trans-2-(4-Bromo-3-fluorophenyl)-5-butyl-[1,3]dioxane

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:

June 03 - July 25, 2019

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 HPLC - DAD.

Vehicle:

yes

Remarks:

water

Details on test solutions:

A saturated solution with a nominal loading of 100 mg test item/L was prepared once 24 ± 1 hour prior to the start of the exposure. An appropriate amount of the test item was weighed out. The test
item was applied onto a glass slide. The glass slide with the test item was inserted into a brown glass bottle with an appropriate amount of dilution water. The saturated solution was
stirred for 24 ± 1 hours (1100 rpm, room temperature) with a magnetic stirrer. After a separation phase of 1 hour the saturated solution was removed by siphoning from the middle of the flask.
Undissolved particles were removed by membrane filtration (membrane filter 0.45 μm, RC, Macherey-Nagel). The filter was saturated in order to avoid adsorption during the filtration. The first
25 ml of the filtrate were discarded. The filtration was interrupted for 15 minutes to allow adsorption and saturation of the filter material with dissolved test item. Thereafter, the filtration was
continued. The next 25 ml were discarded. The following test item solution was used in the test. During filtration, the filter was always kept covered. The saturated solution was checked via laser beam
(Tyndall effect) for undissolved test item. The Tyndall effect was negative.

Test organisms (species):

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

Details on test organisms:

Test organism: Pseudokirchneriella subcapitata HINDAK, CCAP 278/4
Origin:
Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches Institut der Universität Göttingen, Göttingen, Germany

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Details on test conditions:

The study was performed as a static test in open vessels under culture conditions. The flasks contained 100 mL either reconstituted water or test medium (test item group).
The duration of exposure was 72 hours. The algal biomass in each flask was determined daily during the exposure period via Chlorophyll a-fluorescence excitation at 436, emission at 685 nm.
Microscopic evaluation of the cells at the start and at the end of the incubation period was carried out.

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

363 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.:

85 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.:

20 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

The EC50-values with confidence interval for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 363 (314 – 425) µg/L and 97.1 (74.5 - 128) µg/L.

1) Cell Densities

Initial measured test item concentration	Replicate	Cell density [cells/mL]
[µg/L]	No.	0 hours	24 hours	48 hours	72 hours
634	1	5416	7981	7882	6589
	2	5416	8059	9583	9159
	3	5416	7716	9004	9035
	Mean	5416	7919	8823	8261
207	1	5416	10815	49768	269641
	2	5416	10036	52475	290525
	3	5416	11791	64402	449855
	Mean	5416	10881	55548	336674
61.2	1	5416	12837	106695	833550
	2	5416	12966	99948	769536
	3	5416	17825	142192	1152210
	Mean	5416	14543	116278	918432
20.0	1	5416	17389	154752	1241805
	2	5416	19285	173717	1313900
	3	5416	17596	169219	1256166
	Mean	5416	18090	165896	1270624
6.34	1	5416	18859	170514	1399942
	2	5416	17391	122925	1096057
	3	5416	19470	169979	1330573
	Mean	5416	18573	154473	1275524
2.00	1	5416	19957	159951	1338386
	2	5416	18041	150370	1217076
	3	5416	21434	168402	1497108
	Mean	5416	19811	159574	1350857
Control	1	5416	19772	181613	1272936
	2	5416	23700	188341	1535784
	3	5416	20728	195049	1412526
	4	5416	22262	189168	1477903
	5	5416	20446	191223	1451762
	6	5416	19370	176112	1352187
	Mean	5416	21046	186918	1417183

2) Evaluation after 72 hours
Statistically significant differences of growth rates and yield compared to control values are marked (+), not significant differences are marked (-).

Initial measured test item concentration	Replicate	Growth Rate		Inhibition of Growth Rate	Yield		Inhibition of Yield
[µg/L]	No.	[d-1]		[%]	[cells/mL]		[%]
634	1		0.0653	96		1173	100
	2		0.175	91		3743	100
	3		0.171	91		3619	100
	Mean	(+)	0.137	93	(+)	2845	100
207	1		1.30	30		264225	81
	2		1.33	28		285109	80
	3		1.47	21		444439	69
	Mean	(+)	1.37	26	(+)	331258	77
61.2	1		1.68	10		828134	41
	2		1.65	11		764120	46
	3		1.79	4		1146794	19
	Mean	(+)	1.71	8	(+)	913016	35
20.0	1		1.81	2		1236389	12
	2		1.83	1		1308484	7
	3		1.82	2		1250750	11
	Mean	(-)	1.82	2	(-)	1265208	10
6.34	1		1.85	0		1394526	1
	2		1.77	5		1090641	23
	3		1.84	1		1325157	6
	Mean	(-)	1.82	2	(-)	1270108	10
2.00	1		1.84	1		1332970	6
	2		1.81	3		1211660	14
	3		1.87	-1		1491692	-6
	Mean	(-)	1.84	1	(-)	1345441	5
Control	1		1.82			1267520
	2		1.88			1530368
	3		1.86			1407110
	4		1.87			1472487
	5		1.86			1446346
	6		1.84			1346771
	Mean		1.86			1411767

3) Section-by-Section and Average Specific Growth Rates of the Control Group (0 - 72 hours)

	Replicate No.	Specific growth rate [d-1]			Mean (0 - 72 hours)	SD ±	CV [%]	Mean CV [%]
		section-by-section
		0 - 24 hours	24 - 48 hours	48 - 72 hours
Control	1	1.30	2.22	1.95	1.82	0.474	26.1	23.9
	2	1.48	2.07	2.10	1.88	0.352	18.7
	3	1.34	2.24	1.98	1.86	0.463	24.9
	4	1.41	2.14	2.06	1.87	0.397	21.2
	5	1.33	2.24	2.03	1.86	0.475	25.5
	6	1.27	2.21	2.04	1.84	0.497	27.0
				Mean	1.86
				SD ±	0.02
				CV [%]	1.21

4) Environmental Conditions

Initial measured test item concentration		pH-values
[µg/L]		Start; 0 hours	End; 72 hours
634		7.59	7.60
207		7.60	7.89
61.2		7.64	8.30
20.0		7.64	8.45
6.34		7.70	8.53
2.00		7.75	8.60
Control		8.11	8.71
Room temperature [°C]:	min.: 22.0	max.: 23.0	mean value: 22.5
Light intensity [lux]	n = 23	mean value: 5834 range of the measured values: 5143 to 6342 equalling -11.9 to 8.71%	CV [%]: 6.63%

5) Measured Concentration of the test material in the Definitive Test with Algae

Sampling date	Fresh Media, 0 hours	Old Media, 72 hours
Dilution of the saturated Solution [%]	Test Item
	Meas. conc. [mg/L]	Meas. conc. [mg/L]	%
100	0.634	0.625	99
31.6	0.207	0.175	85
10.0	0.0612	0.0564	92
3.16	< LOQ	0.0305	n.a.
1.00	< LOQ	< LOQ	n.a.
0.316	< LOQ	< LOQ	n.a.
Control	< LOQ	< LOQ
Meas. conc. = measured concentration of the test item, dilution factors taken into account % = percent of the initial measured concentration of the test item LOQ = limit of quantification (25 µg test item /L) n.a. = not applicable

Validity criteria fulfilled:

yes

Conclusions:

The EC50-values with confidence interval for inhibition of growth rate (ErC50) was 363 (314 – 425) µg/L. The EC10-values with confidence interval for inhibition of growth rate (ErC10) was 85.0 (57.7 – 113) µg/L.

Executive summary:

The information for this endpoint study record was obtained from an experimental study. The OECD GLP criteria were met and the methods applied are fully compliant with OECD TG 201. The EC50-values with confidence interval for inhibition of growth rate (ErC50) was 363 (314 – 425) µg/L. The EC10-values with confidence interval for inhibition of growth rate (ErC10) was 85.0 (57.7 – 113) µg/L.

Description of key information

The EC50-values with confidence interval for inhibition of growth rate (ErC50) was 363 (314 – 425) µg/L. The EC10-values with confidence interval for inhibition of growth rate (ErC10) was 85.0 (57.7 – 113) µg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

363 µg/L

EC10 or NOEC for freshwater algae:

85 µg/L