Methyl dihydrogen phosphate

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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch: 34448
Purity: 67.9 - 71.2%
Expiry: 30 March 2022

Analytical monitoring:

yes

Remarks:

The validated method is fully described in validation report VB18011104G926

Details on sampling:

Sample preparation
Before measurement the test solution was diluted tenfold with dilution water, to stay in the
calibrated range.
Miscellaneous
On each sampling day, validity of calibration was controlled by measuring QC samples.
(c = 10 mg/L) Because the mean recovery of the QC samples was lower than ± 3 % of the
nominal value, no sensitivity correction factor from the QC samples was taken into account.

Time 0 & 48h

Vehicle:

no

Details on test solutions:

A test solution containing 100.4 mg/L in dilution water was prepared. Because of the acid
character of the test item, the pH of the test solution was adjusted to 7.8

Test organisms (species):

Daphnia magna

Details on test organisms:

Specification
Species Daphnia magna
Authority STRAUS
Strain Berlin
Sex female
Age between 0 and 24 hours
Origin Umweltbundesamt Berlin
In-house breeding since 27. September 2007
Selection of the test system was made following the proposal of the guidelines.

Animal Husbandry
Daphnia magna is bred in the LAUS GmbH throughout the year. The animals are kept for
the use in toxicity tests. They multiply by parthenogenesis, thus being genetically identical.
The keeping is performed similar to the method described in the OECD guideline.

Vessels preserving glasses, nominal volume 2 L
Medium M4-Medium (recipe of ELENDT)
Food green algae (Desmodesmus subspicatus)
Medium renewal twice a week
Photo period 16/8 hours, using neon tubes
Temperature 20  2 °C

Selection of Daphnia
23 hours and 10 minutes before the start of the test, the adult animals were separated from
the young. 40 minutes before test start, the adults were caught with the help of a glass tube,
and the newborn daphnia (age < 24h) were sieved from the medium and immediately placed
into a beaker containing dilution water. After the settling-in period, animals which showed
no apparent damage were used for the test.
Switching from M4-medium (husbandry) to Dilution water (test) has been shown not to cause
any detrimental effects for test daphnia, therefore no acclimation period of 48 h was performed.
This is a deviation from OECD Guideline No. 202 and EU-Method C.2, which can
be considered uncritical.

Test type:

static

Water media type:

freshwater

Remarks:

Elendt M4

Limit test:

yes

Total exposure duration:

48 h

Hardness:

123.30 MgSO4*7H20
64.80 NaHCO3

Test temperature:

19.0 – 20.5 °C

pH:

7.7 - 7.8

Dissolved oxygen:

8.6 - 8.8 mg/L

Salinity:

293.80 CaCl2*2H20
5.80 KCl

Nominal and measured concentrations:

Time 0 mean measured concentration was 94% nominal
48h mean measured concentration was 108% nominal

Reference substance (positive control):

yes

Remarks:

Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9)

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No mortality was observed over 48 hours exposure in either the test group or the negative control.

Results with reference substance (positive control):

Potassium dichromate K2Cr2O7 (CAS No. 7778-50-9) was used as positive control in a current reference study (202005R201). The 24h-EC50 value was determined as 2.01 mg/L. The
value was within the requested range for the 24h-EC50 between 0.6 - 2.1 mg/L of potassium
dichromate K2Cr2O7 as specified in the OECD guideline.

Validity criteria fulfilled:

yes

Conclusions:

The EC50 (48 h) value was determined to be > 100 mg/L

Description of key information

The LC50 (48 h) value was determined to be > 100 mg/L.

Additional information

Investigation of short-term toxicity to Daphnia magna is ongoing and results disseminated by ECHA following REACH registration of a similar multiconstituent substance by other legal entities have been used for purposes of risk assessment.