Bis(pentane-2,4-dionato-O,O')zinc

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)

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

not specified

Vehicle:

no

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

The algea were purchased from the Institut für Pflanzenphysiologie of the University of Göttingen.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

4 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.6 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Reduction of biomass and growth rate by the test substance:

concentration (mg/L)	biomass, % reduction	growth rate, % reduction
0	set to 0	set to 0
0.56	7.3	2.6
1.0	8.4	3.3
1.6	-4.0	-1.9
3.2	11.7	9.4
5.6	55.5	24.9
10	78.6	48.7
16	97.6	84.5
32	100.6	89.8
56	99.8	84.0
100	101.2	92.5

Validity criteria fulfilled:

yes

Conclusions:

The ErC50 72h can be stated as 10 mg/L
The EyC50 72h can be stated as 4 mg/L.
The NOEC based on biomass and growth rate can be stated as 1.6 mg/L

Reference 2

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 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

The test was carried out with the freshwater unicellular algae P. subcapitata (CCAP 278/4) obtained from the Culture Collection of Algae and Protozoa, Dunstaffnage Marine Laboratory, Oban, Argyll, Scotland, UK.

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Test temperature:

22.1 to 22.3 °C

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

0.13 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.:

0.59 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.05 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Reduction of biomass and growth rate by the test substance:

Nominal concentration (mg(L)	mean % inhibition (biomass)	mean % inhibition (growth rate)
0 (control)	set to 0	set to 0
0.015	-2.4	-0.3
0.05	7.6	1.7
0.15	36.1	11.0
0.48	85.2	45.4
1.54	96.3	77.4

Validity criteria fulfilled:

yes

Conclusions:

The ErC10 (72h) was calculated as 0.13 mg/L and the ErC50 (72h) was calculated as 0.59 mg/L (Growth rate) [Nominal concentrations]
The NOEC (72h) was calculated as 0.05 mg/L and the LOEC as 0.15 mg/L. (Growth rate) [Nominal concentrations].

Executive summary:

The toxicity of the test substance to an exponentially growing culture of P. subcapitata was determined over an exposure period of 72 hours. Nominal concentrations of 0.015, 0.05, 0.15, 0.48 and 1.54 mg/L were tested. For the highest 3 concentrations, a statistically significant reduction in growth rate in comparison to the control was detected.

Description of key information

Two studies with the test substance on Desmodesmus subcapitata (earlier study) and Pseodokirchneriella subcapitata (later study), respectively, were conducted.

The results on Desmodesmus subcapitata were:

The ErC50 72h can be stated as 10 mg/L

The EyC50 72h can be stated as 4 mg/L.

The NOEC based on biomass and growth rate can be stated as 1.6 mg/L.

.

The results on Pseodokirchneriella subcapitata were:

The ErC50 72h can be stated as 0.59 mg/L

The NOEC 72h based on growth rate can be stated as 0.05 mg/L.

The later study was performed under GLP with a more detailed report.

Pseodokirchneriella subcapitata is the more sensitive species.

Thus the later study is assumed to be more reliable and the following values were used for classification and assessment:

NOEC 72h: 0.05 mg/L

ErC10 72h: 0.13 mg/L

ErC50 72h: 0.59 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

590 µg/L

EC10 or NOEC for freshwater algae:

50 µg/L