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Key value for chemical safety assessment

Additional information

There are no substance specific data available on the acute toxicity of ashes (residues), cenospheres.

Ashes (residues), cenospheres and ashes (residues), coal share a common production process as substances derived from coal combustion. Ashes (residues), cenospheres represent a fraction of ashes (residues), coal separated by physical means. Both substances exhibit similarities in physicochemical properties and chemical composition. The main differences consist in a much lower content of water soluble matter and the particle size distribution of ashes (residues), cenospheres.

In terms of hazard assessment, studies available for ashes (residues), coal are therefore taken into account by read-across following an analogue approach, the results of these studies being considered a worst case for ashes (residues), cenospheres.


In vitro

A bacterial gene mutation assay was conducted with Ashes (residues) following a protocol compliant with OECD guideline 471 and under GLP conditions. The direct plate incorporation procedure was performed with Salmonella typhimurium TA 98, TA 100, TA 1535 and TA 1537 as well as with Escherichia coli WP2 uvrA at concentrations up to 5000 µg/plate in the absence and in the presence of a metabolic activator (Aroclor 1254-induced rat liver S9). No cytotoxic effects were observed up to the highest concentration as determined with S. typhimurium TA 100. Ashes (residues) did not induce mutations in the bacterial mutation tests in the absence and presence of metabolic activation in any of the strains tested. The positive and negative controls included in the experiments showed the expected results (Täublová, 2008).

Ashes (residues) were assayed in a gene mutation assay in cultured mammalian cells according to OECD guideline 476 and complying with GLP. The test material was suspended in water due to insolubility in any of the other solvents recommended. The suspension, tested up to the highest analysable concentration of 2500 µg/mL in the absence and presence of metabolic activation (S9 mix from Aroclor 1254-induced rats) in two independent experiments, was negative with respect to the mutant frequency in the L5178Y TK +/- mammalian cell mutagenicity test. The positive controls included in the study exerted potent mutagenic effects. No signs of cytotoxicity (decreased survival) were noted in the experiments without and with metabolic activation, immediately after treatment (3 and 24 h without S9 mix; 3 h with S9 mix) and in the following plating for 5-trifluoro-thymidine (TFT) resistance, up to the top concentration of 2500 µg/mL. In addition, no change was noted in the ratio of small to large mutant colonies. Therefore, Ashes (residues) also did not exhibit clastogenic potential at the concentration-range investigated. According to the evaluation criteria for this assay, these findings indicate that Ashes (residues), tested up to the highest analysable concentration of 2500 µg/mL in the absence and presence of metabolic activation did neither induce mutations nor had any chromosomal aberration potential (LPT, 2010).


In vivo

The potential of Ashes (residues) to induce cytogenetic damage in vivo was investigated using Wistar rats in a GLP-study conducted according to OECD 474. The test substance was administered to the test animals by stomach tube in single dose. A dose level of 2000 mg/kg bw was chosen according to the results of a pilot experiment. Bone marrow samples were taken 24 and 48 h after administration. The group of animals without administration and concurrent negative and positive controls were included. Each experimental group consisted of five males and five females. The smears obtained from the bone marrow were examined by light microscope. The test substance, at the dose level of 2000 mg/kg bw, did not induce a significant increase in the number of immature erythrocytes with micronuclei compared with the negative control group. It was therefore concluded that, under the experimental conditions of the study, Ashes (residues) did not give rise to the formation of micronuclei in immature erythrocytes in bone marrow of rat (Valášková, 2008).

Short description of key information:
Based on read-across following an analogue approach, the available data indicate that ashes (residues), cenospheres are not genotoxic.
In vitro:
Negative Ames tests with S. typhimurium TA 1535, TA 1537, TA 98 and TA 100, and E. coli WP2 uvr A, with and without metabolic activation.
Negative results in a mammalian cell gene mutation test using mouse lymphoma L5178Y cells, with and without metabolic activation.
In vivo:
Negative results in a mammalian erythrocyte micronucleus test in rats.

Endpoint Conclusion: No adverse effect observed (negative)

Justification for classification or non-classification

Based on read-across following an analogue approach, the available data on the genotoxic potential of ashes (residues), cenospheres is conclusive but not sufficient for classification according to the DSD (67/548/EEC) and GHS (CLP, 1272/2008/EC) criteria for classification and labelling.