1,2-Ethanediol, reaction products with branched 2-[(4-nonylphenoxy)methyl]oxirane

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:

March - August 2017

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)

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)

GLP compliance:

yes (incl. QA statement)

Specific details on test material used for the study:

The non-GLP certificate of analysis lists the test material as containing 0.18% ethylene glycol and having a viscosity of 33633 cPs at 25°C.
The record of custody lists the test material as 100% of the desired formulation.
The record of custody lists the test material as having a 2 year shelf life.

Analytical monitoring:

yes

Details on sampling:

To confirm test solution preparations and associated stability over the course of the exposure, the collected samples were analyzed for the major structural component of EPON™ Resin CS-337 by high pressure liquid chromatography/mass spectrometry (HPLC/MS-MS). All test solutions were analyzed within 24 hours of preparation; therefore, no stability assessment was required.

Vehicle:

no

Details on test solutions:

Results of the non-GLP range-finding test and preliminary methodology work indicated that the test material was not expected to be completely soluble at the selected test concentrations for the study. Analytical results of a preliminary non-GLP trial indicated that a dosing (loading rate) of 100 mg EPON™ Resin CS-337/L required seven days of slow stirring to reach a equilibrated saturated state (i.e., ≤ 20% measured concentrations between successive sampling events). Based on this information, the study used the water-accommodated fraction (WAF) preparation method (OECD, 2000) to prepare the 10 mg/L test solution. Following direct addition of the test material into LDW and the appropriate mixing time (seven days), the clear portion (i.e., no visible undissolved test material) of the highest loading rate (10 mg/L) was siphoned to produce a WAF test solution. Due to limitations of weighing small amounts of the test material, subsequent loading rates (test solutions) were prepared as serial dilutions of the 10 mg/L WAF test solution. The water control consisted of LDW without the addition of the test material. The prepared test solutions were apportioned into individual test vessels and were clear and colorless over the course of the exposure period. The test solutions were utilized on the same day as preparation; thus, assessment of stability of the test solution 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 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:

Water hardness was 72 mg CaCO3/L at test initiation in the control.
In the highest test level (10 mg/L), water hardness was 76 mg CaCO3/L at test initiation.

Test temperature:

Temperatures ranged from 20-21°C.

pH:

The pH was maintained at 7.8.

Dissolved oxygen:

Dissolved oxygen levels ranged from 8.6-8.7 mg/L (99-100% air saturation)

Conductivity:

Conductivity was 184 μS/cm at test initiation in the water control.
In the highest test level (10 mg/L), conductivity was 185 μS/cm at test initiation.

Nominal and measured concentrations:

Nominal loading rates: 0 (water control), 0.625, 1.25, 2.50, 5.00 and 10.0 mg EPON™ Resin CS-337/L

Details on test conditions:

The water used for daphnid testing and culturing (referred to as laboratory dilution water or LDW) was Lake Huron water supplied to The Dow Chemical Company (TERC Laboratory) by the City of Midland Water Treatment Plant. The water was obtained
from the upper Saginaw Bay of Lake Huron off Whitestone Point and was limed and flocculated with ferric chloride. Before use in the laboratory, the water was sand-filtered, pH-adjusted with gaseous CO2, carbon-filtered, and UV-irradiated. The water is typically monitored weekly for pH, alkalinity, hardness and conductivity. Periodically, the water is monitored for total organic carbon (TOC), total suspended solids (TSS), and selected inorganic and organic compounds. Results from the most recent analysis of the dilution water indicated that TOC was 1.6 mg/L, TSS was < 2 mg/L, and concentrations of contaminants were below levels of concern that may have interfered with the results of this test.

The test vessels were 50-mL glass beakers each containing approximately 40 mL of control or test solution and covered to reduce evaporation. Each test vessel was uniquely labeled for identification purposes (i.e., replicate, study, test level). The definitive test was conducted under static conditions for approximately 48 hours from 21 to 23 March 2017. Four replicate test vessels, each containing approximately 40 mL of the appropriate test solution, were prepared for each test level and water control. Twenty daphnids (five daphnids per replicate) were impartially added to each test level within 30 minutes of completion of test solution preparations. The target test temperature was 20 ± 2°C, and did not vary by > 1ºC over the course of the exposure. The photoperiod was set at 16 hours light/8 hours dark per day. Daphnids were not fed during the exposure period. Daphnids were observed for immobility (inability to swim within approximately 15 seconds after gentle agitation of the test vessel) at approximately 24 and 48 hours of exposure (± 1 hour from exposure initiation). Any sublethal effects (abnormal behavior or appearance) were recorded.

Dissolved oxygen, pH, and temperature were recorded for each bulk test solution at exposure initiation and from all test vessels (spent test solutions) at exposure termination. Water temperature was continuously monitored with a minimum/maximum thermometer placed in a representative vessel. Light intensity was measured at exposure initiation. Water hardness, alkalinity, and conductivity were measured from the control water and the 10 mg/L bulk test solution at exposure initiation.

Reference substance (positive control):

no

Duration:

24 h

Dose descriptor:

EL50

Effect conc.:

> 10 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Key result

Duration:

48 h

Dose descriptor:

EL50

Effect conc.:

7.35 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Duration:

48 h

Dose descriptor:

NOELR

Effect conc.:

5 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat. (dissolved fraction)

Basis for effect:

mobility

Details on results:

Measured concentrations of the major structural component of EPON™ Resin CS-337 in the 0.625, 1.25, 2.50, 5.00 and 10 mg/L bulk test solutions at test initiationwere 0.0307, 0.0553, 0.143, 0.453 and 1.93 mg/L, respectively. Measured concentrations of the major structural component of EPON™ Resin CS-337 in pooled replicate test solutions at exposure termination were 0.0403, 0.0759, 0.172, 0.672 and 2.20 mg/L, equating to 131, 137, 120, 148 and 114% of the measured concentrations at test initiation, respectively. None of the analyses of the controls exhibited a EPON™ Resin CS-337 concentration exceeding the lower limit of quantitation (LLQ) equivalent to 0.01 mg EPON™ Resin CS-337/L (major structural component). Measured concentrations of each loading rate were used to verify test solution preparations and associated stability over the course of the exposure period. The endpoints are reported using the nominal loading rates.

Following 24 hours of exposure, immobility was observed in 30% (6 of 20) of the daphnids at the 10 mg/L test level. At test termination (48-hours of exposure), immobility was observed in 90% (18 of 20) of the daphnids at the 10 mg/L test level. No immobility or sublethal effects (change in daphnid behavior or appearance) were observed at the remaining test levels or water control during the exposure period.

Validity criteria fulfilled:

yes

Conclusions:

The acute toxicity values for Daphnia magna exposed to EPON™ Resin CS-337, over a 48-hour static exposure period and based on nominal loading rates, were as follows:
• The 24-hour EL50 value was empirically determined to be > 10 mg/L (highest loading rate tested).
• The 48-hour EL50 value, calculated by the U.S. EPA Trimmed Spearman-Karber Program, was 7.35 mg/L (95% CI = Not calculable); the Spearman Karber trim was 10.0%.
• The 48-hour NOELR was 5.00 mg/L (Based on the highest loading rate exhibiting no immobility or sublethal effects).

Executive summary:

The purpose of this study was to assess the potential effects of EPON™ Resin CS-337 to the freshwater cladoceran, Daphnia magna, over a 48-hour static exposure period. Due to the limited solubility of this multi-component test material, the study used the wateraccommodated fraction (WAF) preparation method to prepare the test solutions. The study was conducted with four replicate vessels of five daphnids per test level exposed to nominal loading rates of 0 (water control), 0.625, 1.25, 2.50, 5.00, and 10.0 mg EPON™ Resin CS-337/L. Observations were made at 24 and 48 hours (± 1-hour from exposure 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 ranged from 20 to 21ºC. Dissolved oxygen levels ranged from 8.6-8.7 mg/L (99-100% air saturation). The pH was maintained at 7.8 and the light intensity ranged from 204-316 lux. Test solutions were analyzed for the major structural component of EPON™ Resin CS-337 at test initiation and 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 0.01 mg EPON™ Resin CS-337/L (major structural component). Measured concentrations of the major structural component of EPON™ Resin CS-337 at exposure termination ranged from 114 to 148% of the measured concentrations at test initiation. The measured concentrations of the test solutions were used to verify test solution preparations and associated stability over the course of the exposure period. Study endpoints are reported using the nominal loading rates. The acute toxicity values for the daphnid (D. magna) exposed to EPON™ Resin CS-337 over a 48-hour static exposure period and based on nominal loading rates were as follows:

• 24-hour EL50: > 10.0 mg/L (highest loading rate tested)

• 48-hour EL50: 7.35 mg/L (95% CI = Not Calculable)

• 48-hour NOELR: 5.00 mg/L (Based on the highest loading rate exhibiting no immobility or sublethal effects)

Description of key information

The acute toxicity values for the daphnid (D. magna) exposed to EPON™ Resin CS-337 over a 48-hour static exposure period and based on nominal loading rates were as

follows:

• 24-hour EL50: > 10.0 mg/L (highest loading rate tested)

• 48-hour EL50: 7.35 mg/L (95% CI = Not Calculable)

• 48-hour NOELR: 5.00 mg/L (Based on the highest loading rate exhibiting no immobility or sublethal effects)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

7.35 mg/L