Naphthalene-2-sulphonic acid

Endpoint summary

Description of key information

oral
LD50, rat; application per gavage: ca. 1400 mg/kg bw (mortalities due to local corrosive effects in the stomach; standardized test protocol, comp. to OECD 401; BASF AG 1972)
inhalative
no data available 
dermal
no data available 

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Dose descriptor:

LD50

Value:

1 400 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no study available

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

There are valid data available for the assessment of the acute oral toxicity of naphthalene-2 -sulfonic acid.

 

oral

In an acute oral toxicity study following a standardized test protocol, technical pure naphthalene-2-sulfonic acid was administered per gavage in doses between 800 and 3200 mg/kg bw to groups of 5 male and 5 female rats (BASF AG 1972). The test substance was administered as 16% solution in water. The animals were observed for 14 d. The LD50 is ca. 1400 mg/kg bw. for males and females. Mortality and clinical signs appeared in doses >= 1000 mg/kg bw. Clinical signs associated with oral doses included dyspnea, convulsions and staggering. Postmortem examinations showed predominantly hemorrhagic slough eschar in the stomach in the animals that died and, to a lower extend, in surviving animals. Further observations at necropsy were congestive hyperemia, dilatation of the heart, hydrothorax, slight ascites, hemorrhagic slough eschar in the stomach and hematinic intestinal content in animals that died. Emaciation was observed in survivors in a dose-dependent manner. The dominant effect in animals that died seen at necropsy (hemorrhagic slough in the stomach) is a typical observation in the stomach after administration of acids per gavage. Mortalities are therefore considered primarily as consequence of the dominant local corrosion in the stomach.

This assessment is supported by results of two reliable studies with the noncorrosive sodium salts of nathalenesulfonic acids (BASF AG 1978, BASF AG 1964). In these studies, performed after the standard acute method with rats, the LD50 is >5000 mg/kg bw.

 

Inhalation

No experimental data were available. Due to the corrosive effects of the substance, there is no need for testing.

 

Dermal

No experimental data were available. Due to the corrosive effects of the substance, there is no need for testing.

Read across justification:

 

The registration item contains ca. 78.89% of naphthalene-2-sulphonic acid (CAS # 120-18-3) and ca. 6.5 % of naphthalene-1-sulphonic acid (CAS # 85-47-2). These two substances have the same molecular weight and are structurally almost identical. Therefore naphthalene-2-sulphonic acid and naphthalene-1-sulphonic acid and their respective salts are suitable for read across in order to fulfill the data requirements.

Justification for classification or non-classification

Based on the available acute oral and dermal toxicity studies, the substance was classified R22 (according to Directive 67/548/EEC) and Acute toxicity oral Cat 4 (according to CLP).

The available data on naphthalenesulfonic acids for acute oral toxicity indicates that mortalilty can be clearly attributed to the corrosive properties as respective salts had an LD50 > 5000 mg/kg bw. Mortality is caused by local effects and not systemic toxicity.

Data for the acute inhalative and dermal toxicity were not available. Due to the corrosive effects of the substance, there is no need for testing.