Ashes (residues), cenospheres

Endpoint summary

Key value for chemical safety assessment

Effects on fertility

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 an earlier study, fly ash derived from coal combustion was fed at 0, 300 and 1500 g / animal / day to cows over a period of 3 years. After two years the control and intermediate dose groups were exchanged. Pregnancy rates, conception, parturition and body weight development in cows were not disturbed by the oral administration of fly ash. Because treated animals showed a slightly higher milk production rate than control animals, the general condition of treated animals was considered to be better. Necropsy results did not indicate major pathological changes due to fly ash administration. The chemical analyses of milk, blood, urine and faeces indicated that no systemic absorption occurred after oral administration of 1850 mg/kg/day of fly ash (Herrmann, 1955).

This study supports the notion that for ashes (residues), cenospheres no relevant systemic absorption and bioavailability is expected by any route of exposure, based on their physicochemical properties (solid inorganic particles of mostly water insoluble material) and also on the available information on the toxicokinetic behaviour of the main components (SiO2, Al2O3, Fe2O3).

Further evidence for a low level of absorption and toxicity is provided by the available studies on the acute and repeated dose toxicity, genetic toxicity in vivo and skin and eye irritation potential of the analogue substance ashes (residues), coal, in all of which no mortalities occurred and no signs of systemic toxicity were observed. In particular, in the repeated dose 28-day oral toxicity study in rats, no treatment-related effects were observed in reproductive organs of male and female animals given up to 1000 mg/kg bw /day.

Inhalation is the most relevant route of human exposure for ashes (residues), cenospheres. However, data on particle size distribution indicate that only < 1.5% of the particles are contained in the respirable (alveolar) fraction of particles with MMAD < 5 µm. Therefore, ashes (residues), cenospheres have in general a low exposure potential to the alveolar region of the lung. Conducting inhalation toxicity tests with a low-respirable atmosphere would not produce scientifically meaningful results for systemic toxicity. Instead, most of the inhaled material would presumably intercept in the naso-pharyngeal region.

In conclusion, on the basis of the whole body of available data on the physicochemical properties of ashes (residues), cenospheres, the toxicological activity of the analogue substance ashes (residues), coal and human exposure considerations, there are no indications for a toxic potential of ashes (residues), cenospheres to reproduction or (prenatal) development. Therefore, based on the weight of evidence a reproduction and/or (prenatal) development toxicity study by any route of exposure is considered scientifically unjustified and shall be avoided for reasons of animal welfare.

Effects on developmental toxicity

Additional information

Refer to Effects on fertility.

Justification for classification or non-classification

Based on the whole body of available data on the physicochemical properties of ashes (residues), cenospheres, the toxicological activity of the analogue substance ashes (residues), coal and human exposure considerations, there are no alerts for reproductive/developmental toxicity and for effects via lactation.