Magnesium hydrogenorthophosphate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

2006

Justification for type of information:

see analogue justification attached to chapter 13

Reason / purpose for cross-reference:

read-across source

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

Additional information

Data on the acute toxicity of magnesium hydrogen orthophosphate (CAS 7757-86-0) to fish are not available. The assessment was therefore based on a study conducted with the analogue substance calcium hydrogen orthophosphate (7757-93-9) 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 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. Based on the study results for the read across substance calcium hydrogen orthophosphate the assessed substance magnesium hydrogen orthophosphate is considered not acutely toxic to fish.