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EC number: 266-340-9 | CAS number: 66402-68-4 This category encompasses the various chemical substances manufactured in the production of ceramics. For purposes of this category, a ceramic is defined as a crystalline or partially crystalline, inorganic, non-metallic, usually opaque substance consisting principally of combinations of inorganic oxides of aluminum, calcium, chromium, iron, magnesium, silicon, titanium, or zirconium which conventionally is formed first by fusion or sintering at very high temperatures, then by cooling, generally resulting in a rigid, brittle monophase or multiphase structure. (Those ceramics which are produced by heating inorganic glass, thereby changing its physical structure from amorphous to crystalline but not its chemical identity are not included in this definition.) This category consists of chemical substances other than by-products or impurities which are formed during the production of various ceramics and concurrently incorporated into a ceramic mixture. Its composition may contain any one or a combination of these substances. Trace amounts of oxides and other substances may be present. The following representative elements are principally present as oxides but may also be present as borides, carbides, chlorides, fluorides, nitrides, silicides, or sulfides in multiple oxidation states, or in more complex compounds.@Aluminum@Lithium@Barium@Magnesium@Beryllium@Manganese@Boron@Phosphorus@Cadmium@Potassium@Calcium@Silicon@Carbon@Sodium@Cerium@Thorium@Cesium@Tin@Chromium@Titanium@Cobalt@Uranium@Copper@Yttrium@Hafnium@Zinc@Iron@Zirconium
Toxicity to soil macroorganisms except arthropods
Administrative data
Link to relevant study record(s)
Description of key information
Based on the justification of the three main components, it can be concluded:
Aluminium, aluminium powders and aluminium oxide are non hazardous (not classified for the environment). Aluminum (Al) is the most commonly occurring metallic element, comprising eight percent of the earth's crust (Press and Siever, 1974) and is therefore found in great abundance in both the terrestrial and sediment environments.
In the environment, lime substances rapidly dissociate or react with water. From these reactions it is clear that the effect of calcium oxide will be caused either by calcium or hydroxyl ions. Since calcium is abundantly present in the environment and since the effect concentrations are within the same order of magnitude of its natural concentration, it can be assumed that the adverse effects are mainly caused by the pH increase caused by the hydroxyl ions.
Magnesium oxide (MgO) is exempted from registration according to EC 1907/2006 Annex V Section 10.
Key value for chemical safety assessment
Additional information
There are no studies available for “Reaction product of thermal process between 1000°C and 2000°C of mainly aluminium oxide and calcium oxide based raw materials with at least CaO+Al2O3+MgO >80% , in which aluminium oxide, magnesium oxide and calcium oxide in varying amounts are combined in various proportions into a multiphase crystalline matrix”. As this substance is an UVCB substance with aluminium oxide (AL2O3), calcium oxide (CaO) and magnesium oxide (MgO) as main constituents, data and justification based on these main components were taken into account by read across following a structural analogue approach.
Aluminium-compounds:
Aluminium, aluminium powders and aluminium oxide are non hazardous (not classified for the environment). Aluminum (Al) is the most commonly occurring metallic element, comprising eight percent of the earth's crust (Press and Siever, 1974) and is therefore found in great abundance in both the terrestrial and sediment environments. Concentrations of 3-8% (30,000-80,000 ppm) are not uncommon. The relative contributions of anthropogenic aluminium to the existing natural pools of aluminium in soils and sediments is very small and therefore not relevant either in terms of added amounts or in terms of toxicity. Based on these exposure considerations additional sediment and/or soil testing is not warranted. More information about exposure based waiving for aluminium in soil and sediments can be found in attached document (White paper on exposure based waiving for Fe and Al in soils and sediments final 15-03-2010. pdf, see attachment).
One short-term and one long-term study with Eisenia andrei are reported using soluble aluminium salts (Van Gestel and Hogerwerf, 2001). The studies are presented for completeness, but are not considered relevant for assessing the aluminium compounds being assessed in the dossier. In the short-term study, three aluminum salts were tested with an exposure period of 14 days. Three pH (KCl) levels were assessed, namely 3.3, 4.4 and 6.7. Aluminum chloride was most toxic and showed higher toxicity with lower pH levels. At pH (KCl) 4.4 the LC50 was 316 mg/kg dw (Al). Al2O3 did not affect survival at concentrations of 5000 mg/kg dw Al at pH levels of 2.4 and 7.1.
The long-term study was performed with Sulfuric acid, aluminium salt (3:2), octadecahydrate (CAS RN 7784-31-8). The effect on reproduction was assessed in artificial soil. In the main test, earthworms were exposed for 6 weeks to soils treated with Al2(SO4)3. As in the range-finding test, aluminium sulfate was most toxic at a pH of 3.4 with an LC50 of 589 mg/kg dw (Al). At this pH, growth and cocoon production of earthworms were significantly reduced at 320 mg/kg dw (Al), while at 1000 mg/kg dw (Al) all earthworms died. Survival was not affected by 1000 mg/kg dw (Al) at pH 4.3 and 7.3. At pH 4.3, growth was significantly reduced at 1000 mg/kg dw (Al) and cocoon production at 320 and 1000 mg/kg dw (Al). At pH 7.3, aluminium only affected cocoon production at the two highest exposure levels. At the highest two exposure levels at pH 7.3, growth was significantly increased, suggesting a trade-off between growth and reproduction.
Table E: Toxicity to soil macroorganisms
species |
endpoint |
set up |
pH(KCl) |
result (mg/kg dw) |
|
Aluminum chloride |
|||||
Eisenia andrei |
LC50-14d |
Artificial soil |
3.3 4.4 6.7 |
316 359 >1000 |
Al |
Sulfuric acid, aluminium salt (3:2), octadecahydrate (CAS 7784-31-8) |
|||||
Eisenia andrei |
LC50-14d |
Artificial soil |
3.3 4.4 6.7 |
457 >4000 >4000 |
Al |
Eisenia andrei |
NOEC-42d |
Artificial soil |
3.4 |
100 |
Al |
Calcium-compounds:
The short-term toxicity of calcium dihydroxide on mortality and biomass of the earthworm Eisenia fetida (Friedrich, 2007b) was carried out according to OECD test guideline 207. The study is well documented, all validity criteria are fulfilled. As such a Klimisch 1 score was assigned to the study. After 14 days, no significant effect on both mortality and biomass was observed up to the highest tested dose (5000 mg Ca(OH)2 /kg dw)
The chronic study on the effect of calcium dihydroxide on the reproduction of the earthworm Eisenia fetida (Friedrich, 2007a), was carried out according to OECD test guideline 222. The study is well documented, all validity criteria are fulfilled. As such a Klimisch 1 score was assigned to the study. The study resulted in a 4w-EC50 of 4180 mg Ca(OH)2 /kg soil dw and a 4w-NOEC of 2000 mg Ca(OH)2 /kg soil dw.
In the environment, lime substances rapidly dissociate or react with water. These reactions, together with the equivalent amount of hydroxyl ions set free when considering 100mg of the lime compound (hypothetic example), are illustrated below:
Ca(OH)2 <-> Ca2+ + 2OH-
100 mg Ca(OH)2 or 1.35 mmol sets free 2.70 mmol
CaO + H2O <-> Ca2+ + 2OH-
100 mg CaO or 1.78 mmol sets free 3.56 mmol
From these reactions it is clear that the effect of calcium oxide will be caused either by calcium or hydroxyl ions. Since calcium is abundantly present in the environment and since the effect concentrations are within the same order of magnitude of its natural concentration, it can be assumed that the adverse effects are mainly caused by the pH increase caused by the hydroxyl ions. Furthermore, the above mentioned calculations show that the base equivalents are within a factor 2 for calcium oxide and calcium hydroxide. As such, it can be reasonably expected that the effect on pH of calcium oxide is comparable to calcium hydroxide for a same application on a weight basis. Consequently, read-across from calcium hydroxide to calcium oxide is justified.
Magnesium oxide:
Magnesium oxide (MgO) is exempted from registration according to EC 1907/2006 Annex V Section 10.
References:
Van Gestel, Hogerwerf G (2001) Influence of soil pH on the toxicity of aluminium for Eisenia andrei in an artificial soil substrate. Pedobiologia 45: 385-395.
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