Isotridecanol, ethoxylated

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2019-07-03 to 2019-07-24

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

2012

GLP compliance:

yes (incl. QA statement)

Remarks:

Staatliches Gewerbeaufsichtsamt, Hildesheim, Germany

Analytical monitoring:

yes

Details on sampling:

- Concentrations: nominal loading rates 20.5, 51.2, 128, 320, 800 µg/L and the control (at least 3 times during the test in the fresh media at the start of an exposure interval (0 hours) and in the old media at the end of an exposure interval (48 or 72 hours)

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: water accommodated fraction (WAF) preparation according to OECD guidance document No. 23 (2018): One WAF of 1000 µg/L was prepared 24 ± 1 hour prior test start nd each renewal. Appropriate amount of the test item was applied by pipette into a glass flask filled with an appropriate amount of dilution water. Dispersion was shaken for 24 hours. After separation phase of at least 1 hour standing the WAF was removed by siphoning from the middle of the glass flask. Undissolved particles were removed by membrane filtration (membrane filter 0.45 µm, RC, Macherey-Nagel). The filter was saturated in order to avoid adsorption during the filtration. The first 25 mL of the filtrate were discarded. The filtration was interrupted for 15 minutes to allow adsorption and saturation of the filter material with dissolved test item. Thereafter, the filtration was continued. The next 25 mL were discarded. Five loadings of the test item were prepared from the Water Soluble Fraction ith the nominal loading of 1000 µg/L by dilution with dilution water to 20.5, 51.2, 128, 320, 800 µg/L.
- Differential loading: no
- Controls: dilution water only
- Evidence of undissolved material (e.g. precipitate, surface film, etc.): No Tyndall effect was observed.

Test organisms (species):

Daphnia magna

Details on test organisms:

TEST ORGANISM
- Common name: water flea
- Age at study initiation: < 24 h
- Method of breeding: bred in g lass vessels (2 - 3 L capacity) with approximately 1.8 L culture medium, at 20 ± 2°C, in an incubator, 16 hours illumination; light intensity of max. 1500 lux, fed at least 5 times per week ad libitum with a mix of unicellular green algae
- Source: obtained from continuous laboratory cultures at Noack Laboratorien GmbH, Sarsted, Germany, orignally received from Institut für Wasser-, Boden- und Lufthygiene (WaBoLu), Berlin, Germany
- Feeding during test
- Food type: green algae, e.g. Pseudokirchneriella subcapitata and Desmodesmus subspicatus
- Amount: max. 0.2 mg C/daphnia and day
- Frequency: daily

METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES, INCLUDING CULTURING CONDITIONS: juvenile daphnids were removed from the culture vessels at the latest 24 hours before the start of the exposure and discarded. The juveniles born within this period of max. 24 hours preceding the exposure were used for the test. No first brood progeny was used for the test.

Test type:

semi-static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

214 - 288 mg CaCO3/L

Test temperature:

20.5 - 21.8°C

pH:

6.60 - 7.78

Dissolved oxygen:

6.74 - 9.71

Nominal and measured concentrations:

Nominal loading rates: 0 (control), 20.5, 51.2, 128, 320, 800 µg/L
Time weighted mean measured: < LOQ (control), 20.9, 33.5, 84.8, 218, 542 µg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Glass beakers (5 (ID) x 8 (H) cm), 100 mL capacity
- Type: loosely covered with watch glasses
- Fill volume: 50 mL
- Aeration: no
- Renewal rate of test solution: 3 times per week (i.e. on Monday, Wednesday and Friday)
- No. of organisms per vessel: 1
- No. of vessels per concentration (replicates): 10
- No. of vessels per control (replicates): 10

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Elendt M4, according to OECD 211, Annex 2
- Culture medium different from test medium: no
- Intervals of water quality measurement: once per week, at test start and at the end of exposure intervals (48 or 72 hours): pH-values, dissolved oxygen concentration, total hardness and water temperature

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16/8 hours light/dark cycle
- Light intensity: Max. 1500 lux

EFFECT PARAMETERS MEASURED: daily: mortality, number of neonates, number of aborted eggs or dead offspring, abnormalities; at test end: total length excluding the anal spine of each survived parental daphnid and the mean dry weight of the survived parental daphnids of all loading rates and the control

TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.5

- Range finding study
- Test concentrations: 0, 100, 1000 µg/L
- Results used to determine the conditions for the definitive study: 0% mortality at 100 µg/L, 100% mortality at 1000µg/L

Reference substance (positive control):

yes

Remarks:

potassium dichromate (24 h hours acute Immobilisation Test performed once per month)

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

218 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

EC10

Effect conc.:

278 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

reproduction

Remarks on result:

other: 95% confidence limits: 218 - 542 µg/L

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

218 µg/L

Nominal / measured:

meas. (TWA)

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

- Other biological observations: one male was identified at the loading rate 320 µg/L (replicate 8)
- Mortality of control: 0%

Results with reference substance (positive control):

EC50: 1.78 mg/L (95% CI: 1.56 - 1.99 mg/L)

Reported statistics and error estimates:

Differences of reproduction were determined in comparison to the control using statistical standard procedures as normality test (Shapiro-Wilk’s test), variance homogeneity test (Levene’s test), Williams multiple sequential t-test for reproduction and step-down Cochran-Armitage test for adult mortality. Prior to running the multiple loading rate test, a normality test and a variance homogeneity test were performed. P-values of the normality and the variance homogeneity test were 0.01. The α-value (acceptable probability of incorrectly concluding that there is a difference) was α = 0.01 for the normality test and the variance homogeneity test.

Table 1: Measured Concentrations of the Test Item during the Definitive Test (Days 0, 2, 9 and 12)

 

Sampling date	Day 0 Fresh medium 0 hours		Day 2 Old medium 48 hours		Day 9 Fresh medium 0 hours		Day 12 Old medium 72 hours
Nominal test item loading rate [µg/L]	Test item
	Meas. conc. [µg/L]	%	Meas. conc. [µg/L]	%	Meas. conc. [µg/L]	%	Meas. conc. [µg/L]	%
800	683	85	503	63	868	109	253	32
320	285	89	131	41	367	115	104	32
128	134	104	56.5	44	162	127	34.7	27
51.2	58.9	115	23.6	46	54.0	105	< LOQ	-
20.5	34.9	170	< LOQ	-	37.9	185	< LOQ	-
Control	< LOQ		< LOQ		< LOQ		< LOQ

 

Meas.conc.= measured concentration of the testitem, dilution factors taken into account

% = percent of the nominal concentration of the test item

LOQ = limit of quantification (25.0µg/L)

Table 2: Effects on Reproduction for all Introduced Parents (based on the nominal loadings of the water accommodated fractions of the test item [µg/L])

 

Nominal loading rate of the test item [µg/L]	Mean number of offspring per introduced parental daphnid
	Mean	SD	CV
800	21.9	30.5	139
320	94.3	22.7	24.0
128	93.0	25.7	27.6
51.2	104	15.0	14.4
20.5	97.1	13.0	13.4
Control	91.3	8.72	9.5

Table 3: Mortality [%] of the Adult Daphnids after 7, 14 and 21 Days of Exposure (n = 10)

 

Nominal loading rate of the test item [µg/L]	Adult Mortality [%]
	7 days	14 days	21 days
800	50	50	50
320	0	0	0
128	0	0	0
51.2	0	0	0
20.5	0	0	10
Control	0	0	0

Table 4: Validity criteria for OECD 211.

Criterion from the guideline	Outcome	Validity criterion fulfilled
The mortality of the parent animals in the control (female Daphnia) does not exceed 20% at the end of the test.	0%	yes
The mean number of living offspring produced per parent animalsurvivingat the end of the test is ≥ 60 in the control.	91.3	60

Validity criteria fulfilled:

yes

Remarks:

For further details, refer to "Any other information on results incl. tables"

Description of key information

 NOEC (21 d): 218 µg/L (TWA, OECD 211)

Additional information

The chronic toxicity of Isotridecanol, ethoxylated, < 2.5 EO to aquatic invertebrates was studied in a tests following OECD 211. The semi-static test was set up with nominal loading rates of 20.5, 51.2, 128, 320, 800 µg/L (WAF). The test medium was renewed three times a week. An analytical dose verification by LC-MS/MS measurements in fresh (0 h) and aged media (48 or 72 h) was performed. The Time-weighted mean measured concentrations were 20.9, 33.5, 84.8, 218, 542 µg/L. The mortality, number of neonates, number of aborted eggs or dead offspring, abnormalities were recorded daily. Furthermore at test end, the total length excluding the anal spine of each survived parental Daphnids, and the mean dry weight of the survived parental Daphnids of all loading rates and the control were determined. Mortality of adult Daphnids was observed at the highest test concentration leading to a significantly reduced number of offspring at this concentration. Based on the cumulative offspring per introduced parent a NOEC (21 d) of 218 µg/L (TWA) was recorded.