Reaction mass of disodium metasilicate and sodium hydroxide

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2016-02-05 to 2016-04-02

Reliability:

1 (reliable without restriction)

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

GLP compliance:

yes

Specific details on test material used for the study:

The study was conducted with the Water Accommodated Fraction (WAF) of Frit. When Firt is mixed with water, the souble fraction is this test substance.

Analytical monitoring:

no

Details on sampling:

Substance undergoes rapid hydrolysis in water, therefore analytical moitoring was not possible

Vehicle:

yes

Details on test solutions:

All test solutions were prepared separately at loading rates ranging from 1.0 to 100 mg/L in water applying a 30 minute period of ultrasonic waves followed by a two-day period of magnetic stirring. Thereafter, the resulting mixtures were filtered over a 0.45 µm membrane filter (Whatman; RC55). The resulting Water Accommodated Fractions (WAFs) were clear and colourless and used as test solutions. The pH of the highest WAF was set from 10.3 to 8.8 in the combined limit/ range finding test and from10.3 to 8.6 in the limit test with 1M HCl.

Test organisms (species):

Daphnia magna

Details on test organisms:

Daphnia magna (Crustacea, Cladocera) (Straus, 1820), at least third generation, obtained by acyclical parthenogenesis under specified breeding conditions. For the test, young daphnids with an age of < 24 hours were selected from parental daphnids of more than two weeks old.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Remarks on exposure duration:

combined limit/range finding test

Test temperature:

18-22°C

pH:

WAF (mg/L) Start (t=0 h) End (t=48 h)
pH O2 pH O2
Control 7.8 9.4 8.0 9.1
100 8.5 8.7 7.7 9.0

Details on test conditions:

The test conditions remained within the limits prescribed by the study plan (pH: 6.0-8.5, not varying by more than 1.5 units; oxygen: 3 mg/L at the end of the test).

The temperature continuously measured in a temperature control vessel varied between 20 and 21°C during the test, and complied with the requirements as laid down in the study plan (18-22°C, constant within 2°C)

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Remarks:

WAF

Basis for effect:

mobility

Details on results:

Range finder - In the lowest WAF tested, i.e. prepared at a loading rate of 1.0 mg/L, 10 and 20% of the daphnids were immobilised after 24 and 48h, respectively. No immobility was observed in the two higher WAFs tested. In the control group, 45% of daphnids were immobilised after 48h. This response exceeded the 10% tolerance limit for immobility in the control group as described in the study plan. The results of this test were used as a range-finder.

No effects on mobility of daphnids were observed at a loading rate of 100 mg/L for the limit test. Both the 24 and 48 hour EL50 were determined to be >100 mg/L (WAF).

Validity criteria fulfilled:

yes

Conclusions:

The study met the acceptability criteria prescribed by the study plan and was considered valid. 
The 48h-EL50 was beyond the range tested, i.e. exceeded loading rate of 100 mg/L.

Executive summary:

Acute Toxicity Study in Daphnia magna was conducted with Silicic acid (H₄SiO₄), zirconium (4+) salt (1:1), reaction products with sodium hydroxide.

 

The study procedures described were based on the OECD guideline No. 202, 2004. In addition, the procedures were designed to meet the test methods of theCommissionRegulation (EC) No440/2008,Part C.2, 2008 and the OECD series on testing and assessment number 23, 2000.

 

The batch of test item tested was a brown powder not completely soluble in test medium at the loading rates initially prepared.The test item was a UVCB substance. No correction was made for the purity/composition of the test item.

 

A Water Accommodated fraction (WAF) was prepared at a loading rate of 100 mg/L applying a 30 minute period of ultrasonic waves followed by a two-day period of magnetic stirring. Thereafter, the resulting mixture was filtered over a 0.45 µm membrane filter and used as limit concentration. The final test solution was clear and colourless. The pH of the WAF was set from 10.3 to 8.6 with 1 M HCl.

 

A limit test was performed, based on the results of a preceding combined limit/range-finding test.In the limit test, twenty Daphnia per group (four replicates, 5 daphnids per vessel) wereexposed to an untreated control and to a WAF prepared at a loading rate of 100 mg/L. The total exposure period was 48h. No samples were taken to analytically confirm exposure concentrations.

 

The study met the acceptability criteria prescribed by the study plan and was considered valid.

 

The 48h-EL50 was beyond the range tested, i.e. exceeded loading rate of 100 mg/L.

Description of key information

The 48h-EL50 was beyond the range tested, i.e. exceeded loading rate of 100 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L

Additional information

The 48h-EL50 was beyond the range tested, i.e. exceeded loading rate of 100 mg/L.