Bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate

Endpoint summary

Description of key information

Bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate:

• will be rapidly degraded by photochemical processes after evaporation or exposure to the air.


• is not hydrolytically stable.


• is not readily biodegradable (by OECD criteria).


• does not form metabolites fulfilling PBT criteria.


• does not significantly accumulate in organisms.


• is expected to adsorp to the solid soil phase.

 

Additional information

General sumary

The test item and the hydrolysation products have been assessed. The test item is partially degradable and has no properties for bioaccumulation. It due to its physchem properties it will mainly be found in the water, sediment or soil. One metabolite, sebacic acid, is readily biodegradble and has no BCF properties. The other product of hydrolysation, 2,2,6,6-tetramethylpiperidin-4-ol, is not readily biodegradable but is also not a PBT substance. Therefore, no significant hazard for the environmental fate and pathways was identified.

Stability

The test item will react with OH-radicals in the atmosphere and is expected to degrade photolytically. The half-life is estimated with 2.54 hours (0.5E6 radicals per cm³).

According to an OECD TG 111 study, the test item will hydrolyse slowly (pH7: 56.6 days at 25 °C). The identified transformation products were sebacic acid, CAS No. 111-20-6 and 2,2,6,6-tetramethylpiperidin-4-ol, CAS No. 2403-88-5.

Biodegradation

An OECD TG 301B study was conducted to assess the potential for biodegradation of the test item. The mean degradation after 28 days was 12%. Hence, the substance is poorly biodegradable. Additional information on the biodegradation in water sediment systems is not available since the risk assessment did not indicate further need for testing according to Annex IX, Section 9.2 and 9.2.1.4, Column 2. The same applies to biodegradation in soil.

Bioaccumulation

The potential of the test item for bioaccumulation was investigated by a weight of evidence approach. Also, the log kow of 0.35 and QSAR predictions were implemented with the result that bioaccumulation is not expected. The BCF provided by EPI Win is 197.1 L/kg ww. Secondary poisoning is, therefore, highly unlikely to occur in any extent for the test item.

Transport and distribution

The test item hydrolyses slowly. The derived log Koc by an OECD TG 106 was 4.2 at 20°C. Hence, adsorption to soil phase is expected. Derived from the Henry's law constant of 1.61E-7 at 25 °C, it can be stated, that the test item will not evaporate into the atmosphere. Based on the distribution modelling of the uncharged molecule, the majority will deposit in the water and soil or sediment. The latter has to be treated with caution because the uncharged test item predominates only under high pH conditions (pH>10).

Assessment of Degradation products

The following transformation products were proposed: Sebacic acid, CAS No. 111-20-6 and 2,2,6,6-tetramethylpiperidin-4-ol, CAS No. 2403-88-5.

Sebacic acid is registered under REACH Regulation (EC) No 1907/2006. According to the disseminated registration data the substance is well soluble in water, readily biodegradable (7 days; degradation 98%) and will preferable be distributed into water. Due to a log Kow of 1.5 bioaccumulation is very unlikely to occur, thus it was not classified as PBT nor as vPvB substance. Sebacic acid has not been classified as hazardous to the environment according to Regulation (EC) No 1272/2008 (CLP/GHS).

 

2,2,6,6-tetramethylpiperidin-4-ol is registered under REACH Regulation (EC) No 1907/2006. According to the disseminated registration data the substance is well soluble in water,  not biodegradable and will preferable be distributed into water. Due to a BCF of <5.7 bioaccumulation is very unlikely to occur, thus it was not classified as PBT nor as vPvB substance. 2,2,6,6-tetramethylpiperidin-4-ol has not been classified as hazardous to the environment according to Regulation (EC) No 1272/2008 (CLP/GHS).