Registration Dossier

Administrative data

Description of key information

Acute toxicity, oral: LD50 >5000 mg/kg bw 
Acute toxicity, dermal: waiving (LD50 >2000 mg/kg bw (only secondary information))
Acute toxicity, inhalation: waiving

Key value for chemical safety assessment

Additional information

Reason for read across from BaCl2to BaSO4 for acute dermal toxicity:

The toxicity of barium sulfate and barium chloride is based on the Ba2+cation and therefore on the solubility of the test substance. Barium chloride is well water soluble (ca. 375 g/L) at pH ca. 6.5 (pH of artificial sweat solution), whereas barium sulfate is low soluble (3.1 mg/L at pH 9). Due to the fact that Barium chloride seems to be no toxic via the dermal route it can be concluded that barium sulfate will result in a dermal LD50of >>2000 mg/kg bw and should therefore not classified as acute toxic to the dermal route.

Reason for read across from BaCO3 to BaSO4for acute inhalation toxicity:

Barium sulfate (melting point: 1600°C) and barium carbonate (melting point: 1380°C) are very similar in view of the particle size, melting point and density (rel. density: BaSO4: 4.5) and both could be regarded as insoluble in solutions at a pH of 9 (barium sulfate ca. 3.1 mg/L and barium carbonate ca. 14 mg/L). Beside this barium sulfate (the standard powder on the marked) has a larger MMAD/GSD as barium carbonate standard.

Justification for classification or non-classification

Acute oral toxicity

The study performed by Boyd (1966) (see robust study summary chapter 7.2.1) is considered as the key study for acute oral toxicity and will be used for classification. Male Wistar rats were dosed up to 375 g/kg bw orally via gavages. During the conduct of the study mortalities occurred only due to stomach rupture or bowel obstruction, no biologically important body weight loss occurred after dosing, and no gross lesions were present in the rats at necropsy.

LD0 oral, rat 163 g/kg bw.

The classification criteria according to regulation (EC) 1272/2008 as acutely toxic are not met since the ATE is above 2000 mg/kg body-weight, hence no classification required.

 

Specific target organ toxicant (STOT) – single exposure: oral

The classification criteria according to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, oral are not met since no reversible or irreversible adverse health effects were observed immediately or delayed after exposure and no effects were observed at the guidance value, oral for a Category 1 classification of 300 mg/kg bw and at the guidance value, oral for a Category 2 classification of 2000 mg/kg bw. No classification required.

 

Acute dermal toxicity

According to the SIAR 27 prepared for barium chloride, an acute dermal toxicity study on barium chloride was conducted according to OECD TG 402, in compliance with GLP. In this study, the dermal LD50was greater than 2000 mg BaCl2/kg bw in rats. The primary data could not be made available by the registrant but if using the secondary information no classification according to regulation (EC) 1272/2008 will be necessary for barium sulfate by read across from barium chloride.

 

 

Acute inhalation toxicity

A pre test on inhalation was performed with barium carbonate (rel. density: 4.3). Despite extensive effort it was not possible to generate a stable testing atmosphere with an acceptable test concentration (ideally 5.1 mg/L).

 

Barium sulfate (melting point: 1600°C) and barium carbonate (melting point: 1380°C) are very similar in view of the particle size, melting point and density (rel. density: BaSO4: 4.5) and both could be regarded as insoluble in solutions at a pH of 9 (barium sulfate ca. 3.1 mg/L and barium carbonate ca. 14 mg/L). Beside this barium sulfate (the standard powder on the marked) has a larger MMAD/GSD as barium carbonate standard.

 

 

 

deposition fractions

Sample

rel. density

D50 [µm]

MMAD [µm]

GSD

Head [%]

TB [%]

PU [%]

BaSO4HD80 (standard)

4.5 at 20°C

1.16

53.84

2.12

24.28

0.04

0.02

BaCO3(standard)

4.3 at 20°C

2.32

24.22

4.87

45.22

0.95

1.16

 

Based on the technical properties of barium sulfate which are equal or similar to barium carbonate, the performance of an acute inhalation toxicity test is neither technically feasible nor scientifically justified. Due to the low mobility and the negligible volatility of barium sulfate (melting point: 1600°C), the test material can safely be assumed to have a very low potential for human inhalation hazard during handling or application. Hence, no classification is required.

 

Specific target organ toxicant (STOT) – single exposure: inhalation

The classification criteria according to regulation (EC) 1272/2008 as specific target organ toxicant (STOT) – single exposure, inhalation dust/mist/fume are not met since no relevant exposure via inhalation is possible. Based on the technical properties of barium sulfate, the performance of an acute inhalation toxicity test is neither technically feasible nor scientifically relevant for this type of compound, see discussion “acute inhalation toxicity”. Hence, no classification is required.