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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:
experimental study
Adequacy of study:
key study
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Qualifier:
according to
Guideline:
OECD Guideline 211 (Daphnia magna Reproduction Test)
Version / remarks:
Cited as OECD Guide-line 202, part 2 (Daphnia sp., Reproduction Test)
GLP compliance:
yes
Specific details on test material used for the study:
- Name of test material (as cited in study report): methyl methacrylate
- Physical state: clear colourless liquid
- Analytical purity: 99.96 %
- Lot/batch No.: 6/11/96
- Storage condition of test material: stored at room temperature in a dark, ventilated cabinet
- Other: obtained from Rohm and Haas
Analytical monitoring:
yes
Details on sampling:
- Sampling method: Both replicates of each treatment level and the controls were sampled and analyzed for MMA concentration twice prior to the start of the definitive exposure. During the in-life phase of the definitive test, water samples were removed from both replicate vessels of each treatment level and the controls and analyzed for MMA concentrations on test days 0, 7, 14, 15 and 21. Three quality control samples were also prepared at each sampling interval and remained with the appropriate set of exposure solution samples throughout the analytical process.
Vehicle:
no
Test organisms (species):
Daphnia magna
Details on test organisms:
TEST ORGANISM
- Common name: water flea
- Source: Daphnia magna were obtained from laboratory cultures maintained at Springborn
- Age of parental stock (mean and range, SD): at test initial < 24 hours
- Feeding during test
- Food type: algal suspension
- Frequency: two to three times daily
Test type:
flow-through
Water media type:
freshwater
Limit test:
no
Total exposure duration:
21 d
Hardness:
as CaCO3: 160 to 180 mg/L
Test temperature:
19 to 21 °C
pH:
7.9 to 8.3
Dissolved oxygen:
8.6 - 9.1 mg/L
Nominal and measured concentrations:
Nominal test concentration: 13, 25, 50, 100 and 200 mg A.I./L
Mean measured concentration: 3.9, 10, 18, 37 and 68 mg A.I./L
Details on test conditions:
TEST SYSTEM
- Test vessel:
- Material, size, headspace, fill volume: 2 L battery jar filled with 1.8 litre test solution.
- Type of flow-through (e.g. peristaltic or proportional diluter): The toxicity test was conducted using an exposure system consisting of an intermittent flow proportional diluter (Mount and Brungs, 1967).
- Renewal rate of test solution (frequency/flow rate): 6.0 solution volume replacements per day
- No. of organisms per vessel: 20
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water:
- Total organic carbon: 0.86 to 0.91 mg/L
- Alkalinity: 110 - 120 mg/L as CaCO3
- Conductivity: 500 µMhos/cm
- Chlorine: <0.03 mg/L
- Intervals of water quality measurement: pH, dissolved oxygen and temperature daily. Hardness, alkalinity and conductivity at test initiation and weekly thereafter.


OTHER TEST CONDITIONS
- Photoperiod: 16 hours light and 8 hours darkness with transition time
- Light intensity: Exposure vessels were maintained in an area illuminated (32 to 65 footcandles) with Sylvania Cool White® and Duro-Test® Vita-Lite®fluorescent bulbs.


EFFECT PARAMETERS MEASURED:
The number of immobilized adult daphnids and observations of abnormal behavior were recorded at test initiation and on days 1, 2, 4, 7, 9, 11, 14, 16, 18 and 21. Assessments of offspring production were determined on day 7 and three times per week through test termination (day 21). Survival and reproduction were determined by counting and observing adult organisms as they were carefully pipetted from the exposure vessels to a 100 mL beaker containing approximately 50 mL of the respective test solution.
Reference substance (positive control):
no
Key result
Duration:
21 d
Dose descriptor:
NOEC
Effect conc.:
37 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
LOEC
Effect conc.:
68 mg/L
Nominal / measured:
meas. (geom. mean)
Conc. based on:
act. ingr.
Basis for effect:
reproduction
Duration:
21 d
Dose descriptor:
EC50
Effect conc.:
49 mg/L
Conc. based on:
act. ingr.
Basis for effect:
other: survival
Remarks on result:
other: 95% C.I. = 37 - 68 mg/L
Details on results:
The 21-day EC50 was estimated by nonlinear interpolation to be 49 mg A.I./L (corresponding 95 % confidence limit calculated by binominal probability of 37 to 68 mg A.I./L). The data generated during 21-day study established that daphnid survival was significantly affected by exposure to 68 mg A.I./L of methyl methacrylate. Daphnid reproduction was not adversely affected by exposure to concentrations less than those affecting daphnid survival.
Reported statistics and error estimates:
Statistical methods:
Analyses were performed using the mean organism response in each vessel rather than individual response values. All statistical conclusions were made at the 95% level of certainty except in the case of the Shapiro-Wilks Test and the's Test, in which the 99% level of certainty was applied. The following procedures were used:
1.) Significant differences in the percent survival were determined after arcsine square-root percentage transformation of the data.
2.) The Shapiro-Wilks Test for normality was conducted to compare the observed sample distribution with a normal distribution. If the data were not normally distributed, then a non-parametric procedure was used for subsequent analysis.
3.) Test was utilized to verify homogeneity of variance.
4.) Williams' Test was used to evaluate survival and reproduction parameters.
The Maximum Acceptable Toxicant Concentration (MATC) is the theoretical threshold concentration expected to produce no deleterious effects and is equal to the geometric mean of the limits set by the LOEC and the NOEC.

Since the survival among daphnids exposed to the highest concentration of methyl methacrylate tested (68 mg a.i.Ll) was significantly reduced, reproduction data for this

concentration was not statistically analyzed to establish treatment effects. At test termination, the number of offspring released among organisms exposed to the remaining treatment levels

(3.9, 10, 18 and 37 mg a.i./L) averaged 73, 50, 63 and 64 offspring per female, respectively, and  was not significantly different from the number of offspring released by the control organisms

(62 offspring per female). First brood release for the organisms exposed to all of the treatment levels occurred between test days 8 and 9 and was consistent with the control organisms (test

day 8). Throughout the exposure period, no young were observed to be immobilized in any treatment levels tested or the control solutions.

Mean cumulative number of offspring produced per female daphnid (Daphia magna) during the 21-day chronic exposure to methyl methacrylate

Mean measuerd conc

[mg/l]

Mean cumulative number of offspring/female

Day 7

Day 9

Day 11

Day 14

Day 16

Day 18

Day 21

control

0

3

11

31

38

51

52

3.9

0

1

5

36

43

57

73

10

0

4

13

28

36

45

50

18

0

4

18

42

45

57

63

37

0

3

11

27

38

52

64

68

0

1

1

3

9

10

10*

*Data execute from statistical analysis due to a significant survival effect at this treatment level. Statistical analysis was performed only on the reproduction data from test day 21

Validity criteria fulfilled:
yes
Conclusions:
The 21-day NOEC of methyl methacrylate based on reproduction was 37 mg/l. Daphnid reproduction was not adversely affected by exposure to concentrations less than those affecting daphnid survival.
Executive summary:

The 21-day-chronic toxicity of methyl methacrylate to Daphnia magna Straus was studied under flow through conditions according to OECD guideline 211 (cited as OECD Guide-line 202, part 2 (Daphnia sp., Reproduction Test). Daphnids were exposed the test chemical at nominal test concentration of  13, 25, 50, 100 and 200 mg/L corresponding to measured concentrations of 3.9, 10, 18, 37 and 68 mg/L

The 21 d EC50 based on mortality was 49 mg/l ( corresponding 95 % confidence limit calculated by binominal probability of 37 to 68 mg).

The 21-day NOEC based on reproduction was 37 mg/l. Daphnid reproduction was not adversely affected by exposure to concentrations less than those affecting daphnid survival.

Description of key information

The 21-day-chronic toxicity of methyl methacrylate to Daphnia magna Straus was studied under flow through conditions according to OECD guideline 211. The 21-day NOEC based on reproduction was 37 mg/l.

Daphnid reproduction was not adversely affected by exposure to concentrations less than those affecting daphnid survival.

Key value for chemical safety assessment

EC10, LC10 or NOEC for freshwater invertebrates:
37 mg/L

Additional information