Registration Dossier

Administrative data

Link to relevant study record(s)

Description of key information

Absorption of the test substance might be low. However, there is a high probability for metabolic degradation in the liver or even to some extent in the gastro-intestinal tract, leading to a fast elimination. Bioaccumulation can be excluded.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential

Additional information

The test substance is slightly water soluble and has an octanol-water partition coefficient of 2.37 and 2.77, and a molecular weight of 508. It is not bioaccumulating as shown experimentally.

No significant hydrolysis in water was shown experimentally under acidic conditions. However, in neutral or alkaline milieu, hydrolytic degradation takes place. The physico-chemical properties of the test substance and consideration of Lipinsky’s rule of 5 impose that an oral absorption takes place in rather small quantities. Upon oral administration, the test substance might be absorbed to some degree and is subject to hepatic metabolic degradation. A cleavage reaction that might already be induced in the gastro-intestinal tract, is proposed to lead to the hydrolysis products sebacic acid and pentamethylpiperidinol (HPMP). These components have a greater potential to permeate through the gastrointestinal epithelium than the parent compounds.

Pentamethylpiperidinol is subject to further metabolic degradation by the following reactions:

-         oxidative N-demethylation, leading to HTMP (>)

-         hydroxylation of methyl-carbon adjacent to the aliphatic ring

-         oxidation of secondary (alicyclic) alcohol

-         glucuronidation of alicyclic alcohol

Sebacic acid might be subject to urinary excretion with or without glucuronidation steps. Subsequently, the test substance and or its degradation products will be excreted effectively. The elimination pathways might comprise fecal as well as urinary excretion.

Dermal permeation is anticipated to be slight to marginal. No inhalation toxicity data are available but physico-chemical properties indicate that inhalative exposure might be limited concern.

Bioaccumulation as well as enzymatic reactions leading to toxic metabolites can be excluded.