Octylphosphonic acid

Short-term toxicity to fish

Administrative data

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

From 2011-12-16 to 2013-03-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline 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 203 (Fish, Acute Toxicity Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

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

Test material form:

other: white waxy solid

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations:40 mg/L in the definitive test
- Sampling method: the test was semi-static. A daily renewal of the test preparation was performed
- Sample storage conditions before analysis: samplewere stored at approximately -20°C and protected fromm light until analysis

Test solutions

Details on test solutions:

The substance was found to be soluble in dechlorinated tap water at 100 mg/L, with the aid with ultrasonication, however, when left to stand in the test media, the test item precipitated out and formed a layer on the surface of the water. Consequently, preliminary work was conducted to discover the way to prepare the test item that resulted in the highest dissolved test item content possible in a stable solution.

Initially, a prolonged stirring method was conducted, stirring 200 mg/L of the test item in dechlorinated tap water. After stirring for 24 hours at approximately 1500 rpm, any dissolved test item was removed by filtration through a 0.2µm Sartorius Sartopore filter (initial 1 liter discarded). This was added to a tank and samples taken for Total Organic Carbon (TOC) analysis. The solution was left to stand for 1 hour prior to siphoning off the aqueous phase, leaving any precipitate undisturbed, and samples taken again for TOC analysis. After leaving this to stand overnight, it was observed that there was a film of precipitate on the surface. This remained the same after aeration.

Ir was then noted that the lowest EC50 from the acute Daphnia and Algal test was 40 mg/L, so it was decided to conduct work to see if a concentration of 40 mg/L would remain in solution. A solution of 40 mg/L as prepared in dechlorinated tap water using shear mixing and left to stand under gentle aeration for 24 hours. After this, it was again observed that the substance had precipitated out and formed a layer on the surface of the media.

Therefore for the purpose of the fish test, an excess of substance was stirred in dechlorinated tap water for 24 hours using a propeller stirrer. After stirring, any undissolved substance was removed by filtration through a 0.2µM Sartorius Sartopore filter. The dissolved substance concentration was determined using TOC analysis and an appropriate amount of media added to a final volume of 20 liter of dechrlorinated tap water to give the 40 mg/L test concentration.

Test organisms

Test organisms (species):

Oncorhynchus mykiss (previous name: Salmo gairdneri)

Details on test organisms:

- Common name:juvenile rainbow trout (Oncorhynchus mykiss).
- Source: Fish were obtained from Brow Well Fisheries Limited, Hebden, near Skipton, Yorkshire, UK and maintained in-house since 17 october 2012
- Length at study initiation (length definition, mean, range and SD): 5.4 cm (sd = 0.2)
- Weight at study initiation (mean and range, SD): 1.25 g (sd = 0.14)
- Feeding during test: No

ACCLIMATION
- Acclimation period: Fish were acclimatized to test conditions from 26 October to 05 November 2012
- Acclimation conditions (same as test or not): Yes
- Type and amount of food: commercial trout pellets which was discontinued approximately 24 hours prior to the start of the definitive test
- Feeding frequency: No data
- Health during acclimation (any mortality observed): 0 mortality in the 7 days prior to the start of the test

Study design

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Post exposure observation period:

No

Test conditions

Hardness:

140 mg/L as CaCO3

Test temperature:

14°C (Measured every day with a Hanna Instruments HI 93510 digital thermometer)

pH:

7.3 to 8.1 (Measured every day with a Hach HQ30d Flexi handheld meter)

Dissolved oxygen:

93% to 103 % of ASV (dissoled oxygen concentration expressed as a percentage of Air Satured Value)

Salinity:

No applicable (fresh-water)

Nominal and measured concentrations:

See table 5: Results for test sample

Details on test conditions:

TEST SYSTEM
- Test vessel: 20 liter glass exposure vessel covered to reduce evaporation:
- Aeration: aerated via narrow bore glass tubes
- Renewal rate of test solution (frequency/flow rate): a daily renewal of the test preparations
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per vehicle control (replicates): 1

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Laboratory tap water was dechlorinated by passage through an activated carbon filter (Purite Series 500) and partly softened (Elga Nimbus 1248D Duplex Water Softener). After dechlorination and softening the water was passed through a series of computer controlled plate heat exchangers to achieve the required temperature
- Total organic carbon: 0.920 mg/L
- Metals: no data
- Pesticides: 0.009µg/L
- Chlorine: no
- Alkalinity: No data
- Ca/mg ratio: No data
- Conductivity: No data
- Culture medium different from test medium: No applicable
- Intervals of water quality measurement: No data

OTHER TEST CONDITIONS
- Adjustment of pH: No data
- Photoperiod: 16 hours light and 8 hours darkness with 20 minute dawn and dusk transition periods for a period of 96 hours
- Light intensity: No data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
After 3, 6, 24, 48, 72 and 96 hours any mortalities or sub-lethal effects of exposure were determined by visual inspection of the test fish.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: not applicable
- Justification for using less concentrations than requested by guideline: See details on test solution
- Range finding study: No
- Test concentrations: 40 mg/L
- Results used to determine the conditions for the definitive study: studies 41105085 (acute Daphnia Magna) and 41105086 (algal growth inhibition test) showed that the lowest EC50 was 40 mg/L on the algal. Based on these results, a limit test was conducted at a concentration of 40 mg/L to confirm that at the EC50 in the algal test, no mortalities or sub-lethal effects of exposure were observed.

Reference substance (positive control):

no

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 40 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Effect concentrations 2

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

40 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality (fish)

Details on results:

- Behavioural abnormalities: No
- Other biological observations: No
- Mortality of control: No
- Other adverse effects control: No
- Abnormal responses: No
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: Throughout the duration of the test the test preparations were observed to be clear colorless solutions with a very small amount of white precipitate on the surface at 48 and 72 hours.

Results with reference substance (positive control):

Not applicable

Any other information on results incl. tables

Sublethal observations / clinical signs:

Table 2 : Cumulative Mortality Data in the Definitive test

 

Nominal concentration (mg/L)	Cumulative Mortality (initial population = 7)						% mortality
	3 h	6 h	24 h	48 h	72 h	96 h	96 h
Control	0	0	0	0	0	0	0
40	0	0	0	0	0	0	0

 

Table 5: results for test sample

Time point (hour)	Nominal concentration of test item in test sample Cnom [mg/L]	Measured concentration of test item in sample vial X [mg/L]	Sample preparation factor F	Determined concentration of test item in test sample C [mg/L]	% of nominal concentration [%]
0	Control 40	< LOQ 0.459	100 100	< LOQ 45.9	- 115
24	Control 40	< LOQ 0.452	100 100	< LOQ 45.2	- 113
96	Control 40	< LOQ 0.409	100 100	< LOQ 40.9	- 102

LOQ = Limit Of Detection

 - = Not apllicable

For reporting purposes, x has been calculated from c retrospectively

 

 

Physico-Chemical measurements

Nominal concentration (mg/L)	Time (Hour)
	0 hours (Fresh media)				24 hours (old media)				24 hours (fresh media)
	pH	Mg O2/L	% ASV *	T °C	pH	Mg O2/L	% ASV *	T °C	pH	Mg O2/L	% ASV *	T °C
Control	7.5	10.6	103	14	8.1	10.3	100	14	7.7	10.7	104	14
100	7.8	10.4	101	14	8.0	10.2	99	14	7.4	10.6	103	14

 

Nominal concentration (mg/L)	Time (Hour)
	48 hours (old media)				48 hours (fresh media)				72 hours (old media)
	pH	Mg O2/L	% ASV *	T °C	pH	Mg O2/L	% ASV *	T °C	pH	Mg O2/L	% ASV *	T °C
Control	8.0	10.0	97	14	7.4	10.6	103	14	7.8	9.7	94	14
100	8.1	10.0	97	14	7.3	10.6	103	14	7.9	9.9	96	14

 

Nominal concentration (mg/L)	Time (Hour)
	72 hours (fresh media)				96 hours (old media)
	pH	Mg O2/L	% ASV *	T °C	pH	Mg O2/L	% ASV *	T °C
Control	7.4	10.4	101	14	7.8	9.7	94	14
100	7.4	10.5	102	14	7.8	9.6	93	14

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

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity of the test item to the freshwater fish rainbow trout (Oncorhynchus mykiss) has been investigated using the threshold approach and gave a 96-Hour LC50 of greater than 40 mg/L. The No Observed Effect Concentration was 40 mg/L.

Executive summary:

In a 96-h acute toxicity study, rainbow trout (Oncorhynchus mykiss) were exposed to OPA (Octylphosphonic Acid) at 40 mg/L nominal concentrations (limit test) under semi-static conditions according to the OECD guideline N° 203 (1992). 

40 mg/L was considered to be the highest concentration which was possible to be dissolved in the media without precipitation of the substance. That why this test could be considered as a limit test.

The 96-h LC₅₀was >40 mg/L

The NOEC values, based on mortality/sublethal effects, was 40 mg/L.

No sublethal effects were observed. Based on the results of this study, OPA would be not classified to fish.

 

LC₅₀:  >40 mg /L      

NOEL:  = 40 mg /L