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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.

The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.

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Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

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 accountby read across following a structural analogue approach.


Aluminium compounds:

The aluminium (Al) toxicity studies compiled in this section represent tests with aquatic organisms conducted over a pH range from 6 – 8 as being representative of conditions in most European surface waters as evaluated in a preliminary exposure assessment (EURAS 2007). Most of the short-term studies included were only those used for purposes of characterization and to evaluate potential effects of water quality on Al toxicity. The long-term chronic studies represent all known studies of sufficient reliability according to Klimisch criteria levels one (reliable without restriction) and two (reliable with restriction; Klimisch et al. 1997). These data are being assessed with a view towards developing a Probable No Effect Concentration (PNEC) principally for use in setting Environmental Quality Standards (EQS) values. We point out that aluminium chloride was not classified for the aquatic environment by the EU Classification and Labeling Committee, therefore other less soluble forms of Al such as the oxides, powders, and massive metal would also not classify for the aquatic environment (see reference below). Therefore, no PNEC is required for REACH purposes. The long term goal of the industry is to develop an aquatic PNEC that covers the pH range of < 6, 6-7, and > 7. These pH ranges reflect that the form of Al present in water changes significantly as a function of pH. PNEC values calculated in this dossier are preliminary and reflect the state of the science to date. Scientists around the world have worked towards a PNEC for Al for the past 30 years. The aluminum industry over the past 3 years has utilized several decades of work to develop a biotic ligand model (BLM)fish, invertebrates and algae for pH values across the range of 5.5-8.0. The state of the model is summarized in this CSR. It is recognized that there is a need to demonstrate that this model applies to a broader range of aquatic organisms. Efforts to date have focused on salmonids, fathead minnows, daphnids and algae. Studies are on-going at pH 6.0 with a wider range of species to achieve a data base that has 8-10 chronic PNEC values as recommended in the London PNEC Workshop.  The extent of this work to date is presented in this dossier. Studies that are on-going and envisioned for the future were provided to ECHA, July 2, 2010 for their notification.

For all of the aquatic toxicity studies, endpoints are expressed as a function of total Al, rather than as dissolved or monomeric Al. This is because for most test solutions with pH from 6 – 8, Al will be largely insoluble, and so dissolved and monomeric concentrations remain relatively constant even with large increases in total or nominal Al. Thus, dose-dependent responses observed by aquatic organisms can only be reliably quantified using total Al across the full pH range from 5.5-8.0. 


It is important to point out that the substances being registered in this dossier are sparingly soluble forms of aluminium and not soluble metal salts. Therefore the review of the aquatic toxicity literature where aluminium salts were used for assessing the toxicity of the metal ion or hydroxide have limited direct application to the substances represented in this CSR. The use of a PNEC, once derived, has to take into consideration the transformation/dissolution of the sparingly soluble aluminium compounds. There is little or no evidence that aluminium metal, metal powders or metal oxides have ever resulted in aquatic toxicity effects.


Review of Data Leading to Development of an Aluminium Chronic BLM: Toxic effects of aluminium have been observed in several types of aquatic organisms under certain exposure conditions. Factors that influence aluminium toxicity are consistent with the factors that influencealuminiumspeciation (discussed in Section 4.2). These factors include pH, dissolved organic matter concentration (DOC), and water hardness (see Roy and Campbell 1997; and Gensemer and Playle 1999 for relevant reviews). Fluoride has also been shown to influencealuminiumtoxicity (Hamilton and Haines 1995), though fluoride is not commonly found at elevated levels in the environment. Several studies have demonstrated that some forms of aluminium are only bioavailable and potentially toxic in freshly prepared solutions, and that this toxicity declines or is eliminated after several minutes of aging (e.g. Exely et al. 1996 [others too]; Witters et al. 1996; Teien et al. 2006). Toxicity in these cases may depend on short-lived transient chemical forms of aluminium hydroxide whose environmental relevance would be restricted to mixing zones where aluminium-rich acidic waters mix with a more alkaline water.


A biotic ligand model (BLM) was developed to address the bioavailability and toxicity of dissolved, particulate, and transient forms of aluminium. Application of the BLM framework to understanding aluminium toxicity was reasonable because many of the factors that influence aluminium bioavailability are consistent with the factors that influenc ealuminium speciation or forms in the environment. As with BLMs for other metals, the Al BLM combines information about chemical speciation and interaction with gill surfaces to explain and predictaluminiumbioavailability and toxicity (DiToro et al, 2001; Santore et al 2001; Paquin et al 2002). Factors that affectaluminiumbioavailability by altering the chemical speciation of the metal (such as DOC, pH, and fluoride) are directly considered by the speciation model (Tipping 1994; Santore and Driscoll, 1996).  Other factors (such as hardness cations), affect aluminium bioavailability by competing with gill binding sites in a manner similar to what has been observed for other metals (Playle et al 1992; Meyer et al, 1999) and are considered by including interactions for these cations with the BL sites on the gill. The detailed speciation within the aluminium BLM allows the model to predict bioavailability for a number of different aluminium fractions. Depending on available input data, the model can be run with monomeric, dissolved, or total aluminium as the primary input parameter, and the distribution among dissolved species and precipitated forms can be simulated by the model. Comparison of predicted and measured distribution of aluminium fractions in waters where aluminium toxicity has been extensively studied typically shows very good agreement (Figure 7.1.1-1, see attachment).

Factors that are known to affect speciation have also been shown to affect bioavailability and toxicity in both acute and chronic exposures, and the consistency of these affects in different exposure durations allows a common model framework for prediction of both acute and chronic affects. Acute data were useful in model development due in part to the large amount of available data that combined coincident measurement of detailed speciation measurements, measures of Al accumulation in gills, and observation of lethal and sub-lethal effects over wide ranges of water chemistry. Data for development of the Al BLM included atlantic salmon (Salmo salar) and brown trout (Salmo trutta) from studies performed by NIVA and collaborators from UMB (Kroglund et al. 1997; Kroglund et al. 1998a,b,c,d; Erstad et al. 2002; Teien et al. 2004a,b; Teien et al. 2006; Andren et al. 2006). These studies typically investigated the effects of water chemistry on the accumulation of Al on/in the gills of S. salar and S. trutta, but in some cases, mortality was reported. Many of these studies purpose fully investigated the effects of water chemistry on the level of Al accumulation in S. salar and S. trutta gills. The pH conditions varied from approximately pH 5 (Andren et al. 2006) to pH 10 (Erstad et al. 2002). The total organic carbon concentrations (TOC) ranged from approximately 0.5 mg/L to 16 mg/L (Kroglund et al. 1998a,b, and Erstad et al. 2002, respectively). Calcium concentrations ranged from approximately 1 mg/L to 11 mg/L (Kroglund et al. 1998a,b, and Erstad et al. 2002, respectively).

From these data it was clear that observed toxicity was strongly related to aluminium accumulation on the gill (Figure 7.1.1.-2, see attachment). The calibrated Al BLM was able to reasonably predict the level of Al accumulation on the gills of S. salar and S. trutta, with one consistent set of BLM parameters (Figure 7.1.1.-3, see attachment) over a range of approximately 2 orders of magnitude. This wide range in gill accumulation was primarily due to the diverse water chemistry conditions tested, and suggests that the BLM is relatively robust over this wide range of conditions. These data were also used to estimate critical Al accumulation levels for those datasets that reported associated mortality data (i.e. Suldal Fall 1997 – Kroglund et al. 1998a). For example, from Figure 7.1.1-2 (see attachment), critical accumulation levels corresponding to the LC10 and LC50 values for mortality could b derived as 2995 and 4225 nmol/g wet weight, respectively.   

Although data from acute exposures were extensively used to parameterize the prediction of gill-accumulation over a wide range of conditions, the goal in model development is the evaluation of the ability of the Al BLM to predict effects in chronic exposures. The use of data from both acute and chronic exposures in model development is justified by the consistency of the observed effects of changing water chemistry (such as pH, NOM, and hardness) in both acute and chronic exposures. Adjustment of the Al BLM for different exposure durations (acute versus chronic) and endpoints (lethal or sub-lethal) is primarily accomplished by adjustment of the critical accumulation level for each endpoint and exposure condition. Application to chronic data will be further discussed in the sections that follow.

Soluble aluminium salts are not classified; therefore less soluble forms of aluminium are not classified.

Justification: Available data indicate that aluminium salts are relatively non toxic in most waters with circumneutral pH and this was sufficient for the EU Classification and Labelling Committee (1999) to determine that there was no need for classification of aluminium chloride. Therefore it was also concluded that aluminium massive and sparingly soluble forms of aluminium are highly insoluble and non-hazardous. Studies reported in the literature have extensively used test solutions (soluble salts) with aluminium concentrations above that of its solubility limit. Due to physical effects of precipitated material most of these studies are meaningless for the investigation of intrinsic toxicity. Aluminium ions released to surface waters quickly form insoluble aluminium hydroxides in mixing zones. These colloids can sorb to fish gills resulting in asphyxiation and mortality in rare circumstances. Formation of the complex hydroxide causes the aluminium to drop out of solution very rapidly in neutral and alkaline waters. The accumulation of aluminium on fish gills or other organism respiratory membranes may result in physical effects. These conditions however are not typical of most ambient conditions and are more representative of specific mixing zones. The dissolved natural background concentrations of aluminium, in most cases, are at equilibrium therefore an addition of aluminium would lead to the precipitation of aluminium compounds from solution and not result in effects to aquatic life. We conclude that a PNEC is not required for REACH. However, the aluminium industry is continuing its efforts to develop a PNEC for freshwater ecosystems for purposes of the Water Framework Directive. See the PNEC discussion below.


Calcium compounds:

Studies for aquatic toxicity of calcium compounds are available for the following endpoints:

- Short-term toxicity to fish – 2 studies

- Short-term toxicity to aquatic invertebrates – 2 studies

- Long-term toxicity to aquatic invertebrates – 1 study

- Toxicity to aquatic algae – 1 study

- Toxicity to microorganisms – 1 study


Two short-term studies for calcium dihydroxide with fish are provided. One of these both studies, the short-term toxicity study with the freshwater fish rainbow trout (Egeler et al.,2007), was executed according to OECD 203, resulting in a Klimisch 1 score. The biological findings (LC50 = 50.6 mg/L) were closely related to the initial pH of the test solutions. Therefore the initial high pH is considered to be the main reason for the effects of the test item on the fish. The other short-term toxicity study for calcium dihydroxide with the marine species Gasterosteus aculeatus Linnaeus (threespine stickleback) (Locke et al.,2009) was well described and a dose-response relationship was established (LC50 = 457 mg/L). However, the study was not carried out according to GLP, resulting in a Klimisch 2 score.

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.

One long-term chronic toxicity study for calcium dihydroxide with saltwater invertebrates (Crangon septemspinosa) is available. The duration in this study (Locke et al., 2008) was 14 d and this test resulted in a NOEC of 32 mg/L (nominal).

One study for toxicity to freshwater algae is available for calcium dihydroxide. This study (Egeler et al., 2007) was conducted according to OECD 201 with Pseudokirchnerella subcapitata and resulted in EC50 (72h) of 184.57 mg/L (nominal) and NOEC (72h) of 48 mg/L (nominal) based on growth rate.

One study for toxicity to microorganisms is available for calcium dihydroxide. This substance is structurally and compositionally related to aluminium oxide, one main substance of the test material. The study (Egeler & Goth, 2007) was conducted according to OECD 209 with activated sludge and resulted in EC50 (3h) of 300.4 mg/L (nominal) based on respiration rate.

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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