Reaction mass of dioctyl hydrogen phosphate and octyl dihydrogen phosphate

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2017-11-29 - 2018-03-22

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study according to guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Version / remarks:

April 2004

GLP compliance:

yes (incl. QA statement)

Remarks:

March 2015

Analytical monitoring:

yes

Details on sampling:

- Concentrations: 0, 100 mg/L
- Sampling method: Control and test solution were sampled in dupblicate at the start of exposure and at 48h.
- Sample storage conditions before analysis: All samples were stored in amber glass bottles in the dark at a temperature of ≤ -18°C after sampling and before shipment.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
As the test item is poorly water-soluble, the following approach was used taking into account aspects of ISO 14442 (2006), Water quality -- Guidelines for algal growth inhibition tests with poorly soluble materials, volatile compounds, metals and waste water, and OECD 2000, Guidance Document on Aquatic Toxicity Testing of Difficult Substances and Mixtures. OECD Series on Testing and Assessment Number 23. ENV/JM/MONO(2000)6.
A stock solution was prepared at a nominal loading rate of 100 mg/L as described below by adding 0.098 mL of the test item to 1000 mL of the test medium. This stock solution was stirred for 46 hours and 20 minutes at ambient temperature in the dark.
Thereafter this stock solution was filtered, using a glass fibre filter with an average retention capacity of 0.4 µm (MN GF-5). The initial 100 mL of the filtrate were used to rinse the collection vessel and were subsequently discarded.
Particles were visible on the water surface, so the stock solution was filtered once more with a new filter (0.4 µm; MN GF-5). The first 100 mL of the filtrate were used to rinse the collection vessel and were afterwards discarded. After the second filtration a minor number of undissolved particles were visible on the water surface.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Water flea
- Strain/clone: M10
- Source: Daphnia magna STRAUS (clone M10), a water flea, cultured at ECT Oekotoxikologie GmbH since December 22, 2011
- Age of parental stock: < 35 days
- Feeding during test: none

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Hardness:

254 mg/L CaCO3

Test temperature:

20.7 - 21.5 °C

pH:

6.8 - 7.6

Dissolved oxygen:

76 - 94 % of air saturation
6.6 - 8.3 mg/L

Conductivity:

665 µS/cm

Nominal and measured concentrations:

0, 100 mg/L (nominal concentrations)
0, 31.7 mg/L (measured concentrations)

Details on test conditions:

TEST SYSTEM
- Test vessel:100-mL glass beakers, closed by watch glass
- Material, size, headspace, fill volume: 50-60 mL fill volume
- No. of organisms per vessel: 5
- No. of vessels per concentration (replicates): 4
- No. of vessels per control (replicates): 4

TEST MEDIUM / WATER PARAMETERS
- Test medium: Elendt medium M4

OTHER TEST CONDITIONS
- Adjustment of pH: None
- Photoperiod: 16h light / 8h dark
- Light intensity: 388-564 lx

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

EC50

Effect conc.:

> 31.7 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

31.7 mg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

act. ingr.

Basis for effect:

mobility

Details on results:

- Behavioural abnormalities:
- Mortality of control: 0%
- Other adverse effects control: None

Validity criteria:
% of immoible daphnids in the control was less than 10% (0%) and dissolved oxygen concentration in control and test vessels at the end of the test were greater than 3 mg/L (> 8 mg/L)

Results with reference substance (positive control):

24h EC50 0.74 mg/L
The results of this reference test are acceptable and the test conditions are reliable and the sensitivity of the test system could be demonstrated.

Table 1: Cumulative number of immobile Daphnia magna after 24 and 48 h

nominal concentration	total number of introduced daphnids	total number of immobile daphnids	immobile daphnids (% of introduced)	total number of immobile daphnids	immobile daphnids (% of introduced)
[% of filtrate]^1		[24 h]	[24 h]	[48 h]	[48 h]
Control	20	0	0.0	0	0.0
100	20	0	0.0	0	0.0

¹% of filtrate of saturated solution at a loading rate of 100 mg/L

Table 2: Summary of measured concentrations of main constituents during the test

Nominal concentration [mg/L]^a)	Test period [h]	Age of test solution [h]	Measured concentration diester[mg/L]	Measured concentration monoester[mg/L]	Measured concentration^b)[mg/L]	Geometric mean measured concentration^b)over 48 h [mg/L]
0 (control)	0	0	n.d.	n.d.	n.d.	--
100	0	0	2.19	46.4	48.6	--
0 (control)	48	48	n.d.	n.d.	n.d.	n.a.
100	48	48	0.78	19.9	20.7	31.7

^a)Individual filtrate (WAF) at a loading rate of 100 mg/L

^b)sum of main constituents diester + monoester)

Limit of Quantification (LOQ): 1.0 mg/L; n.d.: < 0.3 mg/L; n.a. = not applicable

Validity criteria fulfilled:

yes

Conclusions:

In this limit test no immobile daphnids were observed in the control or in the limit concentration of 100% of a saturated solution at a loading rate of 100 mg test item.

Executive summary:

The acute toxicity of the Reaction mass of dioctyl hydrogen phosphate and octyl dihydrogen phosphate to Daphnia magna was tested according to OECD guideline 202 and GLP conditions.

In this limit test no immobile daphnids were observed in the control or in the limit concentration of 100% of a saturated solution at a loading rate of 100 mg test item. 

It is therefore concluded that the EC₅₀of the test item is higher than the limit concentration tested (nominal:100% of a saturated solution at a loading rate of 100 mg test item). This corresponds to a geometric mean measured concentration of the main constituents (sum of mono- & diester) of 31.7 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

100 mg/L