Barium fluoride

Endpoint summary

Description of key information

Based on its water-solubility, the substance is expected to be absorbed by the gastrointestinal and respiratory tract. In the absence of substance-specific data, a default absorption value of 100% is assumed for the inhalation and 50% for the oral route. Skin penetration of barium fluoride of 0.19% is considered as worst-case situation for workers.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

0.19

Absorption rate - inhalation (%):

100

Additional information

No data are available that describe the toxicokinetics of barium fluoride, therefore relevant substance properties and data from toxicity studies were taken together to assess the general toxicokinetics of the substance. Barium fluoride is a salt with a water solubility of 1.6 g/L at neutral pH. Once dissolved, the substance dissociates into barium and fluoride ions.

Oral and respiratory absorption

The available acute oral toxicity study (dose level: 2000 mg/kg bw) did not reveal any effects which indicate systemic availability of the substance. In the acute inhalation study with barium fluoride, mortality was observed in the high dose group (2.3 mg/L) an therefore it is considered likely that barium fluoride will be absorbed if inhaled. According to the REACHGuidance on information requirements and chemical safety assessment (R.8.4.2), a default value of 50% absorption is assumed for the oral route and 100% for inhalation in theabsence of substance specific quantitative data on absorption.

Dermal absorption

Measured data on dermal absorption of barium fluoride are not available. Solid substances will only penetrate the skin in (aqueous) solution. Barium fluoride is a salt with a water solubility of 1.6 g/L at neutral pH. Once dissolved, the salt is ionized to barium and fluoride ions. The ions are hydrophilic 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. (Chemosphere 2009; 75(11):1440-5), which equals 6 µL per cm2 per 8 hours. Since 6 µL of water can maximally penetrate 1 cm2 of skin per 8 hours, 6 x 1.6 = 9.6 µg of ionized 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 barium fluoride would be experimentally determined according to OECD Guideline 428 using 5 mg/cm2 as exposure condition, a skin penetration of 0.19% (9.6/5000) would be observed maximally. Therefore a skin penetration of barium fluoride of 0.19% is considered a worse-case situation for workers.