Potassium tetrafluoroaluminate

Endpoint summary

Description of key information

Based on read-across from multiconstituent aluminium potassium fluoride, the oral LD50 is 2.41 (2.24-2.60) g/kg bw  for male and 1.91 (1.43-2.56) g/kg bw for female rats for potassium tetrafluoroaluminate, with an average LD50 of 2.16 (1.84-2.58) g/kg for both sexes.
The rat inhalation LC50 for 1 hour is >3.88 mg/L, based on the read-across from multiconstituent aluminium potassium fluoride.
The dermal LD50 value is >2.0 g/kg bw in rabbits based on the read-across from multiconstituent aluminium potassium fluoride.

Additional information

No acute toxicity study is available on potassium tetrafluoroaluminate. However, Article 13 of the REACH legislation states that, in case no appropriate animal studies are available for assessment, information should be generated whenever possible by means other than vertebrate animal tests, i. e., applying alternative methods such as in vitro tests, QSARs, grouping and read-across.

Three acute oral toxicity studies equivalent or similar to OECD guideline 401 are available for a structural analogue of potassium tetrafluoroaluminate, multiconstituent aluminium potassium fluoride. (Hazelton Laboratories, 1985a,b,c). Different multiconstituent aluminium potassium fluoride batches were tested: multiconstituent aluminium potassium fluoride 100 FLUX (AT-1 -KC), multiconstituent aluminium potassium fluoride NK FLUX (AT-2-NK) and multiconstituent aluminium potassium fluoride NK FLUX (AT-3-NL). Different dose levels were tested in the studies. The following results were observed regarding mortality:

Multiconstituent aluminium potassium fluoride 100 FLUX (AT-1-KC):

Males: 2.55 g/kg: 0/5 (0 of 5 animals); 2.75 g/kg: 3/5; 3.57-5.00 g/kg: 5/5;

Females: 1.30 g/kg: 0/5; 1.82 g/kg: 2/5; 2.55 g/kg: 3/5; 3.57-5.00 g/kg: 5/5.

 

Multiconstituent aluminium potassium fluoride NK FLUX (AT-2-NK):

Males: 3.57 g/kg: 0/5 (0 of 5 animals); 5.00 g/kg: 3/5; 7.00 g/kg: 5/5;

Females: 2.55 g/kg: 0/5; 3.57 g/kg: 0/5; 4.25 g/kg: 3/5; 5.00 g/kg: 5/5.

Multiconstituent aluminium potassium fluoride NK FLUX (AT-3-NL):

Males: 3.57 g/kg: 1/5 (1 of 5 animals); 5.00 g/kg: 3/5; 7.00 g/kg: 5/5;

Females: 2.55 g/kg: 0/5; 2.75 g/kg: 3/5; 3.00 g/kg: 5/5; 3.57 g/kg: 5/5; 5.00 g/kg: 5/5.

 

In the animals which died histopathological lesions were observed mainly in the gastro-intestinal tract, primarily in the stomach.

The most critical LD50 values were observed when testing multiconstituent aluminium potassium fluoride 100 FLUX (AT-1-KC): for males the LD50 value was 2.72 (2.52-2.93) g/kg bw and for females the LD50 value was 2.15 (1.61-2.89) g/kg bw. The testing was performed with the substance of composition 70% KAlF₄ and 30% K₂AlF₅.The calculated molecular weight of the substance is 160 g/mol. The main difference between potassium tetrafluoroaluminate and multiconstituent aluminium potassium fluoride lies in the fact that potassium tetrafluoroaluminate is a monoconstituent substance (the concentration of the main constituent KAlF₄is ≥90%), while multiconstituent aluminium potassium fluoride is a multi-constituent substance, containing next to 70% of KAlF₄ 30% of K₂AlF₅. The presence of the latter higher homological salt is, however, not expected to alter significantly the physico-chemical and toxicological properties of multiconstituent aluminium potassium fluoride in comparison to potassium tetrafluoroaluminate. Only a correction for molecular weight (160 g/mol for multiconstituent aluminium potassium fluoride vs. 142 g for potassium tetrafluoroaluminate) is applied. Applying a correction for molecular weight, a LD50 of 2.41 (2.24- -2.60) g/kg bw is calculated for male and 1.91 (1.43 -2.56) g/kg bw for female rats, with the average LD50 for both sexes of 2.16 (1.84 -2.58) g/kg bw.

 

Two acute inhalation toxicity studies with rats are available with multiconstituent aluminium potassium fluoride (American Biogenics Corporation, 1985a,b).

In the first one, one group of 5 male and 5 female rats was exposed to 4.92 mg/L multiconstituent aluminium potassium fluoride for 1 hour, followed by an observation period of 14 days. 1 male and 3 females died. Thus the LC50 for 1 hour was >4.92 mg/L. Clinical signs that were reported were irregular breathing, poor coat quality, yellow/brown stained fur, lethargy, crusty eye, crusty nose and crusty muzzle. Abnormalities of the stomach (multifocal erosions, diffuse red brown discoloration of glandular mucosa), glandular stomach (mucosa smooth and discolored red brown), heart (diffusely pale, tan discoloration, mottling) and small intestine (dark contents) were observed in 2 males and 3 females.

Applying a correction for molecular weight, a LC50 of >4.37 mg/L is calculated for potassium tetrafluoroaluminate.

In the second study, one group of 5 male and 5 female rats was exposed to 3.4 mg/L multiconstituent aluminium potassium fluoride for 1 hour,followed by an observation period of 14 days. One female died. Thus de LC50 for 1 hour was >3.4 mg/L. Clinical signs that were reported were irregular breathing, ataxia, lethargy and crusty nose. No gross abnormalities in the survivors were noted. Abnormalities of the heart and stomach were observed in the female that died during the study. Applying a correction for molecular weight, a LC50 of >3.02 mg/L is calculated for potassium tetrafluoroaluminate.

Using modified Haber's law (Cⁿx t = constant) and using n=1 as a default value in accordance with Chapter R.7.4.4.1 of REACH Guidance on information requirements and chemical safety assessment for extrapolation from shorter to longer exposure duration, the 4 h LC50 is calculated to be >0.97 mg/L (starting point for this calculation is the highest level (corrected for molecular weight) of 4.37 mg/L/1h at which 1 male and 3 female rats died). As at the extrapolated 4 h figure, >1.09 mg/L, the mortality number was 4/10 animals and as the classification limits for aerosols/particulates for classification as harmful are: 1 < LC50 ≤ 5 mg/L/4h, it is expected that the LC50 figure of the substance falls within the classification range for harmful.

Supporting data for not classifying the substance in a higher category is the result that no mortality was observed when rats were exposed 6 hours/day, 5 days/week for 28 days up to a concentration of 0.6 mg/L multiconstituent aluminium potassium fluoride, equal to 0.53 mg/L potassium tetrafluoroaluminate (see section on repeated dose toxicity).

Regarding the dermal route, three studies (equivalent or similar to OECD guideline 402) are available for multiconstituent aluminium potassium fluoride (Hazelton Laboratories, 1985d,e,f). Different multiconstituent aluminium potassium fluoride batches were tested: multiconstituent aluminium potassium fluoride 100 FLUX (AT-1 -KC), multiconstituent aluminium potassium fluoride NK FLUX (AT-2 -NK) and multiconstituent aluminium potassium fluoride NK FLUX (AT-3 -NL). In the studies, five male and five female rabbits were administered a single dermal dose of 2.0 g/kg bw and held for an observation period of 14 days. No mortality and no other effects were observed and/or reported. The LD50 value was >2.0 g/kg bw for all three tested batches of aluminium potassium fluoride. Based on these results, a LD50 >2 g/kg bw is also expected for potassium tetrafluoroaluminate.

Justification for classification or non-classification

Based on the results of the available acute toxicity studies with a read-across candidate multiconstituent aluminium potassium fluoride, no classification is warranted for dermal toxicity.

For oral route of exposure, based on the average LD50 of 2.16 g/kg bw for both sexes, no classification is warranted for potassium tetrafluoroaluminate in accordance with the EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008 and EU Directive 67/548/EEC.

Regarding the inhalation route of exposure, in accordance to Directive 67/548/EEC and EU Classification, Labelling and Packaging of Substances and Mixtures (CLP) Regulation (EC) No. 1272/2008, the substance has to be classified as harmful (Xn); R20 and Cat. 4; H332, respectively.