Sodium 4(-2-hydroxy-1-naphthylazo)naphthalenesulphonate

Endpoint summary

Description of key information

LD50 (oral, rat) > 2000 mg/kg bw

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Dose descriptor:

LD50

Value:

2 000 mg/kg bw

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

The test substance was tested for acute toxicity, according to the EU Method B.1. bis (Fixed Dose Procedure). In the Preliminary Study, the test item was administered to one female at the dose of 500 mg/kg. As no mortality was recorded in this animal, another female was administered at the dose of 2000 mg/kg and also survived the treatment. In the Main Study, five males and five females were treated at the dose of 2000 mg/kg. No mortality was recorded and no signs of toxicity were observed during the experiment.

The LD50 (oral) was found to be greater than 2000 mg/kg bw.

This result is confirmed by another available experimental study performed using the test item.

The acute toxicity of the test item by ingestion was evaluated in an experimental study in a limit test without controls. The test item was prepared as a 50 % suspension in 0.5 % aqueous carboxymethyl-cellulose. 5 male and 5 female Sprague-Dawley rats were exposed to 5000 mg/kg bw test item by oral gavage. Test animals were monitored for mortality and toxic symptoms for 14 days, and all survivng animals were subjected to gross pathology examination at necropsy. No mortality was observed. On the first day following administration of the test item, the general condition of the test animals deteriorated with unspecific toxic symptoms. No organ abnormalities were observed at necropsy.

Based on the obtained results, the LD50 (acute oral, male and female rats) was found to be greater than 5000 mg/kg bw.

Additionally, other studies are available in which other exposure routes were used, i.e. inhalation and intraperitoneal.

The acute toxicity of the test item by inhalation was evaluated in an experimental study following the Concentration×Time method limit test. Air in individual inhalation chambers was enriched with test item using 200 l/hour air flow through the test item in a 20 °C water bath. 12 Sprague-Dawley rats were exposed to the test item at room temperature for either 3, 10 or 30 minutes or 1, 3 or 7 days (two animals per duration), and monitored for mortality and signs of toxicity for 14 days then subjected to gross pathology analysis at necropsy.

No mortality or toxic symptoms were observed. No organ abnormalities were observed at necropsy. Although it was not possible to observe symptoms, the low volatility of the test item should be taken into account when considering toxicity of the test item.

The acute toxicity of the test item by intraperitoneal injection was evaluated in an experimental study in a limit test without controls. 7 % test item suspended in an aqueous solution of 0.5 % carboxymethyl cellulose was administered to 5 male and 5 female NMRI mice at a concentration of 700 mg/kg bw test item by intraperitoneal injection to the abdominal cavity. Mortality and toxic symptoms were observed at 1, 24 and 48 hours and 7 and 14 days after administration and all animals were subjected to gross pathology analysis at necropsy.

After 1 and 24 hours, no mortality was observed. After 48 hours, 3 male and 2 female animals were found dead. No further mortality occurred within the 14-day study period. Unspecific toxic symptoms observed during the study period. No intra-abdominal test item precipitation or lesions were observed in any test animals at necropsy. The LD50 of the test item was estimated to be approximately 700 mg/kg bw in rats following intraperitoneal injection.

Justification for classification or non-classification

In the CLP Regulation (EC) No 1272/2008 acute toxicity is defined as “those adverse effects occurring following oral or dermal administration of a single dose of a substance or a mixture, or multiple doses given within 24 hours, or an inhalation exposure of 4 hours”. A substance can be allocated to one of four toxicity categories based on acute toxicity by the oral, dermal or inhalation route. The numeric criteria based on the acute toxicity estimates (ATE) in mg/kg bodyweight are presented in Annex I, Part 3, Table 3.1.1. For acute oral toxicity: "Category 4: 300 < ATE ≤ 2 000".

Based on the available experimental data on acute oral toxicity (LD50 > 2000 mg/kg bw), no classification for acute oral toxicity is warranted under the CLP Regulation (EC) No 1272/2008.