Trihexyl phosphate

Short-term toxicity to fish

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to fish

Type of information:

experimental study

Adequacy of study:

key study

Study period:

12 - 17 Mar 2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 203 (Fish, Acute Toxicity Test)

Version / remarks:

adopted 17. July 1992

Deviations:

no

Qualifier:

according to guideline

Guideline:

EU Method C.1 (Acute Toxicity for Fish)

Version / remarks:

2008

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

Landesamt für Umwelt, Wasserwirtschaft und Gewerbeaufsicht, Rheinland-Pfalz, Germany

Analytical monitoring:

yes

Details on sampling:

- Concentrations: control and 100 mg/L
- Sampling method: Samples were taken at test start, after 24 h, 24 h (new) and at test end after 48 h

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: Saturated solution was prepared for the test. This was done by pipetting 106 μL/L corresponding to the nominal load 100 mg/L (based on a density of 0.94 g/mL, stated in the MSDS provided by the sponsor) on the surface of tap water and stirring slowly for 23 – 23.5 h. The lower phase was used as test solution. At the beginning and for each medium renewal, the necessary solutions were freshly prepared.
- Controls: yes, only medium

Test organisms (species):

Danio rerio (previous name: Brachydanio rerio)

Details on test organisms:

TEST ORGANISM
- Source: Dehner Garten Center, Neustadt, Germany
- Length at study initiation (length definition, mean, range and SD): 2 ± 1 cm
- Method of breeding: Vessels: polyethylene aquaria; Medium: chlorine-free tap water; Feeding: three times a day with warmwater fishfood, totalling about 1-2% of body weight per day; Photoperiod 12/12 h; Temperature 23 ± 2 °C

ACCLIMATION
- Acclimation period: at least 12 days
- Acclimation conditions: same as test conditions
- Type and amount of food during acclimation: warmwater fishfood , totalling about 1 - 2% of body weight per day
- Feeding frequency during acclimation: three times a day
- Health during acclimation: mortality did not surpass 5%

FEEDING DURING TEST: no feeding during the test; 24 hours before the start of the test, the test fish were no longer fed.

Test type:

semi-static

Water media type:

freshwater

Limit test:

yes

Total exposure duration:

96 h

Hardness:

0.83 mmol/L

Test temperature:

21.2 – 23.1 °C

pH:

7.6 - 8.1 (control)
7.6 - 8.0 (100 mg/L)

Dissolved oxygen:

6.8 - 9.6 mg/L (control)
6.5 - 8.6 mg/L (100 mg/L)

Conductivity:

228 µS/cm at 25 °C

Nominal and measured concentrations:

control and 100 mg/L

Details on test conditions:

TEST SYSTEM
Test vessel:
- Type: open (no detailed information given in the report)
- Material, size, headspace, fill volume: glass aquaria, volume 10 L; completly filled
- Renewal rate of test solution (frequency/flow rate): every 24 h
- No. of organisms per vessel: 7
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1
- Biomass loading rate: 1 fish/L

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Good quality drinking water
- Total organic carbon: <0.50 mg/L
- Water analysis: chromium <0.001 mg/L, cadmium <0.0001 mg/L, aluminium 0.011 mg/L, iron <0.005 mg/L, copper <0.001 mg/L, nickel <0.001 mg/L, mercury <0.0001 mg/L, selenium <0.001 mg/L, benzene <0.1 μg/L, lead <0.001 mg/L, arsenic <0.001 mg/L, antimony <0.001 mg/L
bor <0.01 mg/L, nitrite <0.005 mg/L manganese <0.005 mg/L cyanide <0.005 mg/L ammonium <0.05 mg/L, fluoride <0.1 mg/L, potassium 2.6 mg/L, magnesium 3.6 mg/L, sodium 4.7 mg/L, nitrate 5.5 mg/L, chloride 10 mg/L, sulphate 11 mg/L, calcium 32 mg/L
- Pesticides: < LOD µg/L
- Chlorinated organic compounds <1 μg/L
- Polycyclic aromatic hydrocarbons <0.008 μg/L
- pH 8.16
- Intervals of water quality measurement: Observations were made every 24 hours, measuring pH and O2-concentration of the old and new test solution in each vessel

OTHER TEST CONDITIONS
- Photoperiod: 12/12 h
- Light intensity: neon tubes

EFFECT PARAMETERS MEASURED: Observations were made every 24 h documenting mortalities or abnormal behaviour.

TEST CONCENTRATIONS
- Spacing factor for test concentrations: only one concentration
- Range finding study: no range-finding test was performed

Reference substance (positive control):

no

Duration:

96 h

Dose descriptor:

NOEC

Effect conc.:

>= 150 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

lower phase of saturated test solution was tested

Basis for effect:

mortality (fish)

Remarks on result:

other: limit of solubility

Duration:

96 h

Dose descriptor:

LC50

Effect conc.:

> 150 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

lower phase of saturated test solution was tested

Basis for effect:

mortality (fish)

Remarks on result:

other: limit of solubility

Duration:

96 h

Dose descriptor:

LOEC

Effect conc.:

> 150 µg/L

Nominal / measured:

meas. (geom. mean)

Conc. based on:

test mat.

Remarks:

lower phase of saturated test solution was tested

Basis for effect:

mortality (fish)

Remarks on result:

other: limit of solubility

Details on results:

- Behavioural abnormalities: no abnormal behaviour of the surviving fish was observed.
- Mortality of control: no
- Other: Analytical and biological results are summarized within the tables 1-4 in section "Any other information on results incl. tables"

Sublethal observations / clinical signs:

Analytical Results:

Because the test item is not stable under test conditions, the content of the test item in the test solutions was measured using GC/MSD at the beginning and at the end of the test and at each medium renewal in the fresh and the old solutions. Because of the poor solubility of the test item, the correlation between nominal and measured concentration was weak. Therefore, the determination of the results was based on the geometric mean of the measured concentrations, which is stated as the limit of solubility of the test item under the test conditions.

Table 1: Biological Results

Parameter	Value
24h NOEC	≥ 150 μg/L (limit of solubility)
24h LC50	> 150 μg/L (limit of solubility)
48h NOEC	≥ 150 μg/L (limit of solubility)
48h LC50	> 150 μg/L (limit of solubility)
72h NOEC	≥ 150 μg/L (limit of solubility)
72h LC50	> 150 μg/L (limit of solubility)
96h NOEC	≥ 150 μg/L (limit of solubility)
96h LC50	> 150 μg/L (limit of solubility)

 

Table 2: Analytical Results: Measured Concentrations

Nominal Concentration Test Item	Measured Concentration t = 0 h	Measured Concentration t = 24 h old	Measured Concentration t = 24 h new	Measured Concentration t = 48 h old
mg/L	μg/L	μg/L	μg/L	μg/L
100	133.11	56.89	202.981	165.73

 

Table 3: Analytical Results: Measured Concentrations, Continuation

Nominal Concentration Test Item	Measured Concentration t = 48 h new	Measured Concentration t = 72 h old	Measured Concentration t = 72 h new	Measured Concentration t = 96 h
mg/L	μg/L	μg/L	μg/L	μg/L
100	225.80	114.07	231.76	177.59

 

Table 4: Analytical Results: Geometric Mean

Nominal Concentration Test Item	Geometric Mean of measured concentrations
mg/L	μg/L
100	150.98

Table 5. Validity criteria

Criterion from the guideline	Outcome	Validity criterion fulfilled
The mortality in the control(s) should not exceed 10% (or one fish if less than ten are used) at the end of the test	No mortality occurred	yes

Validity criteria fulfilled:

yes

Description of key information

LC50 (96 h) >150 µg/L (Danio rerio, OECD 203, geometric mean)

Additional information

One experimental study is available investigating the acute toxicity of the substance to fish. The study was conducted according to OECD 203 (GLP). The toxicity against Danio rerio was tested using a semi-static test design (LAUS GmbH, 2017c). The study was performed as a limit test using the nominal concentration 100 mg/L. Because the test item is not stable under test conditions, the content of the test item in the test solutions was measured using GC/MSD at the beginning and at the end of the test and at each medium renewal in the fresh and the old solutions. Because of the poor solubility of the test item, the correlation between nominal and measured concentration was weak. Therefore, the determination of the results was based on the geometric mean of the measured concentrations, which is stated as the limit of solubility of the test item under the test conditions. No mortality was observed at 100 mg/L (nominal, corresponding to 150 µg/L based on the geometric mean measured concentration). Based on these observations the LC50 (96 h) was at >150 µg/L and NOEC at ≥ 150 µg/L.