Octylphosphonic acid

Short-term toxicity to aquatic invertebrates

Administrative data

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 2011-12-16 to 2013-03-15

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2013

Report date:

2013

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

2012-11-30

Test material

Test material information

Constituent 1

Reference substance name:

Octylphosphonic acid

EC Number:

225-218-5

EC Name:

Octylphosphonic acid

Cas Number:

4724-48-5

Molecular formula:

C8H19O3P

IUPAC Name:

octylphosphonic acid

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

Water samples were taken from the control and each test group (Replicates R1-R4 pooled) at 0 end 48 hours for quantitative analysis. All samples were stored at approximately -20°C prior to analysis. Duplicate samples were taken and stored at approximately -20°C for further analysis if necessary.
Samples at the NOEC and above only were analyzed.

Test organisms

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name:Daphnia magna
- Strain:
- Source: In-house laboratory culture
- Age at study initiation (mean and range, SD): less than 24 hours
- Method of breeding: Culture conditions ensured that reprodcution was by pathenogenesis
- Feeding during test: No
- Food type: Algal suspension (Desmodesmus subspicatus and tetramin® flake food suspension
- Amount: No data
- Frequency: Daily

ACCLIMATION
- Acclimation period: No

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

48 h

Test conditions

Hardness:

No data

Test temperature:

18°C to 23°C (see table Physico-chemical measurements)

pH:

7.1 to 8 (see table Physico-chemical measurements)

Dissolved oxygen:

99% to 101% ASV (Air saturation value)

Salinity:

No applicable

Nominal and measured concentrations:

Nominal concentration: 0, 1.0, 1.8, 3.2, 5.6, 10, 18, 32 mg/L
Measured concentration: Started for the 3.2 mg/L concentration: 3.18, 5.80, 10.2, 18.3, 27.3 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: glass jar
- Type (delete if not applicable): covered to prevent evaporation
- Material, size, headspace, fill volume: 250mL filled at 200 mL
- Aeration:No
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
See paragraph any other information on material and methods incl. tables

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: 16 light and 8 hours darkness with 20 minutes dawn ans dusk transition periods
- Light intensity: 751-791 lux

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : Immobilization at 24h and 48h

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable
- Justification for using less concentrations than requested by guideline: The substance was not soluble in the medium above 32 mg/L
- Range finding study: Yes
- Test concentrations: 0.1; 1.0; 10 and 100 mg/L
- Results used to determine the conditions for the definitive study: Immobilisation showed at 10 and 100 mg/L, and limit of solubility of the substance at 32 mg/L

Reference substance (positive control):

yes

Remarks:

*potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

> 32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Effect concentrations 2

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

3.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities:
- Other biological observations: Microscopic examination of the immobilized daphnids after 48-hours exposure showed that at the concentration of 5.6 mf/L and above, particle of test item were adhered to the antenna and tail.
- Mortality of control: No
- Other adverse effects control:No
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: The 32 mg/L test prapration was observed to be slighly cloudy dispersion with particles of test item floating at the water surface at the start of the test. After both 24h and 48h exposure, the preparation was observed to have formed a slightly cloudy dispersion with a layer of test item at the water surface.
- Effect concentrations exceeding solubility of substance in test medium: Significant precipitation was observed to occur at concentration in excess of 32 mg/L

Results with reference substance (positive control):

- Results with reference substance valid?
- Mortality: yes
- EC50/LC50: 0.45 mg/L (0.42-0.48 mg/L at 95% confidences limits

Any other information on results incl. tables

Table2: Cumulative immobilization data in the definitive test

Nominal concentration (mg/L)	Cumulative immobilized Daphnia (Initial pop. = 5 per replicate)
	24 hours						48 hours
	R1	R2	R3	R4	Total	%	R1	R2	R3	R4	Total	%
Control	0	0	0	0	0	0	0	0	0	0	0	0
1.0	0	0	0	0	0	0	0	0	0	0	0	0
1.8	0	0	0	0	0	0	0	0	0	0	0	0
3.2	0	0	0	0	0	0	0	1	0	0	*1	5
5.6	0	0	0	0	0	0	0	1	0	1	2	10
10	0	0	0	0	0	0	2	1	0	0	3	15
18	1	0	0	1	2	10	1	0	1	1	3	15
32	0	0	0	0	0	0	1	0	2	3	6	30

 

R1-R4 = Replicate 1 to 4

* = Single immobilized daphnid considered to be due to natural causes rather than a true toxic response given that less than 10% immobilization occurred.

Analytical results for test samples

Time point (h)	Nominal concentration of test item in test sample Cnom [mg/L]	Measured concentration of test item in sample vial X [mg/L]	Sample preprataion factor   F	Dtermined concentration of test item in test sample C [mg/L]	% of nominal concentration       [%]
0	Control	< LOQ	1	< LOQ	1
	3.2	0.636	5	3.18	99
	5.6	0.580	10	5.80	104
	10	0.510	20	10.2	102
	18	0.458	40	18.3	102
	32	0.546	50	27.3	85
48	Control	< LOQ	-	< LOQ	-
	3.2	0.650	5	3.25	102
	5.6	0.613	10	3.13	109
	10	0.520	20	10.4	104
	18	0.435	40	17.4	97
	32	0.534	50	26.7	83

LOQ = Limit Of Quantification

- = Not applicable

For reporting purpose, X has been calculated from C retrospectively

Physico-Chemical measurements

Nominal concentration (mg/L)		0 Hours			24 hours	48 hours
		pH	Mg O2/L	% ASV*	T°C	T°C	pH	Mg O2/L	% ASV*	T°C
Control	R1	8.0	8.9	100	21	22	7.6	8.7	98	21
	R2	8.0	8.9	100	21	21	7.6	8.7	98	21
	R3	7.9	8.9	100	21	22	7.7	8.7	98	21
	R4	7.9	8.9	100	21	21	7.7	8.7	98	21
1.0	R1	7.9	8.9	100	21	22	7.7	8.7	98	21
	R2	7.9	8.9	100	21	21	7.7	8.7	98	21
	R3	7.9	8.9	100	21	22	7.7	8.7	98	21
	R4	7.9	8.8	99	21	21	7.7	8.7	98	21
1.8	R1	7.9	8.8	99	21	22	7.7	8.7	98	21
	R2	7.9	8.8	99	21	21	7.7	8.7	98	21
	R3	7.9	8.8	99	21	22	7.7	8.7	98	21
	R4	7.8	8.8	99	21	21	7.7	8.7	98	21
3.2	R1	7.8	8.8	99	21	22	7.7	8.7	98	21
	R2	7.8	8.8	99	21	21	7.7	8.7	98	21
	R3	7.8	8.8	99	21	22	7.7	8.7	98	21
	R4	7.8	8.8	99	21	21	7.7	8.7	98	21
5.6	R1	7.7	8.8	99	21	22	7.7	8.7	98	21
	R2	7.7	8.8	99	21	21	7.7	8.7	98	21
	R3	7.7	8.8	99	21	22	7.7	8.7	98	21
	R4	7.7	8.8	99	21	21	7.7	8.7	98	21
10	R1	7.6	8.8	101	22	22	7.7	8.7	98	21
	R2	7.6	8.8	101	22	21	7.6	8.7	98	21
	R3	7.6	8.7	100	22	22	7.6	8.7	98	21
	R4	7.5	8.7	100	22	21	7.6	8.7	98	21
18	R1	7.4	8.7	100	22	22	7.6	8.7	98	21
	R2	7.4	8.7	100	22	21	7.6	8.7	98	21
	R3	7.3	8.7	100	22	22	7.6	8.7	98	21
	R4	7.3	8.7	100	22	21	7.5	8.7	98	21
32	R1	7.2	8.7	100	22	21	7.5	8.7	98	21
	R2	7.1	8.6	99	22	21	7.4	8.7	98	21
	R3	7.1	8.6	100	23	22	7.4	8.7	98	21
	R4	7.1	8.6	100	23	22	7.4	8.7	98	21

* ASV = Dissolved oxygen concentration expressed as a percentage of Air Saturation Value

R1 – R4 = Replicate 1 to 4

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test item to the freshwater invertebrate (Daphnia Magna) has been investigated and gave a 48-hours EC50 of greater than 32 mg/L. The NOEC was 3.2 mg/L.

Due to the limited solubility of the test item in the test media, it was considered to be inappropriate to test at concentrations in excess of 32 mg/L. significant precipitation was observed to occur at concentrations in excess of 32 mg/L which may have exerted physical effects on the test organism wich were unrelated to toxicity. Microscopic examination of the immobilized daphnids after 48 hours exposure showed that the concentration of 5.6 mg/L and above, particles of test item were adhered to the antenna and tail. As such it was not possible to ascertain whether the immobilization observed was due to either a physical and/or a toxicological effect.

Executive summary:

The 48–hr-acute toxicity of OPA to Daphnia magna was studied under static conditions.  Daphnids were exposed to control and test chemical at nominal concentration of 1.0, 1.8, 3.2, 5.6, 10, 18 and 32 mg/L for 48 hr.  Immobility were observed daily. 

The 48– hour EC₅₀was > 32 mg/L. 

The test was not carried at a concentration above than 32 mg/L because it was not possible to solubilize the subtance at a level upper than 32 mg/L in the medium (observations made during the range-finding study)

 

It satisfies the guideline requirements for an acute toxicity study with freshwater invertebrates.

 

Results Synopsis

 Test Organism :Daphnia magna

 NOEC:  3.2 mg.//L   

EC₅₀: >32 mg/L