Cryolite, tripotassium

Endpoint summary

Description of key information

The oral LD50 exceeds 2000 mg/kg body weight.

The inhalatory LC50 (4 hours) was determined at 1 -5 mg/L for male and female rats based on read-across from multiconstituent aluminium potassium fluoride.

Key value for chemical safety assessment

Acute toxicity: via oral route

Endpoint conclusion

Endpoint conclusion:

no adverse effect observed

Quality of whole database:

GLP study according to standard guidelines.

Acute toxicity: via inhalation route

Endpoint conclusion

Endpoint conclusion:

adverse effect observed

Quality of whole database:

GLP study according to standard guidelines.

Acute toxicity: via dermal route

Endpoint conclusion

Endpoint conclusion:

no study available

Additional information

Oral route:

An acute oral toxicity study according to OECD guideline 423 and under GLP conditions is available. The test material was administered at 2000 mg/kg bw by oral gavage. Animals were observed for 14 days and necropsied. No mortality occurred. No clinical signs of systemic toxicity were noted. For this reason, the oral LD50 value of potassium cryolite in Wistar rats was established to exceed 2000 mg/kg body weight.

Inhalation route:

Since no acute inhalation toxicity study is available for potassium cryolite, the results from the structural analogue multiconstituent aluminium potassium fluoride are used instead (for details see Read-across justification as attached in section 13).

The acute inhalation toxicity of multiconsituent aluminium potassium fluoride in the rat was investigated in a GLP compliant, non-guideline study. Despite some minor restrictions in design and/or reporting, the study is considered as adequate for assessment. One group of 5 male and 5 female rats was exposed whole body to a dust atmosphere of the test substance. The duration of the exposure was 1 hour followed by a 14 day observation period. The gravimetric concentration of test article in the test atmosphere was 4.92 mg/l. Particle size analysis of the exposure chamber revealed a mass median diameter of 1.30 µm and geometric standard deviation of 1.58. Four of the test animals died during the study. Irregular breathing, poor coat quality, yellow/brown stained fur, lethargy, crusty eye, crusty nose, and crusty muzzle were observed among the test animals during the study period. Necropsies revealed no gross lesions in 5 of 10 test animals. Abnormalities of the small intestine, stomach, and heart were observed in the remaining test rats. Based on the observed mortality it can be concluded that the 1-hour LC40 of the test substance is 4.92 mg/L which would correspond to a 4-hour LC40 of 1.23 mg/l when applying Haber's rule. The 4 -hour LC50 will be slightly above this concentration.

Based on these results, the inhalatory LC50 (4h) value of potassium cryolite in rats is also expected to fall within the range of 1 - 5 mg/L.

Dermal route:

In accordance with column 2 of REACH Annex VIII-IX, as acute toxicity studies for the oral and inhalation route are available, no study regarding the dermal route is needed.

Justification for classification or non-classification

The oral LD50 of potassium cryolite is determined to be >2000 mg/kg bw in the available acute oral toxicity study. Based on these results,classification of potassium cryolite for acute oral toxicity according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 is not needed.

In the acute inhalation study with the read-across candidate multiconsituent aluminium potassium fluoride, the LC50 value was established to fall within the range of 1 - 5 mg/L. Therefore the substance potassium cryolite needs to be classified as Cat. 4, H332 'Harmful if inhaled' according to the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008.