Registration Dossier
Registration Dossier
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EC number: 253-425-0 | CAS number: 37247-91-9
Endpoint summary
Administrative data
Description of key information
Human data support the finding that effects of calcium magnesium oxide are limited to the external surfaces of the body (local irritation) and no systemic effects are anticipated. If inhaled, the critical effects of burnt dolomitic lime (CaMgO2) dust can be expected to be sensory irritation and a decrease of lung function parameters at long-term exposure, by read-across from CaO and Ca(OH)2.
Calcium supplementation during pregnancy is not adverse, but instead may be beneficial both to the mother and to the offspring.
Calcium appears to reduce the risk of recurrent colorectal adenomas
Toxicokinetics of calcium and magnesium has been investigated in a range of human studies, which are summarised in section 7.1.1 of the technical dossier.
Case reports underline the irritating properties (skin and eye) of Ca(OH)2. This is of limited relevance for CaMgO2, due to its less severe pH effect.
Additional information
Studies summarised in section "Health relate observations" report individual cases or epidemiological data regarding human exposure to lime (or cement as surrogate for the alkaline effects of lime). Cain (2004), Torén (1996), Lahaye (1987), Wegman (1991), Vestbo (1991), Fell (2003), Yang (1996), and Eid (1969) form the basis of the SCOEL recommendation of occupational exposure limits (inhalation). Cain (2008) is provided as a supplementary reference to Cain (2004), confirming the nature of effects upon short-term exposure to CaO, which are described as sensory irritation and slightly increased secretion from the nasal mucosa. Meo (2003), and Al-Neaimi (2001) are provided as additional references describing typical symptoms of long-term over-exposure to cement dust, typically constituting reduced pulmonary function, pleural thickening and chronic bronchitis. Since the primary effect of both CaO/Ca(OH)2 and CaMgO2 upon inhalation are anticipated to be equivalent (local irritation due to pH shift), the above studies are used in support of CaMgO2 by read-across.
Villar (1990), Levine (1997), Koo (1999) are used as supportive data for the endpoint "developmental toxicity/teratogenicity" (section 7.8.2 of the technical dossier), demonstrating either a beneficial effect or lack of adverse effects of calcium in pregnancy, both to mothers and their offspring.
Belizán (1991) reports a protective effect of calcium against hypertensive disorders in pregnant women.
Baron (1999) reports that calcium supplementation is associated with a significant - though moderate - reduction of the risk of recurrent colorectal adenomas.
Kuschner (1997) reports that inhalation of fine and ultrafine MgO particles at concentrations up to 230 mg/m³ over 15 minutes or 143 mg/m³ over 45 minutes did not result in any adverse effects (inflammation markers, or subjective symptoms). This result suggests that inhalation of MgO dust does not produce adverse effects at concentrations approximately a factor 50 higher than the STEL for CaO and Ca(OH)2.
The references Johnston (1992), Lloyd (1993), Elders (1994), Reid (1993), Moser-Veillon (2001), Rosado (2005), Wastney (2000), Braun (2008), Minihane (1998), Sokoll (1992), Kalkwarf (1998), Peacock (2000), Dawson-Hughes (2002), and Bonjour (1997) are dealing with toxicokinetic parameters of calcium and are therefore reflected in section 7.1.1 of the technical dossier (basic toxicokinetics) together with SCF and FAO/WHO documents in a weight-of-evidence approach.Danielson (1979) deals with toxicokinetic parameters of magnesium and is therefore reflected in section 7.1.1 of the technical dossier (basic toxicokinetics), together with SCF and FAO/WHO documents in a weight-of-evidence approach.
No relevant classical epidemiological data have been identified.
In section 7.10.3 of the technical dossier, Hahn et al. (2002) represents a German governmental report of chemical burns due to accidental exposure (both occupational and general population) to building materials consisting of or containing lime. Causes of eye exposure to lime (calcium hydroxide and oxide) are reviewed by Grant (1986). A further study reports a human case of eye irritation due to accidental exposure to calcium hydroxide (Schmidt, 2008), which may be used for read-across of eye irritating properties. Overall, this human case study demonstrates that exposure to hydrated lime may result in severe eye irritation. Sheikh (1987) and Bo-Linn (1984) are provided as supportive information for deriving toxicokinetic information (oral absorption of calcium) and are therefore referred to in the section "basic toxicokinetics". Additional human clinical studies (Firoz, 2001; Fine, 1991; Spencer, 1980; Roth, 1979; Graham, 1960; Schwartz, 1978) deal with oral absorption of magnesium and are hence referred to in section 7.1.1 of the technical dossier (basic toxicokinetics).
No data on sensitisation in humans were retrieved.
Relevant exposure-related observation (section 7.10.5 of the technical dossier) other than those addressed in section 7.10.1 and 7.10.3 of the technical dossier were not identified.
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