Disodium oxybis[methylbenzenesulphonate]

Endpoint summary

Description of key information

No specific study on toxicokinetic, metabolism and distribution is available.

Additional information

The following remarks on the toxicokinetics of ditolylether disulfonic acid disodium salt, isomer mixture are based on the studies described in section 7 Toxicological information. Experimental toxicokinetic studies with ditolylether disulfonic acid disodium salt, isomer mixture are not available.

Ditolylether disulfonic acid disodium salt, isomer mixture is an UVCB substance consisting of positional isomers of two basic structures [sodium salts of disulfonated and trisulfonated ditolylether].

The molecular weight of the constituents of ditolylether disulfonic acid disodium salt, isomer mixture is between 402.35 and 504.39 g/mol.

No melting point could be determined using EU Method A.1 (Melting/Freezing Temperature), because the sample discomposed at 196°C.

Using the Estimation Program Interface (EPI) Suite version 4.1 the vapor pressure at 25 °C was estimated to be 1.04E-15 Pa for sodium salts of disulfonated ditolylether and 1.17E-18 Pa for sodium salts of trisulfonated ditolylether.

The determined water solubility of ditolylether disulfonic acid disodium salt, isomer mixture is 242 g/L at 20 °C.

The estimated partition coefficients (log Kow) of the constituents of ditolylether disulfonic acid disodium salt, isomer mixture are between -4.12 and -1.54.

From these data it can be concluded that exposure to vapor is an unlikely route of exposure and exposure to dust should be considered for ditolylether disulfonic acid disodium salt, isomer mixture.

ABSORPTION

The physico-chemical characteristics of ditolylether disulfonic acid disodium salt, isomer mixture (highly soluble in water, log Kow between -4.12 and -1.54, molecular weight between 402.35 and 504.39 g/mol) are in a range suggestive of intestinal absorption subsequent to oral ingestion. However, single application of 2000 mg/kg bw ditolylether disulfonic acid disodium salt, isomer mixture was tolerated without mortality or any clinical signs during the 14-day observation period and without macroscopic findings at necropsy (Leoni 2011). In addition, repeated dosing of male and female rats with up to 1000 mg/kg bw/day during a period of 28 days was also tolerated without any treatment related clinical, macroscopic or microscopic findings. The NOEL was established at 1000 mg/kg bw/day (Takawale 2013). These observations may reflect the low absorption rate of ditolylether disulfonic acid disodium salt, isomer mixture, but most probably the low intrinsic toxicity of ditolylether disulfonic acid disodium salt, isomer mixture.

Due to the high water solubility and the log Kow between -4.12 and -1.54 no appreciable dermal and/or mucosal absorption of ditolylether disulfonic acid disodium salt, isomer mixture is anticipated. This is confirmed by the studies with local administration of ditolylether disulfonic acid disodium salt, isomer mixture (acute dermal study, study on skin and eye irritation/corrosion in vivo and skin sensitization) in which no systemic intolerance reactions were observed (Leoni 2011 (acute dermal), Schmid 2011 (skin irritation), Stelter 2012 (eye irritation/corrosion), Stelter 2012 (skin sensitization)).

There are no animal experiments available using the inhalation route.

The following toxicokinetic evaluation is done according to chapter R.7c of the ECHA guidance document (version 1.1, November 2012).

Ditolylether disulfonic acid disodium salt, isomer mixture is a solid with very low volatility based on a vapor pressure below 0.5 kPa (estimated vapor pressure at 25 °C: 1.04E-15 Pa for sodium salts of disulfonated ditolylether and 1.17E-18 Pa for sodium salts of trisulfonated ditolylether) and a boiling point above 150 °C (decomposition at 196 °C).

In humans, particles with aerodynamic diameters below 100 μm have the potential to be inhaled. Particles with aerodynamic diameters below 50 μm may reach the thoracic region and those below 15 μm the alveolar region of the respiratory tract. The median diameter of ditolylether disulfonic acid disodium salt, isomer mixture is 16.38 µm. All particles with a mean diameter less than 100 μm have a mass fraction of 1.36%. 1.80% of this mass fraction has a mean diameter less than 4 μm. Overall, the faction of the compound with an aerodynamic diameter below 100 μm is small and it is unlikely that large quantities of the compound are inhaled.

Moderate log Kow values (between -1 and 4) are favorable for absorption directly across the respiratory tract epithelium by passive diffusion. Although the log Kow of ditolylether disulfonic acid disodium salt, isomer mixture (between -4.12 and -1.54) is below the values given in the ECHA guidance document, some absorption might be assumed. Water solubility of ditolylether disulfonic acid disodium salt, isomer mixture is 242 g/l at 20oC which is high ccording to the criteria in chapter R.7c (>100 g/L) and, consequently, may be retained within the mucous.

For absorption of deposited material similar criteria as for gastrointestinal absorption apply. Based on the physicochemical properties the potential for respiratory absorption is low. Taking into account the lack of observed effects after oral ingestion it is likely that the absorption rate via inhalation and oral dosing is low. The absorption via inhalation is considered to be comparable to the absorption via gastrointestinal tract.

DISTRIBUTION

There are no specific investigations available on the distribution of ditolylether disulfonic acid disodium salt, isomer mixture and the above discussed subacute oral study does not provide information on distribution. Because of the results of the subacute oral rat study there is no reason to assume that either unchanged ditolylether disulfonic acid disodium salt, isomer mixture or its metabolites may accumulate in fatty tissues.

METABOLISM

There are no specific investigations available on the metabolism of ditolylether disulfonic acid disodium salt, isomer mixture. Based on the results of the in vitro genotoxicity tests with ditolylether disulfonic acid disodium salt, isomer mixture (Donath 2012 (Ames test), Wallner 2012 (HPRT), Donath 2012 (in vitro MNT) it is concluded that DNA-reactive metabolites of ditolylether disulfonic acid disodium salt, isomer mixture most probably will not be generated in mammals in the course of hepatic biotransformation.

EXCRETION

There is no specific information available on the excretion of ditolylether disulfonic acid disodium salt, isomer mixture. Based on the high water solubility of ditolylether disulfonic acid disodium salt, isomer mixture it is assumed that urinary excretion is the main excretion route.