Potassium tetrafluoroborate

Endpoint summary

Description of key information

The adverse effects observed in the sub-acute oral and inhalation toxicity studies indicate that the substance is absorbed by both the respiratory tract as well as the gastro-intestinal tract. Skin penetration of potassium tetrafluoroborate of 0.65% and 1.8% is considered a worse-case situation for workers and the general population, respectively.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

100

Absorption rate - dermal (%):

1.8

Absorption rate - inhalation (%):

100

Additional information

Oral and respiratory absorption

No data is available on the toxicokinetics of potassium tetrafluoroborate. However, acute and sub-acute oral and inhalation toxicity studies are available. In the sub-acute oral toxicity study increased mortality was observed in rats exposed to 350 mg KBF4 / kg body weight, and decreased body weight and food consumption was observed in rats exposed to 116.5 and 350 mg KBF4/kg body weight. In the sub-acute and subchronic inhalation toxicity studies, impaired growth and reduced food intake in male animals of the high concentration group was observed. These effects indicate that the substance is absorbed by both the respiratory tract as well as the gastro-intestinal tract.

 

Dermal absorption

No acute and sub-acute dermal toxicity studies are available. Solid substances will only penetrate the skin in (aqueous) solution. Pure potassium tetrafluoroborate is a salt with a water solubility of 5.4 g/L. Once dissolved, the salt is hydrolysed to its ions BF4^-, and K⁺. The ions are hydrophylic and due to lack of lipophilicity, they will not have any affinity to skin(lipids). Therefore, skin absorption can only occur through the water that penetrates the skin and the maximum skin absorption is defined by the maximum water solubility of the salts and the maximum amount of water that can penetrate the skin. The maximum amount of water that can penetrate the skin is determined to be 17 µL per 1 cm² per 24 hours (Ten Berge, W. A simple dermal absorption model: derivation and application.Chemosphere2009; 75(11):1440-5), which equals 6 µL per cm² per 8 hours.

 

Skin penetration, dermal absorption percentage for workers

Since 6 µL of water can maximally penetrate 1 cm² of skin per 8 hours, 6 x 5.4 = 32.4 µg of hydrolysed salt may penetrate 1 cm² of skin per 8 hours. In an in vitro skin absorption experiment (according to OECD guideline 428), the application should mimic human exposure, normally 1-5 mg/cm² (1000 -5000 µg/cm²). Thus, in case the skin penetration of pure potassium tetrafluoroborate would be experimentally determined according to OECD guideline 428 using 5 mg/cm² as exposure condition, a skin penetration of 0.65% (32.4/5000) would be observed maximally. Therefore a skin penetration of pure potassium tetrafluoroborate of 0.65% is considered a worse-case situation for workers.

 

Skin penetration, dermal absorption percentage for general population

Since 17 µL of water can maximally penetrate 1 cm² of skin per 24 hours, 17 x 5.4 = 91.8 µg of hydrolysed salt may penetrate 1 cm² of skin per 24 hours. In an in vitro skin absorption experiment (according to OECD guideline 428), the application should mimic human exposure, normally 1-5 mg/cm² (1000-5000 µg/cm²). Thus, in case the skin penetration of pure potassium tetrafluoroborate would be experimentally determined according to OECD guideline 428 using 5 mg/cm² as exposure condition, a skin penetration of 1.8% (91.8/5000) would be observed maximally. Therefore a skin penetration of pure potassium tetrafluoroborate of 1.8% is considered a worse-case situation for the general population.