Benzene, bis(1-methylethyl)-, sulfonated, sodium salts

Carcinogenicity

Description of key information

No carcinogenicity study is available for SDIBP. The read-across is performed from sodium xylenesulphonate (CAS No. 1300-72-7) for carcinogenicity. The read-across study is 2-year rat  dermal exposure study conducted under GLP.  Up to 240 mg sodium xylenesulphonate/kg body weight in 50% ethanol were dosed 5 days per week for 104 weeks. There were no treatment related incidences of mononuclear cell leukemia, neoplasms, or non-neoplastic lesions of the skin and other organs. The increased incidence of epidermal hyperplasia may have been related to exposure to the test substance.  The NOAEL was reported as 240 mg/kg bw/day for rats.

Key value for chemical safety assessment

Carcinogenicity: via dermal route

Endpoint conclusion

Dose descriptor:

NOAEL

240 mg/kg bw/day

Justification for classification or non-classification

Non-carcinogenic. There was no evidence of carcinogenic activity of sodium xylenesulphonate in male or female rats.

Additional information

No carcinogenicity study is available for SDIBP, the read-across is performed from sodium xylenesulphonate (CAS No. 1300-72-7) for carcinogenicity. In a 2 -year study, 50 male and 50 female rats were administered sub-cutaneous applications of up to 240 mg sodium xylenesulphonate/kg body weight in 50% ethanol (USA NIH, 1998). Doses were applied 5 days per week for 104 weeks to the clipped interscapular skin at volumes adjusted for the weights of the animals throughout the study. Animals were housed individually and fed and given water ad libitum. Cages were changed weekly and racks were rotated every 2 weeks. All animals were observed twice daily and clinical findings were recorded monthly. Body weights were recorded weekly for 13 weeks, then monthly thereafter. All animals were necropsied and a complete histopathological examination was performed. All organs and tissues including skin were examined for grossly visible lesions. Major tissues were examined microscopically and slides were evaluated by an independent quality laboratory in addition to the study laboratory pathologist. The study was conducted under GLPs from late 1990 to late 1992 at the Battelle Columbus Laboratories. NTP Technical Report on the Toxicology and Carcinogenesis Studies of Technical Grade Sodium Xylenesulphonate in F344/N Rats and B6C3F1 Mice. NTP TR 464, June 1998. Survival of the dosed males and females was similar to that of the control groups and consistent with historical controls. Mean body weights of dosed males and females were similar to those of the controls throughout and there were no clinical findings considered treatment related in males. In female rats, clinical findings were limited to irritation at the site of application in one control, in 4 at 120 mg/kg bw/day and in 2 at 240 mg/kg bw/day. There were no treatment related incidences of mononuclear cell leukemia, neoplasms, or non-neoplastic lesions of the skin and other organs. The increased incidence of epidermal hyperplasia may have been related to exposure to the test substance.

Category Justification

According to Article 13 of Regulation (EC) No. 1907/2006 "General Requirements for Generation of Information on Intrinsic Properties of substances", information on intrinsic properties of substances may be generated by means other than tests e.g. from information from structurally related substances (grouping or read-across), provided that conditions set out in Annex XI are met. Annex XI, "General rules for adaptation of this standard testing regime set out in Annexes VII to X” states that “substances whose physicochemical, toxicological and ecotoxicological properties are likely to be similar or follow a regular pattern as a result of structural similarity may be considered as a group, or ‘category’ of substances.

Applying the category approach read-across concept to SDIBP, data will be used from a representative member of the hydrotropes category to avoid unnecessary (animal) testing. The endpoints for which the read-across approach to SDIBP is applied, are: toxicokinetics, short-term toxicity to fish, toxicity to microorganism, acute toxicity (inhalation and dermal), skin irritation/corrosivity, skin sensitisation, genetic toxicity (in vitro, in vivo), repeated-dose toxicity (oral and dermal), screening for carcinogenicity, and screening for reproductive / developmental toxicity.

Hazard assessment related key information for SDIBP:

SDIPB and the hydrotrope members exhibit similar levels of low toxicity. Acute toxicity values are above the classification limits, they are not sensitizing and show no genotoxic effects. Both exhibit neglible irritation to the skin, but are moderately irritating to the eyes (Cat 2B). Together with the chemical structure similarity and their similar chemical properties, it is deemed correct to fill the existing data gaps on mammalian toxicity of SDIPB with the data of the hydrotrope category.

Carcinogenicity: via dermal route (target organ): other: all gross lesions and masses