Registration Dossier

Toxicological information

Carcinogenicity

Currently viewing:

Administrative data

Description of key information

According to the NTP study performed 1994, the concentration of 2500 ppm represents a NOAEL for carcinogenicity (corresponding to Ba doses of 60 and 75 mg/kg bw/d to male and female rats, respectively, and 160 and 200 mg/kg bw/d to male and female mice, respectively). Based on this value the NOAEL for BaCO3 is calculated at 86 mg/kg bw/day.

Key value for chemical safety assessment

Additional information

Read across BaCl2*2H2O to BaCO3:

Reliable data for the assessment of carcinogenicity of BaCO3are not available. However, the toxicity of barium substances such as barium carbonate can reasonably assumed to be determined by the availability of barium ions in solution. This was investigated for barium carbonate experimentally in a test for comparative bio-accessibility with barium carbonate and barium chloride in artificial gastric juice (HCl, pH=1.5): an excess of each test item was added to a freshly prepared HCl solutions (pH=1.5) to obtain saturation (for details, please refer to IUCLID section 4.20 “pH” of this dossier). It could be shown that the solubility of barium carbonate in acidic media at 37°C is 3.7 g/L, whereas 510.4 g/L of barium chloride could be dissolved under equal conditions. In consequence, the solubility of barium carbonate under these conditions is more than two orders of magnitude less than that of barium chloride. Therefore, it was decided to waive carcinogenicity testing of barium carbonate and to read across from barium chloride for animal welfare reasons. However, it is to be concluded that this read-across will likely lead to rather conservative no-effect levels.

 

Justification for classification or non-classification

There was no evidence of carcinogenic activity (showing no chemical related increase of malignant or benign neoplasms) of barium chloride in both sexes of rats and mice that received 500, 1250, and 2500 ppm. Thus, the concentration of 2500 ppm represents a NOAEL (corresponding to barium doses of 60 and 75 mg/kg bw/d to male and female rats, respectively, and 160 and 200 mg/kg bw/d to male and female mice, respectively). No classification of the substance as CMR substance is required.