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Short-term toxicity to aquatic invertebrates

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Reference
Endpoint:
short-term toxicity to aquatic invertebrates
Type of information:
experimental study
Adequacy of study:
key study
Study period:
16 to 18 January 2018
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to guideline
Guideline:
OECD Guideline 202 (Daphnia sp. Acute Immobilisation Test)
GLP compliance:
yes (incl. QA statement)
Specific details on test material used for the study:
SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: 26D647
- Purity test date: October 5, 2016

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: Ambient
- Appearance: liquid

Analytical monitoring:
yes
Details on sampling:
Samples were collected from the water control and bulk test solutions at test initiation and 24 hours and from pooled replicate test vessels at 24 hours and exposure termination. All test solutions were analyzed within 24 hours of preparation.
Vehicle:
no
Details on test solutions:
Based on preliminary methodology work and results of the range-finding test, the test material was expected to be completely soluble at the selected test concentrations for the study. Test solutions were prepared at test initiation and renewed at approximately 24 hours. A 1000 mg 2-(Bis(2-ethylhexyl)amino)ethanol/L nominally-dosed saturated solution was prepared via direct addition of the test material (2000 mg) to 2L lab dilution water (LDW). The solution was cloudy with clear liquid/droplets at the surface and throughout. The solution was then sonicated for 30 minutes via water bath sonication. Following sonication, the solution was cloudy with clear liquid/droplets at the surface. Approximately 1400 mL of the nominally-dosed saturated solution was then transferred to a glass beaker via filtering through a Polycap 36 AS Whatman 0.45 µm nylon filter creating a bulk test solution equal to the highest test concentration (100% saturated solution). Remaining bulk test solutions were prepared as dilutions (in LDW) of the 100% saturated solution. The bulk water control consisted of LDW without the addition of the test material. Prepared bulk test solutions were apportioned into individual test vessels. All test solutions were clear and colorless at test initiation and over the course of the entire exposure period. The test solutions were utilized on the same day as preparation; thus, assessment of stability of the test solutions was not required. The dispersal of the test material in the surrounding medium was considered to represent the most probable route of exposure in the environment.
Test organisms (species):
Daphnia magna
Details on test organisms:
The test organism was the freshwater daphnid, Daphnia magna, from in-house cultures initially obtained from Aquatic BioSystems, Inc. Fort Collins, Colorado. This species is widely accepted and recommended for toxicity testing by the test guidelines. Daphnid neonates less than 24-hours old from a laboratory-reared culture were used as the test organisms. Neonates were only used from daphnids which have had at least 3 broods. The day before neonates were needed for testing (<24 hours prior to test initiation), adults within the culture vessels were removed and transferred to new culture vessels. On the following day, neonates produced overnight in these culture vessels were removed and placed into a glass beaker containing lab dilution water (LDW). These neonates (<24 hours old) were held in an incubator until used for the study.
Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
Control Water (Day 0 and Day 1): 68-70 mg CaCO3/L
Highest Test Level (100% saturated) : 66-70 mg CaCO3/L
Test temperature:
Temperature range (°C):
From bulk solutions (Day 0) and individual test vessels (Day 2): 20 (no range)
Continuous monitoring: 20 (no range)
pH:
7.8-8.1
Dissolved oxygen:
8.3-9.1
Salinity:
NA
Conductivity:
Control Water (Day 0 and Day 1): 178-180 uS/cm
Highest Test Level (100% saturated) : 178-186 uS/cm
Nominal and measured concentrations:
The nominal test concentrations in the definitive study were: 0 (water control), 6.25, 12.5, 25.0, 50.0 and 100% of a 1000 mg 2-(Bis(2-ethylhexyl)amino)ethanol/L (LDW) nominally-dosed saturated solution.
The resulting time-weighted mean (TWM) measured concentrations were 0.00100, 0.00183, 0.00290, 0.00536 and 0.00916 mg 2-(Bis(2-ethylhexyl)amino)ethanol/L.
Details on test conditions:
Light intensity ranged from 863-1060 lux.
Alkalinity ranged from 40-48 mg CaCO3/L in the water control. Alkalinity ranged from 44-48 mg CaCO3/L in the highest concentration.
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
> 0.009 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
mobility
Key result
Duration:
48 h
Dose descriptor:
NOEC
Effect conc.:
0.009 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
mobility
Details on results:
Measured 2-(Bis(2-ethylhexyl)amino)ethanol concentrations of freshly prepared bulk test solutions ranged from
No immobility or sublethal effects (changes in daphnid behavior or appearance) were observed in any of the test levels, including the water control, over the course of the exposure.
Validity criteria fulfilled:
yes
Conclusions:
No toxicity was observed at the maximum saturated concentration for 2-[Bis(2-ethylhexyl)amino]ethanol (TWM = 0.00916 mg/L) under the test conditions (i.e., saturation concentration from a 1000 mg/L nominally-dosed solution). Based on the absence of adverse effects observed, the acute toxicity values for Daphnia magna exposed to 2-[Bis(2-ethylhexyl)amino]ethanol over a 48-hour static-renewal exposure period are as follows:
• 24- and 48-hour EC50 : >maximum saturated concentration (TWM = 0.00916 mg/L)
• 48-hour NOEC: maximum saturated concentration (TWM = 0.00916 mg/L)
Executive summary:

The purpose of this study was to assess the potential effects of2-[Bis(2-ethylhexyl)amino]ethanolto the freshwater cladoceran, Daphnia magna, over a 48-hour static-renewal exposure period. The study was conducted with four replicate vessels of five daphnids per test level exposed to nominal concentrations of 0 (water control), 6.25, 12.5, 25.0, 50.0 and 100% of a 1000 mg 2-[Bis(2-ethylhexyl)amino]ethanol/L nominally-dosed saturated solution. Observations were made at 24 and 48 hours (± 1 hour from test initiation) for daphnid immobility (inability to swim within approximately 15 seconds after gentle agitation of the test vessel) and any changes in behavior or appearance. Temperatures during the exposure period were 20ºC. Dissolved oxygen levels ranged from 8.3-9.1 mg/L (93-102% air saturation). The pH ranged from 7.8-8.1 and the light intensity ranged from 863-1060 lux.

Test solutions were analyzed for 2-[Bis(2-ethylhexyl)amino]ethanolconcentrations at test initiation, following 24 hours of exposure and at exposure termination by high performance liquid chromatography/mass spectrometry (HPLC/MS-MS)None of the analyses of the water control exhibited a concentration exceeding the lower limit of quantitation (LLQ) equivalent to 0.00200 mg 2-[Bis(2-ethylhexyl)amino]ethanol/L. Measured concentrations of2-[Bis(2-ethylhexyl)amino]ethanolranged from <LLQ to 0.00218 mg 2-[Bis(2-ethylhexyl)amino]ethanol/L over the course of the exposure period. The resulting time-weighted mean (TWM) measured concentrations were 0.00100, 0.00183, 0.00290, 0.00536 and 0.00916 mg2-[Bis(2-ethylhexyl)amino]ethanol/L. Where measured concentrations were <LLQ (excluding water control analyses), a concentration value of ½ LLQ was utilized for determining mean measured concentrations.

No toxicity was observed at the maximum saturated concentration for2-[Bis(2-ethylhexyl)amino]ethanol(TWM = 0.00916 mg/L) under the test conditions (i.e., saturation concentration from a 1000 mg/L nominally-dosed solution). Based on the absence of adverse effects observed, the acute toxicity values for Daphnia magnaexposed to2-[Bis(2-ethylhexyl)amino]ethanol over a 48-hour static-renewal exposure period are as follows:

24-and48-hourEC50: >maximum saturated concentration (TWM = 0.00916 mg/L)

48-hour NOEC: maximum saturated concentration (TWM = 0.00916 mg/L)

Description of key information

No toxicity was observed at the maximum saturated concentration for 2-[Bis(2-ethylhexyl)amino]ethanol (TWM = 0.00916 mg/L) under the test conditions (i.e., saturation concentration from a 1000 mg/L nominally-dosed solution). Based on the absence of adverse effects observed, the acute toxicity values for Daphnia magnaexposed to 2-[Bis(2-ethylhexyl)amino]ethanolover a 48-hour static-renewal exposure period are as follows:

24-and48-hourEC50: >maximum saturated concentration (TWM = 0.00916 mg/L)

48-hour NOEC: maximum saturated concentration (TWM = 0.00916 mg/L)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
0.009 mg/L

Additional information