Sulphanilic acid

Endpoint summary

Description of key information

In a study according to OECD test guideline 407 in rats under GLP, the NOAEL of the test substance was determined to be 1000 mg/kg bw for both sexes.

Key value for chemical safety assessment

Repeated dose toxicity: via oral route - systemic effects

Endpoint conclusion

Dose descriptor:

NOAEL

1 000 mg/kg bw/day

Study duration:

subacute

Species:

rat

Additional information

In a GLP-study according to OECD test guideline 407, the registered substance was administered daily by oral gavage at dose levels of 63, 250 and 1000 mg/kg body mass (BM) / day to 5 male and 5 female Wistar rats each over a period of 28 days. Another 5 male and 5 female rats received the same volume of water as vehicle control. All liquids were administered to each animal at 4 ml / kg bw. During the in-life phase, all animals were monitored for fatalities, general clinical signs, detailed clinical signs, grip strength and reactivity to sensory stimuli (limb placing test). The bodyweight as well as group food and group water consumption were also recorded. At the end of the in-life phase, blood samples from all animals were collected to provide data on haematology, serum biochemistry and blood coagulation. All animals were sacrificed humanely immediately after bleeding and examined by gross necropsy. Organ mass was recorded, tissues and organs selected therein were preserved and processed histologically. A histopathological examination was conducted on samples from the high dose groups and the vehicle groups.

As, in summary, only very few mild systemic and local effects in test animals treated with the high dose were observed, which did not produce any pathological evidence of a local or systemic toxicity of the substance. Therefore, the NOAEL was considered to be 1000 mg/kg bw.

This result is supported by two chronic toxicity studies (in rats and mice) of the azo dye FD & C Yellow No. 5 (CAS 1934-21-0). This dye is rapidly and almost completely cleaved in the gut by the gut flora to sulfanilic acid, i.e. the regsitered substance, and a rest (see Section 7.12).

For both species, no toxicity was observed for concentration equivalent to at least 2500 mg/kg bodyweight applied for more than two years. Due to the metabolism of the test substance, these results strongly support the practically non-toxic behaviour of sulfanilic acid.

Taking in addittion the rapid excretion of sulfanilic acid mainly in its original form into account, it is concluded that sulfanilic acid is highly unlikely chronically toxic. Therefore and for animal welfare reasons, a sub-chronic toxicity study is considered to be not justified.

Justification for classification or non-classification

As the substance did not show any toxic effects for concentrations up to 1000 mg/kg bw in a repeated dose toxicity study, no classification is warranted.