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Environmental fate & pathways

Adsorption / desorption

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Description of key information

Waiver. Study scientifically unjustified.

Key value for chemical safety assessment

Additional information

As stated in section 5.2.1, Alcohols, C20-30 (even numbered), is a UVCB substance that comprises several linear long chain alcohols, predominantly tetracosan-1-ol (C24), hexacosan-1-ol (C26) and octacosan-1-ol (C28). Together, these constituents make up approximately 70% of the composition of Alcohols, C20-30 (even numbered). Experimental data for the LCA Category was evaluated and trends in the environmental fate of long chain alcohols was used to assess Alcohols, C20-30 (even numbered).

 

Reliable experimental studies (Klimisch scores 1 and 2) were performed in accordance with OECD Guidelines on eicosan-1-ol (C20), docosan-1-ol (C22), 2-decyltetradecanol (C24) and tetradecyloctadecan-1-ol (C32) that are constituents of and analogous to primary constituents of Alcohols, C20-30 (even numbered) and the LCA Category. The key study by Flach (2014) reported 90% biodegradation of tetradecyloctadecan-1-ol in an OECD 301B CO2-evolution test over 28 days. More than 60% of tetradecyloctadecan-1-ol had degraded within the 10-day study window. The key study demonstrates that tetradecyloctadecan-1-ol, a C32 long chain alcohol, is readily biodegradable. Supporting studies also confirmed the ready biodegradability of LCAs including constituents and analogue constituents of Alcohols, C20-30 (even numbered).

 

According to Annex IX Column 2 of Regulation (EC) No 1907/2006 REACH concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals an absorption/desorption study does not need to be conducted if the substance and its relevant degradation products decompose rapidly. Nevertheless, predictions using established QSAR approaches were undertaken for information purposes.

 

An estimated Koc value of 112000 L/Kg was obtained for both docosan-1-ol and icosan-1-ol using an appropriate TGD Non-hydrophobics [o1] equation estimation method. The result is considered to be reliable and acceptable for use in environmental exposure modelling. In line with the read-across justification this estimated value can be considered for the relevant Alcohols, C20-30 (even numbered), endpoint. For comparative purposes only, Koc were calculated for tetracosan-1 -ol, hexacosan-1 -ol and octacosan-1 -ol using default Log Kow in the KOCWIN version 2.00 model and measured Log Kow (see Partition Coefficient section). A summary of the results is presented in the table below. The substances will neither persist nor be bioavailable due to their ready biodegradability and adsorption coefficients.

Test substance

Method

Adsorption coefficient (Koc) in L/kg

Remarks

Reference

Icosan-1-ol and Docosan-1-ol

QSAR: Technical Guidance Document (TGD) Non-hydrophobics equation

112000

Reliable read-across study

OECD (2005c)

Tetracosan-1-ol

QSAR: EpiSuite KOCWIN version 2.00 using Kowwin estimate

2571000

Reliable read-across study

EpiSuite version 4.1. calculation

Hexacosan-1-ol

QSAR: EpiSuite KOCWIN version 2.00 using Kowwin estimate

9070000

Reliable read-across study

EpiSuite version 4.1. calculation

Octacosan-1-ol

QSAR: EpiSuite KOCWIN version 2.00 using Kowwin estimate

31600000

Reliable read-across study

EpiSuite version 4.1. calculation

Tetracosan-1-ol , Hexacosan-1-ol and Octacosan-1-ol

QSAR: EpiSuite KOCWIN version 2.00 using Log Kow of 15 (the Log Kow for Alcohols, C24 -28 is > 15; see section on physico-chemical properties)

646600000

Reliable read-across study

EpiSuite version 4.1. calculation