Magnesium bis(dihydrogenorthophosphate)

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
See read-across justification report under Section 13 ‘Assessment Reports’.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
In accordance with REACH Annex XI, Section 1.5, of Regulation (EC) No. 1907/2006 (REACH) the standard testing regime may be adapted in cases where a grouping or read-across approach has been applied.

The similarities may be based on:
(1) a common functional group
(2) the common precursors and/or the likelihood of common breakdown products via physical or biological processes, which result in structurally similar chemicals; or
(3) a constant pattern in the changing of the potency of the properties across the category


1. Both substances are inorganic salts of a monovalent cation from Group 2 of the periodic table, calcium or magnesium, and phosphoric acid. Thus, they all share the Ca2+ or Mg2+ cation and the PO43- anion as common functional groups.
2. Both substances will ultimately dissociate into the common breakdown products of the Ca2+ or Mg2+ cations and the PO43- anion.
3. Calcium and magnesium orthophosphates have been shown to have a similar toxicological profile and physicochemical nature and therefore this data is considered to be adequate and reliable for use in read-across. Any further testing would not be scientifically justified as all substances will dissociate to their anionic and cationic forms in natural waters and these ions (Ca2+, Mg2+ and PO43-) are all ubiquitous and are not considered to pose a risk of ecotoxicity.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See read-across justification report under Section 13 ‘Assessment Reports’.

3. ANALOGUE APPROACH JUSTIFICATION
See read-across justification report under Section 13 ‘Assessment Reports’.

4. DATA MATRIX
See read-across justification report under Section 13 ‘Assessment Reports’.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

not specified

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control and 100 mg/L. Samples were taken at 0 and 48 h

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Although the quoted water solubility was 20 mg/L, the test substance is very poorly soluble in water. Preliminary solubility test also indicated that the test substance was not dissolved in organic solvents such as aceton, DMSO and ethanol. Therefore, the test concentrations were prepared by directly adding the test substance into dilution water as a concept of loading rate. 10 mg of the test substance was added in test medium and filled up to 100 mL in the 150 mL crystallizing dish to prepare the test solution of 100 mg/L and then homogenized with digital homogenizer. Only the dilution water was used for the control.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Source: The Ecotoxicology Research Team, Korea Institute of Toxicology (KIT), KRICT, Deajeon, Korea (origin: the Institute of Ecological Chemistry, GSF, Germany)
- Age at study initiation (mean and range, SD): <24 h

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

243 mg/L CaCO3

Test temperature:

20.6 ± 0.5 °C

pH:

7.77 to 7.94

Dissolved oxygen:

8.2-8.9 mg/L

Nominal and measured concentrations:

Nominal test concentration: 100 mg/L

The concentrations of calcium ion were measured to be 80.3-87.1 mg/L at control, which is attributed to calcium ion (CaCl2 · 2H2O) present in the M4 culture medium.

Details on test conditions:

TEST SYSTEM
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: M4 medium


OTHER TEST CONDITIONS
- Photoperiod: 16:8 h day-night regime
- Light intensity: 620 and 650 Lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Immobility after 0, 24 and 48 hours

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: control, 0.1, 1, 10, and 100 mg/L.
- Results used to determine the conditions for the definitive study: No immobility was observed at 100 mg/L

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 5.35 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

No immobilisation and adverse effects were observed in control and 100 mg/L for 48 hours. All results were expressed in terms of nominal concentration.

Reported statistics and error estimates:

No statistics performed

Validity criteria fulfilled:

not specified

Conclusions:

No immobilisation and adverse effects were observed in control and 100 mg/L for 48 hours.

Reference 2

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2006

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: GLP guideline study, data originate in part from a secondary source

Justification for type of information:

REPORTING FORMAT FOR THE ANALOGUE APPROACH
See read-across justification report under Section 13 ‘Assessment Reports’.

1. HYPOTHESIS FOR THE ANALOGUE APPROACH
In accordance with REACH Annex XI, Section 1.5, of Regulation (EC) No. 1907/2006 (REACH) the standard testing regime may be adapted in cases where a grouping or read-across approach has been applied.

The similarities may be based on:
(1) a common functional group
(2) the common precursors and/or the likelihood of common breakdown products via physical or biological processes, which result in structurally similar chemicals; or
(3) a constant pattern in the changing of the potency of the properties across the category


1. Both substances are inorganic salts of a monovalent cation from Group 2 of the periodic table, calcium or magnesium, and phosphoric acid. Thus, they all share the Ca2+ or Mg2+ cation and the PO43- anion as common functional groups.
2. Both substances will ultimately dissociate into the common breakdown products of the Ca2+ or Mg2+ cations and the PO43- anion.
3. Calcium and magnesium orthophosphates have been shown to have a similar toxicological profile and physicochemical nature and therefore this data is considered to be adequate and reliable for use in read-across. Any further testing would not be scientifically justified as all substances will dissociate to their anionic and cationic forms in natural waters and these ions (Ca2+, Mg2+ and PO43-) are all ubiquitous and are not considered to pose a risk of ecotoxicity.

2. SOURCE AND TARGET CHEMICAL(S) (INCLUDING INFORMATION ON PURITY AND IMPURITIES)
See read-across justification report under Section 13 ‘Assessment Reports’.

3. ANALOGUE APPROACH JUSTIFICATION
See read-across justification report under Section 13 ‘Assessment Reports’.

4. DATA MATRIX
See read-across justification report under Section 13 ‘Assessment Reports’.

Reason / purpose for cross-reference:

read-across: supporting information

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control and 100 mg/L. Samples were taken at 0 and 48 h

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: A stock solution of test substance was prepared by adding 1.0111g to the test water and fill up to the marker in 100 mL volumetric flask. 2 mL of stock solution was added in the test water and filled up to the marker in 200 mL beaker to prepare test solutions.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Age at study initiation (mean and range, SD): <24 h
- Source: Environmenal toxicity lab., Safety Assessment Center, Korea Testing and Research Institute
- Food type (breeding): unicellular green algae, Chlorella vulgaris, daily

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

224 mg/L CaCO3

Test temperature:

20.28 ± 0.2 ℃

pH:

7.8-8.14

Dissolved oxygen:

7.73-8.18 mg/L

Nominal and measured concentrations:

Nominal test concentration: 100 mg/L
The mean concentration was analyzed to be 2.75 mg/L at a nominal concentration of 100 mg/L (2.9% of nominal concentration) at 0 and 48 hours.

Details on test conditions:

TEST SYSTEM
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: M4 medium


OTHER TEST CONDITIONS
- Photoperiod: 16:8 h day-night regime

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Immobility after 0, 24 and 48 hours

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: control, 0.1, 1, 10, and 100 mg/L.
- Results used to determine the conditions for the definitive study: No immobility was observed at 100 mg/L

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 2.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

After 24 hours and 48 hours exposure, no daphnia was immobilised in 100 mg/L of test solution. No abnormal behavior and intoxication symptoms were observed in control and treatment groups during limit test.

Reported statistics and error estimates:

No statistics performed

Table 1. Cumulative immobilization data forDaphnia magna

Nominal concentration (mg/L)	Measured concentration (mg/L)	Number of daphnids tested	Cumulative immobilized Daphnia magna (%)
			24 hours	48 hours
Control	ND	30	No immobilization	No immobilization
100	2.9	30	No immobilization	No immobilization

Table 2. Symptoms on intoxication of the test substance toDaphnia magna

Nominal concentration (mg/L)	Measured concentration (mg/L)	Symptoms of intoxication
		24 hours	48 hours
Control	ND	NOR (30)	NOR (30)
100	2.9	NOR (30)	NOR (30)

ND : Not detected, ( ) : Number of Daphnia magna, NOR : Normal

Description of key information

Two key studies to assess the short-term toxicity to aquatic invertebrates of magnesium bis(dihydrogenorthophosphate) exist. This study has been conducted on analogous substances. On this basis magnesium orthophosphates are not considered to be toxic to aquatic invertebrates. No further testing is justified.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L

Additional information

The acute toxicity of tricalcium bis(orthophosphate) and calcium hydrogen orthophosphate to aquatic invertebrates was investigated in a study following OECD guideline 202 (Kim et al. 2013). The study was conducted as a limit test under static conditions. Daphnia magna were exposed to a nominal test substance concentration of 100 mg/L for 48 hours. The results were as follows:

Tricalcium bis(orthophosphate):

The mean measured substance concentration was 5.35 mg/L. Mortality or symptoms of intoxication were not observed. At test termination an EC50(48 h) >5.35 mg/L (nominal: EC50(48 h) >100 mg/L) based on the mean measured concentration was determined. Based on the study results for the read across substance calcium hydrogen orthophosphate the assessed substance magnesium bis(dihydrogenorthophosphate) is considered not acutely toxic to aquatic invertebrates.

Calcium hydrogen orthophosphate:

The mean measured substance concentration was 2.75 mg/L. Mortality or symptoms of intoxication were not observed. At test termination an EC50(48 h) >2.75 mg/L (nominal: EC50(48 h) >100 mg/L) based on the mean measured concentration was determined. Based on the study results for the read across substance calcium hydrogen orthophosphate the assessed substance magnesium bis(dihydrogenorthophosphate) is considered not acutely toxic to aquatic invertebrates.