Oligomerisation products of beta-pinene

Endpoint summary

Description of key information

As part of a WoE biodegradation screening tests have been conducted with the substance as such, alongside similar substances. Due to the limitations in some of the ready biodegradation tests, these were repeated using enhancement measures alongside an inherent degradation test (OECD 302C). The outcomes of the majority of testing indicate the substance is not readily biodegradable. This is most likely due to bioavailability issues of the complex UVCB substance constituents.

In relation to simulation testing the requirement for these tests have been waived in accordance with column 2 of REACH annex IX, further degradation testing does not need to be conducted: based on weight of evidence, removal from the water compartment by adsorption followed by slow biodegradation (in sediment, water or soil) is predicted and the chemical safety assessment does not indicate a need for further investigation.

The testing is also waived in accordance with REACH Annex XI, Section 2 (testing is technically not possible). It is not feasible to conduct simulation tests with complex UVCB substances which are only designed for monoconstituents. Issues with radio-labelling and the potential for varying solubilities make such testing impossible. Some constituents of the UVCB substance were investigated to see whether it would be feasible to isolate and test them individually. However, after extensive discussions with testing labs and the material supplier it was not possible to isolate and purify representative constituents of the UVCB substance.

Additional information

 

In water, pinene oligomers are not readily biodegradable (8% degradation after 28 days in OECD 301D test). Testing with a mixed and adapted inoculum (otherwise OECD 301B test method) found negligible biodegradation, but adsorption of test substance onto vessel walls prior to testing made bioavailability uncertain. The ready biodegradation test was repeated in accordance with OECD 301B due to limitations in the above testing and included enhancement measures alongside an inherent test (OECD 302C). Both tests indicated negligible degradation.

Read-across to the analogue limonene (readily biodegradable) and other considerations, including reports of extensive microbial metabolism of mixed phytoterpenes by marine microbes lead to a weight-of-evidence conclusion of inherent biodegradability (not fulfilling specific criteria).

Biodegradation of close chemical analogues of pinene oligomers by soil microbes is confirmed in a study using both liquid phase and soil slurry tests. Other publications provide supporting evidence of the wide distribution of phytoterpenes and the ability of bacteria and microfungi to metabolise them. It is concluded that pinene oligomers will be biodegraded by soil microbes: half-life in soil cannot be accurately predicted, but seems likely to be weeks or months according to local conditions.

Adsorption coefficient has been determined to be >28840 (Log Koc = >4.46). This indicates that pinene oligomers will bind strongly to organic matter. A supporting study indicates such binding to soil particulates by close chemical analogues.