2-(4-Bromphenyl)-5-butyl-1,3-dioxane, trans-

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:

26.06.2018 - 21.09.2018

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

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 (see Table 2). 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):

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

Details on test organisms:

Test organism: PPseudokirchneriel/a 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

Test temperature:

22.0-23.0 °C

pH:

7.59 - 8.97

Nominal and measured concentrations:

The geometric mean measured test item concentrations were calculated to: 5.32 - 19.0 - 63.1 - 195 - 674 μg/L

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.
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.:

407 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

196 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

cell number

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

63.1 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.:

19 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Basis for effect:

cell number

Results with reference substance (positive control):

The toxicity of potassium dichromate (SIGMA ALDRICH, batch number MKBV0900V, purity 99.0%, GAS RN 7778-50-9) to the unicellular freshwater green alga Pseudokirchnerief/a subcapitata was determined over a period of 72 hours from 2018-03-26 to 2018-03-29. The reference item toxicity is in the valid range following test facility SOPs.
ErC50 = 1.09 mg/L, EyC50 = 0.548 mg/L

Reported statistics and error estimates:

The EC50-values for inhibition of growth rate (ErC50) and yield (EyC50) after 72 hours were 407 (264 - 600) μg/L and 196 (173 - 239) μg/L, respectively. The NOEC for growth rate and yield were 63.1 and 19.0 μg/L, respectively.

1) Cell Densities

Geometric mean measured test item concentration	Replicate	Cell density [cells/mL]
[µg/L]	No.	0 hours	24 hours	48 hours	72 hours
674	1	6442	7281	13515	21677
	2	6442	8751	14356	28477
	3	6442	7130	14915	29899
	Mean	6442	7721	14262	26684
195	1	6442	17598	89799	645368
	2	6442	17152	100315	649563
	3	6442	20399	108100	701671
	Mean	6442	18383	99405	665534
63.1	1	6442	24577	148118	1203409
	2	6442	19994	148317	1134743
	3	6442	19140	121595	1089363
	Mean	6442	21237	139343	1142505
19.0	1	6442	22107	155308	1300028
	2	6442	22553	141515	1153759
	3	6442	19902	143352	1126104
	Mean	6442	21521	146725	1193297
5.32	1	6442	21690	159548	1153660
	2	6442	23874	134514	1150085
	3	6442	24080	146371	1117167
	Mean	6442	23215	146811	1140304
Control	1	6442	22313	184998	1435622
	2	6442	20538	154722	1375149
	3	6442	22345	144256	1295560
	4	6442	21814	152418	1189954
	5	6442	22906	162983	1276047
	6	6442	22042	176746	1327087
	Mean	6442	21993	162687	1316570

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

Geometric mean measured test item concentration	Replicate	Growth Rate		Inhibition of Growth Rate	Yield		Inhibition of Yield
[µg/L]	No.	[d-1]		[%]	[cells/mL]		[%]
674	1		0.404	77		15235	99
	2		0.495	72		22035	98
	3		0.512	71		23457	98
	Mean	(+)	0.471	73	(+)	20242	98
195	1		1.54	13		638926	51
	2		1.54	13		643121	51
	3		1.56	12		695229	47
	Mean	(+)	1.55	13	(+)	659092	50
63.1	1		1.74	2		1196967	9
	2		1.72	3		1128301	14
	3		1.71	4		1082921	17
	Mean	(-)	1.73	3	(+)	1136063	13
19.0	1		1.77	0		1293586	1
	2		1.73	2		1147317	12
	3		1.72	3		1119662	15
	Mean	(-)	1.74	2	(-)	1186855	9
5.32	1		1.73	2		1147218	12
	2		1.73	3		1143643	13
	3		1.72	3		1110725	15
	Mean	(-)	1.73	3	(+)*	1133862	13
Control	1		1.80			1429180
	2		1.79			1368707
	3		1.77			1289118
	4		1.74			1183512
	5		1.76			1269605
	6		1.78			1320645
	Mean		1.77			1310128

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	1.24	2.12	2.05	1.80	0.486	27.0	27.0
	2	1.16	2.02	2.19	1.79	0.550	30.8
	3	1.24	1.87	2.20	1.77	0.483	27.3
	4	1.22	1.94	2.06	1.74	0.454	26.1
	5	1.27	1.96	2.06	1.76	0.431	24.4
	6	1.23	2.08	2.02	1.78	0.474	26.7
				Mean	1.77
				SD ±	0.02
				CV [%]	1.22

4) Environmental Conditions

Geometric mean measured test item concentration		pH-values
[µg/L]		Start; 0 hours	End; 72 hours
674		7.59	7.69
195		7.64	8.08
63.1		7.68	8.62
19.0		7.82	8.73
5.32		7.95	8.87
Control		8.15	8.97
Room temperature [°C]:	min.: 22.0	max.: 23.0		mean value: 22.5
Light intensity [lux]	n = 23	mean value: 6046 range of the measured values: 5348 to 6530 equalling -11.6 to 8.00%		CV [%]: 6.25%

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

Sampling date	Fresh Media, 0 hours	Old Media, 72 hours
Dilution level of the saturated solution [%]	Test material			Geometric mean measured concentration of the test item [µg/L]
	Meas. conc. [µg/L]	Meas. conc. [µg/L]	%
100	699	650	93	674
31.6	211	181	86	195
10.0	73.5	54.2	74	63.1
3.16	23.5	15.4	66	19.0
1.00	6.84	4.14	61	5.32
Control	< LOQ	< LOQ

Validity criteria fulfilled:

yes

Conclusions:

The 72 h EC50 for growth rate was 407 µg/L. The NOEC values for inhibition of growth rate after 72 h was 63.1 µg/L.

Executive summary:

The informtion 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 study was conducted under static conditions with an initial cell density of 6442 cells/mL. A saturated solution with a nominal loading of 100 mg/L was prepared with dilution water. Out of the saturated solution five concentration levels were tested in a geometrical series with a dilution factor of √10: 1.00 - 3-16 - 10.0 - 31.6 - 100 %, corresponding to the geometric mean measured test item concentration of: 5.32 – 19.0 – 63.1 – 195 – 674 µg/L.

Three replicates were tested for each test item concentration level and six replicates for the control. The environmental conditions were within the acceptable limits.

The initially measured concentrations of the test material were: 6.84 – 23.5 – 73.5 – 211 – 699 µg/L. At the end of exposure after 72 hours, the measured concentrations were in the range of 61 to 93% of the initially measured concentrations.

The 72 h EC50 for growth rate and yield were 407 and 196 µg/L. The NOEC values for inhibition of growth rate and yield after 72 h were 63.1 and 19 µg/L.

Description of key information

The 72 h EC50 for growth rate was 407 µg/L. The NOEC values for inhibition of growth rate  after 72 h was 63.1 µg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

407 µg/L

EC10 or NOEC for freshwater algae:

63.1 µg/L