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Environmental fate & pathways

Bioaccumulation: aquatic / sediment

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Description of key information

For the hydrolysis product valeric acid, significant accumulation 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 hydrolysis product valeric acid (CAS 109 -52 -4) (Q)SAR results were used for assessment of 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 aquatic bioaccumulation are not provided.

Assessment

Valeryl chloride rapidly hydrolyses in contact with water to form valeric acid (CAS 109 -52 -4) and hydrogen chloride (HCl, CAS 7647-01-0). Due to this rapid hydrolysis, the assessment of the bioaccumulation potential of the parent compound is considered to be of low relevance.

No data for bioaccumulation of HCl are available. However, the substance cannot be measured in organisms as it dissociates completely under environmentally relevant conditions into H+ (H3O+) and Cl-. The resulting pH effect will be buffered in natural systems. Chlorine is abundant in organisms and will be excreted via urine/faeces. Therefore, no study and data will be provided for this hydrolysis product.

Therefore, the assessment of bioaccumulation potential is based solely on the data available for valeric acid.

No studies are available for the bioaccumulation assessment of the parent compound valeryl chloride and its hydrolysis product valeric acid. According to Regulation (EC) 1907 (2006) Annex IX, Section 9.3.2, Column 2, a study on bioaccumulation does not need to be conducted as the substance has a low potential for bioaccumulation. Valeryl chloride (CAS 638 -29 -9) has an estimated log Kow of 1.0 (weight-of-evidence, see IUCLID Ch. 4.7).

The substance decomposes rapidly to form HCl (CAS 7647 -01 -0) and valeric acid (CAS 109 -52 -4). The experimental log Kow of 1.39 (PhysProp database of EPI Suite v4.11) and the calculated log Kow of 1.56 (KOWWIN v1.68, EPI Suite v4.11) for the hydrolysis product valeric acid do not indicate a significant potential for bioaccumulation. Regarding these values, accumulation of the substance in organisms is not to be expected. Therefore, and for reasons of animal welfare, a study on bioaccumulation is not provided.

However, in order to assess the bioaccumulation potential of valeric acid, the BCF was calculated with several estimation models. The table below lists the applied (Q)SAR models, the estimated BCF values and basic information on the applicability domain (AD). 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.

 

Summary of relevant information on aquatic bioaccumulation: Predicted BCF values for applied QSAR models (AD = Applicability Domain)

Model

BCF [L/kg]

In AD

Remarks

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

1.83

yes

Based on the mean absolute errors of the models the confidence in the predicted results is high.

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

3.16

yes

-

BCF base-line model v3.10 (OASIS Catalogic v5.13.1): Considering all mitigating factors

3.8

yes

-

BCF base-line model v3.10 (OASIS Catalogic v5.13.1): Without considering any mitigating factors

31.2

yes

-

The applied estimation models predicted for valeric acid (CAS 109 -52 -4) BCF values in a range between 1.83 L/kg (US EPA T.E.S.T. v4.2.1, substance within AD) and 31.2 L/kg (BCF base-line model v03.10 (OASIS Catalogic v5.13.1.156): not considering mitigating factors ; substance within AD).

Conclusion:

Based on the available measured and calculated data on the log Kow of valeric acid (log Kow = 1.39 and 1.56, EPI Suite v4.11) and supported by a weight-of-evidence approach from calculated data, it can be concluded that significant accumulation in organisms is not to be expected.