4'-bromo-3-chloropropiophenone

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:

Jul 03 - Sep 14, 2020

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

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

The concentrations of the test item were determined in fresh media (0 hours) and at the end of the exposure interval (72 hours) via GC/MS.

Vehicle:

yes

Remarks:

water

Details on test solutions:

A supersaturated stock solution of 100 mg test item/L was prepared by dissolving 89.2 mg test item into 892 mL test water by intense stirring for 6 hours at room temperature in the dark. Then, non-dissolved fractions of the test item were separated from the test medium by membrane filtration (0.45 μm cellulose acetate filter). Adequate volumes of this stock solution were diluted with test water to prepare the test media of the desired dilutions of 1:20, 1:64, 1:205, 1:655 and 1:2098.
The test media were prepared just before introduction of the algae (= start of the test)

Test organisms (species):

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

Details on test organisms:

Pseudokirchneriella subcapitata, Strain No. 61.81 SAG formerly known as Selenastrum capricornutum, and recently renamed as Raphidocelis subcapitata.
Cultivated in the laboratories of ibacon; original source: "Sammlung von Algenkulturen, Albrecht-von-Haller-Institut für Pflanzenwissen-schaften, Universität Göttingen", 37073 Göttingen, Germany.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22.4 to 23.7 °C

pH:

pH value in the control at test start: 8.2,
pH value in the control at test end: 10.0;
pH values in the test item treatments at test start: 8.0 to 8.2,
pH values in the test item treatments at test end: 7.8 to 9.9;

Nominal and measured concentrations:

The dilutions of a filtrate of 100 mg/L were tested: 1:20, 1:64, 1:205, 1:655 and 1:2098 (spacing factor 3.2). Additionally a control was tested in parallel. This corresponds to the following geometric mean measured concentrations of the test item: 6.83, 3.58, 2.28, 1.20 and 0.651 μg test item/L and a control.

Details on test conditions:

This study encompassed 6 treatment groups (5 dose rates of the test item and a control) with three replicates per test concentration and six replicates for the control. At test start 50 mL of the test media were inoculated with nominal 5000 algal cells per mL test medium and defined volumes of the algal suspensions were sampled after 24, 48 and 72 hours for determination of cell densities by spectrophotometric measurement.
The dilutions of a filtrate of 100 mg/L were tested: 1:20, 1:64, 1:205, 1:655 and 1:2098 (spacing factor 3.2). Additionally a control was tested in parallel. This corresponds to the following geometric mean measured concentrations of the test item: 6.83, 3.58, 2.28, 1.20 and 0.651 μg test item/L and a control.

Water temperature: 22.4 to 23.7 °C;
pH value in the control at test start: 8.2,
pH value in the control at test end: 10.0;
pH values in the test item treatments at test start: 8.0 to 8.2,
pH values in the test item treatments at test end: 7.8 to 9.9;
continuous illumination; mean light intensity: 5585 lux (5350 to 5870 lux).

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.13 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

1.42 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

1.2 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The 72-hour EyC50 was calculated to be 2.18 μg test item/L and the 72-hour ErC50 value was calculated to be 3.13 μg test item/L. The 72-hour NOEyC was determined to be 1.20 μg test item/L and the associated 72-hour LOEyC was 2.28 μg test item/L. The 72-hour NOErC was determined to be 1.20 μg test item/L and the associated 72-hour LOErC was 2.28 μg test item/L.
The initial concentrations and the maintenance of the exposure concentrations during the test were determined in the analytical part. All reported results refer to geometric mean concentrations, since the test item concentrations were not within ± 20 % of the measured initial concentrations during the test.

Algal Cell Densities during the Test Period of 72 Hours

Geometric mean measured concentration [µg test item / mL]	Flask No	Density of algal cells [10000 cells / mL] after
		24 h	48 h	72 h
Control	1	2.899	23.899	162.740
	2	2.692	26.637	156.494
	3	2.899	26.005	148.325
	4	3.520	27.058	161.058
	5	2.692	25.163	155.773
	6	3.106	27.900	165.863
	m	2.968	26.110	157.376
	s	0.312	1.427	6.223
0.651	1	2.485	24.741	152.890
	2	2.692	26.426	153.130
	3	2.899	27.268	176.194
	m	2.692	26.145	160.738
	s	0.207	1.287	13.386
1.20	1	2.899	20.951	137.033
	2	2.485	23.268	156.013
	3	2.485	19.056	135.592
	m	2.623	21.092	142.879
	s	0.239	2.109	11.397
2.28	1	1.243	10.213	81.775
	2	1.864	9.581	74.087
	3	1.450	8.949	71.685
	m	1.519	9.581	75.849
	s	0.316	0.632	5.271
3.58	1	0.621	1.790	3.694
	2	0.828	1.579	3.453
	3	0.828	2.001	2.252
	m	0.759	1.790	3.133
	s	0.120	0.211	0.772
6.83	1	0.621	0.500	0.500
	2	0.621	0.500	0.500
	3	0.621	0.500	0.500
	m	0.621	0.500	0.500
	s	0.000	0.000	0.000

Validity criteria fulfilled:

yes

Conclusions:

The purpose of this test was to determine the inhibitory effect of the test item on the growth of the freshwater green algae Pseudokirchneriella subcapitata.

72-hour ErC50: 3.13 μg test item/L
72-hour NOErC: 1.20 μg test item/L
72-hour LOErC: 2.28 μg test item/L.

Description of key information

The 72-hour E_rC50 value was calculated to be 3.13 μg test item/L. The 72-hour NOE_rC was determined to be 1.20 μg test item/L and the associated 72-hour LOErC was 2.28 μg test item/L and the ErC10 was determined to be 1.41 μg test item/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

3.13 µg/L

EC10 or NOEC for freshwater algae:

1.42 µg/L