Farnesol

Endpoint summary

Description of key information

Hydrolysis: The hydrolysis test has been waived as the test substance is readily biodegradable.

Biodegradation in water (screening tests): The test item is readily biodegradable based on the weight of evidence. Over 70% biodegradation has been reported after 28 days in two studies, and a third study demonstrated 51.7% degradation after 28 days. As the substance is a mixture of E and Z isomers, the 10-day window criterion does not apply (EFEO/IFRA Guidelines on the Environmental Assessment of Natural Complex Substances (NCS), 2016).

Adsorption / desorption: Based on a log Kow of 4.72 (weighted average), the Koc was 1332 L/kg and the log Koc was 3.1244. Based on the molecular connectivity index, the Koc was 1666 L/kg and the log Koc was 3.22. Using the mean of the results from the log Kow and MCI method, the Koc was determined to be 1499 L/kg and the log Koc was 3.176.

Henry's Law constant: The Henry's law constant is calculated to be 578 Pa m3/mol at 25°C.

Additional information

Environmental fate endpoints are completed for this substance based on test data following standard guidelines or data waivers. All data are therefore considered to be reliable and relevant for the endpoint concerned.

Hydrolysis: The hydrolysis test has been waived in accordance with section 9 of REACH Annex VIII, as the substance is readily biodegradable.

Biodegradation in water (screening tests): Biodegradation of the test item was determined in the three reliable studies, reporting 51.7 to 80% biodegradation over 28 days (1996, 1997, 2011). According to EFEO/IFRA Guidelines on the Environmental Assessment of Natural Complex Substances (NCS) (2016), "the 10 day window may be waived for a complex multi-constituent substance with structurally similar constituents and only the pass level of 60% at 28 days applied for a readily biodegradability classification". The test item is a mixture of E and Z isomers, therefore the 10-day window criterion does not apply. Considering the weight of evidence, farnesol can be considered to be readily biodegradable.

Adsorption / desorption: The adsorption coefficient has been calculated by QSAR (KOCWIN v2.0) and is considered reliable with restriction (Klimisch 2) for this endpoint as it is within the molecular weight domain and a correction factor is available for a suitable substance structural fragment. Based on a log Kow of 4.72 (weighted average), the Koc was 1332 L/kg and the log Koc was 3.1244. Based on the molecular connectivity index, the Koc was 1666 L/kg and the log Koc was 3.22. Using the mean of the results from the log Kow and MCI method, the Koc was determined to be 1499 L/kg and the log Koc was 3.176.

Henry's Law constant: The Henry's law constant for the test substance was calculated according to ECHA guidance R.16: Environmental exposure assessment (ECHA 2016), using experimental data for water solubility and vapour pressure. The Henry's law constant is calculated to be 578 Pa m3/mol at 25°C. This result is reliable with restrictions (Klimisch 2) as the experimental values were reported from two good quality studies (Klimisch 1).