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Description of key information

The free acid was tested for acute oral toxicity in OECD guideline conform studies (OECD SISDS SIAM 19). The substance caused gastro-intestinal irritation and mottled liver, and mortalities occured within 35 min - 1 day after administration. LD50 was calculated to be 823 mg/kg bw/day. An acute dermal toxicity study was also performed but poorly documented and not sufficient for a statement on classification.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion
Dose descriptor:
LD50
Value:
823 mg/kg bw

Additional information

Reasons for read across

The test item is the sodium salt of a naphthoic acid. In an acidic enviroment (e.g. stomach), the salt complex becomes dissociated into the sodium cation and the organic acid. Therefore, it is acceptable to derive acute toxicity data from the free acid.

Assessment acute toxicity according OECD SIDS (SIDS Initial Assessment Report For SIAM 19 - 3-Hydroxy-2-naphthoic acid)

The free acid was tested for its acute oral toxicity in two studies performed in accordance with OECD TG 401. In these studies, an oral LD50 in the range between 823 and 1040 mg/kg bw was determined in rats of both sexes. Clinical signs included reduced activity, accelerated breathing, closure of eyes, and diarrhoea. All deaths occurred between 35 minutes and one day after exposure. Gastro-intestinal irritation and dark or mottled livers were seen in the animals that had died during the study, whilst the surviving animals were free of pathological changes at the end of the 14-day observation period LD50 values in the range between 800 and 2450 mg/kg bw have been reported for the rat in other, poorly documented and limited studies and publications.

In a poorly documented, old and very limited study, a dose of 2000 mg/kg bw applied dermally caused the death of a guinea pig, whilst 1000 mg/kg bw were non-lethal (Eastman Kodak, 1954). In this study, only one animal was used per dose level, and the exposure was for 24 hours under occlusive conditions. At the highest dose level (approximately 2000 mg/kg bw; applied as a 10% solution in acetone:corn oil) necroses were seen which covered about one half of the total application area.

Conclusion

The acute oral LD50 in rat was between 823-1040 mg/kg bw. Clinical signs included reduced activity, accelerated breathing, closure of eyes, and diarrhea. Gastro-intestinal irritation and dark or mottled livers were seen in the animals that had died during the studies.

A poorly documented study showed that 10% solution of 3-hydroxy-2-naphthoic acid (approx. 2000 mg/kg bw) was lethal to guinea pigs when applied dermally for 24 hours under occlusive conditions.

Justification for classification or non-classification

Dangerous Substance Directive (67/548/EEC)

The available oral studies are considered reliable and suitable for classification purposes under 67/548/EEC. As a result the substance is considered to be classified for acute oral toxicity under Directive 67/548/EEC, as amended for the 28th time in Directive 2001/59/EC.

 

Classification, Labelling, and Packaging Regulation (EC) No. 1272/2008

The available experimental test data on oral toxicity are reliable and suitable for classification purposes under Regulation 1272/2008. As a result the substance is considered to be classified for acute oral toxicity under Regulation (EC) No. 1272/2008.