C16-18 (evennumbered, C18 unsaturated) alkyl bis(2-hydroxyethyl) amine oxide

Endpoint summary

Description of key information

No toxicokinetics data (animal or human studies) are available for this substance. Also due to its structure it is not possible to run QSRA models to generate physico chemical model data.

The physico-chemical properties used are in general applicable for pure substances only. Hence the (physico-chemical properties) values used in this assessment are intended to describe the intrinsic properties of the UVCB substance as a whole.

Ethanol, 2, 2’-iminobis-N-tallow alkyl derivatives, N-oxides CAS No 61791-46-6 is very unlikely by inhalation due to the extremely low vapour pressure (0.0015 pa at 20°C) and its physical form which is a paste at ambient temperatures. Ingestion is not a likely route of exposure. The physical form as a paste will also limit the potential for repeated or prolonged skin exposure through splashes so dermal absorption should be limited. It is likely that once this substance enters the body due to its lipophilic nature to be transported via the lymphatic system to the nearest draining lymph node rather than in the blood. This is supported by evidence from oral dosing studies in animals which indicate that in digestive tract the test substance when absorbed it is transported to the draining mesenteric lymph nodes (based on information on the read across substances for repeat dosing studies. It is likely that the macrophages will then ingest the material and it would then be metabolised.

Ethanol, 2, 2’-iminobis-N-tallow alkyl derivatives, N-oxides has relatively low water solubility of 10mg/L and moderate Octanol Water Partition coefficient of 2.95. While it is a surfactant the lack a serious skin irritation should ensure some limitation of its absorption through the skin. In view of its low water solubility (10 mg/L), penetration into the lipid-rich stratum corneum will be enhanced also dermal absorption is favoured as the log P of the substance is between 1 and 4 indicating sufficiently lipophilic to cross the stratum corneum. However partition from the stratum corneum into the epidermis after penetration will be inhibited due to the low water solubility. This supports the use of 50% absorption as a default for dermal absorption.

Once absorbed there is no specific information on the metabolism, distribution and excretion of primary fatty amine ethoxylates or the corresponding N-oxide as in this case. However there is information on the related primary fatty amines, metabolism distribution and excretion of the primary fatty amine ethoxylate N-oxides are expected to be similar.

Primary alkyl amines are not bioaccumulating and are metabolized rapidly by general oxidative pathways. They are oxidatively deaminated by monoaminooxidases with concomitant formation of ammonia and the corresponding alkylamine aldehyde. Subsequently, the aldehydes are oxidised by aldehyde dehydrogenases to the corresponding carboxylic acids, which, in turn, are further metabolized by B-oxidation. Carbon dioxide as the final product from B-oxidation is exhaled. Urinary excretion is a minor elimination pathway.

Key value for chemical safety assessment

Bioaccumulation potential:

low bioaccumulation potential

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

50

Absorption rate - inhalation (%):

100

Additional information

The absorption percentages are based on ECHA defaults where inhalation is assumed to have 100% absorption, twice that of the oral route which is therfore 50% with the dermal route being the same as the oral route so also 50%.