Calcium dihydroxide

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Acceptable, well-documented publication, which meets basic scientific principles. No reproduction assessed.

Reason / purpose for cross-reference:

reference to same study

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

Analytical monitoring:

no

Details on sampling:

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

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 (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)

Test type:

semi-static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

14 d

Post exposure observation period:

not applicable

Hardness:

no data

Test temperature:

no data

pH:

7.95-9.78

Dissolved oxygen:

no data

Salinity:

no data

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).

Reference substance (positive control):

not specified

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

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

14 d

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth

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.

Results with reference substance (positive control):

not applicable

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)

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.

Description of key information

Klimisch 2 study (Locke et al., 2009): nominal 14d-NOEC value for growth and mortality of Crangon septemspinosa = 32 mg Ca(OH)2/L

Key value for chemical safety assessment

Marine water invertebrates

Marine water invertebrates

Effect concentration:

32 mg/L