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Long-term toxicity to aquatic invertebrates

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Reference
Endpoint:
long-term toxicity to aquatic invertebrates
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
key study
Study period:
28 Jan 2009 - 10 July 2009
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
other: Guideline study conducted in compliance with GLP regulations
Justification for type of information:
REPORTING FORMAT FOR THE ANALOGUE APPROACH

For the acrylate esters, LC50 values in freshwater fish ranged from 1.81 and 5.2 mg/L, EC50 values in freshwater invertebrates (Daphnia magna) were between 1.3 and 8.74 mg/L, and EC50 values in freshwater algae were between 1.71 and 14.6 mg/L, respectively. Thus, effect values were all in the same range of concentrations with Daphnia magna as the most sensitive freshwater species by a narrow margin. A 21-day chronic life-cycle study with Daphnia magna is available with ethyl acrylate (CAS No. 140-88-5) with a NOEC of 0.19 mg/L, and another with n-butyl acrylate (CAS No. 141-32-2) with a NOEC of 0.136 mg/L. In addition, several NOEC values from studies in algal species are available ranging from 0.45 to 3.85 mg/L.
Reason / purpose for cross-reference:
read-across source
Qualifier:
according to guideline
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Deviations:
no
GLP compliance:
yes (incl. QA statement)
Analytical monitoring:
yes
Details on sampling:
- Concentrations:
1. From the stock solution:
Samples were taken on the following days:
Day 0 (fresh stock solution)
Day 1 (fresh stock solutions)
Day 2 (fresh and 24 hours old stock solutions)
Day 3 (fresh and 24 hours old stock solutions)
Day 4 (24 hours old stock solutions)
Day 10 (fresh stock solution)
Day 11 (24 hours old stock solution)

2. From the test solutions:
Samples were taken from the following test groups: 0.46, 1.0, 2.2 mg/L
Samples were taken on the following days:
Day 16 (fresh test solution)
Day 17 (24 hours old test solution)
Day 17 (fresh test solution)
Day 18 (24 hours old test solution)
Day 20 (fresh test solution)
Day 21 (24 hours old test solution)

- Sampling method: The concentration of the test substance was determined in each freshly prepared test solution (test vessels without daphnids) and in the 24 hour old test solutions before renewal (combined sample from test vessels with daphnids).
- Sample storage conditions before analysis: ambient temperature / samples were analyzed immediately
Vehicle:
no
Details on test solutions:
PREPARATION AND APPLICATION OF TEST SOLUTION
- Method: The test substance was homogenized by shaking the container before use. The stock solution (10 mg/L) was prepared by dissolving 10 mg of test substance in 1 L of test medium and stirring for approximately 5 min at 20 ± 2 °C. The test solutions were prepared by dilution of this stock solution. Before the dilution was performed, the stock solution was checked for complete dissolution of the test substance.
Fresh stock solution and test solutions were prepared and renewed daily.
- Controls: negative control (only test medium)
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no. All stock solutions were visibly colorless and clear after preparation.
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Strain/clone: Daphnia magna STRAUS
- Source: The clone of Daphnia magna STRAUS 1820 used was supplied by the Institut National de Recherche Chimique Appliquée, France, in 1978.
From this date on this clone was cultured and bred continuously in the Laboratory of Ecotoxicology of the Experimental Toxicology and Ecology of BASF SE in Ludwigshafen.
- Age of parental stock (mean and range, SD): no data
- Feeding during test
- Food type: Unicellular green algae (Desmodesmus subspicatus CHODAT)
- Amount: d 0-3: 0.10 mg TOC; d 4-5: 0.12 mg TOC; d 6-7: 0.14 mg TOC; d 8-21: 0.20 mg TOC/parent animal/day
- Frequency: daily


ACCLIMATION
- Acclimation period: Since the culturing and testing parameters of temperature, dilution water hardness, and lighting were the same, no acclimation period was necessary.
- Acclimation conditions (same as test): yes
- Health during acclimation (any mortality observed): no mortality, no signs of stress, disease, or physical damage


QUARANTINE (wild caught)
- Duration:
- Health/mortality:


METHOD FOR PREPARATION AND COLLECTION OF EARLY INSTARS OR OTHER LIFE STAGES:
Test type:
semi-static
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Post exposure observation period:
none
Hardness:
2.20 – 3.20 mmol/L
Test temperature:
20 – 21 °C (continuous monitoring)
pH:
8.0 – 8.2
Dissolved oxygen:
8.8 - 9.1 mg/L
Nominal and measured concentrations:
- Nominal concentrations: 0, 0.1, 0.22, 0.46, 1.0, 2.2 mg/L
- Analytical concentrations: 0, 0.136 (nominal 0.46), 0.457 (nominal 1.0), 1.226 (nominal 2.2) mg/L
The mean values of n-Butyl Acrylate (n-BA) in M4-medium were found to be in the range of 9.3 – 80.0 % of the nominal concentration.
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Type: closed
- Material, size, headspace, fill volume: Numbered glass flasks (nominal volume 50 mL), covered with ground glass stoppers (closed test vessels).
- Aeration: no (To assure optimal dissolved oxygen levels, the M4 medium was aerated for approximately 24 hours prior to use.)
- Renewal rate of test solution (frequency/flow rate): daily
- No. of organisms per vessel: 1 animal / test vessel
- No. of vessels per concentration (replicates):
- No. of vessels per control (replicates):
- Biomass loading rate: 0.02 animals / mL


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: A synthetic fresh water (Elendt M4) was used as media for culture and test purposes. For the composition of this M4 medium see OECD 211.
- Ca/mg ratio: about 4 : 1
- Conductivity: 550 - 650 μS/cm
- Acid capacity up to pH 4.3: 0.80 – 1.00 mmol/L
- Culture medium different from test medium: no
- Intervals of water quality measurement: once weekly



OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: 16 hours light : 8 hours darkness
- Light intensity: About 615 - 700 lux at a wave length of 400 -750 nm (recommended values in lux units provided in ISO 10706)


EFFECT PARAMETERS MEASURED (with observation intervals if applicable):
- Daily observation of young production, mortality of the parent animals and young, and presence of aborted eggs.
- Daily observation of the appearance of the test solutions and dissolution behavior of the test substance.
- Determination of the chemical and physical parameter of the test medium prior to use: Total hardness, acid capacity, pH value and conductivity of the water after aeration and new preparation.
- Measurement of pH, oxygen and temperature in the test solutions: In the old and in the freshly prepared test solution in replicate 1 of each concentration for one interval per week.
- Measurement of hardness in the test solutions: In the freshly prepared test solution in an additional replicate of each concentration for one interval per week and in the old test solution in a combined replicate of each concentration for one interval per week.
- Measurement of temperature continuously during the whole period in a separate vessel filled with water proximal to the test vessels.
- The body length of the parent animals was determined at the end of exposure. The body length (excluding the anal spine and protruding second antennae) was determined with a microscope (Leitz Diavert) and the scale used was checked with a standardized slide.



VEHICLE CONTROL PERFORMED: no


RANGE-FINDING STUDY
- Results used to determine the conditions for the definitive study: In a preliminary test (experimental conduct in accordance with GLP but without a GLP status), after 19 days exposure to the test substance, no significant effect on reproduction was observed at 0.1 mg/L; however, a small reduction in offspring was observed at 1 mg/L.
Reference substance (positive control):
not specified
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
0.457 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.136 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
1.226 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
: length
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
0.457 mg/L
Nominal / measured:
meas. (TWA)
Conc. based on:
test mat.
Basis for effect:
growth
Remarks:
: length
Details on results:
- Mortality of parent animals: no mortality related to the test substance
- Mean dead young: none
- Type and number of morphological abnormalities: none
- Type and number of behavioural abnormalities: none
- Time to first brood release: 11 days (except in the highest concentration: 12 days)
- Mean aborted eggs:
control: 0.1
0.1 mg/L: 0.0
0.22 mg/L: 0.6
0.46 mg/L: 0.8
1.0 mg/L: 1.2
2.2 mg/L: 0.3

Validity criteria:

• In the control the mortality of parent animals up to the end of the test was 0 %.

• In the control the mean number of living young per parent animal that survived the test was 95.

• No ephippia were produced in the controls.

In conclusion the test was considered to be valid.

 

 

ANALYTICAL CONCENTRATION CONTROL

 

At the start of exposure, samples for analysis were collected from the stock solution only because the analytical laboratory reported an LOQ of 4.648 mg/L. For each measurement interval, the stock solution was kept under test conditions. During course of the experiment, the analytical lab lowered the LOQ to 0.513 mg/L. Based on this information, the three highest test concentrations were analyzed over 3 daily renewal intervals starting on day 16 of the study. The final calculated LOQ reported by the analytical laboratory was 0.104 mg/L.

The analytically measured concentrations of the stock solution were lower than the expected nominal concentrations, most likely due to some volatilization of the test substance during solution preparation. However, all measured concentrations were within ± 20% of the measured mean initial concentration indicating that the test substance was stable under test conditions at the stock concentration.

The analytically determined concentrations of the test substance in the test solutions deviated by more than 20% from the nominal or mean initial measured concentrations. Therefore the time-weighted mean measured concentrations were calculated and will be used to evaluate the biological results.

 

Analytically measured concentrations of n-Butyl acrylate in the stock solutions:

 

Nominal concentration

Time period

Analytically measured concentration

 

 

Overall mean

Mean initial

[mg/L]

 

[mg/L]

[%]a

[mg/L]

[%]b

10

Day 0

6.933

102

6.823

68

Day 1-2

Day 2-3

Day 3-4

Day 10-11

a: % of mean initial

b: % of nominal

 

Analytically measured concentrations of n-Butyl acrylate in the test solutions:

 

Nominal concentration

Time period

Analytically measured concentration

 

 

Initial

24 h old

Time-weighted mean

[mg/L]

 

[mg/L]

[mg/L]

[mg/L]

[%]a

[%]b

0

Day 16-17

n.d.

n.d.

n.d.

-

-

Day 17-18

n.d.

n.d.

Day 20-21

n.d.

n.d.

0.46

Day 16-17

0.234

0.071

0.136

56

30

Day 17-18

0.250

0.043

Day 20-21

0.240

0.091

1

Day 16-17

0.553

0.310

0.457

79

46

Day 17-18

0.583

0.324

Day 20-21

0.607

0.427

2.2

Day 16-17

1.352

0.992

1.226

88

56

Day 17-18

1.370

0.986

Day 20-21

1.465

1.235

a: % of mean initial

b: % of nominal

n.d.: not determined

BIOLOGICAL RESULTS

 

Reproduction and Growth Summary (mean per surviving replicates after 21 days):

 

Nominal concentration

Reproduction

Growth

[mg/L]

Mean living young

% effectb

Mean length [mm]

% effectb

0

95.3 (9.6%a)

-

4.0

-

0.1

100.3

-

4.1

-

0.22

92.7

-

4.1

-

0.46

94.4

-

4.1

-

1.0

84.7*

11.1*

4.1

-

2.2

68.1**

28.5**

3.6**

10**

a: Coefficient of variation for control fecundity

b: Effect relative to control (only calculated for statistically significant effects).

*: p<0.05

**: p<0.01

Validity criteria fulfilled:
yes

Description of key information

In the structurally related n-butyl acrylate and ethyl acrylate NOECs of 0.136 and 0.19 mg/L respectively were determined for long-term toxicity towards Daphnia magna. 
Data from the structurally related n-butyl acrylate:
NOEC (reproduction) = 0.136 mg/L (Daphnia magna, OECD 211, semi-static)
Data from the structurally related ethyl acrylate:
NOEC (reproduction) = 0.19 mg/L (Daphnia magna, EPA OTS 797.1330, flow-through)

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates
Effect concentration:
0.136 mg/L

Additional information

There are no data on long-term toxicity towards invertebrates for methyl acrylate. But for the structurally related ethyl acrylate and n-butyl acrylate 21 -day chronic toxicity studies are available (BAMM 1997, BASF SE 2009).

 

A 21 -day Daphnia magna Reproduction Test sponsored by The Acrylate REACh Task Force was performed with n-Butyl acrylate under semi-static conditions in accordance with OECD TG 211 and GLP regulations (BASF SE, 2009). Nominal test concentrations were 0, 0.1, 0.22, 0.46, 1.0, and 2.2 mg/L. Since the mean values of n-Butyl Acrylate in M4-medium were found to be in the range of 9.3 – 80.0 % of the nominal concentrations, the effect concentrations were based on the time-weighted mean analytically detected concentrations. The most sensitive effect values were concerning reproduction: NOEC (reproduction) = 0.136 mg/L; LOEC (reproduction) = 0.457 mg/L. Survival of the parent or young daphnia was not effected, but the growth of the parent animals: NOEC (body length) = 0.457 mg/L; LOEC (body length) = 1.226 mg/L.

 

In addition, a 21-day chronic study with Ethyl acrylate in Daphnia magna was conducted under flow-through conditions according to EPA OTS 797.1330 (BAMM, 1997). Nominal exposure concentrations ranged from 0.38 to 6.0 mg/L. Mean measured test concentrations ranged from 0.19 to 3.2 mg/L. Effect concentrations based on measured values were as follows: EC50 was 0.5 mg/L; NOEC (reproduction) = 0.19 mg/L; LOEC (reproduction) = 0.45 mg/L and MATC (reproduction) = 0.29 mg/L.