Diantimony pentoxide

Endpoint summary

Description of key information

Acute toxicity, oral:

LD50 > 2000 mg/kg bw

Acute toxicity, inhalation:

LC50 > 5.40 mg sodium hexahydroxoantimonate/L air

Based on the results of the histopathological and macroscopic investigations, sodium hexahydroxoantimonate (and by read-across antimony pentoxide and sodium antimonate) does not require classification for respiratory irritation.

Acute toxicity, dermal:

Conduct of an acute dermal toxicity study is unjustified as inhalation of the substance is considered as major route of exposure and physicochemical properties of the substance do not suggest a significant rate of absorption through the skin (cf. Annex VIII section 8.5 Column 2 of regulation (EC) 1907/2006).

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

Key study available.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

Key study available.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Acute oral toxicity testing was conducted with diantimony pentoxide and acute inhalation toxicity testing was conducted with sodium hexahydroxoantimonate.

Based on the fact that diantimony pentoxide, sodium hexahydroxoantimonate and sodium antimonate contain antimony in the pentavalent oxidation state and that water solubility testing as well as transformation dissolution testing has shown similar dissolution pattern of pentavalent antimony cations form all three substances, read-across among the pentavalent antimony compounds (i.e. sodium hexahydroxoantimonate, sodium antimonate and diantimony pentoxide) is considered justified.

Justification for selection of acute toxicity – oral endpoint

Read-across data.

Justification for selection of acute toxicity – inhalation endpoint

Key study.

Justification for classification or non-classification

Acute oral toxicity

The reference Robertson (2005) (read-across from antimony pentoxide) is considered as the key study for acute oral toxicity and will be used for classification. Female Wistar rats were dosed at 2000 mg/kg orally via gavage. During the conduct of the study no mortalities occurred, no biologically important body weight loss occurred after dosing, and no gross lesions were present in the rats at necropsy.

LD50 oral, rat > 2,000 mg/kg bw

The classification criteria according to regulation (EC) 1272/2008 as acutely toxic are not met since the ATE is above 2000 mg/kg body-weight, hence no classification required. Result is read-across to sodium hexahydroxoantimonate and sodium antimonate.

 

Specific target organ toxicant (STOT) – single exposure: oral

The classification criteria according to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, oral are not met since no reversible or irreversible adverse health effects were observed immediately or delayed after exposure and no effects were observed at the guidance value, oral for a Category 1 classification of 300 mg/kg bw and at the guidance value, oral for a Category 2 classification of 2000 mg/kg bw. No classification required. Result is read-across to sodium hexahydroxoantimonate and sodium antimonate.

 

Acute inhalation toxicity

The reference Leuschner (2010) is considered as the key study for acute inhalation toxicity and will be used for classification. Rats were nose only exposed towards sodium hexahydroxoantimonate dust for 4 hours at 5.40 mg/L air. During the conduct of the study no mortalities occurred.

LC50 inhalation, rat > 5.40 mg/L air

The classification criteria according to regulation (EC) 1272/2008 as acutely toxic are not met since the ATE for dusts and mists is above 5.0 mg/L, hence no classification required.

 

Specific target organ toxicant (STOT) – single exposure: inhalation

The classification criteria according to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, inhalation dust/mist/fume are not met since no reversible or irreversible adverse health effects were observed immediately or delayed after exposure and no effects were observed at the guidance value, inhalation dust/mist/fume for a Category 1 classification of 1.0 mg/L/4h and at the guidance value, inhalation dust/mist/fume for a Category 2 classification of 5.0 mg/L/4h. Therefore, no classification is required. Finally, any category 3 classification should primarily be based on human data. However, such classification is also not warranted, since observations on respiratory irritation in test animals were not observed at the highest inhalation exposure level. No relevant pulmonary changes were observed in the 5 localisations of the lung neither in the rats sacrificed 14 days after exposure nor the rats sacrificed 24 hours after exposure. No classification required.