Registration Dossier
Registration Dossier
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EC number: 200-848-3 | CAS number: 75-20-7
Endpoint summary
Administrative data
Description of key information
Calcium carbide is an inorganic substance for which the biodegradation endpoints are not applicable.
However, upon contact with water/moisture calcium carbide instantly hydrolysis to the decomposition products calium hydroxide (Ca(OH)2) and acetylene (C2H2). Therefore, the assessment has to be based on the decomposition products and not on the parent substance itself.
Calcium hydoxide is an inoragnic substance, and biodegradation endpoints are as such not applicable for the substance.
Upon contact with water Ca(OH)2 will dissociate to Ca2+ and 2 OH-.
OH- will rapidly be neutralised in the environment. Calcium is a mineral nutrient and ubiquitous in nature. Negative effects of Ca2+ based on potential release of CaC2 to the environment are thus not expected (for details please refer to the information provided for the endpoint bioaccumulation).
Acetylene is a short-chain gaseous hydrocarbon. However, the water solubilty for aceytelene (1200 mg/L at 20 °C, CRC Handbook, see IUCLID section 4.8) is relatively high. Thus, residues of acetylene in the water phase cannot be excluded, although the vapour pressure and Henry Law constant are high1.
QSAR estimates by means of BIOWIN v4.10 predict that acetylene is readily biodegradable. Based on the very short-chain, non-branched chemical structure of the substance, this prediction is considered appropriate for chemical safety assessment.
Due to the ready biodegradability of the volatile gas acetylene, higher-tier studies on biodegradation in surface water, sediment and soil do not have to be conducted (see REACH Annex IX, column, 2, points 9.2.1.2, 9.2.1.3, and 9.2.1.4).
1Solubilty in water: 1200 mg/L; vapour pressure: 4.04 x 10^4 mm Hg at 25 °C (Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989; cited in HSDB)
=> approximate Henry Law constant = vapour pressure/ aqueous solubility = 5386224 Pa / 46.08 mol/m³ = ~ 116,900 Pa m³/mol
Additional information
Calcium carbide is an inorganic substance for which the biodegradation endpoints are not applicable.
However, upon contact with water/moisture calcium carbide instantly hydrolysis to the decomposition products calium hydroxide (Ca(OH)2) and acetylene (C2H2). Therefore, the assessment has to be based on the decomposition products and not on the parent substance itself.
Calcium hydroxide is an inorganic substance, and biodegradation endpoints are as such not applicable for the substance.
Upon contact with water Ca(OH)2 will dissociate to Ca2+ and 2 OH-.
OH- will rapidly be neutralised in the environment. Calcium is a mineral nutrient and ubiquitous in nature. Negative effects of Ca2+ based on potential release of CaC2 to the environment are thus not expected (for details please refer to the information provided for the endpoint bioaccumulation).
Acetylene is a short-chain gaseous hydrocarbon. However, the water solubility for acetylene (1200 mg/L at 20 °C, CRC Handbook, see IUCLID section 4.8) is relatively high. Thus, residues of acetylene in the water phase cannot be excluded, although the vapour pressure and Henry Law constant are high1.
QSAR estimates by means of BIOWIN v4.10 predict that acetylene is readily biodegradable. Based on the very short-chain, non-branched chemical structure of the substance, this prediction is considered appropriate for chemical safety assessment.
Due to the ready biodegradability of the volatile gas acetylene, higher-tier studies on biodegradation in surface water, sediment and soil do not have to be conducted (see REACH Annex IX, column, 2, points 9.2.1.2, 9.2.1.3, and 9.2.1.4).
1Solubilty in water: 1200 mg/L; vapour pressure: 4.04 x 10^4 mm Hg at 25 °C (Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989; cited in HSDB)
=> approximate Henry Law constant = vapour pressure/ aqueous solubility = 5386224 Pa / 46.08 mol/m³ = ~ 116,900 Pa m³/mol
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