3,5-dihydroxy-2,6,6-tris(3-methylbuten-2-yl)-4-(3-methyl-1-oxobutyl)cyclohexa-2,4-dien-1-one

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Justification for type of information:

Guideline study to GLP
The study performed on hop extract is relevant for beta acids, since hop extract may contain up to ca. 64% beta acids, and the extract tested here contained 38% beta acids. A further study has been planned for beta acids and will be entered as an update.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Freshwater Alga and Cyanobacteria, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

Batch no. 160025

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

Strain CCAP 278/4

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

20.7 - 26.0 oC

pH:

7.53 - 8.08

Reference substance (positive control):

yes

Remarks:

Separate GLP rerefence study on potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 86.7 mg/L

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 83.1 mg/L

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 25 mg/L

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

ca. 42.7 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 52.5 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 12.5 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

Notes from report:

The definitive test conducted from 06 to 09 March 2018 was performed according to the OECD 201 (2011) guideline.
The growth curves demonstrate that the algae in the control were in logarithmic growth for the duration of the study.
The 48 hour EC(r)50 and EC(y)50 of HOP EXTRACT to Pseudokirchneriella subcapitata were 86.7mg/l and 42.7mg/l respectively (both determined by Maximum Likelihood-Logit).
The 72 hour EC(r)50 and EC(y)50 of HOP EXTRACT to Pseudokirchneriella subcapitata were
83.1mg/l and 52.4mg/l respectively (both determined by Maximum Likelihood-Logit).
The 0 to 72-hour NOEC(r) was 25mg/l and the 0-72 hour LOEC was 50mg/l (both determined by direct observation).
The 0 to 72-hour NOEC(y) was 12.5mg/l and the 0-72 hour LOEC was 25mg/l (both determined by direct observation).
The algal cells were examined microscopically during the determination of cell concentration.
All cells within the control and test concentrations appeared normal, no abnormalities were observed
(see section 3.2).
All validity criteria for the definitive test were met (see section 3.5).
The water quality measurements and incubation conditions are given in the summary tables in
Appendix 2 and were within accepted limits.
Analytical measurements of the freshly prepared exposure solutions indicated that the initial measured concentrations were not within 20% of nominal concentrations. In addition, analytical measurements of the 48 hour aged exposure solutions could not detect the test substance in the samples and therefore were also not within the ± 20% of nominal concentrations or ± 20% of the initial measured concentrations. This was expected due to the lack of water-solubility of HOP EXTRACT. All effect loading rates of the test substance are reported as nominal concentrations of the test substance.

Executive summary:

The study performed on hop extract is relevant for beta acids, since hop extract may contain up to ca. 64% beta acids, and the extract tested here contained 38% beta acids. A further study has been planned for beta acids and will be entered as an update.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

72 hours

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)

Specific details on test material used for the study:

Batch no. DB EXP 10

Analytical monitoring:

yes

Vehicle:

no

Test organisms (species):

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

Details on test organisms:

Strain CCAP 278/4

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

20.7 - 21.8 oC

pH:

7.71 - 8.12

Reference substance (positive control):

yes

Remarks:

Separate GLP rerefence study on potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 11.31 mg/L

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

< 0.403 mg/L

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

ca. 18.57 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 0.992 mg/L

Conc. based on:

test mat.

Basis for effect:

growth rate

Validity criteria fulfilled:

yes

Conclusions:

The definitive test conducted from 21 to 24 August 2018 was performed according to the OECD 201 (2011) guideline.
The growth curves demonstrate that the algae in the control were in
logarithmic growth for the duration of the study.
The 48 hour EC(r)50 and EC(y)50 of Potassium salt of Beta acids to Pseudokirchneriella
subcapitata were 18.99 mg/L and 13.0 mg/L respectively (determined by Linear Interpolation).
The 72 hour EC(r)50 and EC(y)50 of Potassium salt of Beta acids to Pseudokirchneriella
subcapitata were 18.57 mg/L and 11.31 mg/L respectively (determined by Linear Interpolation).
The 0 to 72-hour NOEC(r) was 0.992 mg/L and the 0-72 hour LOEC was 2.968 mg/L (both determined by Bonferroni t Test).
The algal cells were examined microscopically during the determination of cell concentration. All cells within the control and test concentrations appeared normal, no abnormalities were observed. All validity criteria for the definitive test were met.
The water quality measurements and incubation conditions were within accepted limits. Analytical confirmation of the test concentrations was performed. The measured dissolved concentrations were lower than the nominal concentrations as Potassium salt of Beta acids partially dissolves in aqueous alkaline solutions. Beta acids dissolve up to 7.7g/litre in water with the other constituents remaining undissolved. All analysis of the test material is based on the test material being 70% pure Beta acids as per the sponsor and reported as initial measured concentrations (time 0).

Key value for chemical safety assessment

EC50 for freshwater algae:

18.57 mg/L

EC10 or NOEC for freshwater algae:

0.992 mg/L