Magnesium bis(dihydrogenorthophosphate)

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

short-term toxicity to fish

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 203 (Fish, Acute Toxicity Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control and 100 mg/L. Samples were taken after 1, 24, 48, 72, and 96 hours.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 518 mg of the test substance was directly dissolved in 5,000 mL of dilution water and homogenized to prepare a test solution of 100 mg/L. The control used dilution water only.

Test organisms (species):

Oryzias latipes

Details on test organisms:

TEST ORGANISM
- Common name: Japanese rice fish
- Source: The Ecotoxicology Research Team, Korea Institute of Toxicology (KIT), KRICT, Deajeon, Korea (origin: Laboratory of Freshwater Fish stocks, Bioscience Center, Nagoya University, Japan)
- Age at study initiation (mean and range, SD): 3-4 month
- Length at study initiation (length definition, mean, range and SD): 2.8 cm (S.D. = 0.1 cm)
- Weight at study initiation (mean and range, SD): 0.18 g (S.D. = 0.02g)
- Feeding during test: none


ACCLIMATION
- Acclimation period: 7 days
- Acclimation conditions: same as in test
- Feeding frequency: not fed 24 hours prior to test

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

41.7 mg/L as CaCO3

Test temperature:

23.7 ± 0.2 °C

pH:

7.13 - 7.95

Dissolved oxygen:

5.38 - 8.3 mg/L

Nominal and measured concentrations:

Nominal test substance concentration: 100 mg/L
The concentrations of the test substance were measured to be 0.53-2.14 mg/L at 100 mg/L (nominal)

Details on test conditions:

TEST SYSTEM
- Aeration:none
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Filtered tap water (1 µm, membrane filter), residual chlorine or organic substances were removed by filtering through an activated carbon filter.
- Chlorine: < 0.01 mg/L


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

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Mortality and abnormality after 1, 24, 48, 72, and 96 hours
- Light intensity: 780-800 lux

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

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 2.14 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

> 2.14 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

There were no mortalities and adverse effects observed in any of the fish exposed to control and 100 mg/L treatment groups during the test. All results are expressed in terms of nominal concentration as the concept of loading rate.

Reported statistics and error estimates:

No statistics performed

Validity criteria fulfilled:

not specified

Conclusions:

There were no mortalities and adverse effects observed in any of the fish exposed to control and 100 mg/L treatment groups during the test.

Reference 2

Endpoint:

short-term toxicity to fish

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 203 (Fish, Acute Toxicity Test)

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control and 100 mg/L. Samples were taken after 1, 24, 48, 72, and 96 hours.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: Tap water was passed through a membrane filter (1 μm) to remove particulate matter and then a high-grade activated carbon filter to remove any organic contaminants. Preliminary solubility trials indicated that this test substance did not produce test solution of 100 mg/L using organic solvents such as acetone, dimethyl sulfoxide (DMSO), ethanol, and N,N-dimethylformamide (DMF). Therefore, the test solution was prepared by direct addition of the test substance to dilution water.

Test organisms (species):

Oryzias latipes

Details on test organisms:

TEST ORGANISM
- Common name: Japanese rice fish
Source: Korea Institute of Toxicology (KIT), KRICT, Deajeon, Korea
- Age at study initiation (mean and range, SD): 3-4 month
- Length at study initiation (length definition, mean, range and SD): 2.0±1.0 cm
- Weight at study initiation (mean and range, SD): 0.19 g (S.D. = 0.03 g)
- Feeding during test: none


ACCLIMATION
- Acclimation period: 7 days
- Acclimation conditions: same as in test
- Feeding frequency: not fed 24 hours prior to test

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

10-250 mg/L CaCO3

Test temperature:

23.3 ± 0.1 °C

pH:

7.18-7.97

Dissolved oxygen:

5.2-8.5 mg/L

Salinity:

<0.01 mg/L (residual chlorine)

Nominal and measured concentrations:

Nominal test substance concentration: 100 mg/L
The concentrations of the test substance were measured to be 13.0-14.2 mg/L at a nominal concentration of 100 mg/L (13.0-14.2% of nominal concentration) at 0, 48, and 96 hours.

Details on test conditions:

TEST SYSTEM
- Aeration:none
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Filtered tap water (1 µm, membrane filter), residual chlorine or organic substances were removed by filtering through an activated carbon filter.
- Chlorine: < 0.01 mg/L


OTHER TEST CONDITIONS
- Photoperiod: 16:8 h day-night regime
- Light intensity: 990-1060 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Mortality and abnormality after 1, 24, 48, 72, and 96 hours

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

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 13.5 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

> 13.5 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

There were no mortalities and adverse effects observed in any of the fish exposed to control and 13.5 mg/L treatment effect group during the test. All results were expressed in terms of the mean measured concentration.

Reported statistics and error estimates:

No statistics performed

Sublethal observations / clinical signs:

Table 1. Cumulative mortality of Oryzias latipes

Nominal concentration (mg/L)	Mean measured concentration (mg/L)	Number of organisms tested	Cumulative number of dead fish
			24-hour	48-hour	72-hour	96-hour
Control	ND	7	0	0	0	0
100	13.5	7	0	0	0	0

* ND : Not detected

Table 2. Symptoms of intoxication of the test substance to Oryzias latipes

Nominal concentration (mg/L)	Mean measured concentration (mg/L)	Symptoms of Intoxication
		24-hour	48-hour	72-hour	96-hour
Control	ND	NOR(7)	NOR(7)	NOR(7)	NOR(7)
100	13.5	NOR(7)	NOR(7)	NOR(7)	NOR(7)

* ND : Not detected

* ( ) : Number of fish

* NOR : Normal

Description of key information

Two key studies are submitted to assess the short-term toxicity to fish of magnesium bis(dihydrogenorthophosphate, this study is conducted on two analogous substances (see justification below). On this basis calcium and magnesium orthophosphates are not considered to be toxic to fish. In addition, a number of literature papers investigating the bioavailability of phosphorus and calcium from calcium bis(dihydrogenorthophosphate) in fish are included in section 6.6, 'Additional ecotoxicological information' . Although these studies are not toxicity studies they do support the conclusions that inorganic phosphates are well tolerated by fish and is therefore unlikely to be toxic. As such, no further testing is justified.
The additional supporting data provided were not considered to be adequate or reliable to fulfil neither the guideline nor the regulatory requirement and there is no evidence within this data to suggest that essential validity criteria are met.

Key value for chemical safety assessment

Fresh water fish

Fresh water fish

Effect concentration:

100 mg/L

Additional information

Data on the acute toxicity of magnesium bis(dihydrogenorthophosphate) (CAS 13092 -66 -5) to fish are not available. The assessment was therefore based on a study conducted with the analogue substances calcium hydrogen orthophosphate (CAS 7757 -93 -9) tricalcium bis(orthophosphate) (CAS 7758-87-4) as part of a read across approach, which is in accordance with Regulation (EC) No. 1907/2006, Annex XI, 1.5.

The acute toxicity of calcium hydrogen orthophosphate and tricalcium bis(orthophosphate) to fish was investigated in a study following OECD guideline 203 (Kim et al. 2013).

Calcium hydrogen orthophosphate:

The acute toxicity of calcium hydrogen orthophosphate to fish was investigated in a study following OECD guideline 203 (Kim et al. 2013). The test was set up as a limit test under static conditions. Fish of the species Oryzias latipes were exposed to a nominal test substance concentration of 100 mg/L. The analytical recovery rate of the test substance was 13.0-14.2% of the nominal concentration. During the test period of 96 hours mortality and abnormal behavior of the test organisms were determined after 1, 24, 48, 72, and 96 hours. Mortality or adverse effects of the test substance were not observed. Based on the mean measured concentration an LC50(96 h) > 13.5 mg/L (nominal: LC50(96 h) >100 mg/L) was determined.

Tricalcium bis(orthophosphate):

The test was set up as a limit test under static conditions. Fish of the species Oryzias latipes were exposed to a nominal test substance concentration of 100 mg/L. The analytical recovery rate of the test substance was 0.53-2.14 mg/L at 100 mg/L nominal concentration. During the test period of 96 hours mortality and abnormal behavior of the test organisms were examined after 1, 24, 48, 72, and 96 hours. Mortality or adverse effects of the test substance were not observed. Based on the mean measured concentration a LC50(96 h) > 2.14 mg/L (nominal: LC50(96 h) >100 mg/L) was determined.

Based on the study results for the read across substances calcium hydrogen orthophosphate and tricalcium bis(orthophosphate) the assessed substance trimagnesium bis(orthophosphate) is considered not acutely toxic to fish.