Calcium hydride

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

other: read-across based on hydrolysis product (Ca(OH)2)

Adequacy of study:

supporting study

Reliability:

1 (reliable without restriction)

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
Metal hydrides react quickly with water, forming metal hydroxide and hydrogen gas. Calcium hydride has been shown to be hydrolytically unstable at various temperature and pH conditions (see section 5.1.2 Hydrolysis for further details) . The hydrolysis study has been shown that the reaction speed was less than 1 seconde at all conditions. Therefore, calcium hydride cannot be found as such in the environment. However, instead of calcium hydride, the hydrolysis product "calcium dihydroxide" (Ca(OH)2) is the form which will be available in the environment. The water solubility of Ca(OH)2 is about 1.7 g/L*.
Due the particular environmental fate of calcium hydride, a read-across with the toxicity of calcium hydroxide has been made to better assess the risk when the environment is facing to a calcium hydride release.

* GESTIS database on hazardous substances, www.dguv.de/ifa/gestis/index-2.jsp

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
Hydrolysis product of calcium hydride in water following normal environmental conditions. The hydrolysis product present in water would be the "calcium dihydroxide" (Ca(OH)2).

3. ANALOGUE APPROACH JUSTIFICATION
--> See point 1. "HYPOTHESIS FOR THE ANALOGUE APPROACH"

4. DATA MATRIX
Not applicable

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 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

yes

Remarks:

The pH increased significantly and was not neutralized

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

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The short-term toxicity test with Daphnia magna (Egeleret al., 2007) was carried out according to the OECD 202 guidance following GLP standards. The biological findings for Daphnia magna(immobility) were related to the initial pH of the test solutions, which ranged from 7.7 in the controls to 9.5, 9.7, 10.1, 10.7 and 11.1 at 14.8, 22.2, 33.3, 50 and 75 mg Ca(OH)2/L, respectively.
Therefore, the pH is considered to be the main reason for the effects of calcium dihydroxide on Daphnia magna(Egeleret al., 2007).