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:

supporting study

Study period:

No data

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Study not conducted according to OECD guideline.

Principles of method if other than guideline:

Trochophore larvae at a density of 25/ml were placed into 9-cm diameter fingerbowls containing 100 ml of the phosphate compounds in 25°/ºº artificial
seawater. The compound has been employed in concentrations of 15 ppm and 150 ppm phosphate.
The effect of the test material, SHMP (sodium hexametaphosphate), was compared with other phosphate compounds, specifically, STTP (sodium tripolyphosphate), MSP (monosodium orthophosphate), TSPP (tetrasodium pyrophosphate).

Larval densities were initially determined by taking 1 mL samples from cultures agitated by a plunger, stirred by a magnetic stir bar and finally inverted in a 100 mL graduated cylinder.
The fingerbowls containing the larvae were covered with perforated plastic film and placed into a waterbath at 25°C.
After 24, 48 and 72 hr-exposure to phosphates or seawater alone, the percentage mortality, abnormality, and shell size were determined. The maximum shell diameter, length, and width of the larvae contained in five 1 mL culture samples were measured using a calibrated ocular micrometer. Shell birefringence was observed with a polarizing microscope as an indicator of shell calcification. Statistical significance was evaluated as an indicator of shell calcification.
Statistical significance was evaluated using ANOVA and the Student-Newman-Keuls test at p < 0.05.

GLP compliance:

no

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: sodium hexametaphosphate, purchased from Sigma Chemical Co. (analytical grade).

Test organisms (species):

other: Crassostrea virginica, trochophore larvae stage

Details on test organisms:

Specimens of Crassostrea virginica were collected from Wachapreague, VA, Beaufort and Wilmington, NC, during spring and summer of 1985 and spring of 1986.
Gametes were collected by macerating ripe gonads in situ with scissors, being careful not to pierce the underlying stomach, and flushed free of the
body with a jet of mixed (natural and artificial) sea waters. Sperm was passed through a 35p, Nytex sieve using minimal volume to lessen dilution of stock. Eggs were separated from gonadal tissue by passing through a 75p, Nytex sieve and then collected and washed on a 35p, Nytex sieve. One ml of concentrated sperm was added to a gently stirred suspension of eggs in 1 liter of seawater. A second and third ml of sperm were added at 10-min intervals. Eggs were observed for fertilization membranes and the first polar body. The fertilized egg suspension was again passed through a 75p, Nytex sieve to remove any aggregated material and then collected and washed on a 35p, sieve to remove excess sperm. Eggs retained by the filter were placed in 4-liter aquaria containing 3 liters of aerated 0.45p, filtered artificial seawater of 25° /oo salinity. The aquaria were placed in a waterbath at 25°C.
A 100 W light bulb was suspended approx. 60 em above the aquaria to promote aggregation of larvae. Larvae were collected 18-24 hr after fertilization by siphoning the upper layers of water into a 35J.L sieve. Larval culture densities were determined using a Sedgewick-Rafter counting cell.

Test type:

static

Water media type:

saltwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

Following exposure the test animals were killed to enable shell inspection.

Hardness:

No data

Test temperature:

25ºC

pH:

8.0

Salinity:

Artificial sea water,

Details on test conditions:

Trochophore larvae at a density of 25/ml were placed into 9-cm diameter fingerbowls containing 100 ml of the phosphate compounds in 25°/ºº artificial
seawater.
Eggs retained by the filter were placed in 4-liter aquaria containing 3 liters of aerated 0.45p, filtered artificial seawater of 25° /ºº salinity.

After 24, 48, and 72 hours exposure to the phosphate or sea water alone, the percentage mortality, developmental abnormality and shell size and shell calcification were determined.

Reference substance (positive control):

not required

Key result

Duration:

72 h

Dose descriptor:

LC50

Effect conc.:

15 other: ppm

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

After 72 hours the mortality in the control vessel averaged 23%.
The vessel containing SHMP present at 15 ppm caused ca. 68% mortality, and at 150 ppm caused ca.80% mortality (72h).
After 72-hr exposure to 15 ppm or 150 ppm, SHMP had retarded growth by 10-25%. Shell calcification was inhibited by SHMP, its effects were less than that of the other phosphates tested.

Validity criteria fulfilled:

not applicable

Conclusions:

After a 72-hr exposure at 15 ppm, sodium hexametaphosphate morphological developmental changes, increased mortality, and inhibition of shell growth at both 15 ppm and 150 ppm.

Executive summary:

Trochophore larvae were exposed to sodium hexametaphosphate (SHMP), at concentrations of 15 ppm and

150 ppm phosphate for 24, 48, and 72 hr.

The compound caused morphological developmental changes, increased mortality, and inhibition of shell growth at both 15 ppm and 150 ppm.

Description of key information

Supporting study:

Trochophore larvae were exposed to sodium hexametaphosphate (SHMP), at concentrations of 15 ppm and 150 ppm phosphate for 24, 48, and 72 hr.

The compound caused morphological developmental changes, increased mortality, and inhibition of shell growth at both 15 ppm and 150 ppm.