1,2-dichloro-4-nitrobenzene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2009

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

2006

Deviations:

yes

Remarks:

the study data were analysed on a 48 h basis

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Version / remarks:

2009

Deviations:

yes

Remarks:

the study data were analysed on a 48 h basis

Principles of method if other than guideline:

The study data were analysed on a 48 h basis, because the coefficient of variation between daily sectional growth rates over 72 h exceeded 35 %. As cell numbers increased well above 16-fold over 48 h, and all other validity criteria are met, this is an option explicitly covered by OECD TG 201 (2006) and EU method C.3 (2009).

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

stock solutions: at 0 hours
control: at 0 and 72 hours
test concentrations: at 0 and 72 hours

Vehicle:

no

Details on test solutions:

- A stock solution was prepared by weighing 20.5 mg of the test item into 1 litre of dilution water, treated for 1 hour in an ultrasonic bath and stirred for 24 h on a magnetic stirrer
- undissolved particles of the test item were removed by filtration using a folded filter of pore size 7-12 µm
- The pH was measured to be pH 6.6
- The concentration of the stock solution was determined analytically by HPLC to be 19.0 mg/L resulting in initial concentrations of 0.09, 0.19, 0.43, 0.94, 2.1, 4.5 and 10 mg/L
- To produce the different test item concentrations appropriate amounts of the prepared stock solution were diluted with dilution water to a volume of 80 mL
- 10 mL of nutrient medium and 10 mL of algal inoculum with a cell density of 5000 cells/mL were added
- For each test item concentration and control 3 replicates were prepared

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

Strain No. 86.81 SAG
obtained from 'The Collection of Algal Cultures' of the Institute of Plant Physiology at the University of Göttingen (Germany)

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

21 to 24 °C

pH:

at t0: 8.5 to 8.6
at t72 h: 8.0

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Type: Erlenmeyer flasks with cotton stoppers
- Initial cells density: 5000 cells per mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): none

GROWTH MEDIUM
- Standard medium used: according to Bringmann & Kühn (1977)

TEST MEDIUM / WATER PARAMETERS
- Culture medium different from test medium: yes

OTHER TEST CONDITIONS
- Photoperiod: continuous uniform illumination
- Light intensity and quality: spectral range 400 to 700 nm, intensity 4000 to 8000 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: microcell counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.2
- Test item concentrations (nominal): 0.09, 0.19, 0.43, 0.94, 2.1, 4.5 and 10 mg/L

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

0.36 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 % CL 0.29 - 0.43

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

2.5 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95 % CL 2.29-2.75 mg/L

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

0.15 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

48 h

Dose descriptor:

EC10

Effect conc.:

0.22 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95 % CL 0.16 - 0.23

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

0.77 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95 % CL 0.68 - 0.87

Details on results:

The results are expressed in terms of geometric mean measured concentrations. Effective concentrations ranged from 88.9 - 96.8% of nominal values at 0 hours and from 66.7 - 73.0% of nominal values at 72 hours, respectively.

The study data were analysed on a 48 h basis, because the coefficient of variation between daily sectional growth rates over 72 h exceeded 35 %. As cell numbers increased well above 16-fold over 48h, and all other validity criteria are met, this is an option explicitly covered by OECD TG 201 (2006) and EU method C.3 (2009).

Validity criteria fulfilled:

yes

Conclusions:

Toxicity to aquatic algae and cyanobacteria test was done according to the EU Method C.3. Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) was exposed to test item for 72 hours. EC50(48 h) of 2.50 mg/L and NOEC of 0.15 mg/L referring to the reduction of the growth rate were observed. Effective concentrations are based on the geometric mean of measured concentrations.

Executive summary:

Toxicity to aquatic algae and cyanobacteria test was done according to the EU Method C.3. Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) was exposed to test item for 72 hours. EC50(48 h) of 2.50 mg/L and NOEC of 0.15 mg/L referring to the reduction of the growth rate were observed. Effective concentrations are based on the geometric mean of measured concentrations.

Description of key information

Toxicity to aquatic algae and cyanobacteria test was done according to the EU Method C.3. Desmodesmus subspicatus (previous name: Scenedesmus subspicatus) was exposed to test item for 72 hours. EC50(48 h) of 2.50 mg/L and NOEC of 0.15 mg/L referring to the reduction of the growth rate were observed. Effective concentrations are based on the geometric mean of measured concentrations.

Key value for chemical safety assessment

EC50 for freshwater algae:

2.5 mg/L

EC10 or NOEC for freshwater algae:

0.15 mg/L

Additional information

The study data were analysed on a 48 h basis, because the coefficient of variation between daily sectional growth rates over 72 h exceeded 35 %. As cell numbers increased well above 16-fold over 48 h, and all other validity criteria are met, this is an option explicitly covered by OECD TG 201 (2006) and EU Method C.3 (2009).

Furthermore, effects based on the biomass were reported yielding more sensitive results than effects based on the growth rate. But, according to the Guidance Document R.7b (ECHA, 2008) results based on the biomass should not be used for assessment since biomass results depend on the growth rate of the species as well as the test duration and other elements of the test design. Thus, the results based on the biomass are not used for the hazard assessment.