Aluminate(1-), tetrafluoro-, cesium (1:1), (T-4)-

Endpoint summary

Description of key information

Based on its water-solubility, low molecular weight and the effects observed in rats upon subacute oral exposure and acute inhalation exposure, 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 route and 50% for the oral route. Skin penetration of cesium tetrafluoroaluminate of 1.6% is considered a worst-case situation for workers.

Key value for chemical safety assessment

Bioaccumulation potential:

no bioaccumulation potential

Absorption rate - oral (%):

50

Absorption rate - dermal (%):

1.6

Absorption rate - inhalation (%):

100

Additional information

No data are available that describe the toxicokinetics of cesium tetrafluoroaluminate, therefore relevant substance properties and data from toxicity studies indicating systemic bioavailability were taken together to assess the general toxicokinetics of the substance. Cesium tetrafluoroaluminate (molecular weight of 236 g/mol) is a salt with a water solubility of 13 g/L at neutral and acidic pH. Once dissolved, the substance dissociates into cesium, aluminium and fluoride ions.

Oral and respiratory absorption

The available acute oral toxicity study (dose level: 2000 mg/kg) revealed effects which may indicate systemic availability of the test substance (Pels-Rijcken WR, 1998). One female was found dead on day 2 and one male was found dead on day 4. Autopsy of the rats that died as a result of treatment revealed dark red discoloration of the glandular mucosa of the stomach, reduction in size of the spleen and haemorrhages in the thymus. In the sub-acute oral toxicity study in which rats were exposed to 30, 150 and 750 mg/kg/day, treatment related mortality was observed among animals receiving 750 mg/kg/day. The observed effects in rats treated at 150 mg/kg/day consisted of findings in the stomach, kidneys and spleen.

In an acute inhalation study (single exposure of 4 hours to 1 and 5 mg/L) mortality was observed in the high dose group. At 5 mg/L, two animals were sacrificed on Day 2 for ethical reasons. On Day 3, one animal was found dead and the other animals were sacrificed for ethical reasons. No mortality was observed at 1 mg/L. Macroscopic post mortem examination revealed abnormalities in the lungs (discoloration pale or gray-white, fluid or foamy fluid released from the bronchi, dark red foci) of three animals exposed to 5 mg/L. No further abnormalities were found in any of the animals.

As systemic toxicity (mortality) was observed in the acute inhalation toxicity study in rats, it is likely that the substance will also be absorbed if it is inhaled.

According to the REACH Guidance 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 the absence of substance specific quantitative data on absorption.

Dermal absorption

Measured data on dermal absorption of cesium tetrafluoroaluminate are not available. Solid substances will only penetrate the skin in (aqueous)

solution. Cesium tetrafluoroaluminate is a salt with a water solubility of 13 g/L at neutral pH. Once dissolved, the salt is ionized to cesium, aluminium and fluoride ions. The ions are hydrophylic and due to lack of lipophilicity, they will not have anyu 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 13 = 78 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 cesium tetrafluoroaluminate would be experimentally determined according to OECD guideline 428 using 5 mg/cm2 as exposure condition, a skin penetration of 1.6% (78/5000) would be observed maximally. Therefore a skin penetration of cesium tetrafluoroaluminate of 1.6% is considered a worse-case situation for workers.