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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

Study period:

February to April 2019

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)

Vehicle:

yes

Test organisms (species):

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

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Test temperature:

21-23 ºC

pH:

7.33-8.12

Nominal and measured concentrations:

0.0, 0.1, 0.3, 0.8, 2.0 and 5.0 mg of POLIOL MB 600/L

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 0.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

ca. 0.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

ca. 0.17 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

biomass inhibition

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

ca. 0.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

ca. 0.17 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield inhibition

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

ca. 0.24 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

0.47 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

biomass inhibition

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

ca. 0.23 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield inhibition

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 0.48 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.:

ca. 1.07 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

biomass inhibition

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 0.44 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: yield inhibition

Details on results:

The cell concentration in control cultures was increased by factor of 137.2 times within the three-day test period. In treated groups, biomass was decreased with increased concentration of POLIOL MB 600 during 72h exposure period
The coefficient of variation of average specific growth rate during the whole test period (0-3) in replicate control culture was 0.61%. The mean coefficient of variation for day 0-1, 1-2 and 2-3 in control culture was 5.71%
The percent inhibition of biomass was 0.45, 42.77, 93.10, 97.29 and 98.93 for 0.1, 0.3, 0.8, 2.0 and 5.0 mg POLIOL 600/L, respectively
The percent inhibition of growth rate was 0.15, 12.57, 65.06, 78.51 and 85.53 for 0.1, 0.3, 0.8, 2.0 and 5.0 mg POLIOL 600/L, respectively
The percent inhibition of yield was 0.33, 45.80, 96.60, 98.56 and 99.21 for 0.1, 0.3, 0.8, 2.0 and 5.0 mg POLIOL 600/L, respectively

Results with reference substance (positive control):

The cell concentration in control cultures was increased by factor of 185.8 times within the three-day test period. In the treated groups, biomass was decreased with increased concentration of Potassium dichromate during 72h exposure period
The coefficient of variation of average specific growth rate during the whole test period (0-3) in replicate control culture was 3.45%. The mean coefficient of variation for day 0-1, 1-2 and 2-3 in control culture was 2.61%
The percent inhibition of biomass was 0.82, 29.27, 82.92, 98.36 and 100.23 for test concentrations levels 0.1, 0.3, 0.8, 2.0 and 5.0 mg/L, respectively
The percent inhibition of growth rate was 0.28, 6.64, 39.00, 82.71 and 93.64 for test concentrations levels 0.1, 0.3, 0.8, 2.0 and 5.0 mg/L, respectively
The percent inhibition of yield was 0.44, 30.95, 87.46, 99.19 and 99.75 for test concentrations levels 0.1, 0.3, 0.8, 2.0 and 5.0 mg /L, respectively

Validity criteria fulfilled:

yes

Conclusions:

The cell concentration in control cultures was increased by factor of 137.2 times within the three-day test period. In treated groups, biomass was decreased with increased concentration of POLIOL MB 600 during 72h exposure period
The coefficient of variation of average specific growth rate during the whole test period (0-3) in replicate control culture was 0.61%. The mean coefficient of variation for day 0-1, 1-2 and 2-3 in control culture was 5.71%
The percent inhibition of biomass was 0.45, 42.77, 93.10, 97.29 and 98.93 for 0.1, 0.3, 0.8, 2.0 and 5.0 mg POLIOL 600/L, respectively
The percent inhibition of growth rate was 0.15, 12.57, 65.06, 78.51 and 85.53 for 0.1, 0.3, 0.8, 2.0 and 5.0 mg POLIOL 600/L, respectively
The percent inhibition of yield was 0.33, 45.80, 96.60, 98.56 and 99.21 for 0.1, 0.3, 0.8, 2.0 and 5.0 mg POLIOL 600/L, respectively

Executive summary:

 This study was performed to assess inhibitory effects of POLIOL MB 600 

on the growth of alga Pseudokirchneriella subcapitata, under static condition. 

 

Exponentially growing cultures of P.subcapitata were exposed to nominal test concentrations 0.0 (control), 

0.1, 0.3, 0.8, 2.0, and 5.0 mg POLIOL MB 600/L. Algal cultures were assessed for their growth by visual 

cell count at 24, 48, and 72 h.  

 

The stability of the test item in test media was performed during method validation (JRF Study N° 228-2- 

13-21963) and the test item in test media was stable up to 72 h (>80% of nominal concentration). Test 

media was analysed for POLIOL MB 600 active ingredient concentration and stability to monitor the 

concentration of the test solution at 0 and 72 h, during the main study. The active ingredient concentration 

of the test item in test media was within acceptable limit (>80% of nominal concentration).  

 

A concentration-effect relationship was observed and statistically analysed to obtain effect concentrations. 

The growth rate inhibition effect concentrations with their respective 95% lower and upper confidence 

limits for the inhibition of growth rate were ErC10 = 0.30 (0.19 – 0.50) mg/L, ErC20 = 0.47 (0.27 – 0.80) 

mg/L and ErC50 = 1.07 (0.57 – 1.98) mg/L. 

 

The biomass inhibition effect concentrations with their respective 95% lower and upper confidence limits 

for the biomass inhibition were EbC10 = 0.17 (0.10 – 0.27) mg/L, EbC20 = 0.24 (0.15 – 0.40) mg/L and EbC50 

= 0.48 (0.27 – 0.86) mg/L.  

 

The yield inhibition effect concentrations with their respective 95% lower and upper confidence limits for 

the yield were EyC10 = 0.17 (0.10 – 0.28) mg/L, EyC20 = 0.23 (0.13 – 0.40) mg/L and EyC50 = 0.44 (0.24 – 

0.81) mg/L. 

 

Based on results of statistical analysis, the NOEC and LOEC values for biomass (cell growth), growth rate, 

and yield were 0.1 and 0.3 mg POLIOL MB 600/L, respectively.  

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Justification for type of information:

Read across from structural analogue, justification can be found attached in section 13.2.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 0.44 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 1.07 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 0.48 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

ca. 0.23 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

ca. 0.47 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

ca. 0.24 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

ca. 0.17 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

yield

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

ca. 0.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

ca. 0.17 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

ca. 0.3 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.:

ca. 0.1 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

The cell concentration in control cultures was increased by factor of 137.2 times within the three-day
test period. In treated groups, biomass was decreased with increased concentration of the substance during 72h exposure period
The coefficient of variation of average specific growth rate during the whole test period (0-3) in r
eplicate control culture was 0.61%. The mean coefficient of variation for day 0-1, 1-2 and 2-3 in co
ntrol culture was 5.71%
The percent inhibition of biomass was 0.45, 42.77, 93.10, 97.29 and 98.93 for 0.1, 0.3, 0.8, 2.0 and
5.0 mg substance/L, respectively
The percent inhibition of growth rate was 0.15, 12.57, 65.06, 78.51 and 85.53 for 0.1, 0.3, 0.8, 2.0 and
5.0 mg substance/L, respectively
The percent inhibition of yield was 0.33, 45.80, 96.60, 98.56 and 99.21 for 0.1, 0.3, 0.8, 2.0 and 5.0
mg substance/L, respectively

Description of key information

EC50 for freshwater algae 0.48 mg/L

EC10 for freswhater algae 0.3 mg/L

Key value for chemical safety assessment

EC50 for freshwater algae:

0.48 mg/L

EC10 or NOEC for freshwater algae:

0.3 mg/L