Glycerol monomyristate

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:

25 April - 19 May 2017

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Remarks:

Use of THF as test material carrier

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Version / remarks:

Adopted 23 March 2006

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

The Department of Health of the Government of the United Kingdom, London, UK

Analytical monitoring:

yes

Details on sampling:

- Concentrations: culture medium control, solvent control, 0.056, 0.1, 0.18, 0.32, 0.56 and 1.0 mg/L
- Sampling method: Samples were taken at 0 (test start), 24, 48 and 72 (test end) hours.

Vehicle:

yes

Remarks:

THF

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: A primary stock concentrate of the test item, with a nominal concentration of 10 g/L, was prepared by adding a nominal 0.1 g of test substance to 10 mL of tetrahydrofuran (THF). The stock solution was used to prepare the test solutions by the direct addition of the appropriate amount of concentrate to dilution water via a microliter syringe into a stirring solution in a volumetric flask. The solvent control was prepared in the same way using solvent only. The control consisted of culture medium only.
- Controls: culture medium control, solvent control
- Chemical name of vehicle: Tetrahydrofuran (THF)
- Concentration of vehicle in test medium: 100 μl/L in all exposure solutions (except blank control)

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Freshwater algae
- Source: laboratory cultures
- Age of inoculum (at test initiation): 3 days
- Method of cultivation: grown in medium under test condition

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Test temperature:

22 ± 2°C

pH:

range at test start: 6.99 - 7.33
range at test end: 8.18 - 8.42

Nominal and measured concentrations:

nominal: (control and solvent control), 0.056, 0.1, 0.18, 0.32, 0.56 and 1.0 mg/L
mean measured (0-72h): (control and solvent control), 0, 0, 0.067, 0.080, 0.14, 0.28 mg/L.
Where values were less than LOQ, 0 was used to calculate the mean.

Details on test conditions:

TEST SYSTEM
- Test vessel: glass conical flasks of 250 mL nominal capacity closed with foam bungs
- Type: closed
- Material, size, headspace, fill volume: each flask contained 100 mL of test solution
- Initial cells density: 0.5 × 10^4 cells/mL (nominal)
- Control end cells density: 53.65 (mean at 72 h)
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes, AAP medium

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Light intensity and quality: 5865 lux (± 15%)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 1.75 - 1.80
- Range finding study: yes, no results reported
- Results used to determine the conditions for the definitive study: yes

Reference substance (positive control):

no

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

> 0.28 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 0.28 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

0.14 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

- Exponential growth in the control (for algal test): yes

Reported statistics and error estimates:

The growth rates were examined by one-way analysis of variance and a two-sample t test to identify significant differences (p<0.05) between the control and solvent control. There was no significant effect (p=0.1208) between the control and solvent control. Therefore, the solvent control was compared to the treatments by one-way analysis of variance and Bonferroni adjusted t test to identify significant differences (p<0.05).

Table 1: Analytical Results

Nominal concentration of test item (mg/L)	Measured concentration of test item				Mean measured concentration (mg/L)	Mean measured concentration (%)
	0 hour		72 hour
	(mg/L)	% of nominal	(mg/L)	% of nominal
Control	<LOQ	-	<LOQ	-	-	-
Solvent Control	<LOQ	-	<LOQ	-	-	-
0.056	<LOQ	0	<LOQ	0	0	0
0.1	<LOQ	0	<LOQ	0	0	0
0.18	0.13	75	<LOQ	0	0.067	37
0.32	0.16	50	<LOQ	0	0.080	25
0.56	0.29^a	51	<LOQ^b	0	0.14	26
1.0	0.56	56	<LOQ	0	0.28	28

All measurements are quoted to 2 significant figures

a) Mean of triplicate analyses: 0.30, 0.29, 0.27 mg/L

b) Mean of triplicate analyses: 0, 0, 0 mg/L

The limit of quantification (LOQ) in the study was 0.1 mg/L. Where values were less than LOQ, 0 was used to calculate the mean.

Table 2: Algal cell particle density

Nominal concentration of test item (mg/L)	Mean measured concentration of test item (mg/L)	Replicate	Algal cell particle density (10^4cells/mL)
			24 hours	48 hours	72 hours
Culture medium control	-	A	2.32	10.80	50.90
		B	2.64	11.30	50.60
		C	2.49	11.10	57.00
		D	2.36	10.50	47.00
		E	2.58	10.60	51.30
		F	2.65	12.70	65.10
		Mean	2.51	11.17	53.65
Solvent control	-	A	2.11	11.00	48.70
		B	2.09	10.50	50.20
		C	2.23	10.70	56.00
		D	2.05	9.11	43.60
		E	2.14	10.20	50.50
		F	1.91	11.20	49.70
		Mean	2.09	10.45	49.78
0.056	0	A	1.93	10.50	39.80
		B	2.22	10.20	45.60
		C	2.18	10.40	45.60
		Mean	2.11	10.37	43.67
0.1	0	A	2.13	10.30	51.00
		B	2.14	10.10	43.70
		C	2.36	10.40	47.40
		Mean	2.21	10.27	47.37
0.18	0.067	A	2.01	9.94	47.90
		B	2.40	11.20	58.30
		C	2.16	9.97	46.90
		Mean	2.19	10.37	51.03
0.32	0.080	A	2.21	10.70	44.70
		B	2.44	10.50	49.60
		C	2.17	11.00	47.80
		Mean	2.27	10.73	47.37
0.56	0.14	A	1.99	10.40	50.10
		B	2.26	11.90	57.00
		C	2.75	11.70	57.60
		Mean	2.33	11.33	54.90
1.0	0.28	A	1.93	9.20	42.10
		B	2.12	9.34	38.10
		C	2.04	9.24	41.80
		Mean	2.03	9.26	40.67

Inoculum (Day 0) cell density = 0.578 x 104 cells/mL

All values are quoted to 2 decimal places

Table 3: Mean growth rates over the test period

Nominal concentration of the test item (mg/L)	Mean measured concentration of the test item (mg/L)	Mean growth rate/day (0-72 hours)	Mean growth rate/day 95% Cl	Percentage of solvent control (%)
Culture medium control	-	1.51	1.47-1.55	102
Solvent control	-	1.49	1.46-1.51	-
0.18	0.067	1.49	1.39-1.59	101
0.32	0.080	1.47	1.43-1.51	99
0.56	0.14	1.52	1.45-1.58	102
1.0	0.28	1.42*	1.37-1.46	95

* Significant difference (p <0.05) from the solvent control

All biological measurements are quoted to 3 significant figures and percentages to the nearest integer

Table 4: Mean yields over the test period

Nominal concentration of the test item (mg/L)	Mean measured concentration of the test item (mg/L)	Mean yield (0-72 hours) (10^4Cells/ml)	Percentage of solvent control (%)
Culture medium control	-	53	108
Solvent control	-	49	-
0.18	0.067	50	103
0.32	0.080	47	95
0.56	0.14	54	110
1.0	0.28	44	90

No significant differences (p <0.05) from the control

All measurements are quoted to 2 significant figures and percentages to the nearest integer

NOEyC(72 h): >= 0.28 mg/L, EyC10(72 h): 0.26 mg/L EyC50(72 h) >0.28 mg/L

Table: 5 Validity criteria for OECD 201.

Criterion from the guideline	Outcome	Validity criterion fulfilled
The biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72-hour test period.	factor 93 (control) factor 86 (sovent control)	yes
The mean coefficient of variation for section-by-section specific growth rates (days 0-1, 1-2 and 2-3, for 72-hour tests) in the control cultures must not exceed 35%	4.5% (control) 13% (sovent control)	yes
The coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 7% in tests with Pseudokirchneriella subcapitata and Desmodesmus subspicatus. For other less frequently tested species, the value should not exceed 10%.	2.6% (control) 1.8% (sovent control)	yes

 

Validity criteria fulfilled:

yes

Remarks:

see Table 5 at "Any other information on results incl. tables"

Description of key information

Aquatic algae:

ErC50 (72 h) >0.28 mg/L (meas. arith. mean)

ErC10 (72 h) was >0.28 mg/L (meas. arith. mean).

Additional information

The toxicity of the source substanceGlycerol monomyristate (CAS 27214-38-6) to aquatic algaewas tested according to OECD 203 under GLP conditions. The green algae Pseudokirchneriella subcapitata was exposed to nominal test substance concentrations of 0.056, 0.1, 0.18, 0.32, 0.56 and 1.0 mg/L. The test concentration was prepared using tetrahydrofuran (THF) as vehicle. The concentration of vehicle in test medium was 0.1 mL/L. The test substance concentration was analytically verified by HPLC with a detection limit of 0.1 mg/L. The mean measured test substance concentrations were 0, 0, 0.067, 0.080, 0.14, 0.28 mg/L. In case measured values were less than LOQ, 0 mg/L was used to calculate the mean.

Based on the algal growth rate an ErC50 (72 h) >0.28 mg/L (meas. arith. mean) was determined. The reported ErC10 (72 h) was >0.28 mg/L (meas. arith. mean).

The growth rate in the highest test concentration (0.28 mg/L, mean measured) was reduced by approx. 5% compared to the solvent control and thus a NOEC of 0.14 mg/L was reported. However, an effect below 10% is considered not relevant in algal growth tests. Thus according to the Guidance on the Application of the CLP Criteria (ECHA, 2017) preference is given to the EC10 for the assessment of the chronic aquatic toxicity of a substance.