Registration Dossier

Administrative data

Description of key information

Toxicity via the oral route is addressed by upper intake levels (UL) for adults determined by the Scientific Committee on Food (SCF), being
UL = 2500 mg/d, corresponding to 36 mg/kg bw/d (70 kg person) for calcium
UL = 250 mg/d, corresponding to 3.6 mg/kg bw/d (70 kg person) for magnesium.
Toxicity of CaCO3.MgO via the dermal route is not considered as relevant.
Toxicity of CaCO3.MgO via inhalation (local effect, irritation of mucous membranes) is addressed by read-across from an 8-h TWA determined for CaO and Ca(OH)2 by the Scientific Committee on Occupational Exposure Limits (SCOEL) of 1 mg/m³ respirable dust.

Key value for chemical safety assessment

Additional information

Guideline-compliant repeated-dose toxicity studies in rodents with oral administration of the various calcium compounds (28-day study according to OECD TG 407 or 90-day study according to OECD TG 408) are not available. None of the five animal studies available for various calcium salts allows the derivation of a NOAEL or LOAEL for quantitative risk assessment purposes.

However, the Scientific Committee on Food has determined an upper intake level (UL) of calcium for adults of 2500 mg/d, corresponding to 36 mg/kg bw/d, taking into account an average body weight of 70 kg/person.

No relevant oral repeated-dose toxicity study for magnesium was identified. However, the Scientific Committee on Food has determined an upper intake level (UL) of calcium for adults of 250 mg/d, corresponding to 3.6 mg/kg bw/d, taking into account an average body weight of 70 kg/person.

A dermal repeated-dose toxicity study for CaCO3.MgO is considered to be scientifically unjustified.

A repeated-dose toxicity study for CaCO3.MgO via the inhalation route is considered to be scientifically unjustified. Instead, the adopted Recommendation from the Scientific Committee on Occupational Exposure Limits (SCOEL) for Calcium oxide (CaO) and calcium hydroxide (Ca(OH)2) has determined an 8-h TWA of 1 mg/m³ (respirable dust) which is considered protective against adverse effects in case of long-term exposure to CaO and Ca(OH)2. Effects upon inhalation of calcined dolomite are purely local, i.e. irritation provoked by a pH shift. Since CaCO3.MgO only contains magnesium as an additional element and carbonate as a second – physiologically neutral – counter-ion, is less soluble and produces a lower pH shift than CaO and Ca(OH)2, the respective 8-h TWA can be adopted for CaCO3.MgO by read-across.

Justification for classification or non-classification

The only toxicologically relevant effect of CaCO3.MgO is local irritation through a pH shift, which is not relevant for classification for repeated-dose toxicity. Therefore, classification of CaCO3.MgO for toxicity upon prolonged exposure is not required.