Reaction mass of Limestone and dicalcium silicate

Toxicity to soil macroorganisms except arthropods

Administrative data

Endpoint:

toxicity to soil macroorganisms except arthropods: short-term

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

June 26, 2007 - July 10, 2007

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

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 Ca(OH)2 + 2Ca2SiO4 +9CaCO3 + 13H2O <-> 14Ca2+ + 2SiO2 + 9CO2 + 28OH- 100 mg “Reaction mass of limestone and dicalcium silicate” or 0.08 mmol sets free 2.24 mmol OH- has to be noted that CO32- is not expected to directly release two hydroxyl ions under most environmental conditions (depends on CO2 concentrations and pH) and this is therefore a worst case assumption. From these reactions it is clear that the effect of "Reaction mass of limestone and dicalcium silicate" will be caused either by calcium or hydroxyl ions. Since calcium is abundantly present in the environment and since the effect concentrations are within the same order of magnitude of its natural concentration, 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 lime (chemical), hydraulic and calcium hydroxide. As such, it can be reasonably expected that the effect on pH of "Reaction mass of limestone and dicalcium silicate" is comparable to calcium hydroxide for a same application on a weight basis. Consequently, read-across from calcium hydroxide to "Reaction mass of limestone and dicalcium silicate" is justified.

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 207 (Earthworm, Acute Toxicity Tests)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

Calcium dihydroxide

EC Number:

215-137-3

EC Name:

Calcium dihydroxide

Cas Number:

1305-62-0

Molecular formula:

CaH2O2

IUPAC Name:

calcium dihydroxide

Details on test material:

IUPAC name: Calcium dihydroxide
Product type: precal 50S
Name active ingredient: Calcium dihydroxide
Batch No. 7025
Received: 2007-01-30
Purity active ingedient: 98.2 %
Expiry date: January 2009
Appearance: solid, white powder
Water solubility (20°C): 1.26 g/l
Stability: at least for 2 years when stored at recommended conditions
Storage conditions: room temperature, under dry conditions

Sampling and analysis

Analytical monitoring:

no

Test substrate

Vehicle:

no

Test organisms

Test organisms (species):

Eisenia fetida

Animal group:

annelids

Study design

Study type:

laboratory study

Substrate type:

artificial soil

Limit test:

no

Total exposure duration:

14 d

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

> 5 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Remarks:

(Ca(OH)2)

Basis for effect:

mortality

Effect concentrations 2

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

>= 5 000 mg/kg soil dw

Nominal / measured:

nominal

Conc. based on:

act. ingr.

Remarks:

(Ca(OH)2)

Basis for effect:

other: biomass

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

(Adult mortality: ≤ 10% (being 0% after 14 days).)

Conclusions:

After 14 days of exposure to Calcium dihydroxide in artificial soil the LC50 for Eisenia fetida was estimated to be higher than 5000 mg Calcium dihydroxide/kg soil d.w. The NOEC was determined to be 5000 mg Calcium dihydroxide/kg soil d.w.