Triethyl phosphonoacetate

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:

Between 16 december 2011 to 29 june 2012

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

Study conducted in compliance with international standard guidelines under GLP conditions. The study report was well documented with all mandatory information included.

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

2011-08-31

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0.1, 1.0, 10, 100 mg/L for the pretest and 100 mg/L for the definitive test
- Sampling method: Sampling of test preparation at 0h and 72h
- Sample storage conditions before analysis: -20°C

Vehicle:

no

Details on test solutions:

For the range finding test:
An amount of test item (50 mg) was dissolved in culture medium and the volume adjusted to 500 mL to give a 100 mg/L stock solution from which a series of dilutions was made to give further stock solution of 10, 1.0 and 0.1 mg/L. An aliquot (450 mL) of each of the stock solution was separately inoculated with Algal suspension(6.5 mL) to give the required test concentration of 0.1, 1.0, 10 and 100 mg/L.

For the definitive test:
The test item was dissolved directly in culture medium. An amount of test item was dissolved in culture medium and the volume adjusted to 1 litre to give a 100 mg/L stock solution. This stock solution was inoculated with algal suspension (14.6 mL) to give the required test concentration of 100 mg/L
The stock solution and the prepared concentration were inverted several times to ensure adequate mixing and homogeneity
The concentration and stability of the test item in the preparations were verified by chemical analysis at 0 and 72h

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: CCAP 278/4
- Source (laboratory, culture collection):Culture Collection of Algae and Protozoa (CCAP) , SAMS Research services Ltd, Scottish Marine Institute, Oban, Argyll, Scotland.
- Age of inoculum (at test initiation): No data
- Method of cultivation: Culture in culture medium under constant aeration and illumination at 21°C ± 1

ACCLIMATION
- Acclimation period: No data
- Culturing media and conditions (same as test or not): Yes

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

72 h

Post exposure observation period:

No

Hardness:

No data

Test temperature:

24°C ± 1 (throughout the test)

pH:

7.4 to 8.6 (measured at 0h and 72h) (See Cell densities and pH value in the definitive test)

Dissolved oxygen:

No data

Salinity:

Not applicable

Nominal and measured concentrations:

nominal : 100 mg/L. the recovery after 72h was 84% of the start concentration

Details on test conditions:

TEST SYSTEM
- Test vessel: glass conical flask
- Type (delete if not applicable): plugged with polyurethane foam bungs
- Material, size, headspace, fill volume: 250 mL filled at 100mL
- Aeration: No
- Initial cells density: 5x10e3/mL
- Control and cells density, No. of organisms per vessel: See figure 1
- No. of vessels per concentration (replicates): 6
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): 6

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: No measured using WTW PH 320 pH meter
- Photoperiod: light 24h/24h provided by warm white lighting (380-730 nm)
- Light intensity and quality: approximately 7000lux
- incubator: INFORS Multitron version 2 incubator

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: Coulter multisizer particle Counter


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 10
- Justification for using less concentrations than requested by guideline:
- Range finding study: yes
- Test concentrations: 0.1, 1, 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: In the pretest, no inhibition of the growth rate occurred

Reference substance (positive control):

yes

Remarks:

Potassium dichromate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

growth rate

Details on results:

In the valid pre-test study, four concentrations (Max 100 mg/L) of the test item were used. In this study, no inhibition on the growth of the Algal occurred.
The main study was performed likewise as a limit test using the concentration 100 mg/L. No inhibition occurred in the tested concentration.
At the beginning and the end of the test, the content of the test item in the test solutions was determined using a HPLC-MS.
The recovery after 72h was 84% of the start concentration, the determination of the biological results was based on the nominal concentration.

Results with reference substance (positive control):

- Results with reference substance were valid
ErC50(0 -72h): 1.4 mg/L, 95% confidence limits 1.2 -1.7 mg/L
EyC50(0 -72h): 0.59 mg/L, 95% confidence limits 0.53 -0.65 mg/L

Reported statistics and error estimates:

A student's t-test incorporating Bartlett's test for homogeneity of variance (Sokal and Rohlf 1981) was carried out on the growth rate and yield data after 72 hours for the control and the 100 mg/L test concentration to determine any statistically significant differences between the test and the control groups. All statistical analysis were performed using the SAS computer software package (SAS 1999-2001).

Cell densities and pH value in the definitive test

 

Nominal Concentration (mg/L)		pH	Cell densities * (Cell per mL)				pH
		0h	0h	24h	48h	72h	72h
control	R1	7.4	5.45 .10^3	1.89. 10^4	8.41. 10^4	5.97. 10^5	8.6
	R2		5.15 .10^3	2.07. 10^4	8.56. 10^4	4.14. 10^5
	R3		5.54 .10^3	2.25. 10^4	1.13. 10^5	5.72. 10^5
	R4		5.27 .10^3	1.94. 10^4	1.05. 10^5	4.76. 10^5
	R5		5.76 .10^3	2.43. 10^4	1.05. 10^5	5.47. 10^5
	R6		5.37 .10^3	2.16. 10^4	1.02. 10^5	4.92. 10^5
	Mean		5.42 .10^3	2.12. 10^4	9.91. 10^4	5.16. 10^5
100	R1	7.4	6.33 .10^3	2.17. 10^4	1.17. 10^5	4.56. 10^5	8.5
	R2		5.86 .10^3	2.28. 10^4	9.24. 10^4	4.64. 10^5
	R3		5.13 .10^3	1.86. 10^4	9.69. 10^4	5.69. 10^5
	R4		5.94 .10^3	2.49. 10^4	1.16. 10^5	6.20. 10^5
	R5		5.66 .10^3	1.94. 10^4	1.05. 10^5	3.88. 10^5
	R6		5.50 .10^3	2.50. 10^4	1.08. 10^5	4.75. 10^5
	Mean		5.74 .10^3	2.21. 10^4	1.06. 10^5	4.95. 10^5

 

* = Cell densities represent the mean number of cell per mL calculated from the mean of the cell counts from 3 counts for each of the replicate flasks

R1-R6 = Replicates 1 to 6

 

Daily specific Growth rates for the control Cultures in the Definitive Test

 

		Daily specific growth rate (cells/mL/hour)
		Day 0-1	Day 1-2	Day 2-3
control	R1	0.055	0.062	0.082
	R2	0.059	0.059	0.066
	R3	0.063	0.057	0.068
	R4	0.056	0.071	0.063
	R5	0.066	0.061	0.069
	R6	0.061	0.065	0.066
	Mean	0.060	0.064	0.069

R1-R6 = Replicates 1 to 6

 

Inhibition of growth rate and yield in the definitive test

 

Nominal Concentration (mg/L)		Growth Rate (cells/mL/hour)		Yield (Cells/mL)
		0-72h	% inhibition	0-72h	% inhibition*
control	R1	0.066	-	5.92	-
	R2	0.061		4.09
	R3	0.066		5.66
	R4	0.063		4.70
	R5	0.0652		5.42
	R6	0.064		4.87
	Mean	0.064		5.11
	SD	0.002		6.82
100	R1	0.063	2	4.50
	R2	0.063	2	4.58
	R3	0.066	[3]	5.64
	R4	0.067	[5]	6.14
	R5	0.060	6	3.82
	R6	0.063	2	4.70
	Mean	0.064	1	4.90	4
	SD	0.003		8.42

 

* = In accordance with the OECD test guideline only the mean value for yield is calculed

R1-R6 = Replicates 1 to 6

SD = Standard Deviation

[Increase in growth as compared to controls]

Validity criteria fulfilled:

yes

Conclusions:

From the different data, it is clear that the growth rate (r) and the yield (y) of Pseudokirchneriella subcapitata (CCAP 278/4) were not affected by the presence of the test item at a nominal concentration of 100 mg/L over 72-Hour exposure

Executive summary:

In a 72 hour acute toxicity study, cultures of Pseudokirchneriella subcapitata were exposed to TEPA at nominal concentrations of 100 mg/L under static conditions in accordance with the OECD 201.

The following results were determined:

NOEC = 100 mg/L

ErC50 (0 -72h) >100 mg/L

EyC50(0-72h) > 100 mg/L

In both studies (pre-test and main study), no inhibition on the growth of algae occurred. This toxicity study is considered as acceptable and satisfies the guideline requirements.

Description of key information

In a 72 hour acute toxicity study, cultures of Pseudikirchneriella subcapitata were exposed to TEPA at nominal concentrations of 100 mg/L under static conditions in accordance with the OECD guideline 201.

The following results were determined:

NOEC = 100 mg/L

ErC50(0 -72h) > 100 mg/L

EyC50(0-72h) > 100 mg/L

In the both study (pre-test and main study), no inhibition on the growth of algae occured. This toxicity study is classified as acceptable and satisfies the guideline requirements for toxicity study.

Key value for chemical safety assessment

EC50 for freshwater algae:

100 mg/L

EC10 or NOEC for freshwater algae:

100 mg/L