the training set have experimental values that slightly or 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

- reliability of logP value used by the model is not optimal

- predicted substance is out of the the Applicability Domain of the model.

These studies were therefore assigned as Klimisch 3 level studies and the values obtained using these studies were not used to calculate the geometric mean.

 

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 using the models considered to be reliable are above the threshold value quoted in the REACH Regulation of 2000 or 5000 which indicates the potential to bioaccumulate. In order to derive a BCF for the purposes of dossier preparation, it is considered appropriate to utilise a geometric mean across the Klimisch 2 studies. The document “Guidance on information requirements and chemical safety assessment Chapter R.10: Characterisation of dose [concentration]-response for environment” states under section“R.10.2.2 Evaluation and interpretation of data” that:

 

Where there is more than one set of data on the same species, (strain if known), endpoint, duration, life stage and testing condition the greatest weight is attached to the most reliable and relevant one. When there is more than one set of data with the same reliability rating, it might be necessary to look into more detail at the study reports to see whether a specific reason could explain the difference. If no explanation can be found and the results are for the same species and endpoints and are not more than one order of magnitude apart, they can be harmonised by a geometric mean.

 

A geometric mean BCF is therefore applied for the purposes of hazard assessment.

 

Endpoint study

BCF (L/kg ww) (geometric mean)

EPIWIN BCFBAF Results [L/kg]

798.6

BCF Read-Across (version 1.0.0) [L/kg]

184

Geometric Mean BCF overall

383.3

 

Whilst this mean result is presented as only a general indication, this supports the overall conclusion that the substance is not considered to be bioaccumulative.