Potassium hexadecyl hydrogen 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:

2013-01-08 to 2013-02-05

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Remarks:

The study is regarded as reliable without restrictions because it was conducted in compliance with GLP regulation and guideline.

Qualifier:

according to guideline

Guideline:

OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.2 (Acute Toxicity for Daphnia)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

yes

Details on sampling:

Duplicate samples from the freshly prepared test medium of the only test concentration and the control were taken at the start of the test.
For the determination of the stability of the test item under the test conditions and of the maintenance of the test item concentration during the test period, duplicate samples from the test medium of the only test concentration and the control were collected at the end of the test (after 48 hours).

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The test item was not well soluble in test water. To avoid physical effects of undissolved test item on the daphnids, no concentration above the solubility limit of the test item in test water was tested. Therefore, a supersaturated stock solution of nominal 100 mg test item/L was prepared by suspending 53.6 mg of test item in 536 mL test water. The stock solution was stirred for 23.75 hours in the dark to dissolve as much test item as possible. Then, the undissolved test item was separated by filtration (0.45 µm cellulose nitrate filter) and the filtrate was used as test medium. The test medium was prepared just before introduction of the daphnids (= start of the test).

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: Daphnia magna
- Source: The daphnids introduced in the test were taken from in house laboratory culture.
- Age at study initiation: From 2.5 to 18.5 hours old
- Method of breeding: The daphnids were bred under similar temperature and light conditions as used in the test. The cultivation of the parental daphnids was performed in the same reconstituted water as the test water used in the test. The test organisms were not first brood progeny. The daphnids in the stock culture were fed at least on all working days with green algae (Desmodesmus subspicatus).
- Feeding during test: none

ACCLIMATION
Was not necessary, since the test was performed in the same medium as the culturing.

Test type:

static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

48 h

Test temperature:

19 to 21 °C at test start
19 to 20 °C at test end

pH:

7.8 to 7.9 at test start
7.8 at test end

Dissolved oxygen:

8.8 to 9.1 mg/L at test start
8.3 to 8.5 mg/L at test end

Nominal and measured concentrations:

A filtrate of a supersaturated stock suspension of nominal 100 mg/L. No measured concentrations are available (below LOD).

Details on test conditions:

TEST SYSTEM
- Test vessel: 100 mL
- No. of organisms per vessel: 5
- No. of vessels per concentration: 4
- No. of vessels per control: 4

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Analytical grade salts and additives were added at the following nominal concentrations in deionised water (conductivity < 5 µS.cm-1):

Main Compounds
CaCl2x2 H2O 293.80 mg/L;
MgSO4x7 H2O 123.30 mg/L;
KCl 5.80 mg/L;
NaHCO3 64.80 mg/L;
Na2SiO3x9 H2O 10.00 mg/L;
NaNO3 0.27 mg/L;
KH2PO4 0.14 mg/L;
K2HPO4 0.18 mg/L

Trace Elements
H3BO3 2860 µg/L;
MnCl2x4 H2O 361 µg/L;
LiCl 306 µg/L;
RbCl 71 µg/L;
SrCl2x6 H2O 152 µg/L;
NaBr 16 µg/L;
Na2MoO4x2 H2O 63 µg/L;
CuCl2x2 H2O 17 µg/L;
ZnCl2 13 µg/L;
CoCl2x6 H2O 10 µg/L;
KI 3.3 µg/L;
Na2SeO3 2.2 µg/L;
NH4VO3 0.6 µg/L;
Na2EDTAx2 H2O 2.5 mg/L,
FeSO4x7 H2O 1.0 mg/L

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 h light : 8 h dark
- Light intensity: The light intensity was 690 - 750 lux (measured once during the test).

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Key result

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: up to the water solubility of the test item no mortality of the test animals occurred.

Duration:

24 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: up to the water solubility of the test item no mortality of the test animals occurred.

Key result

Duration:

48 h

Dose descriptor:

NOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: up to the water solubility of the test item no mortality of the test animals occurred.

Duration:

24 h

Dose descriptor:

NOEC

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

mortality

Remarks on result:

other: up to the water solubility of the test item no mortality of the test animals occurred.

Details on results:

After 48 hours of exposure no immobilisation of the test animals was observed in the control and in the test group of nominal 100 mg/L.

Results with reference substance (positive control):

- Results with reference substance valid: yes (potassium dichromate)
- EC50: 0.706 mg/L
- NOEC: 0.28 mg/L

Table 1 Influence of the test item on the Mobility of Daphnia magna

Nominal Concentration	No. of daphnids tested	No. of immobilised daphnids after		% of immobilised daphnids after
[mg test item/L]		24 h	48 h	24 h	48 h
Control	20	0	0	0	0
100	20	0	0	0	0

 

Table 2 Biological endpoints after 48 hours exposure period

EC50 [mg test item/L]:	>100
95 % CI [mg test item/L]:	n.d.
EC20 [mg test item/L]:	>100
95 % CI [mg test item/L]:	n.d.
EC10 [mg test item/L]:	>100
95 % CI [mg test item/L]:	n.d.
NOEC [mg test item/L]:	100
LOEC [mg test item/L]:	>100

Values refer to nominal test concentrations

CI: Confidence interval

n.d.: not determinable

All Endpoints were determined directly from the raw data.

Table 3 Results for the Determination of the Test Item in the Test Samples

sample description	age		test item found [µg/L]*	D.F.	calculated test item [µg/L]*
	day	[h]
control	0	0	<LOD	100	n.a.
control	2	48	<LOD	100	n.a.
Filtrate of 100 mg test item/L	0	0	<LOD	100	n.a.
Filtrate of 100 mg test item/L	0	0	<LOD	100	n.a.
Filtrate of 100 mg test item/L	2	48	<LOD	100	n.a.
Filtrate of 100 mg test item/L	2	48	<LOD	100	n.a.

* The tabulated results represent rounded results calculated on the exact raw data

** The results represent rounded values

LOD: Limit of Detection = 1.6 µg test item/L
n.a.: not applicable
D.F.: Dilution factor 

Validity criteria fulfilled:

yes

Conclusions:

Up to the water solubility of the test item no mortality of the test animals occurred. Thus, the 48-h EC50 value based on mortality was determined to be greater than 100 mg/L and the 48-h NOEC was determined to be greater than 100 mg/L.

Executive summary:

The purpose of this study was to evaluate the influence of the test item potassium hexadecyl hydrogen phosphate on the mobility of Daphnia magna according to OECD TG 202 and Regulation (EC) No 440/2008 method C.2. The test was performed as static limit test. Young daphnids were exposed 48 hours to test water containing the test item at the concentration of nominal 100 mg test item/L. This limit test was performed in compliance with the test guidelines to demonstrate that the test item has no toxic effect on daphnids up to at least this concentration.

 

This study was conducted using two treatment groups: one control and a filtrate of a supersaturated stock suspension of nominal 100 mg/L was tested (no concentrations above the solubility limit of the test item in the used test water were tested to avoid physical effects of undissolved test item onto the daphnids). Each treatment group contained 20 individuals. The mobility of the daphnids was determined in a static 48-hour test by visual observation after 24 and 48 hours. The collected samples analysed via LC-MS/MS-method. As the solubility of the test item in aquatic test media is very low, the concentrations of dissolved test item were below the Limit of Detection (0.2 µg test item/L). However, all reported results refer to nominal loading rate. The EC50 for the reference substance potassium dichromate was determined to be 0.706 mg/L. All validation criteria according to OECD TG 202 were met. The 48-hour NOEC was determined to be 100 mg test item/L (nominal). The 48-hour EC50 value was determined to be greater than 100 mg test item/L (nominal). Thus, no toxic effects on daphnia magna were observed up to the water solubility of the test item.

Description of key information

Up to the water solubility of the test item no mortality of the test animals occurred. Thus, the 48-h EC50 value based on mortality was determined to be greater than 100 mg/L.

Additional information

The purpose of this study was to evaluate the influence of the test item potassium hexadecyl hydrogen phosphate on the mobility of Daphnia magna according to OECD TG 202 and Regulation (EC) No 440/2008 method C.2. The test was performed as static limit test. Young daphnids were exposed 48 hours to test water containing the test item at the concentration of nominal 100 mg test item/L. This limit test was performed in compliance with the test guidelines to demonstrate that the test item has no toxic effect on daphnids up to at least this concentration.

 

This study was conducted using two treatment groups: one control and a filtrate of a supersaturated stock suspension of nominal 100 mg/L was tested (no concentrations above the solubility limit of the test item in the used test water were tested to avoid physical effects of undissolved test item onto the daphnids). Each treatment group contained 20 individuals. The mobility of the daphnids was determined in a static 48-hour test by visual observation after 24 and 48 hours. The collected samples analysed via LC-MS/MS-method. As the solubility of the test item in aquatic test media is very low, the concentrations of dissolved test item were below the Limit of Detection (0.2 µg test item/L). However, all reported results refer to nominal loading rate. The EC50 for the reference substance potassium dichromate was determined to be 0.706 mg/L. All validation criteria according to OECD TG 202 were met. The 48-hour NOEC was determined to be 100 mg test item/L (nominal). The 48-hour EC50 value was determined to be greater than 100 mg test item/L (nominal). Thus, no toxic effects on daphnia magna were observed up to the water solubility of the test item.