Docosyl stearate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Remarks:

Summary of available data used for the endpoint assessment of the target substance

Adequacy of study:

key study

Justification for type of information:

Please refer to the analogue justification attached to IUCLID section 13.

Reason / purpose for cross-reference:

read-across: supporting information

Parameter:

% degradation (O2 consumption)

Value:

75.3

Sampling time:

28 d

Parameter:

% degradation (test mat. analysis)

Value:

86

Sampling time:

28 d

Validity criteria fulfilled:

no

Interpretation of results:

readily biodegradable

Conclusions:

The target substance is readily biodegradable according to OECD criteria, based on experimental findings from a structurally closely related source substance (biodegradation is > 60% after 28 d, no 10-day window required, OECD 301C, CAS 17671-27-1).

Description of key information

Readily biodegradable: 75.3% (BOD) after 28 d (OECD 301C), read-across

Key value for chemical safety assessment

Biodegradation in water:

readily biodegradable

Type of water:

freshwater

Additional information

No data are available on the biodegradation in water of the target substance docosyl stearate (CAS 22413-03-2). Thus, a weight of evidence approach is applied in accordance to the REACh Regulation (EC) No 1907/2006, Annex XI General rules for adaptation of the standard testing regime set out in Annexes VII to X, 1.2. The weight of evidence combines data on the read across substance docosyl docosanoate (CAS 17671-27-1) as well as (Q)SAR predictions (VEGA v1.2.3) for the target substance itself. The experimental data from the chemically and structurally closely related source substance docosyl docosanoate (CAS 17671-27-1) were used for read-across. This read-across is in accordance with Regulation (EC) No. 1907/2006 Annex XI, 1.5. In this case of read-across, the best suited (highest degree of structural similarity, nearest physico-chemical properties) read-across substance was used for the assessment. This read-across is justified in within the analogue justification in IUCLID Section 13.

The study with the read-across substance docosyl docosanoate was performed according to OECD 301C (GLP) under aerobic conditions using a mixture of activated sludge from STP with freshwater from rivers and lakes, marine water and marine sediment as inoculum with a test substance concentration of 100 mg/L (Ministry of Economy, Trade and Industry, Japan, 1992). A biodegradation of 75.3% (BOD) was observed after 28 d. Since the substance reached the pass level for OECD 301C (biodegradation is > 60% after 28 d, no 10-day window required) docosyl docosanoate is readily biodegradable according to the OECD criteria.

Furthermore, the (Q)SAR model for ready biodegradability (VEGA v1.2.3, IRFMN 1.0.9) predicts ready biodegradability of the target substance itself. The substance lie within the applicability domain of the model and fulfilled all the measured applicability domain scores listed in the VEGA report (see endpoint study record). The overall model performance is good. Thus, the result is reliable and is considered adequate for regulatory purposes under Regulation (EC) No 1907/2006.

Based on the high degree of structural and chemical similarity between the target and the selected source substance, the target substance is expected to exhibit a similar environmental fate profile as the source substance. Therefore, it is concluded that the target substance docosyl stearate (CAS 22413-03-2) is readily biodegradable according to OECD guideline criteria, based on the available experimental results and QSAR prediction.