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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:
2017-06-29 to 2017-10-06
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)
Deviations:
no
Qualifier:
according to guideline
Guideline:
EPA OPPTS 850.1010 (Aquatic Invertebrate Acute Toxicity Test, Freshwater Daphnids)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
Analytical Sampling
Test water samples were collected from the batches of test solution prepared for each treatment and control group at the beginning of the test, and from two of the four replicate test chambers in each treatment and control group at 48 hours (± 1 hour) to measure concentrations of the test substance.
Samples (20 mL) were collected from mid-depth and placed in glass vials. Concentrated phosphoric acid (20.0 µL) was added to each vial, and the samples were processed immediately for analysis.
Vehicle:
no
Details on test solutions:
Dilution Water
The water used for organism holding and testing was freshwater obtained from a well approximately 40 meters deep located on the EAG Laboratories site in Easton, Maryland. The well water was passed through a sand filter to remove particles greater than approximately 25 ¿m, and pumped into a 37,800-L storage tank where the water was aerated with spray nozzles. Prior to use in the test system, the water was filtered to 0.45 ¿m to remove fine particles and was passed through an ultraviolet (UV) sterilizer.

The well water is characterized as moderately-hardwater. The specific conductance, hardness, alkalinity, pH and total organic carbon (TOC) content of the well water during the approximate four-week period immediately preceding the test as well as the results of periodic analyses performed to measure the concentrations of selected organic and inorganic constituents in the well water are presented in "any other information on materials and methods incl. tables".

Preparation of Test Concentrations
A primary stock solution was prepared by mixing a calculated amount of test substance in a 2-L volumetric flask with dilution water at a nominal concentration of 100 mg a.i./L, the highest concentration tested. The stock solution concentration was adjusted to 100% active ingredient during preparation, based on the reported test substance purity (84.6%). The stock solution was partially brought to volume with dilution water and sonicated for 15 minutes. The flask was then brought to volume and stirred on a magnetic stir plate for 15 minutes, and appeared clear and colorless with no visible precipitates. Aliquots of the primary stock solution were proportionally diluted in 1-L volumetric flasks with dilution water to prepare four additional test solutions at nominal concentrations of 6.3, 13, 25 and 50 mg a.i./L. The
solutions were stirred on a magnetic stir plate for 15 minutes, and approximately 200 mL of solution was placed in each of four replicate test chambers per treatment group. The negative control solution was dilution water only.

Test organisms (species):
Daphnia magna
Details on test organisms:
The cladoceran, Daphnia magna, was selected as the test species for this study. This species is representative of an important group of aquatic invertebrates and was selected for use in the test based upon past history of use in the laboratory. Daphnids used in the test were <24-hour old neonates obtained from cultures maintained by EAG Laboratories in Easton, Maryland. Identification of the species was verified by the supplier of the original stock culture.

Adult daphnids were cultured in water from the same source and at approximately the same temperature as used during the test. During the 2-week period immediately preceding the test, water temperatures in the cultures ranged from 19.7 to 20.8ºC, the pH of the water ranged from 8.0 to 8.5, and the dissolved oxygen concentrations were >= 7.6 mg/L (¿ 84% of saturation). The three adult daphnids used to supply neonates for the test were held for 13 days prior to collection of the juveniles for testing, and had each produced at least one previous brood. Adult daphnids in the culture had produced an average of at least three young per adult per day over the 7-day period prior to the test. The adults showed no signs of disease or stress, no ephippia were produced during the holding period, and mortality in the culture stock was 0% in the two-day period prior to test initiation.

Feeding
Daphnids in the cultures were fed daily a mixture of yeast, cereal grass media and trout chow (YCT), supplemented with a vitamin stock solution and a suspension of the freshwater green alga, Raphidocelis subcapitata. The adults were fed during the 24-hour period prior to test initiation, but neonates were not fed during the test.

Test type:
static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
48 h
Hardness:
144 mg/L as CaCO3
Test temperature:
19.5 - 20.5 (see table below)
pH:
8.1 - 8.5 (see table below)
Dissolved oxygen:
8.3 - 9.1 mg/L (see table below)
Nominal and measured concentrations:
Nominal concentrations: 0, 6.3, 13, 25, 50 mg/L
Reference substance (positive control):
no
Key result
Duration:
48 h
Dose descriptor:
EC50
Effect conc.:
19 mg/L
Nominal / measured:
meas. (arithm. mean)
Conc. based on:
test mat.
Basis for effect:
mobility

Table 4.

Cumulative Immobility and Observations

 

Mean

Measured

Concentration

(mg a.i./L)

 

 

 

Rep.

 

 

No.

Exposed

~ 3.5 Hours

 

24 Hours

 

48 Hours

 

Cumulative

Percent

Immobile

Number Immobile1

 

Observations2

 

Number Immobile1

 

Observations2

 

Number Immobile1

 

Observations2

Negative

A

5

0

5 AN

 

0

5 AN

 

0

5 AN

0

Control

B

5

0

5 AN

 

0

5 AN

 

0

5 AN

 

 

C

5

0

5 AN

 

0

5 AN

 

0

5 AN

 

 

D

5

0

5 AN

 

0

5 AN

 

0

5 AN

 

 

 

 

 

 

 

 

 

 

 

 

 

6.1

A

5

0

5 AN

 

0

5 AN

 

0

5 AN

0

 

B

5

0

5 AN

 

0

5 AN

 

0

5 AN

 

 

C

5

0

5 AN

 

0

5 AN

 

0

5 AN

 

 

D

5

0

5 AN

 

0

5 AN

 

0

5 AN

 

 

 

 

 

 

 

 

 

 

 

 

 

13

A

5

0

5 AN

 

0

5 AN

 

0

2 C; 1 Q,AN; 2 AN

0

 

B

5

0

5 AN

 

0

5 AN

 

0

2 C; 1 Q,C; 2 AN

 

 

C

5

0

5 AN

 

0

5 AN

 

0

2 C; 1 Q,AN; 2 AN

 

 

D

5

0

5 AN

 

0

5 AN

 

0

2 C; 1 Q,AN; 2 AN

 

 

 

 

 

 

 

 

 

 

 

 

 

25

A

5

0

5 AN

 

2

1 C; 2 AN

 

5

--

90

 

B

5

0

5 AN

 

4

1 C

 

5

--

 

 

C

5

0

5 AN

 

1Q+1

3 AN

 

1Q+3

1 C

 

 

D

5

0

5 AN

 

1Q+3

1 AN

 

1Q+3

1 C

 

1   Cumulative number of immobile daphnids. Any immobile daphnids were removed from the test chambers at each observation interval.

2   Observations of surviving organisms: AN = appear normal; C = lethargy; Q = trapped at water surface; Q,AN = trapped at water surface but appear normal after gentle submersion; Q,C = trapped at water surface and appear lethargic after gentle submersion.

Table 4 (Continued)

Cumulative Immobility and Observations

 

Mean

Measured

Concentration

(mg a.i./L)

 

 

 

Rep.

 

 

No.

Exposed

~ 3.5 Hours

 

24 Hours

 

48 Hours

 

Cumulative

Percent

Immobile

Number Immobile1

 

Observations2

 

Number Immobile1

 

Observations2

 

Number Immobile1

 

Observations2

49

A

5

0

5 AN

 

5

--

 

5

--

100

 

B

5

0

5 AN

 

4

1 AN

 

5

--

 

 

C

5

0

5 AN

 

3

1 Q,C; 1 AN

 

2Q + 3

--

 

 

D

5

0

5 AN

 

5

--

 

5

--

 

 

 

 

 

 

 

 

 

 

 

 

 

99

A

5

0

5 AN

 

5

--

 

5

--

100

 

B

5

0

5 AN

 

5

--

 

5

--

 

 

C

5

0

5 AN

 

5

--

 

5

--

 

 

D

5

0

5 AN

 

5

--

 

5

--

 

1  Cumulative number of immobile daphnids. Any immobile daphnids were removed from the test chambers at each observation interval.

2  Observations of surviving organisms: AN = appear normal; C = lethargy; Q = trapped at water surface; Q,C = trapped at water surface and appear lethargic after gentle submersion.

Table 5

EC50ValuesBased on Mean Measured Test Concentrations

 

 

Time

EC50

(mg a.i./L)

95% Confidence Interval

(mg a.i./L)

Statistical

Method

24 Hours

27

22 – 32

Probit Analysis

48 Hours

19

13 – 25

Binomial Analysis1

1 The EC50value was estimated using non-linear interpolation between 13 and 25 mg a.i./L; the 95% confidence limits were determined by binomial probability.

 

RESULTS AND DISCUSSION

Measurement of Test Concentrations

Nominal concentrations selected for use in this study were 6.3, 13, 25, 50 and 100 mg a.i./L. Test solutions in the test chambers at these nominal concentrations appeared clear and colorless during the test, with no evidence of precipitation observed.

Results of analyses to measure concentrations of 1,3-butylene glycol diacrylate in the test solution samples collected during the test are presented in Table 1. Measured concentrations of the samples ranged from approximately 94 to 102% of nominal. When measured concentrations of the samples were averaged, the mean measured test concentrations for this study were 6.1, 13, 25, 50 and 100 mg a.i./L, representing 97, 98, 99, 100 and 100% of nominal concentrations, respectively. The results of the study were based on the mean measured concentrations.

Observations and Measurements

Measurements of temperature, pH and dissolved oxygen of the water in the test chambers are presented in Table 2. Water temperatures were within the 20 ± 1¿C range established for the test. Measurements of pH ranged from 8.1 to 8.5. Dissolved oxygen concentrations remained = 8.3 mg/L (= 91% of saturation) throughout the test. The measurements of hardness, alkalinity, specific conductance and TOC in the dilution water at the beginning of the test were typical of EAG Laboratories-Easton well water (Table 3). Light intensity at the beginning of the test was 750 lux at the surface of the water of one representative test chamber.

Daily observations of immobility and other signs of toxicity observed during the test are presented in Table 4. All daphnids in the negative control appeared normal throughout the test. All daphnids in the 6.1 mg a.i./L treatment group also appeared normal throughout the test, with no immobile daphnids or overt signs of toxicity observed. Percent immobility in the 25, 50 and 100 mg a.i./L treatment groups at test termination were 90, 100 and 100%, respectively. Signs of toxicity observed among the surviving daphnids in the 13, 25, 50 and 100 mg a.i./L treatment groups at test termination included lethargy and floating. Therefore in this study, the no-immobility concentration was 13 mg a.i./L, and the NOEC was 6.1 mg a.i./L. EC50 values at 24 and 48 hours were determined from the immobility

data and are shown in Table 5.

Conditions for the Validity of the Test

The following criteria were used to judge the validity of the test and were met in this study:

1. Immobility of the daphnids in the control group will not exceed 10% by the end of the test. In this study, immobility in the control group was 0%.

2. The dissolved oxygen concentration will be at least 60% of the air-saturation value throughout the test. In this study, the dissolved oxygen concentration remained = 91% of saturation.

 
Validity criteria fulfilled:
yes
Conclusions:
The cladoceran, Daphnia magna, was exposed for 48 hours under static conditions to five mean measured concentrations of 1,3-butylene glycol diacrylate ranging from 6.1 to 100 mg a.i./L. Based on the mean measured concentrations, the 48-hour EC50 value was 19 mg a.i./L, with a 95% confidence interval of 13 to 25 mg a.i./L. The no-immobility concentration was 13 mg a.i./L, and the NOEC was 6.1 mg a.i./L.
Executive summary:

The cladoceran, Daphnia magna, was exposed for 48 hours under static conditions to five mean measured concentrations of 1,3-butylene glycol diacrylate ranging from 6.1 to 100 mg a.i./L. Based on the mean measured concentrations, the 48-hour EC50 value was 19 mg a.i./L, with a 95% confidence interval of 13 to 25 mg a.i./L. The no-immobility concentration was 13 mg a.i./L, and the NOEC was 6.1 mg a.i./L.

Description of key information

A study assessing the acute toxicity of 1,3-BUTYLENE GLYCOL DIACRYLATE (CAS 19485-03-1) to Daphnia magna was conducted in accordance with the OECD 202 and OPPTS 850.1010 Test Guidelines and GLP requirements.

The 48h-EC50 was determined to be 19 mg/L.

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
19 mg/L

Additional information