Hexadecylamine

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

May 2002

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

yes

Remarks:

use of natural river water as dilution water; recovery not in the range of 80 - 120%, but based on nominal concentrations

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control, stock solution and highest concentration (2.5 mg/L) at beginning and end of test

Vehicle:

no

Details on test solutions:

A natural river water of agricultural background, middle reach of the river "Böhme", lower saxony was used as dilution water.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: SAG 86.81
- Source (laboratory, culture collection): Sammlung von Algenkulturen (SAG), Pflanzenphysiologisches Institut Universität Göttingen
- Age of inoculum (at test initiation): 3 day old preculture

Test type:

static

Water media type:

freshwater

Total exposure duration:

72 h

Post exposure observation period:

After 72h algae from the nominal dosage levels 0.6 - 2.5 mg/L were transferred to fresh untreated dilution water and allowed to grow for further 4-6 days

Test temperature:

21.8 - 23.2°C (mean 22.5°C)

pH:

8.0-8.2

Nominal and measured concentrations:

Nominal: 0.15, 0.3, 0.6, 1.3, 2.5 mg/L
Measured: x, x, x, x, 1.8 mg/L after 0h,

Details on test conditions:

TEST SYSTEM
- Test vessel material, size, headspace, fill volume: 250 mL Erlenmeyer flasks, 100mL test volume
- Initial cells density: 1x10^4 cells/mL
- Control end cells density: 1.5x10^5 cells/mL
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, Nutrient medium Z according to LUTTGE et al (1994)

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Natural river water of agricultural background (river Böhme, lower Saxony, Germany)
- Total organic carbon: DOC: 7.3 mg C/L
- Suspended matter: 17.4 mg/L (mean of 2 measurements)
- Conductivity: 397 µS/cm
- Culture medium different from test medium: yes
- Intervals of water quality measurement: at 0, 72 hours

OTHER TEST CONDITIONS
- Sterile test conditions: no, but river water was stored at -18 +/- 2°C until use. Freezing was found to be suitable to minimize the content of vital natural alge cells of the water as well as to reduce microbial (bacterial) activity.
- Adjustment of pH: no
- Photoperiod: 24 h
- Light intensity and quality: 90.3-116.4 µE/m²*s (mean 101.3 µE/m²*s)

EFFECT PARAMETERS MEASURED
growth rate inhibition, inhibition of biomass growth
- Determination of cell concentrations: via Chlorophyll-a-fluorescence, excitation at 435 nm, emission at 685 nm (Chlorophyll-impulsfluorometer)

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2
- Range finding study
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 0.44-0.49

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.15 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks on result:

other: 95% CL: 0.36-0.39

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.15 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

- Exponential growth in the control: yes
- Post exposure observations: The test item effect was observed to be reversible at the concentration levels observed (0.6 - 2.5 mg/L) within 4 - 6 days.
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: Substance is known to adsorb to glassware and organic material. Measured concentrations for highest test concentration showed a clear decrease of test substance during the test duration.

Results with reference substance (positive control):

Experimental date: 27 to 30 Nov 2001
ErC50 0.94 mg/L; 95% CL: 0.82-1.07 mg/L

Reported statistics and error estimates:

The NOEC was determined carrying out an ANOVA and a Bonferroni t-test.
The EC50 values and confidence intervals were calculated by probit analysis.

The Substance is known to adsorb to glassware and organic material. Nevertheless actual concentrations were only measured in the highest concentration (2.5 mg/L) and the control. Already at the beginning only 72% of the nominal concentration was recovered for the highest concentration and after 72 hours the recovery could not be determined as the concentration present in sample was below the LOQ (Tab. 1). Due to the deepfreezing of the river water before test start a microbial degradation of the test substance is unlikely and the decrease of the test substance in the test solutions can probably be explained with the adsorption of the test substance to particulate matter, humic acids and the surface of the test vessels.

As the actual concentrations are not within the range of +/- 20% analysis of the nominal concentrations, the results should be based on the geometric mean concentration during exposure. As these values are not available no reliable EC values can be derived from this study.

Table 1: Concentrations of Octadec-9-enylamine in stock solution and highest test solution

Sampling date	2002-06-03 new medium			2002-06-06 old medium
Start of analysis	2002-06-03			2002-06-06
Nominal conc [mg/L]	mean measured conc [mg/L]	RR		mean measured conc [mg/L]	RR
20	16.7	84		9.6	48
2.5	1.8	72		< LOQ
Control	< LOQ			< LOQ

RR = recovery rate

Table 2: Statistically significant differences of biomass integrals and growth rates compared to control values are marked (+), not significant differences are marked (-) (DUNNETT'S test).

Test item [mg/L] Nominal	RE No.	Biomass integral	Inhibition of biomass [%]	Growth rate	Rate-related inhibition [%]
2.5	1	-14138	100.00	-0.42	100.00
	2	-13495	100.00	-0.44	100.00
	3	-12311	100.00	-0.43	100.00
	Mean	(+) -13315	100.00	(+) -0.43	100.00
1.3	1	-9214	100.00	-0.42	100.00
	2	-7639	100.00	-0.18	100.00
	3	-6768	100.00	-0.19	100.00
	Mean	(+) -7873	100.00	(+) -0.25	100.00
0.6	1	13025	92.27	0.39	58.60
	2	21255	87.38	0.50	47.01
	3	11886	92.94	0.39	58.08
	Mean	(+) 15390	90.86	(+) 0.43	54.16
0.3	1	89033	47.13	0.80	15.25
	2	72257	57.09	0.71	23.85
	3	115092	31.66	0.87	7.06
	Mean	(+) 92125	45.29	(+) 0.80	14.78
0.15	1	226526	-34.52	1.02	-8.25
	2	197780	-17.45	0.99	-5.98
	3	238625	-41.7	1.04	-11.12
	Mean	(-) 220977	-31.22	(-) 1.02	-8.51
Control	1	157456		0.97
	2	149711		0.91
	3	152776		0.92
	4	180587		0.91
	5	179204		0.96
	6	190870		0.96
	Mean	168399		0.94

RE= Replicate

Validity criteria fulfilled:

yes

Conclusions:

In this study the test item was found to inhibit the growth of the freshwater green alga Desmodesmus subspicatus. The EC50 values with 95 % confidence intervals for inhibition of biomass growth (EbC50) and specific growth rate (ErC50) after 72h were 0.38 (0.36 - 0.39) and 0.46 (0.44 - 0.49) mg/L, respectively.

Executive summary:

The toxicity of the test item to the unicellular freshwater green alga Desmodesmus subspicatus was determined according to the principles of OECD-Guideline 201 (1984) for the determination of the NOEC and EC of growth rate and biomass production over a period of 72 h. Natural water from the river “Böhme“ was used as test medium. The chosen water originated from a predominantly agricultural region. From a limnological point of view this sampling site represents typical conditions for a river of this classification (middle reach). The river water enabled the increase of cell density more than 16-fold when incubated for 72 h. The study was conducted under static conditions with an initial cell density of 10^4 cells/mL. 5 concentration levels were tested in a geometrical series with a dilution factor of 2: 0.15 - 0.3 - 0.6 – 1.3 -2.5 mg/L. Three replicates were tested for each concentration level and 6 replicates for control. The test item was clearly dissolved throughout the test. Microscopic evaluation of the cells at the start of the incubation period revealed no morphological abnormalities. Water quality parameters of pH value, measured at 0 and 72 h, and room temperature, measured continuously, were determined to be within the acceptable limits. The highest tested concentration, the stock solution and the control were analytically verified via GC/MS analysis. The test item concentration had decreased at the end of the test. Biotic degradation of the test item is not regarded to be the reason for the decrease of the test item concentration. The natural river water used for the preparation of the test media has been frozen for at least 14 days to reduce microbial activity. Therefore a biological degradation of the test item seems to be unlikely. The most probable reason for the decrease or incomplete recovery of test item concentrations during the test is adsorption on particulate matter and humic acids. The results are therefore based on nominal concentrations representing the total exposure concentration (dissolved and adsorbed). The variation in the recovery rates are most likely caused by small differences in the concentration of suspended matter. The results of the study showed a clear dose response relationship with respect to the rate related inhibition and the inhibition of biomass growth. Therefore it can be suggested that the test item concentrations in the lower dosage levels met the nominal values when being prepared freshly.

All effect levels are given based on nominal concentrations. The EC50 values with 95 % confidence intervals for inhibition of biomass growth (EbC50) and specific growth rate (ErC50) after 72h were 0.38 (0.36 - 0.39) and 0.46 (0.44 - 0.49) mg/L, respectively. The NOEC and LOEC were 0.15 and 0.3 mg/L, respectively for both growth rate and biomass. After 72 h algae were transferred from the nominal dosage levels 0.6 – 2.5 mg/L to fresh untreated medium and allowed to grow for further 4 to 6 d under test conditions. The test item effect was observed to be reversible at these concentration levels.

Reference 2

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

March - May 2002

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Principles of method if other than guideline:

River water was used, results are basen on nominal values.

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Separate replicates for the test item analysis after 0 and 72 h were prepared (test beginning provided without alga and test end with same density of alga as the test replicates) and incubated under test conditions.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: stock solution (20 mg/L) was prepared with natural river water. Dispersion carried out with: 30 min ultrasound at 40 °C

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name: Green algae
- Strain: Desmodesmus subspicatus CHODAT SAG 86.81
- Source: The algae culture was optained from the Institut of plant physiology, University of Göttingen, Germany;
- Method of cultivation: Fresh stock solutions were prepared every month on Z-agar. Light intensity amounted 35-70 µE/m²

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

After 72 h algae were transferred from concentration levels to untreated dilution water and allowed for growth for a period of 4 -6 d to determine whether the effects of the item is reversible.

Hardness:

91.3 mg CO3/L

Test temperature:

23 ± 2 °C

pH:

8.06 - 8.23

Nominal and measured concentrations:

Nominal concentrations: control, 0.125, 0.25, 0.5, 1, 2 and 4 mg/L
Measured concentrations: x, x, x, x, x, 2.9 mg/L after 0h, 0.9 after 72h (x=not measured)

Details on test conditions:

TEST SYSTEM
- Test vessel material, size, fill volume: 250 mL-Erlenmayer-flasks with 100 mL test volume
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6

GROWTH MEDIUM
- Standard medium used: Yes

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: A natural river water of agricultural backround, middle reach of the river "Böhme", Lower-Saxony was used.
Test water parameter:
pH: 8.2
Conductivity [μS/cm]: 397
DOC [mg C/L]: 7.3
TOC [mg C/L]: 9.9
Ammonium-N [mg N/L]: 0.141
Nitrate-N [mg N/L]: 2.38
o-Phosphate-P [mg P/L]: 0.031
Total Phosphate [mg P/L]: 0.128
Suspended Matter [mg/L]: 17.4
Total Hardness [mg CO3/L]: 91.3
- Culture medium different from test medium: yes
- Intervals of water quality measurement: cell density was measured every 24 hours. Temperature was measured permanently and the pH value was determinated at the beginning and the end of the test.

OTHER TEST CONDITIONS
- Photoperiod: Permanent illumination (24h)
- Light intensity and quality: 60-120 µE/m²*s

EFFECT PARAMETERS MEASURED
- Determination of cell concentrations: fluorimeter and microscopic evaluation

Reference substance (positive control):

yes

Remarks:

potassium dicromate

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.39 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.125 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.31 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.125 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Details on results:

After 72 h algae from the nominal dosage levels 0.5 - 4 mg/L were transferred to fresh untreated dilution water according OECD 201 and allowed to grow for further 4 - 6 d under test conditions. The test item effect was observed to be reversible at these concentration levels within 4 - 6 d.

Results with reference substance (positive control):

The acute toxicity of potassium dichromate to the unicellular freshwater green alga Desmodesmus subspicatus was determined over a period of 72 h from November 27 to 30, 2001. The EC50 (biomass) was calculated to be 0.49 mg/L, the EC50 (growth) was calculated to be 0.94 mg/L. The EC50 - values of the reference item potassium dichromate after 72 h met the validity criteria according to EEC Directive 92/69/EEC Method C.3 Annex 2 (prescribed ranges are 0.20 - 0.75 mg/L and 0.60 - 1.03 mg/L potassium dichromate for inhibition of biomass growth and rate-related inhibition, respectively).

Reported statistics and error estimates:

The No Observed Concentration Level (NOEC) is the highest tested concentration where no effects were observed. One Way Analysis of Variance (ANOVA) and the DUNNETT'S test were carried out for the determination of statistically significant differences compared to control replicates. When running a One Way Analysis of Variance a Normality Test and an Equal Variance Test were done first. P-values for both Normality and Equal Variance Tests were 0.05. The a-value for ANOVA and DUNNETT'S test was a=0.05. EC50 values and confidence intervals after 72 h were calculated by probit analysis. Probit values were taken from WEBER (1986). Confidence intervals were calculated according to a standard procedure (BREITIG & TOMPLING 1982). The data for the tables in this report were computer generated and have been rounded for presentation from the full derived data. Consequently if calculated manually based on the given data minor variations may occur from these figures. Calculations were carried out using software
- SigmaPlot rel. 2000 (2000), SPSS INC.
- SigmaStat rel. 2.03 (1992-1997), SPSS INC.
- Excel rel. 2000 (2000), MICROSOFT CORPORATION

Table 1: Concentration of the test item:

Nominal test item conc. [mg/L]	Calc. conc. [mg/L] after 0 h	Calc. conc. [mg/L] after 3 d
20.00	19.2	11.9
4.00	2.9	0.9
Control	< detection limit	< detection limit

Table 2: Statistically significant differences of biomass integrals and growth rates compared to control values are marked (+), not significant differences are marked (-) (DUNNETT'S test).

Test item [mg/L] nominal	RE. No.	Biomass integral	inhibition of biomass[%]	Growth rate	Rate-related inhibition[%]
4	1	-16746	100.00	-0.41	100.00
	2	-14496	100.00	-0.40	100.00
	3	-15575	100.00	-0.40	100.00
	Mean	(+) -15606	100.00	(+) -0.40	100.00
2	1	-15282	100.00	-0.43	100.00
	2	-15414	100.00	-0.35	100.00
	3	-16607	100.00	-0.43	100.00
	Mean	(+) -15768	100.00	(+) -0.40	100.00
1	1	-12861	100.00	-0.25	100.00
	2	-11066	100.00	-0.23	100.00
	3	-16014	100.00	-0.31	100.00
	Mean	(+) -13314	100.00	(+) -0.26	100.00
0.5	1	8760	94.80	0.37	61.06
	2	6005	96.43	0.34	63.90
	3	19703	88.30	0.51	45.19
	Mean	(+) 11490	93.18	(+) 0.42	55.73
0.25	1	74586	55.71	0.78	16.68
	2	101667	39.63	0.84	10.75
	3	106267	36.90	0.90	4.54
	Mean	(+) 94173	44.08	(+) 0.84	10.41
0.125	1	176084	-4.56	0.92	1.68
	2	188615	-12.00	0.98	-4.29
	3	192221	-14.15	0.94	-0.47
	Mean	(-) 185639	-10.24	(-) 0.95	-1.17
Control	1	157456		0.97
	2	149711		0.91
	3	152776		0.92
	4	180587		0.91
	5	179204		0.96
	6	190670		0.96
	Mean	168399		0.94

Validity criteria fulfilled:

yes

Conclusions:

In this study the test item was found to inhibit the growth of the freshwater green alga Desmodesmus subspicatus. The EC50 values with 95 % confidence intervals for inhibition of biomass growth (EbC50) and specific growth rate (ErC50) after 72h were 0.31 (0.30 - 0.32) and 0.39 (0.38 - 0.41) mg/L, respectively.

Executive summary:

The toxicity of the test item to the unicellular freshwater green alga Desmodesmus subspicatus was determined according to the principles of OECD-Guideline 201 (1984) for the determination of the NOEC and EC of growth rate and biomass production over a period of 72 h. Natural water from the river “Böhme“ was used as test medium. The chosen water originated from a predominantly agricultural region. From a limnological point of view this sampling site represents typical conditions for a river of this classification (middle reach). The river water enabled the increase of cell density more than 16-fold when incubated for 72 h. The study was conducted under static conditions with an initial cell density of 10^4 cells/mL. 6 concentration levels were tested in a geometrical series with a dilution factor of 2: 0.125 - 0.25 - 0.5 - 1 -2-4 mg/L. Three replicates were tested for each concentration level and 6 replicates for control. The test item was clearly dissolved throughout the test. Microscopic evaluation of the cells at the start of the incubation period revealed no morphological abnormalities. Water quality parameters of pH value, measured at 0 and 72 h, and room temperature, measured continuously, were determined to be within the acceptable limits. The highest tested concentration, the stock solution and the control were analytically verified via GC/MS analysis. The test item concentration had decreased at the end of the test. Biotic degradation of the test item is not regarded to be the reason for the decrease of the test item concentration. The natural river water used for the preparation of the test media has been frozen for at least 14 days to reduce microbial activity. Therefore a biological degradation of the test item seems to be unlikely. The most probable reason for the decrease or incomplete recovery of test item concentrations during the test is adsorption on particulate matter and humic acids. The results are therefore based on nominal concentrations representing the total exposure concentration (dissolved and adsorbed). The variation in the recovery rates are most likely caused by small differences in the concentration of suspended matter. The results of the study showed a clear dose response relationship with respect to the rate related inhibition and the inhibition of biomass growth. Therefore it can be suggested that the test item concentrations in the lower dosage levels met the nominal values when being prepared freshly. All effect levels are given based on nominal concentrations. The EC50 values with 95 % confidence intervals for inhibition of biomass growth (EbC50) and specific growth rate (ErC50) after 72h were 0.31 (0.30 - 0.32) and 0.39 (0.38 - 0.41) mg/L, respectively. The NOEC and LOEC were 0.125 and 0.25 mg/L, respectively for both growth rate and biomass. After 72 h algae were transferred from the nominal dosage levels 0.5 - 4 mg/L to fresh untreated medium and allowed to grow for further 4 to 6 d under test conditions. The test item effect was observed to be reversible at these concentration levels.

Reference 3

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

key study

Justification for type of information:

Please refer to Chapter 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.46 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 0.44 - 0.49

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.15 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.38 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.15 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Reference 4

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

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

Adequacy of study:

weight of evidence

Justification for type of information:

Please refer to Chapter 13.

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.39 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

0.31 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

0.25 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Key result

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.125 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.125 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

biomass

Description of key information

No study with the test item is available. Two tests with the read-across substances number 3 and number 1 according to OECD 201 were used for the Weight-of-Evidence approach, with EC50 values of 0.46 and 0.39 mg/L and NOEC values of 0.15 and 0.125 mg/L (reference 6.1.5 -1 and reference 6.1.5 -2). The mean values are EC50=0.425 mg/L and NOEC=0.1375 mg/L.

Key value for chemical safety assessment

EC50 for freshwater algae:

0.425 mg/L

EC10 or NOEC for freshwater algae:

0.138 mg/L

Additional information

No study with the target substance is available. Details on the two studies with source substances, which were used for the weight-of-evidence approach, are presented below:

The toxicity of the third read across substance to the unicellular freshwater green alga Desmodesmus subspicatus was determined according to the principles of OECD-Guideline 201 (1984) for the determination of the NOEC and EC of growth rate and biomass production over a period of 72 h. Natural water from the river “Böhme“ was used as test medium. The chosen water originated from a predominantly agricultural region. From a limnological point of view this sampling site represents typical conditions for a river of this classification (middle reach). The river water enabled the increase of cell density more than 16-fold when incubated for 72 h. The study was conducted under static conditions with an initial cell density of 10^4 cells/mL. 5 concentration levels were tested in a geometrical series with a dilution factor of 2: 0.15 - 0.3 - 0.6 – 1.3 -2.5 mg/L. Three replicates were tested for each concentration level and 6 replicates for control. The test item was clearly dissolved throughout the test. Microscopic evaluation of the cells at the start of the incubation period revealed no morphological abnormalities. Water quality parameters of pH value, measured at 0 and 72 h, and room temperature, measured continuously, were determined to be within the acceptable limits. The highest tested concentration, the stock solution and the control were analytically verified via GC/MS analysis. The test item concentration had decreased at the end of the test. Biotic degradation of the test item is not regarded to be the reason for the decrease of the test item concentration. The natural river water used for the preparation of the test media has been frozen for at least 14 days to reduce microbial activity. Therefore a biological degradation of the test item seems to be unlikely. The most probable reason for the decrease or incomplete recovery of test item concentrations during the test is adsorption on particulate matter and humic acids. The results are therefore based on nominal concentrations representing the total exposure concentration (dissolved and adsorbed). The variation in the recovery rates are most likely caused by small differences in the concentration of suspended matter. The results of the study showed a clear dose response relationship with respect to the rate related inhibition and the inhibition of biomass growth. Therefore it can be suggested that the test item concentrations in the lower dosage levels met the nominal values when being prepared freshly. All effect levels are given based on nominal concentrations. The EC50 value after 72h with 95% confidence interval for inhibition of biomass growth (EbC50) was measured to be 0.38 (0.36 - 0.39), the EC50 value for specific growth rate (ErC50) was measured to be 0.46 (0.44 - 0.49) mg/L.The NOEC and LOEC were 0.15 and 0.3 mg/L, respectively for both growth rate and biomass. After 72 h algae were transferred from the nominal dosage levels 0.6 – 2.5 mg/L to fresh untreated medium and allowed to grow for further 4 to 6 d under test conditions. The test item effect was observed to be reversible at these concentration levels.

 

In a second test the toxicity of the first source substance to the unicellular freshwater green alga Desmodesmus subspicatus was determined according to the principles of OECD-Guideline 201 (1984) for the determination of the NOEC and EC of growth rate and biomass production over a period of 72 h. Natural water from the river “Böhme“ was used as test medium. The chosen water originated from a predominantly agricultural region. From a limnological point of view this sampling site represents typical conditions for a river of this classification (middle reach). The river water enabled the increase of cell density more than 16-fold when incubated for 72 h. The study was conducted under static conditions with an initial cell density of 10^4 cells/mL. 6 concentration levels were tested in a geometrical series with a dilution factor of 2: 0.125 - 0.25 - 0.5 - 1 -2-4 mg/L. Three replicates were tested for each concentration level and 6 replicates for control. The test item was clearly dissolved throughout the test. Microscopic evaluation of the cells at the start of the incubation period revealed no morphological abnormalities. Water quality parameters of pH value, measured at 0 and 72 h, and room temperature, measured continuously, were determined to be within the acceptable limits. The highest tested concentration, the stock solution and the control were analytically verified via GC/MS analysis. The test item concentration had decreased at the end of the test. Biotic degradation of the test item is not regarded to be the reason for the decrease of the test item concentration. The natural river water used for the preparation of the test media has been frozen for at least 14 days to reduce microbial activity. Therefore a biological degradation of the test item seems to be unlikely. The most probable reason for the decrease or incomplete recovery of test item concentrations during the test is adsorption on particulate matter and humic acids. The results are therefore based on nominal concentrations representing the total exposure concentration (dissolved and adsorbed). The variation in the recovery rates are most likely caused by small differences in the concentration of suspended matter. The results of the study showed a clear dose response relationship with respect to the rate related inhibition and the inhibition of biomass growth. Therefore it can be suggested that the test item concentrations in the lower dosage levels met the nominal values when being prepared freshly. All effect levels are given based on nominal concentrations. The EC50 value after 72h with 95% confidence interval for inhibition of biomass growth (EbC50) was measured to be 0.31 (0.30 - 0.32), the EC50 value for specific growth rate (ErC50) was measured to be 0.39 (0.38 - 0.41) mg/L. The NOEC and LOEC were 0.125 and 0.25 mg/L, respectively for both growth rate and biomass. After 72 h algae were transferred from the nominal dosage levels 0.5 - 4 mg/L to fresh untreated medium and allowed to grow for further 4 to 6 d under test conditions. The test item effect was observed to be reversible at these concentration levels.

The mean effect concentration of both tests are EC50=0.425 mg/L and NOEC=0.1375 mg/L.