Sodium metaphosphate

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:

20/10/1992-22/10/1992

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

EPA OTS 797.1300 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

Deviations:

yes

Remarks:

One concentration and a no-treatment control were tested in triplicate

Principles of method if other than guideline:

Not applicable

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: samples were collected from the control treatment groups at 0 and 48 hrs.

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances):
- Controls: vehicle
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): filtered (milli-Q filter) deionized, well water

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna (water flea)
- Source: Stock cultures maintained at ESE.
- Age at study initiation (mean and range, SD): <24hr
- Feeding during test - no
- Food type (pre-test): YTC (synthetic food composed of yeast, trout chow and cereal leaves)

Test type:

static

Water media type:

freshwater

Total exposure duration:

48 h

Post exposure observation period:

No

Hardness:

167 mg/L as CaCO3 at 0h

Test temperature:

20 ± 2°C

pH:

Control test: 8.3-8.4 (measured at 0, 24 and 48hr)
Test substance: 7.3-8.2 (measured at 0, 24, 48hr)

Dissolved oxygen:

Control test: 8.3-8.4 mg/L (measured at 0, 24 and 48hr)
Test substance: 8.3-8.5 mg/L (measured at 0, 24, 48hr)

Salinity:

Not applicable

Nominal and measured concentrations:

Control:
nominal concentration: 0 mg/L
mean measured concentration: <0.06 mg/L

Test:
nominal concentration: 500 mg/L
mean measured concentration: 485 ± 2.8 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: cylindical, glass, exposure chambers ( 100 mm diameter X 50 mm height)
- Type: closed
- No. of organisms per vessel: 10
- No. of vessels per concentration (replicates): 3
- No. of vessels per vehicle control (replicates): 3



TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Milli-Q water. Pumped from a deep well and passed through activated charcoal, cation, anion and mixed beds and then through the Milli-Q system prior to use. Sample was collected on April 29, 1992.
- Total organic carbon: <1.0 mg/L
- Metals:
arsenic: <2.3 µg/L
aluminium: <42.9 µg/L
cadmium: <0.2 µg/L
calcium: 0.073 mg/L
chromium: <7.4 µg/L
cobalt: <18 µg/L
copper: <3.8 µg/L
iron: <10.1 µg/L
mercury: 0.18 µg/L
magnesium: <0.037 µg/L
nickel: <17.4 µg/L
selenium: <2.0 µg/L
silver: <6.1 µg/L
sodium: <0.162 µg/L
zinc: <6.5 µg/L
- Pesticides:
Pesitcides-Organochlorine & PCB's: <0.006 µg/L
Pesticides-Organophosphate: <2.94 µg/L
- Alkalinity: 6.0 mg/L as CaCO3

OTHER TEST CONDITIONS
- Photoperiod: 16-hours light and 8-hours dark with a 15 minute dawn/dusk transition
- Light intensity: no data


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
Test organisms were observed daily for immobilisation (upon prodding) and any behavioural changes , and paralysed organisms removed.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable
- Justification for using less concentrations than requested by guideline: In a range-finding test, 500 mg test substance/L of exposure water was not acutely toxic to the test organisms.
- Range finding study
- Test concentrations: up to 500 mg/L
- Results used to determine the conditions for the definitive study: no data

Reference substance (positive control):

no

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 485 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

other: analysis of total phosphates and conversion factor from total phosphate to sodium hexametaphosphate

Basis for effect:

mobility

Remarks:

immobilisation

Results with reference substance (positive control):

Not applicable

Reported statistics and error estimates:

Not applicable

 

Table 2: Immobility of water fleas (D. magna) exposed to sodium hexametaphosphate in a 48-hr static , acute toxicity test.

 

Mean measured concentration of sodium hexametaphosphate (mg/L)	Cumulative number of immobilised organisms and Percent mortality (parenthic value)
	24 hr	48 hr
<0.06 (control)	0(0)	0(0)
485	0(0)	0(0)

 

Validity criteria fulfilled:

yes

Conclusions:

The test substance, sodium hexametaphosphate, was not acutely toxic to the water flea, Daphnia magna, at a mean measured concentration of 485 mg/L.
This study is conducted according to an appropriate guideline and under the conditions of GLP and therefore the study is considered to be acceptable and to adequately satisfy both the guideline requirement and the regulatory requirement as a key study for this endpoint.

Description of key information

Two studies are available to assess the short-term toxicity of sodium metaphosphate to aquatic invertebrates. The key study (Yurk, 1993) has been conducted to an appropriate guideline and under the conditions of GLP. 

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L

Additional information

The test substance, sodium hexametaphosphate, was not acutely toxic to the water flea, Daphnia magna, at a mean measured concentration of 485 mg/L.