Reaction mass of Limestone and dicalcium silicate

Long-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

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

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

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:

publication

Title:

Unnamed

Year:

2009

Materials and methods

Principles of method if other than guideline:

Toxicity test was conducted by a standard method developed by the laboratory. Test organisms were exposed, 14 d, to different concentrations of the test item in test solutions, prepared in natural seawater.

GLP compliance:

not specified

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
Agricultural grade hydrated lime from Havelock Lime Co., Havelock, NB

Sampling and analysis

Analytical monitoring:

no

Details on sampling:

Temperature was checked daily. Water quality was measured three timed a week.

Test solutions

Vehicle:

no

Details on test solutions:

Test solutions were prepared for the samples in natural seawater, acclimated to 15+/-1°C, and initial water quality was measured.

Test organisms

Test organisms (species):

Crangon septemspinosa

Details on test organisms:

- common name: sand shrimp
- source: collected from Kouchibouguac Bay, NB, Canada
- wet weight: mean 3.00 +/- 1.307 mg (n = 20)

Study design

Test type:

semi-static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

14 d

Test conditions

pH:

7.95-9.78

Nominal and measured concentrations:

nominal concentrations: 0, 3.2, 10, 32, 100, 320 mg/L

Details on test conditions:

- 20 replicates per test concentration
- water renewal: 80 % of test solution replaced 3 times a week with fresh solution
- feeding frequency: 3 times a week
- feed: 100 mg frozen brine shrimp with some live brine shrimp for the first week, and 200 mg frozen brine shrimp in week two
- after 14 days each sand shrimp was weighed (dry weight).

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

14 d

Dose descriptor:

LC50

Effect conc.:

53.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: 95% CL: 48.3-58.4 mg/L

Effect concentrations 2

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

- at concentrations of 100 and 320 mg/L a 100 % mortality was observed
- at other concentrations mortality ranged between 5 and 15 %
- no effects on growth were observed.

Reported statistics and error estimates:

- LC50s were calculated following Stephan (1977)
- Analysis of variance was used to examine the effect of treatments on sand shrimp weights (log-transformed to normalize) (JMP version 4, SAS Institute 2000)

Applicant's summary and conclusion

Validity criteria fulfilled:

not specified

Conclusions:

In the current test with sand shrimp, the 14d-LC50 for hydrated lime was 53.1 mg/L. Based on pH values measured at t=0 this is equivalent to 9.20 (9.12-9.28) pH units. No effects on growth were observed.