11β,17α-Dihydroxy-6α-methylpregna-1,4-diene-3,20-dione

Toxicity to aquatic algae and cyanobacteria

Administrative data

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

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2017

Report date:

2017

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

(1R,3aS,3bS,5S,9aR,9bS,10S,11aS)-1-acetyl-1,10-dihydroxy-5,9a,11a-trimethyl-1H,2H,3H,3aH,3bH,4H,5H,7H,9aH,9bH,10H,11H,11aH-cyclopenta[a]phenanthren-7-one

EC Number:

614-710-9

Cas Number:

6870-94-6

Molecular formula:

C22H30O4

IUPAC Name:

(1R,3aS,3bS,5S,9aR,9bS,10S,11aS)-1-acetyl-1,10-dihydroxy-5,9a,11a-trimethyl-1H,2H,3H,3aH,3bH,4H,5H,7H,9aH,9bH,10H,11H,11aH-cyclopenta[a]phenanthren-7-one

Sampling and analysis

Analytical monitoring:

yes

Remarks:

LC-MS/MS TOF

Test organisms

Test organisms (species):

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

Details on test organisms:

The test organism was originally obtained from the culture collection of algae and protozoa and is a representative specie of the freshwater aquatic phytoplankton.
Prior to testing, duplicate starter cultures were prepared and incubated under test conditions to obtain sufficient algal cells in exponential growth and to achieve a starting algae cell density of 1x10e+4 cells/mL.

Study design

Test type:

static

Water media type:

other: alga nutrient medium (EC medium)

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

Cell density counts were performed after incubation using a particle counter and confirmed manually using a haemocytometer.

Test conditions

Hardness:

Not specified

Test temperature:

22.2-23.3°C

pH:

7.70 to 9.79

Dissolved oxygen:

Not specified

Nominal and measured concentrations:

Nominal: 100%
Measured: 7.74 mg/L [8.68 mg/L (0h, new media), 6.91 mg/L (72h, old media)

Details on test conditions:

Incubation under 7110-7620 lux light intensity

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 7.74 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 2

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 7.74 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 7.74 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Effect concentrations 4

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 7.74 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

other: yield

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 7.74 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Effect concentrations 6

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

ca. 7.74 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

As the 72 hour measured concentration was not maintained within 80 to 120% of the initial measured concentration, the results have been based on geometric mean measured concentration as recommended in the OECD 201 guideline.
Based on geometric mean measured concentrations, the 72-h EyC50 (yield), EbC50 (area under the curve) and ErC50 (growth rate) values were calculated to be > 7.74 mg/L, respectively. The corresponding NOEC values for yield, biomass and specific growth rate after 72 hours wer