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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

Significant accumulation of MCHAmix (EC 943-517-5) in organisms is 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. 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 Reaction product of 2,4-Dinitrotoluene and 2,6-Dinitrotoluene and hydrogen, deaminated (MCHAmix EC 943 -517 -5) (Q)SAR results were used for the estimation of the bioaccumulation factor. 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, further experimental studies on the bioaccumulation potential are not provided.

Assessment:

No experimental data on the bioaccumulation potential of the Reaction product of 2,4-Dinitrotoluene and 2,6-Dinitrotoluene and hydrogen, deaminated (EC 943-517-5, MCHAmix) are available. In order to assess the bioaccumulation potential of the substance, the BCF was calculated with several estimation models for two representative constituents of MCHAmix: 2-Methylcyclohexylamine (CAS 7003-32-9) and 4-methylcyclohexylamine, mixed isomers (CAS 6321-23-9).

The table below lists the applied (Q)SAR models, the estimated BCF values and basic information on the applicability domain (AD) for the substances. Detailed information on the model’s results and the AD are given in the endpoint study records of IUCLID Chapter 5.3.1. The selected models comply with the OECD principles for (Q)SAR models.

In accordance with column 2 of REACH Annex IX, a bioaccumulation study does not need to be conducted since the constituent substances (CAS 7003-32-9, CAS 6321-23-9) have log Kow values of less or equal than 3 (CAS 7003-32-9, CAS 6321-23-9: log Kow = 2.05, calculated, 25 °C, EPI Suite v4.11, see IUCLID Ch. 4.7).

Summary of relevant information on aquatic bioaccumulation: Predicted BCF values for applied QSAR models sorted by BCF:

(AD = Applicability Domain)

Model

BCF [L/kg]

In AD

Restraints

Read-Across to CAS 7003-23-9

CAESAR v2.1.14 (VEGA v1.1.3)

5

No

The following relevant fragment have been found: NH2 group (PG 07) The presence of polar groups increases

hydrophilicity, related to lower values of BCF

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

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

BCF KNN/Read-Across v1.1.0 (VEGA v1.1.3)

5.1

Yes

-

US EPA T.E.S.T. v4.2.1: Bioaccumulation: Consensus method

8.35

Yes

Based on the mean absolute errors of the models compared to the training set data, the confidence in the predicted results is high

Meylan v1.0.3 (VEGA v1.1.3)

10

Yes

With regard to the reliability of the log P value, it can be stated that the model uses estimated values based on the KOWWIN method which has been assessed separately (see IUCLID Ch. 4.7: KOWWIN v1.68, BASF SE, 2017).

BCFBAF v3.01 (EPI Suite v4.11): Meylanet al. (1997/1999)

10.4

Yes

-

BCFBAF v3.01 (EPI Suite v4.11): Arnot-Gobas BCF, upper trophic, incl. biotransformation

12.05

No

The substance appreciably ionizes at physiologically relevant pH;

BCFBAF v3.01 (EPI Suite v4.11): Arnot-GobasBCF, upper trophic, incl. biotransformation of zero

12.85

No

The substance appreciably ionizes at physiologically relevant pH

BCF baseline model v.02.09 (OASIS Catalogic v5.11.19): incl. mitigating factors

22.91

No

With regard to the parametric, structural and mechanistic domain, the test substance is not within the structural applicability domain of the model. Therefore, the estimation is not reliable.

BCF baseline model v.02.09 (OASIS Catalogic v5.11.19): not considering mitigating factors

42.85

No

With regard to the parametric, structural and mechanistic domain, the test substance is not within the structural applicability domain of the model. Therefore, the estimation is not reliable.

 

Read-Across to CAS 6321-23-9

BCF KNN/Read-Across v1.1.0 (VEGA v1.1.3)

5.1

No

Some similar molecules found in the training set have experimental values that disagree with the predicted value

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

CAESAR v2.1.14 (VEGA v1.1.3)

6

No

The following relevant fragment have been found: NH2 group (PG 07) The presence of polar groups increases

hydrophilicity, related to lower values of BCF;

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

been found

- some similar molecules found in the training set have experimental values that disagree with

thepredictedvalue

US EPA T.E.S.T. v4.2.1: Bioaccumulation: Consensus method

7.09

Yes

Based on the mean absolute errors of the models compared to the training set data, the confidence in the predicted results is high.

Meylan v1.0.3 (VEGA v1.1.3)

10

Yes

With regard to the reliability of the log P value, it can be stated that the model uses estimated values

based on the KOWWIN method which has been assessed separately (see IUCLID Ch. 4.7: KOWWIN v1.68, BASF SE, 2017).

BCFBAF v3.01 (EPI Suite v4.11): Meylanet al. (1997/1999)

10.4

Yes

-

BCFBAF v3.01 (EPI Suite v4.11): Arnot-Gobas BCF, upper trophic, incl. biotransformation

12.05

No

The substance appreciably ionizes at physiologically relevant pH;

BCFBAF v3.01 (EPI Suite v4.11): Arnot-GobasBCF, upper trophic, incl. biotransformation of zero

12.85

No

The substance appreciably ionizes at physiologically relevant pH

BCF baseline model v.02.09 (OASIS Catalogic v5.11.19): incl. mitigating factors

22.4

No

With regard to the parametric, structural and mechanistic domain, the test substance is not within the structural applicability domain of the model. Therefore, the estimation is not reliable.

BCF baseline model v.02.09 (OASIS Catalogic v5.11.19): not considering mitigating factors

42.8

No

With regard to the parametric, structural and mechanistic domain, the test substance is not within the structural applicability domain of the model. Therefore, the estimation is not reliable.

Considering all models applied to both constituents, the estimated BCF values range from 5 to 43 L/kg. Based on the available information on the log Kow and supported by a weight-of-evidence approach on the calculated bioaccumulation factors, it can be concluded that significant accumulation of MCHAmix (EC 943-517-5) in organisms is not to be expected.