Trimanganese bis(orthophosphate)

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: samples of all tested concentrations were taken at test start and test end.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: water accomodated fractions (WAF) were prepared acc. to OECD guidance documents No. 23 and 29. The test concentrations were prepared separately by adding the aquired amount of substance to 1 litre growth medium. The solutions were stirred for 60 hours (20°C) and subsequently filtered (0.2 µm).

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Strain: 61.81 SAG.
- Source (laboratory, culture collection): SAG, Culture Collection of Algae at Pflanzenphysiologisches Institut of the University at Göttingen, Germany
- Method of cultivation: stock cultures were maintained acc. to OECD guideline

ACCLIMATION
- Acclimation period: A pre-culture was reared (3 days prior to test start)
- Culturing media and conditions (same as test or not): OECD standard growth medium

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21.5 – 22.5 °C

pH:

test concentrations: 7.93 - 8.45
control: 7.90 - 8.31

Nominal and measured concentrations:

Nominal test substance concentrations: 60, 120 and 240 mg test item/L (corresponding to 22.9, 45.7 and 91.4 mg Mn/L).
Initial measured concentrations: 4.00, 4.24 and 4.41 mg Trimanganese bis(orthophosphate) [Mn3(PO4)2 × 3H2O]/L.(corresponding to 1.63, 1.72 and 1.79 mg Mn/L)

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks
- Fill volume: 100 mL
- Initial cells density: 10 000 cells/mL
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 8

GROWTH MEDIUM
- Standard medium used: yes, sterilised synthetic growth medium acc. to OECD guideline 201

OTHER TEST CONDITIONS
- Sterile test conditions: yes/no
- Adjustment of pH: no
- Photoperiod: contionous illumination
- Light intensity and quality: 90.5 to 93.5 μE/m2 s (OSRAM Standard “cool white”)


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter (CASY 1 Model TT, OMNI Life Science GmbH & Co. KG, Bremen, Germany). The cell concentrations were determined after 24, 48 and 72 hours

TEST CONCENTRATIONS
- Range finding study
- Test concentrations: 12, 38 and 120 mg test item/L
- Results used to determine the conditions for the definitive study: There was a significant inhibition of algal growth up to the highest nominal test item loading of 120 mg/L.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 240 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 60 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 4.41 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Remarks:

recaluclated from measured Mn concentration

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 4 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Remarks:

recaluclated from measured Mn concentration

Basis for effect:

growth rate

Results with reference substance (positive control):

Nominal ErC50 (obtained in August 2015): 2.62 mg/L (2.52 - 2.72 mg/L, 95 % confidence limits).

Reported statistics and error estimates:

Since there were no concentration-dependent effects on the growth of the green alga up to the highest test concentrations, EC-values were not calculated.
The NOEC values were determined using appropriate statistical methods (Williams` Multiple Sequential t-Test. The computer program ToxRat® was used for statistical evaluations.

Description of key information

Not acutely toxic to aquatic algae.

Additional information

The toxicity of trimanganese bis(orthophosphate) (CAS 14154-09-7) to the green algae Pseudokirchneriella subcapitata was tested in a study following OECD guideline 201. The algae were exposed to nominal test substance concentrations of 60, 120 and 240 mg/L. The test solutions were prepared separately by applying the Water Accommodated Fraction (WAF) approach according to the OECD guidance No. 23 and 29.The concentrations of trimanganese bis(orthophosphate) in the test media were determined by chemical analyses of manganese in the aqueous phase at the start and at the end of the test using ICP-OES (LOQ 9.78 μg Mn/L). The test substance concentrations were recalculated from the measured manganese concentrations. Based on the algal growth rate an EC50(72 h) > 4.41 (initially measured) was determined (EC50(72h) >240 mg/L (nominal)). The NOEC was NOEC < 4 mg/L (initially measured) (NOEC < 60 mg/L (nominal)).           

Based on the experimental results trimanganese bis(orthophosphate) is not acutely toxic to aquatic algae.