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EC number: 281-192-5 | CAS number: 83897-84-1
Toxicity to soil macroorganisms except arthropods
Administrative data
Link to relevant study record(s)
Description of key information
Klimisch 1 study: short-term toxicity of calcium dihydroxide on mortality and biomass of the earthworm Eisenia fetida (Friedrich, 2007b).
Klimisch 1 study: chronic study on the effect of Ca(OH)2 on the reproduction of the earthworm Eisenia fetida in an artificial soil (Friedrich, 2007a).
Rationale for read-across: in the environment, lime substances rapidly dissociate or react with water. These reactions, together with the equivalent amount of hydroxyl ions set free when considering 100mg of the lime compound (hypothetic example), are illustrated below:
Ca(OH)2 <-> Ca2+ + 2OH-
100 mg Ca(OH)2 or 1.35 mmol sets free 2.70 mmol OH-
CaCO3.MgO + 2H2O <-> Ca2+ + Mg2+ + CO2 + 4OH-
100 mg CaCO3.MgO or 0.71 mmol sets free 2.86 mmol OH-
From these reactions it is clear that the effect of dolomite calcined will be caused either by calcium ions, magnesium ions or hydroxyl ions. Since calcium and magnesium are abundantly present in the environment and since the effect concentrations are within the same order of magnitude of their natural concentrations, it can be assumed that the adverse effects are mainly caused by the pH increase caused by the hydroxyl ions. Furthermore, the above mentioned calculations show that the base equivalents are within a factor 2 for dolomite calcined and calcium hydroxide. As such, it can be reasonably expected that the effect on pH of dolomite calcined is comparable to calcium hydroxide for a same application on a weight basis. Consequently, read-across from calcium hydroxide to dolomite calcined is justified.
Key value for chemical safety assessment
- Long-term EC10, LC10 or NOEC for soil macroorganisms:
- 2 000 mg/kg soil dw
Additional information
The short-term toxicity of calcium dihydroxide on mortality and biomass of the earthworm Eisenia fetida (Friedrich, 2007b) was carried out according to OECD test guideline 207. The study is well documented, all validity criteria are fulfilled. As such a Klimisch 1 score was assigned to the study. After 14 days, no significant effect on both mortality and biomass was observed up to the highest tested dose (5000 mg Ca(OH)2 /kg dw)
The chronic study on the effect of calcium dihydroxide on the reproduction of the earthworm Eisenia fetida (Friedrich, 2007a), was carried out according to OECD test guideline 222. The study is well documented, all validity criteria are fulfilled. As such a Klimisch 1 score was assigned to the study. The study resulted in a 4w-EC50 of 4180 mg Ca(OH)2 /kg soil dw and a 4w-NOEC of 2000 mg Ca(OH)2 /kg soil dw.
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