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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
Short-term toxicity to aquatic invertebrates
Administrative data
Link to relevant study record(s)
Description of key information
Based on the justification of the three main components of the test substance:
The available 48-h EC/LC50 values for aluminium compounds varied from 0.071 to > 99.6 mg Al/L. The acute NOECs (48 h) varied from > 0.005 to > 0.135 mg Al/L. Most of the variation in results can be explained by differences in hardness and DOC in the test media.
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:
Twelve short-term toxicity studies to six aquatic invertebrate species were identified for aluminium compounds. The available 48-h EC/LC50 values varied from 0.071 to > 99.6 mg Al/L. The acute NOECs (48 h) varied from > 0.005 to > 0.135 mg Al/L. Most of the variation in results can be explained by differences in hardness and DOC in the test media.
Calcium-compounds:
Two short-term toxicity studies with aquatic invertebrates are available for calcium dihydroxide. One study was conducted with Daphnia magna and the other one with a marine species. The short-term toxicity test with Daphnia magna (Egeler et al.,2007) was carried out according to the OECD 202 guidance taking into account GLP and thus resulting in a Klimish 1 score. The biological findings for Daphnia magna (immobility) were closely related to the initial pH of the test solutions, which ranged from 7.7 in the controls to 9.5, 9.7, 10.1, 10.7 and 11.1 at 14.8, 22.2, 33.3, 50 and 75 mg Ca(OH)2 /L, respectively. Therefore the initial pH is considered to be the main reason for the effects of calcium dihydroxide on Daphnia magna (Egeler et al.,2007).
The short-term toxicity test with the marine species Crangon septemspinosa Say (Locke et al., 2009) was conducted by a standard methodology developed by the laboratory. Test conditions are well described, a dose-response relationship was established (96h-LC50 = 158 mg/L); no statistics were reported. This resulted in a Klimish 2 score.
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.
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