Benzenesulfonic acid, 4-C10-13-alkyl derivs.-, salts with amines, C16-C18 (even numbered) alkyl

Endpoint summary

Key value for chemical safety assessment

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

50

Absorption rate - inhalation (%):

100

Additional information

No experimental toxicokinetic study is available on the registered substance. However, as per REACH guidance document R7.C, information on absorption, distribution, metabolism and excretion may be deduced from the physicochemical properties and observations from studies conducted on the registered substance.

ABSORPTION
Benzenesulfonic acid, 4-C10-13-alkyl derivs.-, salts with amines, C16-C18 (even numbered) alkyl is a salt of C16-18-(even numbered)-alkylamines) with Benzenesulfonic acid, 4-C10-13-sec-alkyl derivs.
Considering its composition, the substance is not expected to be available as a salt but as its individual constituents following exposure via the oral and inhalation routes, and following absorption.

C16-18-(even numbered)-alkylamines):
- Molecular weight: 241 to 269.
- Water solubility: 38 mg/L
- Partition coefficient: 4.33 (worst-case)

Benzenesulfonic acid, 4-C10-13-sec-alkyl derivs.:
- Molecular weight: 300 to 340.
- Water solubility: 139 g/L
- Partition coefficient: 2.2

Oral absorption
The physicochemical characteristics of Benzenesulfonic acid, 4-C10-13-sec-alkyl derivs. suggest absorption of this fraction following an exposure via the oral route, since it has a molecular weight below 500 and a Log Kow between -1 and 4. This is supported by experimental data on this fraction. Considering that the partition coefficient of C16-18-(even numbered)-alkylamines) is above 4, despite its favourable molecular weight, it could limit the absorption of this fraction following an oral exposure. However, this value represents a worst-case scenario based on information on similar substances.
Most adverse effects observed following an exposure to the registered substance via the oral route could be the consequence of stress, local effects with subsequent inflammatory reaction, or poor general condition of the animals. Macroscopic and microscopic findings in the lungs may be indicative of an oral absorption of the fractions of the registered substance.
In the absence of experimental data on the absorption of the registered substance, it is considered that oral absorption in the rat is 50% less effective than the human absorption by inhalation in accordance with ECHA Guidance.

Inhalation absorption
The registered substance was found to have a vapour pressure of 0.000096Pa, and is therefore not volatile.
100% of inhalation absorption in taken into account for risk assessment in accordance with the ECHA Guidance.
There is no study available on the toxicity of the registered substance following an exposure via inhalation.

Dermal absorption
Considering the higher water solubility and Log Kow < 4 of Benzenesulfonic acid, 4-C10-13-sec-alkyl derivs., this fraction of the registered substance could be expected to be better absorbed than the C16-18-(even numbered)-alkylamines) fraction.
Absorptions by dermal and oral routes are not known; therefore, it is considered that oral absorption in the rat was equivalent to human absorption via the dermal route in accordance with ECHA Guidance, i.e. 50% of the absorption following exposure via inhalation.
There is no study available on the toxicity of the registered substance following a dermal exposure. In vitro studies were conducted to address skin irritation and skin sensitisation endpoints.

DISTRIBUTION
Both fractions of the registered substance have a molecular weight below 500 and a Log Kow > 0. It can therefore be expected that distribution into cells and the intracellular concentration may be higher than extracellular concentration particularly in fatty tissues.
According to the EU Risk Assessment on Primary Alkyl Amines, bioavailable amount of the C16-18-(even numbered)-alkylamines) fraction should be rapidly distributed into the lungs, brain, heart, spleen, kidneys and liver. Findings in lungs during a repeated-dose toxicity study conducted via the oral route with the registered may therefore be related to distribution of the C16-18-(even numbered)-alkylamines) fraction.

METABOLISM
Sulphophenyl butanoic acid and sulphophenyl pentatonic acid were identified as metabolites of benzenesulfonic acid, C10-13-alkyl derivs.
According to the EU Risk Assessment on Primary Alkyl Amines, the C16-18-(even numbered)-alkylamines) fraction should be oxidatively deaminated by monoaminooxidases with concomitant formation of ammonia and the corresponding alkylamine aldehyde. Subsequently, the aldehydes are oxidised by aldehydedehydrogenases to the corresponding carboxylic acids, which, in turn, are further metabolised by ß-oxidation.

ELIMINATION
The urinary route was identified as the main route of excretion for Benzenesulfonic acid, 4-C10-13-sec-alkyl derivs.
According to the EU Risk Assessment on Primary Alkyl Amines, metabolised C16-18-(even numbered)-alkylamines fraction should be eliminated mainly via inhalation, with urinary excretion being only a minor route.