Benzene, 1,1'-oxybis[methyl-, sulfonated, ammonium salts

Endpoint summary

Description of key information

Physical data as well as information from toxicological data indicate that the substance is absorbed and metabolized in the body. Furthermore, there are no indications for accumulation and the substance or its metabolites are likely eliminated from the body.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Additional information

A toxicokinetic assessment based on the physical properties (see ECHA Guidance on Information Requirements and Chemical Safety Assessment, R7c, version 3.0, June 2017) and toxicity data was performed. NOTE: this is mostly a generic assessment based on general statements in the guidance document that are derived from physical parameters.

The substance Benzene, 1,1'-oxybis[methyl-, sulfonated, ammonium salts] (CAS no. of the main component: 75314-26-0) is a UVCB substance (substance of Unknown or Variable composition, Complex reaction products or Biological materials) consisting of different derivates of sulfonated 1,1’-Oxybismethylbenzene (OMB) varying in number of sulfonated and methylated diphenyl ether groups as well as number of sulfonated groups. The main constituents have one or two sulfate groups and possess Mono-, Di- or Trimers of sulfonated and methylated diphenyl ether groups. Physical and chemical parameters vary within the derivatives of OMB based on their chemical structure, hence some of the physical and chemical properties are stated as ranges.

Based on the molecular weight (295-913 g/mol) and moderate log P values (-1.08 to 2.35) of the derivates of OMB as well as high water solubility (558 g/l) of the substance, absorption through aqueous pores or carriage with the bulk passage of water and absorption by passive diffusion is possible; the molecular weight of some of the derivates of OMB (those >500 g/mol) could hinder their absorption. The structure of the derivates (OMB: varying number of sulfate groups) suggest that the compounds may be ionized which could hinder their ability to diffuse across biological membranes.

An oral acute toxicity test showed no signs of toxicity for the substance (preliminary result, study in progress). In a combined repeated dose toxicity study with the reproduction/ developmental toxicity screening the substance administered at 100, 300 or 1000 mg/kg bw/day by oral gavage did not cause signs of systemic toxicity and did not adversely influence the reproductive performance (gonad function, mating behavior, conception, parturition) in parental male and female Hsd.Han: Wistar rats (NOAEL: 1000 mg/kg bw/d). Further, the development of the F1 offspring was not impaired from birth to post-natal day 13 at any dose level after repeated oral administration of dams (NOAEL: 1000 mg/kg bw/d).

The substance is a solid which decomposes before boiling and the melting point is above 300 °C. Therefore, the substance is not present in a gaseous state and absorption through inhalation is therefore unlikely. If the substance should still reach the respiratory tract, the main constituents can cross the alveolar and capillary membranes by passive diffusion. Toxicity data via inhalation is not available.

Considering the physical state in which the substance is used (liquid) and the molecular weight (some derivates of OMB with a molecular weight <500), some constituents of the substance may be absorbed through skin; the derivates of OMB with

a molecular weight >500 may be too large to be absorbed. Based on the high water solubility (558 g/l)

and moderate log P values (-1.08 to 2.35) suggest that the constituents with a log P value >1 favor dermal

absorption; log P values <0 will limit penetration into the stratum corneum and hence dermal absorption. Animal

studies showed no clinical signs of skin irritation/corrosivity or skin sensitization. Furthermore, there were no signs of systemic toxicity in the in vivo skin sensitation study.

Based on the high water solubility and size of the smaller derivates of OMB, distribution in the body is expected; the greater molecular weights of the bigger derivates will hinder their distribution. In contrast to derivates of OMB with a log P >0 that are likely to distribute into cells, distribution into cells of the derivates with greater log P values is unlikely.

None of the main constituents have a log P value greater than 4 (ranging from -1.08 to 2.35) and are unlikely to accumulate in the lipid rich stratum corneum; substances with a log P value <3 are not likely to accumulate in the adipose tissue with the repeated intermittent exposure patterns normally encountered in the workplacebut may accumulate if exposures are continuous. Once exposure to the substance stops, the substance will be gradually eliminated at a rate dependent on the half-life of the substance.

There is no experimental data available regarding the metabolism of the substance.

Based on the amphipathic structure and high molecular weight of the derivates of OMB, excretion via the bile is

the most likely pathway of excretion.