CHEMICAL SUBSTANCE DATASHEET
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CHEMICAL SUBSTANCE IDENTIFICATION |
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Chemical name |
Calcium dihydroxide[1] |
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Synonyms |
calcium hydroxide/caustic lime/hydrated lime/slaked lime [1] |
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IUPAC name |
calcium dihydroxide [1] |
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CAS No |
1305-62-0 [1] |
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REACH registration number |
fully registered [1] |
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EC No |
215-137-3 [1] |
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Molecular formula |
CaH2O2 [1] |
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Substance group/chemical family |
Mono constituent substance/ inorganic [1] |
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Appearance Physical state Odour Form Colour |
solid @ 20°C and 1013 hPa [1] Odourless (86%), Other (14%) [1] Powder (71%), Crystalline (29%) [1] colourless or white [3] |
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USES AND HANDLING ISSUES |
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Relevant identified uses |
In mortar, plaster, cement and other binding and paving materials; in lubricants, drilling fluid, pesticides, fireproofing coatings, water paint; as egg preservative; manufacture of paper pulp; in SBR rubber vulcanization; in water treatment; as absorbant for carbon dioxide; dehairing hides, calcium salts, causticizing soda, depilatory, whitewash, soil conditioner, ammonia recovery in gas manufacturing, disinfectant, water softening, purification of sugar juices, petrochemicals, food additive as buffer and neutralizing agent, shell-forming agent (poultry) [3] |
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Handling considerations |
Avoid contact with skin and eyes. Wear protective equipment. Keep dust levels to a minimum. Minimise dust generation. Enclose dust sources, use exhaust ventilation (dust collector at handling points). Handling systems should preferably be enclosed. When manually handling bags usual precautions should be paid to the risks outlined in the Council Directive 90/269/EEC. |
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PHYSICO-CHEMICAL PROPERTIES |
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Molecular weight |
74.09 g/mol [3] |
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Bulk density/Specific gravity |
2.22 - 2.26 @ 20 - 22.5 °C [1] |
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pH |
12.4 (aqueous solution saturated at 25 °C) [3] |
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Particle size |
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EC |
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Melting/Freezing point |
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Boiling point |
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Flash point |
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Flammability |
Non flammable (100%) [1] |
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Vapour density |
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Vapour pressure |
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Solubility in water |
999 - 1 844.9 mg/L @ 20 °C and pH 12.4 [1] |
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Solubility in organic solvents |
Insoluble in ethanol, sugar. Soluble in glycerol. Insoluble in alcohol. [3] |
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Solubility in inorganic solvents |
Soluble in ammonium chloride solution; soluble in acids with evolution of much heat [3] |
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Hydrolysis |
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Ionicity in water |
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Surface tension |
72 mN/m @ 1000 mg/L and 20 °C [1] |
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Dispersion properties |
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Explosiveness |
Non-explosive (100%) [1] |
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Other properties |
Non oxidising (100%) [1] |
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Stability and reactivity |
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Chemical stability |
Readily absorbs carbon dioxide from air forming calcium carbonate. [3] |
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Reactivity hazards |
Phosphorus boiled with alkaline hydroxides yields mixed phosphines which may ignite spontaneously in air. [3] Violent reaction with maleic anhydride, nitroethane, nitromethane, nitroparaffins, nitropropane, phosphorus. [3] Reaction with polychlorinated phenols + potassium nitrate forms extremely toxic products. [3] |
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Corrosivity |
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Polimerization |
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Incompatibility with various substances |
Phosphorus boiled with alkaline hydroxides yields mixed phosphines which may ignite spontaneously in air. [3] |
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Special remarks on reactivity |
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Physical, chemical and biological coefficient |
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Koc |
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Kow |
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pKa |
12.6 @ 20 °C [1] For calcium dihydroxide the pH of a saturated solution was 12.4, which correlated to the pKa of 12.6 reported in the literature for the Calcium (II) ion. [2] |
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log Kp |
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Henry-constant |
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ENVIRONMENTAL FATE AND BEHAVIOUR |
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Artificial pollution sources |
Calcium hydroxide's production and use may result in its release to the environment through various waste streams; its use in drilling fluid, mortar, plaster, cement and other binding and paving materials and as a soil conditioner will result in its direct release to the environment. [3] |
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General terrestrial fate |
In soil as well as in sediment-water systems, calcium (di)hydroxide will react and release calcium ions and hydroxyl ions. Therefore, relevant information on adsorption/desorption of calcium (di)hydroxide can be broadened to data on adsorption/desorption of calcium. The behaviour of hydroxyl ions depends on the pH buffer capacity of the tested medium. The pH buffer capacity is controlled by a whole range of processes (mineral dissolution/precipitation, protonation/deprotonation of pH dependent charge sites, reaction with CO2, biological processes etc.). Therefore, determining a Kd-value for calcium dihydroxide is not relevant. Reliable Kd-values for calcium range from 5.3 L/kg to 49.1 L/kg and are added as supportive information. The Kd-concept is not relevant for hydroxyl ions, since the behaviour of these ions depends on the pH buffer capacity of the tested medium. [2] |
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General aquatic fate |
When mixing calcium (di)hydroxide with water, the substance will be completely dissociated into its ions as the water solubility is relatively high compared to the environmental background concentration of calcium and due to dilution effects. Depending on the properties of the test medium, calcium (di)hydroxide will be strongly neutralised in the initial period after application, by formation of calcium carbonate. [2] Aquatic toxicity is the function of an alkalinity effect. Addition of lime to soft water lakes has increased biological activity, possibly by providing a carbon dioxide reservoir. [3] |
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General atmospheric fate |
Calcium hydroxide does not degrade by photooxidation; it is neutralized by absorption of atmospheric carbon dioxide. [3] |
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General persistence and degradability |
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Abiotic degradation and metabolites |
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Biodegradation and metabolites |
Biotic degradation is not relevant for inorganic substances. [2] |
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Bioconcentration |
no bioaccumulation potential [2,3] Bioaccumulation is not relevant for calcium dihydroxide. In the aquatic environment and in soil, exposure to calcium dihydroxide actually comes down to exposure to calcium and hydroxyl ions. There will be no intake of calcium dihydroxide as such from water or soil, nor will calcium dihydroxide prevail under its original form in the organisms. Moreover, both the intake of the essential element calcium and the internal pH (hydroxyl ions) of an organism are actively regulated (homeostasis). [2] |
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Volatilization |
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Photolysis |
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Hydrolysis |
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Soil adsorption and mobility |
In soil as well as in sediment-water systems, calcium (di)hydroxide will react and release calcium ions and hydroxyl ions. Therefore, relevant information on adsorption/desorption of calcium (di)hydroxide can be broadened to data on adsorption/desorption of calcium. The behaviour of hydroxyl ions depends on the pH buffer capacity of the tested medium. The pH buffer capacity is controlled by a whole range of processes (mineral dissolution/precipitation, protonation/deprotonation of pH dependent charge sites, reaction with CO2, biological processes etc.). Therefore, determining a Kd-value for calcium dihydroxide is not relevant. Reliable Kd-values for calcium range from 5.3 L/kg to 49.1 L/kg and are added as supportive information. The Kd-concept is not relevant for hydroxyl ions, since the behaviour of these ions depends on the pH buffer capacity of the tested medium. [2] |
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ENVIRONMENTAL CONCENTRATIONS |
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Measured data |
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ECOTOXICOLOGICAL INFORMATION |
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General adverse effects on ecosystem |
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Acute toxicity (LC50, EC50) |
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Aquatic systems |
LC50 (4 days) for freshwater fish: 50.6 mg/L [1] LC50 (4 days) for marine water fish: 457 mg/L [1] EC50 / LC50 (48h) for freshwater invertebrates: 49.1 mg/L [1] EC50 / LC50 (4 days) for marine invertebrates: 158 mg/L [1] EC50 (72h) for freshwater algae: 184.57 mg/L [1] EC50 (3 h) for microorganisms: 300.4 mg/L [1] |
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Terrestrial systems |
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Chronic toxicity (NOEC, LOEC) |
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Aquatic systems |
EC10 / LC10 or NOEC (14 days) for marine invertebrates: 32 mg/L [1] EC10 or NOEC (72 h) for freshwater algae: 48 mg/L [1] |
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Terrestrial systems |
EC10 / LC10 / NOEC (28 days) for terrestrial macroorganisms except arthropods: 2 g/kg soil dw [1] EC10 / LC10 / NOEC (21 days) for terrestrial plants: 1.08 g/kg soil dw [1] EC10 / NOEC (3.2 months) for soil microorganisms: 4 g/kg soil dw [1] |
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HUMAN HEALTH EFFECTS and PROTECTION |
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Routes of human exposures |
Occupational exposure to calcium hydroxide may occur through inhalation of dust and dermal contact with this compound at workplaces where calcium hydroxide is produced or used. Use data indicate that the general population may be exposed to calcium hydroxide via ingestion of food and drinking water, and dermal contact with consumer products containing calcium hydroxide. [3] |
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General effects |
irritation eyes, skin, upper respiratory system; eye, skin burns; skin vesiculation; cough, bronchitis, pneumonitis [3] |
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Endocrine disruption |
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Mutagenicity |
The results of in vitro gene mutation studies in bacteria, in vitro chromosome aberration studies in mammalian cells and in vitro gene mutation studies in mammalian cells performed using calcium dihydroxide or calcium carbonate were all negative. It is concluded that both calcium dihydroxide and calcium carbonate are not genotoxic and neither chemical nor mixtures of these chemicals warrants classification for mutagenicity under CLP. [2] |
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Carcinogenicity |
Neither calcium, calcium dihydroxide nor calcium carbonate are carcinogenic. Classification for carcinogenicity is not warranted. [2] |
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Reprotoxicity |
Calcium is an essential mineral nutrient for mammals including humans. Based on evaluation of a wealth of human medical and nutritional data it is concluded that calcium, therefore also calcium dihydroxide and calcium carbonate, does not pose any hazard for reproduction and/or developmental toxicity. Classification for toxicity to reproduction is not warranted. [2] |
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Teratogenicity |
Calcium is an essential mineral nutrient for mammals including humans. Based on evaluation of a wealth of human medical and nutritional data it is concluded that calcium, therefore also calcium dihydroxide and calcium carbonate, does not pose any hazard for reproduction and/or developmental toxicity. Classification for toxicity to reproduction is not warranted. [2] |
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Skin, eye and respiratory irritations |
Adverse effect observed (irritating) (skin, eye, respiratory) [1] Based on experimental results and human data, calcium dihydroxide requires classification as Skin Irrit 2 (H315 – Causes skin irritation). Based on experimental results and human data, calcium dihydroxide requires classification as Eye Damage 1 (H318 - Causes serious eye damage). Based on human data as summarised and evaluated in the SCOEL recommendation it is proposed to classify calcium dihydroxide as STOT SE 3 (H335 - May cause respiratory irritation). [2] |
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Metabolism: absorption, distribution & excretion |
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Exposure limits |
DNEL(Workers, inhalation, local effects, long term): 1 mg/m³ [1] DNEL (Workers, inhalation, local effects, acute/short term): 4 mg/m³ [1] DNEL(General population, inhalation, local effects, long term): 1 mg/m³ [1] DNEL (General population, inhalation, local effects, acute/short term): 4 mg/m³ [1] According to OSHA [3]: REL-TWA (Time Weighted Average): 5 mg/m³ PEL-TWA (8-Hour Time Weighted Average): 15 mg/m³ (total dust), 5 mg/m³ (respirable fraction) According to ACGIH [3]: TLV 8 hr Time Weighted Avg (TWA): 5 mg/ m³. |
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Drinking water MAC |
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Other information |
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Animal toxicity data |
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Acute toxicity (LD50) |
LD50 2 000 mg/kg bw (rat, oral route) No adverse effect observed Discriminating dose 2 000 mg/kg bw [1] LC50 (4 h) 6.04 mg/L air (rat, inhalation route) Adverse effect observed Discriminating conc. 6 040 mg/m³ [1] LD50 2 500 mg/kg bw (rabbit, dermal route) No adverse effect observed Discriminating dose 2 500 mg/kg bw [1] |
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Chronic toxicity (NOEL, LOEL) |
Inhalation route - systemic effects (repeated dose toxicity) [1]: No adverse effect observed NOAEC 107 mg/m³ (subacute, rat) Inhalation route - local effects, repeated dose toxicity) [1]: No adverse effect observed NOAEC 107 mg/m³ (subacute, rat) |
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ENVIRONMENTAL STANDARDS AND REGULATIONS |
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REACH/CLP |
Danger! According to the classification provided by companies to ECHA in REACH registrations this substance causes serious eye damage, causes skin irritation and may cause respiratory irritation. Additionally, the classification provided by companies to ECHA in CLP notifications identifies that this substance causes severe skin burns and eye damage. [1] According to REACH registrations [1]: H318: Causes serious eye damage H315: Causes skin irritation H335: May cause respiratory irritation not classified According to some CLP notifications [1]: H318: Causes serious eye damage H315: Causes skin irritation H335: May cause respiratory irritation H314: Causes severe skin burns and eye damage H370: Causes damage to organs H373: May cause damage to organs through prolonged or repeated exposure |
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EINECS regulation |
listed |
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OSHA regulations etc. |
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Disposal considerations |
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OTHER INFORMATION, SPECIAL REMARKS |
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Classification and proposed labelling with regard to toxicological data |
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CREATED, LAST UPDATE |
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Created |
2020.06.09 |
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Last update |
2020.06.10 |
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REFERENCES |
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[1] ECHA, Calcium dihydroxide, brief profile, https://echa.europa.eu/hu/brief-profile/-/briefprofile/100.013.762, Accessed: 2020.06.09. [2] ECHA, Calcium dihydroxide, https://echa.europa.eu/hu/registration-dossier/-/registered-dossier/16187, Accessed: 2020.06.10. [3]PubChem, Calcium-hydroxide. https://pubchem.ncbi.nlm.nih.gov/compound/Calcium-hydroxide#section=Structures, Accessed: 2020.06.10. |
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