Sodium 2-[methyl(1-oxododecyl)amino]ethanesulphonate

Endpoint summary

Description of key information

No ADME studies concerning toxicokinetics are available for the registration substance. However, structure related consideration suggests enzymatic degradation in analogy to accepted metabolic pathways for amide hydrolysis and fatty acid  ß-oxidation. The assumed metabolism will not generate metabolites of toxicological concern. Excretion of postulated final metabolic products is considered fast and complete. Due to its solid state, the moderate water solubility, the moderate molecular weight close to 500  and the ionic nature, only reduced dermal penetration is anticipated.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

100

Absorption rate - dermal (%):

20

Additional information

No information is available on the specific toxicokinetic behaviour of the target substance SMLT. However, the metabolism of the target and source substances SLMT, SMCT and SOMT (see read-across justifiation in section 13) is expected to follow a pathway involving amide hydrolysis and fatty acid beta-oxidation (Farrell et al, 2012). The initial step consists of the hydrolysis of the amide linkage catalyzed by fatty acid amide hydrolase (FAAH), resulting in N-methyltaurate and the respective fatty acid. FAAH is the principal catabolic enzyme for fatty acid amides and exhibits both, esterase and amidase activity. The resulting anionic N-methyltaurate may then be either directly excreted into urine or converted to a dianionic salt with glucuronic acid that is excreted. The remaining fatty acid is metabolized in a second step via the ß-oxidation pathway.

 

Metabolites of toxicological significance are not expected from the target (SMLT) or source substances (SCMT, SOMT). This metabolic behaviour was also considered by the US EPA during the establishment of an exemption from tolerance requirements of the source SMOT residues in animals and food when used as an inert ingredient in pesticide formulations (EPA, 2009). The metabolic breakdown of SMOT into N-methyltaurine and oleic acid by the aerobic gram-negative bacterium Pseudomonas alcaligenes was experimentally verified by Denger et al. 2008.

 

Experimental data on adsorption and distribution is not available for the target or the source substances. From structure-property relationship considerations, it is anticipated that the target substance SLMT will be absorbed from the gastro-intestinal tract following oral ingestion. Due to its solid physical state, moderate water solubility, the moderate molecular weight close to 500 g/mol and the anionic nature, dermal penetration of the substance is considered to be low in accordance with REACH Guidance (R7.12). An absorption rate of 20% is taken which is in line with an exposure assessment carried out by the US EPA on the read-across analogue SOMT (EPA, 2009).

As a conclusion from the available data, no conspicuous toxicokinetic behaviour is attributable to the registration substance. For risk assessment purposes, a value of 100% for oral uptake and a value of 20% is taken as conservative assumption for dermal penetration. Rapid and complete metabolism is anticipated with no resulting metabolites of significant toxicological concern.

 

Potential for significant bioaccumulation of SMLT can be excluded based on its high solubility in water, poor solubility in octanol and its rapid biotransformation and biodegradation properties (Denger, 2008).

 

Further details on the toxicokinetic behaviour ofalkyl taurate amide salts is described in the Cosmetic Ingredient Review (CIR) expert panel safety evaluation report (CIR, 2016) (CIR, 2016; EPA, 2009).