Registration Dossier

Classification & Labelling & PBT assessment

PBT assessment

Administrative data

PBT assessment: overall result

PBT status:
the substance is not PBT / vPvB
Justification:

Persistent

Hydrolysis data on the test substance has shown the half life to be greater than 1 year under the conditions of the test. In a study to determine the ready biodegradability, <2.6% biodegradation was observed over 28 days, therefore the substance cannot be considered to be readily biodegradable. As a result of the available data, 2,2,6,6-tetramethyl-4-oxopiperidinooxy is considered to meet the criteria for 'persistent' and possibly 'very persistent'.

 

Bioaccumulative

The substance has a Log Kow of 0.28 indicating low potential to bioaccumulate, therefore does not fulfil the criteria set out to define bioaccumulation.

 

Toxic

The substance has a long-term no-observed effect concentration (NOEC) for Daphnia Magna of 2.3 mg/L and based on submitted data is not classified as carcinogenic, mutagenic or toxic to reproduction. There is no evidence of chronic toxicity therefore the substance does not fulfil the criteria for 'toxic'.

 

2,2,6,6-tetramethyl-4-oxopiperidinooxyl is considered to be persistent or very persistent based on the available test data, however as the criteria for bioaccumulation or toxicity are not met, the substance is not considered to be a PBT or vPvB substance.

Likely routes of exposure:

As 2,2,6,6,-tetramethyl-4-oxopiperidinooxyl does not meet the PBT or vPvB criteria and as a result of its enclosed manufacturing process and/or use as a processing aid in the production of monomers in the polymer industry, no emission characterisation is required.

The most likely route of exposure to the substance is from small scale drips and sampling. From an environmental perspective, the contained manufacturing process and specific use on large industrial sites by trained personnel is not expected to result in environmental exposure.