Registration Dossier
Registration Dossier
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EC number: 270-659-9 | CAS number: 68475-76-3 A complex combination of finely divided inorganic particles separated from the exit gases formed during the manufacture of Portland cement. The flue dust consists of uncalcined raw materials along with partially calcined materials. Some Portland cement clinker is usually included. The major constituents of kiln dust are calcium carbonate, clays, shales, quartz and sulfate salts. The following materials may also be present:@Dolomite@Ca(OH)2@Feldspars@CaSO4@Fly ash@KCl@Iron oxides@K2CO3@CaF2@K2SO4@CaO@Na2SO4@Glasses of SiO2, Al.s@Portland cement chemicals [659
Endpoint summary
Administrative data
Link to relevant study record(s)
Description of key information
Key value for chemical safety assessment
Additional information
No experimental data concerning inhalation, dermal or oral kinetics are available for Flue dust. Therefore, an assessment of the toxicokinetic behaviour is based on the physico-chemical properties and the results of toxicological investigations with Flue dust.
Physical-chemical properties
Flue dust is a complex mixture of finely divided inorganic particles separated from the exit gases formed during the manufacture of Portland cement clinker which is produced by thermal processing of raw materials (naturally occurring minerals and alternative raw materials) and fuels (fossil and alternative). Flue dust is a powdery UVC substance, whose constituents are minerals and therefore inorganic solids at room temperature.The melting points of the constituents are all above 300 °C and the constituents have no vapour pressure. The solubility properties of the substance can differ substantially from what is observed for each individual constituent of the substance. The highly soluble constituents of Flue dust are potassium sulfate, sodium sulfate, calcium sulfate, potassium chloride, potassium sodium sulfate and potassium calcium sulfate (all together about 15 %) and the moderate soluble calcium hydroxide (a reaction product of the cement clinker phases and calcium oxide, solubility is about 1.5 g/L, the amount depends on the reaction degree and the amount of calcium oxide, which is 10 % in the Flue dust). Due to the broad range of the constituents of the substance, no definite solubility can be given.The test item has a particle size range between 0 and 175 µm.
Data from acute toxicity studies
Acute toxicity data showed low toxicity. In an acute dermal toxicity study in rats with Flue dust, the LD50 was > 2000 mg/kg bw (TNO, 2010). From an acute inhalation toxicity study in rats with Flue dust, it was concluded that the 4-hour LC50 for Flue dust was above 6.04 g/m³ (TNO, 2010). Only local effects (effects on the respiratory tract and skin) were observed in the acute inhalation and dermal toxicity study. No systemic effects were reported.
Data from repeated dose toxicity studies
A combined repeated dose and reproduction / developmental screening (OECD 422) in rats was performed with dose levels of 2000, 6000 and 16000 mg/kg diet (nominal in diet) / 119-164, 374-483 and 1010-1216 mg/kg bw/day in which the males were exposed for 28 days and females for 6-7 weeks(TNO, 2010). In this study the following findings were noted:
Body weight change of the female animals of the high-dose group was statistically significantly decreased during the lactation period. Haemoglobin and mean corpuscular volume were statistically significantly decreased in high-dose females. Haemoglobin also tended to be decreased in high-dose males. In males of the high-dose group, a statistically significant increase was observed in the mean amount of plasma urea. Urea also tended to be increased in high-dose females.
Based on the available toxicity data no firm conclusion can be drawn on the toxicokinetic behaviour of Flue dust. The toxicological findings in the highest dose group in the oral repeated dose study were decreased body weight change during lactation, decreased haemoglobin in females and increased plasma urea in males. From these data it may be concluded that after oral exposure some components of the test substance are absorbed to some extent.
Dermal absorption
Flue dust consists of water insoluble and water soluble components. Dermal absorption of the water insoluble components is considered negligible. The highly soluble constituents of Flue dust are potassium sulfate, sodium sulfate, calcium sulfate, potassium chloride, potassium sodium sulfate and potassium calcium sulfate (all together about 15%) and the moderate soluble constituent is calcium hydroxide (the amount depends on the reaction degree and the amount of calcium oxide, which is 10% in the Flue dust). These constituents will dissolve at the skin surface and be present as ions. Dermal absorption of these ionic species is also considered negligible.
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