1-bromo-4-propylbenzene

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Study period:

Aug 28- 31, 2006

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: all
- Sampling method: -
- Sample storage conditions before analysis: direct analysis

Vehicle:

no

Details on test solutions:

Reconstituted water

Macro nutrients:
NaHCO3 50 mg/L
CaCl2 x 2 H2O 18 mg/L
NH4Cl 15 mg/L
MgSO4 x 7 H2O 15 mg/L
MgCI2 x 6 H2O 12 mg/L
KH2PO4 1.6 mg/L



Trace elements:

Na2EDTA x 2 H2O 100.00 µg/L
FeC13 x 6 H2O 80.00 µg/L
MnC12 x 4 H2O 415.00 µg/L
H3BO3 185.00 µg/L
Na2MoO4 x 2 H2O 7.00 µg/L
ZnC12 3.00 µg/L
CoCl2x 6 H2O 1.50 µg/L
CuC12 x 2 H2O 0.01 µg/L

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Desmodesmus subspicatus
- Strain: No. SAG 86.81
- Source (laboratory, culture collection): Sammlung von Algenkulturen, Pflanzenphysiologisches Institut der Universitat Göttingen, Germany
- Age of inoculum (at test initiation): freshly prepared
- Method of cultivation: under standardised lab conditions

ACCLIMATION
- Acclimation period: Prior to start the study, the algae were grown in reconstituted water as preculture and the growth rate was determined.
- Culturing media and conditions (same as test or not): same
- Any deformed or abnormal cells observed: no

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Hardness:

250 mg/L

Test temperature:

22 -23 °C

pH:

7.6 - 10.5

Nominal and measured concentrations:

nominal: 1, 1.78, 3.16, 5.62, 10.0 mg/L
measured: 0.04, 0.07, 0.15, 0.31, 0.66 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: headspace
- Aeration: no
- Initial cells density: 10000
- No. of organisms per vessel: 10000
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 3
- No. of vessels per vehicle control (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.25 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 0.22-0.28

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.4 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 0.36-0.45

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.07 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Details on results:

- Pretest

In the preculture, the factor of cell growth was approx. 74.5. The algae increased from 10000 cells/ml at the start to 744661 cells/ml after 72 hours.

- Main study

The nominal test material concentrations and the growth inhibition data (mean) after 72 hours exposure are given below:

---------------------------------------------------------------------------------------------------
Nominal
conc. (mg/L) Cell density per mL Growth
inhibition
(0-72 hours)
nominal analytical 0 hour 24 hours 48 hours 72 hours IA lµt
---------------------------------------------------------------------------------------------------
Control 10000 82620 294570 784431
1.00 0.04 10000 79449 284631 782379 1.9 0.1
1.78 0.07 10000 75672 278517 697302 8.9 2.7
3.18 0.15 10000 64272 226973 618030 22.7 5.5
5.62 0.31 10000 62160 151761 295834 54.8 22.3
10.00 0.66 10000 28221 21828 17550 95.5 87.1
---------------------------------------------------------------------------------------------------

IA = inhibition of cell growth in percent
Iµt= inhibition of growth rate in percent

Validity criteria fulfilled:

yes

Conclusions:

The test material, prepared in reconstituted  water, was tested in the Algae growth  inhibition test using a closed static test system. The solubility in water was very poor. Nevertheless high toxicity was observed as the 72 hours EC50-values to Desmodesmus subspicatus were calculated to be 0.40 mg/L based on growth rate. The 72-h NOEC was determined to be 0.07 mg/L.

Executive summary:

Study design

The influence of the test material on the growth and growth rate of the green algae species Desmodesmus subspicatus was tested.
Due to the volatility of the test material 100 ml Erlenmeyer flasks were filled with 120 ml test medium and sealed with ground stoppers to form a closed system reducing the loss of the test material concentrations within the exposure period.
The algae were exposed to different concentrations of test material and the growth was calculated after 24, 48, or 72 hours of exposure in the test media.
Based on the results of a pretest, the main study was performed with nominal concentrations of 1.00, 1.78, 3.16, 5.62, and 10.00 mg test material/L reconstituted water. The study design included three replicates per test material concentration, each containing about 120 ml test medium and 10000 cells/ml at the start of the experimental phase and a control without algae. Analyses of the test material concentrations were performed with all doses at the start and after 24, 48, or 72 hours.
This study was performed according to GLP and the methods applied are fully compliant with OECD TG 201.

Results

The limit of quantification of the analytical method was about 0.02 mg/L. At the start, the analytically determined concentrations were about 4 to 5 % and at the end about 3 to 7 % of the nominal concentrations. The analytical test concentrations were calculated the geometric mean individual values. The EC50 values were calculated with these geometric mean exposure concentrations.

The following results were obtained after exposure of Desmodesmus subspicatus to different concentrations of the test material:

Concentration in [mg/ml]		Mean Cell Density per ml				Growth Inhibition (0-72h)
nominal	analytical	0 h	24 h	48 h	72 h	Biomass	Growth rate
0	0	10000	82620	294570	784431	-	-
1.00	0.04	10000	79449	284631	782379	1.9	0.1
1.78	0.07	10000	75672	278517	697302	8.9	2.7
3.18	0.15	10000	64272	226973	618030	22.7	5.5
5.62	0.31	10000	62160	15176	295834	54.8	22.3
10.00	0.66	10000	28221	21828	17550	95.5	87.1

The median effective concentration (EC50), which would result in a 50 % growth inhibition and  the 95% confidence interval compared to tbe control, was calculated from the analytically determined concentrations. The analytical EC50s and the NOEC are given below:

Biomass: 72 h EC50 = 0.25 (0.22-0.28) mg/L
Growth Rate. 72 h EC50 = 0.40 (0.36-0.45) mg/L
NOEC = 0.07 mg/L
 

Conclusion

The test material, prepared in reconstituted  water, was tested in the Algae growth  inhibition test using a closed static test system. The solubility in water was very poor. Nevertheless high toxicity was observed as the 72 hours EC50-values to Desmodesmus subspicatus were calculated to be 0.40 mg/L based on growth rate. The 72-h NOEC was determined to be 0.07 mg/L.

Description of key information

The test material, prepared in reconstituted  water, was tested in the Algae growth  inhibition test using a closed static test system. The solubility in water was very poor. Nevertheless high toxicity was observed as the 72 hours EC50-values to Desmodesmus subspicatus were calculated to be 0.40 mg/L based on growth rate. The 72-h NOEC was determined to be 0.07 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.4 mg/L

EC10 or NOEC for freshwater algae:

0.07 mg/L