Reaction mass of calcium carbonate and calcium dihydroxide and silicon dioxide

Endpoint summary

Description of key information

Instead of conducting new in vivo tests, available data on the constituents of the reaction mass of calcium carbonate and calcium dihydroxide and silicon dioxide were used to evaluate the toxic potential of the substance. The available data indicate that the substance is not toxic after repeated oral or dermal exposure. Systemic effects of any constituent(s) are not expected, because they all are inorganic salts which have a low solubility in water and thus low bioavailability or which dissociate in ions which are efficiently regulated in the human body, i.e. OH- and Ca2+. Local effects can occur and these are associated to the irritation/corrosion potential of the substance, mainly related its alkalinity (calcium dihydroxide).
However when considering repeated exposure to the substance via inhalation, the potential effect related to silicon dioxide requires to be taken into consideration, because epidemiological and experimental data has shown that chronic exposure to crystalline silica can lead to fibrotic changes and/or lung cancer.

Additional information

Instead of conducting new in vivo tests, available data on the constituents of the reaction mass of calcium carbonate, calcium dihydroxide and silicon dioxide were used to evaluate the toxic potential of the substance. The available data indicate that the substance is not toxic after repeated oral or dermal exposure. Systemic effects of any constituent(s) are not expected, because they all are inorganic salts which have a low solubility in water and thus low bioavailability or which dissociate in ions which are efficiently regulated in the human body, i.e.OH^-and Ca2⁺. Local effects can occur and these are associated to the irritation/corrosion potential of the substance, mainly related its alkalinity (calcium dihydroxide).

Up to 70% of the substance (typical concentrations) consists of calcium carbonate and calcium hydroxide which are accepted additives to food (respectively E 170 and E 526, Annex 1 of EU directive No 92/2/EC).

Toxicity of calcium 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.

However when considering repeated exposure to the substance via inhalation, the potential effect related to silicon dioxide requires to be taken into consideration, because epidemiological and experimental data has shown that chronic exposure to crystalline silica can lead to fibrotic changes and/or lung cancer.

 

Information sources:

European chemical Substances Information System http://ecb.jrc.ec.europa.eu/esis/

International Programme on Chemical Safety, Concise international chemical assessment document No.24, Crystalline silica, Quartz, 09-21-10, http://www.inchem.org/documents/cicads/cicads/cicad24.htm

International chemical Safety Cards, National Instutute for occupational Safety and Health http://www.cdc.gov/niosh/ipcsneng/neng0808.html

International chemical Safety Cards, National Instutute for occupational Safety and Health http://www.cdc.gov/niosh/ipcsneng/neng0408.html

International chemical Safety Cards, National Instutute for occupational Safety and Health 

http://www.cdc.gov/niosh/ipcsneng/neng0409.html

IMA-Europe Position Paper (February 2010) on the classification and labelling of respirable crystalline silica (RCS) http://www.ima-reach-hub.eu/index.php?option=com_docman&task=doc_download&gid=141&Itemid=26

Recommendation from the Scientific Committee on Occupational Exposure Limits for Calcium oxide (CaO) and Calcium Hydroxide (Ca(OH)2), European Commission, DG Employment, social Affairs and Equal Opportunities, SCOEL/SUM/137, February 2008

Threshold Limit Values & Biological Exposure Indices for Chemical Substances and Physical Agents, ACGIH®, Signature Publications, 2010

Opinion of the Scientific Committee on Food on the tolerable upper intake level of calcium European Commission,SCF/CS/NUT/UPPLEV/64 Final, 2003-04-23

IARC (1997) Silica, some silicates, coal dust and para –aramid fibrils., International Agency for Research on Cancer, pp. 1-242 (IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, Vol. 68).

Repeated dose toxicity: inhalation - systemic effects (target organ) respiratory: lung

Justification for classification or non-classification

Considering the existing knowledge on the constituents of the reaction mass of calcium carbonate, calcium dihydroxide and silicon dioxide, no classification is deemed necessary for repeated exposure via oral or dermal route. When taking into account the potential effect related to silicon dioxide and the proposal by IMA-Europe to classify respirable crystalline silica (respirable quartz and respirable cristobalite) as STOT RE 1 for the silicosis hazard, a classification of the reaction mass of calcium carbonate, calcium dihydroxide and silicon dioxideis considered justified. Based on the particle size distribution of the representative form of the substance, up to 5% of the inhalable fraction is respirable. The maximum level of respirable crystalline silica in the substance is thus well below 10%. Therefore a classification as STOT RE2 (H371: May cause damage to organs, target organ: lung) is proposed.

IMA-Europe Position Paper (February 2010) on the classification and labelling of respirable crystalline silica (RCS) http://www.ima-reach-hub.eu/index.php?option=com_docman&task=doc_download&gid=141&Itemid=26