Triethyl phosphonoacetate

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 2016-05-31 to 2017-03-13

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 211 (Daphnia magna Reproduction Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Single samples for analysis were taken from all test concentrations and the control.

Sampling: Frequency At the beginning and at the end of three intervals of 48 hours (nominal days 2 and 4, 8 and 10, 14 and 16).
Volume 3.0 mL
Storage Samples were stored in a freezer (≤15°C) until analysis.

At the end of the refreshment period, the replicates were pooled at each concentration before sampling.
Additionally, reserve samples of 3.0 mL were taken from all test solutions for possible analysis.
If not already used, these samples were stored in a freezer (≤15°C) for a maximum of three months after delivery of the draft report, pending on the decision of the sponsor for additional analysis.

Vehicle:

yes

Remarks:

medium

Details on test solutions:

The batch of TRIETHYL PHOSPHONOACETATE tested was a colourless liquid with a purity of 99.3% (area) and the item was completely soluble in test medium at the concentrations tested. No correction was made for the purity/composition of the test substance.

Preparation of test solutions started with a stock solution of 100 mg/L (range-finding test) or the highest test concentration of 4.6 mg/L (final test). No special treatment other than a magnetic stirring period of approximately 15 minutes was needed to completely dissolve the test item in test medium. The lower test concentrations were prepared by subsequent dilutions of the stock or highest test concentration in test medium. All final test solutions were clear and colourless.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna (Crustacea, Cladocera) (Straus, 1820), at least third generation, obtained by a cyclical parthenogenesis under specified breeding conditions.
- Source: In-house laboratory culture with a known history.
- Age of parental stock (mean and range, SD): To initiate the test, young daphnids < 24 hours old were selected, from parental daphnids greater than two weeks old.
- Feeding during test: Daily, a suspension of fresh water algae

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

from 196 to 214 mg/L expressed as CaCO3

Test temperature:

19.5 to 20.8°C

pH:

7.6 to 8.3

Dissolved oxygen:

7.8 mg/L to 10.1 mg/L

Salinity:

not applicable, fresh water

Nominal and measured concentrations:

nominal: 0.22, 0.46, 1.0, 2.2 and 4.6 mg/L
Measured: 0.16, 0.38, 0.93, 1.7 and 3.6 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: Volume: 60 ml (6 x Ø 3.5 cm), all-glass covered with a Perspex plate.
- Aeration: No
- Renewal rate of test solution (frequency/flow rate):
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per vehicle control (replicates): 20
- Biomass loading rate: Twice daily an amount of 0.25 ml of a Chlorella sp. suspension . On weekend days an amount of 0.50 ml was added in one single feed. This daily ration corresponded to 0.2 mg C/Daphnia/day, which is the recommended value for daily feeding per daphnid in the reproduction test according to the OECD Guideline 211.

TEST MEDIUM / WATER PARAMETERS
M7 medium

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16h photoperiod daily
- Light intensity: intensity at the start: 608-831 lux, intensity at the end: 679-782 lux


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Reproduction, mortality & growth

TEST CONCENTRATIONS
- Range finding study: yes
- Test concentrations: 0.10, 1.0 and 10 mg/L
- Results used to determine the conditions for the definitive study: No significant mortality was observed in the control and the two lowest test concentrations, while all daphnids exposed to the highest test concentration of 10 mg/L died within 3 days of exposure. The first recordings of the presence of eggs in the brood pouch and the first offspring were similar to the control in the two lowest test concentrations. The total numbers of offspring produced were also comparable between the control and the two lowest test groups.

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

3.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

3.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

3.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

> 3.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

> 3.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

mortality

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

> 3.6 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth

Concentrations of the test item in test medium - final test

 

Time of sampling [days]	Date of sampling	Date of analysis^1	Concentration [mg/L]		Relative to nominal [%]	Relative to initial [%]
			Nominal	Analysed
2 (fresh)	01-Sep-2016	13-Sep-2016	0	n.d.^2	n.a.
			0.22	0.182	83
			0.46	0.374	81
			1.0	0.910	91
			2.2	1.85	84
			4.6	4.05	88
4 (old)	03-Sep-2016	13-Sep-2016	0	n.d. 2	n.a.	n.a.
			0.22	0.156	71	85
			0.46	0.347	76	93
			1.0	0.875	87	96
			2.2	1.80	82	97
			4.6	3.63	79	89
8 (fresh)	07-Sep-2016	13-Sep-2016	0	0.018^3	n.a.
			0.22	0.177	81
			0.46	0.369	80
			1.0	0.960	96
			2.2	1.89	86
			4.6	4.01	87
10 (old)	09-Sep-2016	13-Sep-2016	0	0.018^3	n.a.	n.a.
			0.22	0.172	78	97
			0.46	0.381	83	103
			1.0	0.795	79	83
			2.2	1.73	79	92
			4.6	3.73	81	93
14 (fresh)	13-Sep-2016	26-Sep-2016	0	n.d.	n.a.
			0.22	0.134	61
			0.46	0.362	79
			1.0	0.990	99
			2.2	1.58	72
			4.6	3.10	67
16 (old)	15-Sep-2016	26-Sep-2016	0	n.d.	n.a.	n.a.
			0.22	0.128	58	96
			0.46	0.439	95	121
			1.0	1.04	104	105
			2.2	1.46	66	92
			4.6	3.19	69	103

¹     Samples were stored in the freezer (≤ -15°C) until the day of analysis.

²     Result of re-analysis, because first results were not reliable due to carry-over.

³     Estimated value, calculated by extrapolation of the calibration curve. This is probably caused by carry over since a similar response was observed in the analytical blank.

n.d.Not detected.

n.a.Not applicable.

Mortality (immobility) of parental daphnids at the end of the test 

TRIETHYL PHOSPHONOACETATE Average conc. (mg/L)	Introduced	Mobile	Immobile	% Immobility
Control	20	18	2	10
0.16	10	10	0	0
0.38	10	10	0	0
0.93	10	9	1	10
1.7	10	9	1	10
3.6	10	9	1	10

 

Age at first reproduction (day) 

TRIETHYL PHOSPHONOACETATE Average conc. (mg/L)	Mean	Median	Min	Max	n
Control	9.2	9.5	8.5	12.5	19
0.16	8.8	8.5	8.5	9.5	10
0.38	8.8	8.5	8.5	10.5	10
0.93	8.9	8.5	8.5	10.5	10
1.7	8.7	8.5	8.5	10.5	10
3.6	8.7	8.5	7.5	9.5	9

Min –minimum value, Max – maximum value

 

Group mean cumulative number of juveniles per surviving parent and reduction of reproduction at the end of the test 

TRIETHYL PHOSPHONOACETATE Average conc. (mg/L)	Mean	Std. Dev.	n	%Reduction
Control	135.3	15.07	18
0.16	134.0	25.67	10	0.9
0.38	134.4	14.92	10	0.6
0.93	133.3	12.48	9	1.4
1.7	129.9	15.18	9	4.0
3.6	124.9	13.32	9	7.7

Incidence of immobilised offspring and aborted eggs 

Abnormality	TRIETHYL PHOSPHONOACETATE, Average conc. (mg/L)
	Control	0.16	0.38	0.93	1.7	3.6
Immobile offspring	3	2	2	2	2	3
Aborted eggs	50	30	44	30	31	8

n.o. – not observed

Group mean body lengths (mm) and reduction of growth of parental daphnids at the end of the test. 

TRIETHYL PHOSPHONOACETATEAverage conc. (mg/L)	Mean (mm)	Std. Dev.	n	%Reduction
Control	4.83	0.481	18
0.16	5.10	0.169	10	-5.5
0.38	5.20	0.226	10	-7.6
0.93	5.32	0.107	9	-10.2
1.7	5.21	0.176	9	-7.8
3.6	5.07	0.286	9	-4.9

 

Validity criteria fulfilled:

yes

Conclusions:

Under the conditions of the present study TRIETHYL PHOSPHONOACETATE did not affect survival, growth or reproduction of Daphnia magna at an average measured concentration of 3.6 mg/L after 21 days of exposure (NOEC).

Executive summary:

This study was designed to determine the chronic toxicity of triethylphosphonoacetate to Daphnia magna, according to the OECD 211 guideline and under GLP conditions. Exposure was conducted under semi-static conditions for 21 days.

Parental daphnids were exposed to triethylphosphonoacetate concentrations of 0.16, 0.38, 0.93, 1.7 and 3.6 mg/L and to a control treatment. The number of living adults and offsprings were counted daily. At the end of the test period, a maximum of 10% adults died. The reproduction rates are not significantly different from that of the blank control. The 21-day NOECs on Daphnia magna were equal to 3.6 mg/L based on survival and to 3.6 mg/L based on reproduction; showing that triethylphosphonoacetate is not harmful to aquatic invertebrates with long-lasting effects.

Description of key information

The 21-day chronic toxicity of TEPA to Daphnia magna was studied under semi-static conditions according to OECD guideline 211.  Daphnids were exposed to control and test chemical at measured concentration of 0.16, 0.38, 0.93, 1.7 and 3.6 mg/L for 21 days.

The 21-day NOEC for reproduction was 3.6 mg/L (the highest dose tested).

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Effect concentration:

3.6 mg/L