Dizinc pyrophosphate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

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:

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: 0.75, 1.5, 3.0, 6.0 and 12.0 mg test/L sampled at test start (0 h) and termination (72 h).
- Sample storage conditions before analysis: samples were immediately stabilised by adding 0.2 mL conc. HNO3 to 20 mL test media. Samples which could not be measured on the day of sampling, were immediately stored at 4 °C until analysis.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: a stock solution was prepared by adding 100.2 mg/k test item to 1 L sterile growth medium. The solution was stirred for 24 hours at 20°C and subsequently filtered through a 0.22 µm PES filter. The test solutions were prepared by diluting the stock solution.

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: green algae
- Source (laboratory, culture collection): Culture Collection of Algae at Pflanzenphysiologisches Institut of the University at Göttingen, Catalog No 61.81 SAG

ACCLIMATION
- Acclimation period: pre-culture for 3 days

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22.0 °C

pH:

7.28 - 7.90

Nominal and measured concentrations:

Nominal test substance concentrations: 0.75, 1.5, 3.0, 6.0 and 12.0 mg test item/L
equivalent to 0.32, 0.64, 1.29, 2.57 and 5.15 mg Zn/L (42.9% Zn in the test item)

measured concentrations 0 h: 0.0264 0.045, 0.087, 0.185 and 0.355 mg Zn/L (6.74 – 7.40% of nominal)
measured concentrations 72 h: 0.014, 0.032, 0.076, 0.168 and 0.319 mg Zn/L (4.47 – 6.53% of nominal; 60.4 – 90.6% of initial).
Geometric mean measured Zn concentration: 0.018, 0.038, 0.081, 0.176 and 0.336 mg Zn/L
Geometric mean measured test substance concentration: 0.043, 0.089, 0.190, 0.411 and 0.784 mg test item/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glass flasks
- Fill volume: 100 mL
- Initial cells density: 10,000 cells/mL
- Control end cells density:
- No. of vessels per concentration (replicates):4
- No. of vessels per control (replicates): 4

GROWTH MEDIUM
- Standard medium used: yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: sterilised grwoth medium according to OECD 201
- Metals: ZnCl2: 0.003 (Zn = 1.44 μg/L)


OTHER TEST CONDITIONS
- Sterile test conditions: yes
- Photoperiod: continous illumination
- Light intensity and quality: 90.35 to 92.25 μE m-2 s-1


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); cell densitiy was determined daily


TEST CONCENTRATIONS
- Spacing factor for test concentrations:
- Range finding study
- Test concentrations: 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: Strong inhibitiory effects on the growth of the algae was observed at nominal test concentrations of 10 and 100 mg/L.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorphenol

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.233 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 %-cl lower-upper: 0.223 - 0.243

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.094 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 %-cl lower-upper: 0.086 - 0.103

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.043 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Results with reference substance (positive control):

Routinely chekced twice a year
- EC50: 2.90 mg/L (nominal; 95% confidence limits: 2.66 – 3.16 mg/L)

Inhibition of growth rate compared to controls after 72 hours

Mean measured test item concentration [mg/L]	Growth rate
	Growth rate [1/d]	% Inhibition
Control	1.5914	-
0.043	1.6083	-1.06 (-)
0.089	1.5094	5.15 (+)
0.190	0.9353	41.23 (+)
0.411	0.3523	77.86 (+)
0.784	0.0903	94.33 (+)

Validity criteria fulfilled:

yes

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

supporting study

Study period:

30. Sep. - 10 Nov 2003

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

no GLP, no analytical monitoring

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

EN ISO 8692/EU-Richtlinie C.3

GLP compliance:

not specified

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test was conducted using the water soluble fraction of the substance. The test solution was prepared by adding the required amount of test substance to the test medium and shaking the mixture for 24 hours. Subsequently the mixture was filtered (membrane filtration).

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: Desmodesmus subspicatus CHODAT
- Source (laboratory, culture collection): Sammlung von Algenkulturen, Institute for plant physiology, University of Göttingen.

ACCLIMATION
- Acclimation period: 3-4 days
- Culturing media and conditions (same as test or not):same

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

23 ±2°C

Nominal and measured concentrations:

First test: nominal test substance concentrations: control, 1.0, 1.6, 2.5, 4.0, 6.3, 10 mg/L
Second test: nominal test substance concentrations: control, 1.6 and 4 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 8 ml cuvettes
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6



EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: spectrophotometer PU 8625 at 440 nm after 0, 24, 48 and 72 hours


TEST CONCENTRATIONS
- Range finding study
- Test concentrations: first range finding study: 10, 100, 1000 mg/L; second range finding study: 1, 0.1, 0.01 mg/L
- Results used to determine the conditions for the definitive study: Since an algal growth could not be determined in the first range finding study, a second study with lower substance concentrations was started. The grwoth rate was decreased by 2.0 % at a concentration of 0.01 mg/L and by 2.2% at 0.1 mg/L. Whereas a concentration of 1 mg/L lead to a decrease by 0.6%

Duration:

72 h

Dose descriptor:

other: NOEL

Effect conc.:

< 1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4.7 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Description of key information

EC50 (72 h) 0.233 mg test item /L (meas. geom. mean)

EC10 (72 h): 0.094 mg test item/L (meas. geom. mean)

Key value for chemical safety assessment

EC50 for freshwater algae:

0.233 mg/L

EC10 or NOEC for freshwater algae:

0.094 mg/L

Additional information

The toxicity of dizinc pyrophosphate to freshwater algae was tested according to OECD guideline 201 (GLP). The test was conducted with Pseudokirchneriella subcapitata as test organism. The algae were exposed to nominal substance concentrations of 0.75, 1.5, 3.0, 6.0 and 12.0 mg test item/L. The test concentrations were prepared by adding the required amount of test substance to sterile growth medium. The solution was stirred for 24 hours at 20°C and subsequently filtered through a 0.22 µm PES filter. The test solutions were prepared by diluting the stock solution. The concentrations at 0 h and 72 h were analytically verified by ICP-MS and ICPOES. The geometric mean measured concentrations were 0.043, 0.089, 0.190, 0.411 and 0.784 mg test item/L corresponding to 0.018, 0.038, 0.081, 0.176 and 0.336 mg Zn/L. A significant inhibition of the algal growth rate was observed. The determined EC50(72 h) was 0.233 mg test item /L (meas. geom. mean). The reported EC10(72 h) is 0.094 mg/test item/L (meas. geom. mean); the NOEC (72 h) is 0.043 mg test item/L (meas. geom. mean).

A second studyon the toxicity of dizinc pyrophosphate following OECD guideline 201 is available. The test was conducted with Desmodesmus subspicatus as test organism. The algae were exposed for 72 hours to nominal test substance concentrations of 1.0, 1.6, 2.5, 4.0, 6.3 and 10 mg/L. The test solutions were prepared separately by adding the required amount of test item to the test medium and subsequent shaking of the mixture for 24 hours. The water soluble fraction was separated by filtering (membrane filtration). Analytical dose verification was not performed. Based on the algal growth rate an EC(L)50 (72 h) of 4.7 mg/L (nominal) was determined. The determined NOEL (72 h) was < 1.0 mg/L (nominal).

Based on the test results dizinc pyrophosphate is considered very toxic to aquatic algae with long lasting effects.