Methacrylic acid

Long-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

long-term toxicity to aquatic invertebrates

Type of information:

experimental study

Adequacy of study:

key study

Study period:

24.07.1995 to 14.08.1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: see 'Remark'

Remarks:

According to OECD-guideline no. 202, part II, 21 days flow through conditions, five concentrations (14, 30, 53, 110 and 230 mg/l; measured) were tested. Due to the steep dose/response curve in both acute and chronic daphnia toxicity study, the missing result of the 30 mg/l concentration group is without relevance because this concentration was less than the established NOEC (53 mg/l).

Qualifier:

equivalent or similar to guideline

Guideline:

OECD Guideline 211 (Daphnia magna Reproduction Test)

Version / remarks:

TSCA Test Guideline 797.1330. Daphnid chronic toxicity tes and OECD Guide-line 202, part 2 (Daphnia sp., Reproduction Test)

GLP compliance:

yes

Specific details on test material used for the study:

Glacial methacrylic acid; purity: 97.11 %.
Clear liquid.
Lot number 0034D002
Supplier: Rohm and Haas
Storage conditions: at room temperature in the dark.

Analytical monitoring:

yes

Details on sampling:

Both replicates of each treatment level and control were analyzed for MAA concentration twice prior to the start of the definitive exposure. Each replicate solution was sampled and analyzed for MAA concentration on day 0 and weekly thereafter (day 7, 14 and 21).
Each sample was collected from the approximate midpoint of the test vessel by volumetric pipette.
Three quality control samples (QC) were also prepared at each sampling interval.

Vehicle:

no

Details on test solutions:

Nominal concentrations were maintained by introducing approximately 6.0 aquarium volumes per day of newly prepared test solution via an intermittent proportional flow through dilution apparatus.

Test organisms (species):

Daphnia magna

Details on test organisms:

Organisms were obtained from laboratory cultures maintained at Springborn. Culture water was prepared by fortifying well water and filtering. Two weeks prior to study intiation the water had total hardness and total alkalinity ranges of as CaCO3 of 160-180 and 110-120 mg/L, respectively, a pH range of 7.4 to 8.5, a specific conductance range of 500-600 µmhos/cm and a dissolved oxygen concentration >60%. Light intensity ranged from 70-90 footcandles. The culture solution temperature was maintained at 20 +/-2C. Daphnia were fed once daily.
Age of daphnids at study initiation: < 24 hours
Daphnids culture area: 16 hours light, 8 hours dark
Light intensity: 70 to 90 footcandles
Temperature: 20 +/- 2 °C
Feeding: Combination of unicellular green algae (Ankistridemus falctus, 4x10E7 cll/ml) and Selenastrum capricornutum (3.5 x 10 E7 cell/ml) one daily. Food was perodically analysed for the precence of psticides, PCBs and toxic metlas.

Test type:

flow-through

Water media type:

freshwater

Limit test:

no

Total exposure duration:

21 d

Hardness:

160-180 mg CaCO3/L.

Test temperature:

20 - 21°C

pH:

5.6 - 8.1 (at 14 - 110 mg/l)
4.2 - 5.7 (at 230 mg/l)

Dissolved oxygen:

8.6 - 9.2 mg/l

Nominal and measured concentrations:

The defiintitive study was performed at nominal concentrations of 13, 25, 50, 100 and 200 mg a.i./L.
Based on results of weekly analysis, mean measured concentrations of MAA averaged 110% of nominal concentrations and defined the exposure concentrations as 14, 30, 53, 110 and 230 mg a.i./L.Test concentrations were chosen based on two preliminary studies

Details on test conditions:

TEST SYSTEM
- Test vessel: Set of 12 exposure vessels. The test system was designed to provide five concentrations of the test material and a dilution water control
2 replicates per dose group.
20 daphnids per test vessel

- Material, size, headspace, fill volume: glass test vessel (1.6-L battery jar) maintained a constant solution volume of 1.4 L and a solution depth of approximately 15 cm

- Aeration: no aeration
- Type of flow-through: intermittend flow through diluter apparatus
- Renewal rate of test solution (frequency/flow rate): daily renewal
- No. of organisms per vessel: 20 daphnids per replicate vessel
- No. of vessels per concentration (replicates): 2
- No. of vessels per control (replicates): 2
- No. of vessels per vehicle control (replicates): not applicable
- Biomass loading rate: Biomass will not exceed 0.1 grams for each 11ter per day of test solution flow

TEST MEDIUM / WATER PARAMETERS
- pH: 7.9 to 8.3

- Source/preparation of dilution water:
- Alkalinity: Total alkalinity as CaC03: 110 to 120 mg/L
- Ca/mg ratio: Total hardness as CaC03: 160 to 180 mg/L
- Conductivity: 500 to 600 μmhos/cm
- TOC concentration of the dilution water source was 0.60 and 0.59 mg/l for the month of July and August 1995. No additives were used in the test system.


Culture and test dilution water were prepared in 1900-liter batches by fortifying well water according to the formula for hard water (U.S. EPA, 1975) and filtering it through an Amberlite
XAD-7 resin column to removed any potential organism contaminants. Generally, several batches of water were prepared each week. The frequency at which the dilution water was
prepared depended on the requirements of the laboratory. Fortified water was discarded if not used within 14 days of preparation.
Representative samples of the dilution water source were analyzed periodically for the presence of pesticides, PCBs and toxic metals (Appendix IV). None of these compounds have been
detected at concentrations that are considered toxic in any of the water samples analyzed, in agreement with ASTM (1989) standard practice.

OTHER TEST CONDITIONS
- Photoperiod: 16 hours of light and 8 hours of darkness
- Light intensity: 70 to 90 footcandles

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
The number of immobilized adult daphnids and abservation of abnormal behavior were recorded on test days 1, 2, 4, 7, 8, 9, 11, 14, 16, 18 and 21.
Assessment pf offspring production were determined on day 7 and three times per week.

Test concentrations
Two preliminary ests were performed. The first test was perforemd with 10 daphnids each per vessel in duplicate at conc of 1.6; 3.1; 6.3; 13 and 25 mg/l. After 8 days 100 % survival was observed. In a second preliminray test 5 daphnids per vessel in duplicate were exposed to test con of 13; 25; 50; 100 and 200 mg/l. Follwing 1 day no surviving organisms at 200 mg/l were observed. 100 % survival was observed at the remaining treatment levels of 13 to 100 mg/l.

Reference substance (positive control):

no

Key result

Duration:

21 d

Dose descriptor:

NOEC

Effect conc.:

53 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

reproduction

Duration:

21 d

Dose descriptor:

other: EC100

Effect conc.:

110 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

mortality

Details on results:

Exposure solutions were clear, colorless and contained no visible signs of undissolved material throughout the test. Total alkalinity and pH of the solutions decreased with increasing concentration of MAA.
Following 21 days of exposure survival of control Daphnids was 95%. No organism survived the 21 day exposure to the two highest dose levels (110 and 230 mg a.i./L). Survival of 85 and 90% was observed among the organisms exposed to 14 and 53 mg a.i./L, respectively, and was not significantly different from controls.

At test termination ( day 21), reproduction among organisms exposed to the 14 and 53 mg/l treatment levels was 70 and 50 offspring per female, respectively, and was not significantly different as compared to the performance of control organisms (56 offspring per female). Since organism survival was significantly affected by exposure to 110 and 230 mg /l methacrylic acid, reproduction data for these two exposure concentrations were not statistically analyzed to establish treatment effects on reproduction. Time to first brood release by organisms exposed to 14 and 53 mg/l methacrylic acid was day 7, which was similar to the time to first brood release by the control population.
The no observed effect level NOEC was 53 mg/l for reproduction.

Reported statistics and error estimates:

At end of study, data obtained from survival and reproduction were stistically analyzed. Analyses were performed using the mean organism response in each replicate vessel rather than individual response.
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 (:Neber et a!., 1989) was conducted to compare the observed sample distribution with a normal distribution. The assumption that observations are normally distributed must be validated before subsequent analyses, following parametric procedures, can be performed. lf the data are not normally distributed, then a non-parametric procedure is used for subsequent analyses.
3. As a check on the assumption of homogeneity of variance implicit in parametric statistics, data for each endpoint were analyzed using Bartlett's Test (Sokal and Rohlf, 1981).
4. The Williams' Test (Williams, 1971, 1972) is a parametric procedure and is preferred for evaluating data obtained during chronic toxicity tests. Both survival and reproduction data met assumptions for normal distribution. Williams' Test was used to establish treatment effects for survival data. Tukey's Test (Zar, 1984) was used to establish treatment effects for reproduction data.
5. Daphnid survival data were analyzed before reproduction; if there were concentrations that caused significant survival effects, then those levels were excluded from the analysis of daphnid reproduction. For the purpose of determining survival effects, immobilized organisms were considered to be dead.

Mean measured concentrations tested and corresponding mean percent survival of parental daphnids (Daphnia magna) during the 21-day chronic exposure to methacrylic acid

Mean measured concentration	Mean percent survival [%]
	Day 1	Day2	Day4	Day7	Day8	Day9	Day11	Day14	Day16	Day18	Day21
Control	100	100	100	100	100	100	98	95	95	95	95
14	100	100	98	93	93	93	93	93	90	90	85
30^a	100	100	100	93	93	85	40	13	13	7.5	5
53	100	100	98	95	93	93	93	93	93	93	90
110	100	95	95	65	65	65	63	50	23	7.5	0^b
230	0	0	0	0	0	0	0	0	0	0	0^b

^aDue to the diluter system malfunction which resulted in the direct addition of the test material to this test conc, the biological-response data of the 30 mg/l-level were not used in the statistical analysis
^bSignificant different (p<=0.005) from the control organisms

Cumulative number of offspring produced per female

daphnid (Daphnia magna) during the 21-day chronic

exposure to methacrylic acid.

		Mean Cumulative Number of Offspring/Female
Mean Measured Concentration (mg A.I.IL)	Day:	7	8	9	11	14	16	18	21
Control		0	3	4	12	23	30	39	56
14		1	4	6	21	36	40	51	70
30 (a)		0	0	0	0	0	0	0	5
53		0	2	4	13	21	31	39	50
110		0	0	0	0	0	0	0	0 (b)
230		0	0	0	0	0	0	0	0 (b)

 

(a)       Due to the diluter system malfunction which resulted in the direct addition of test material to this test concentration, the biological-response data for this treatment level was not used in the statistical analysis to evaluate the toxicity of methacrylic acid to D. magna. 

(b)      Significantly different (p ~ 0.005) from the control organisms.

At test termination (day 21), reproduction among organisms exposed to the 14 and 53 mg /l treatment levels was 70 and 50 offspring per female, respectively, and was not

significantly different as compared to the performance of control organisms (56 offspring per female). Since organism survival was significantly affected by exposure to 110 and 230 mg/l methacrylic acid, reproduction data for these two exposure concentrations were not statistically analyzed to establish treatment effects on reproduction. Time to first brood release

by organisms exposed to 14 and 53 mg/l methacrylic acid was day 7, which was similar to the time to first brood release by the control population

Total number of offspring alive and immobilized at each observation interval during the 21-day chronic exposure of daphnids (Daphnia magna) to methacrylic acid

Mean Measured Concentration (mg/l)	Number of offspring alive (# Offspring immobilized)
	Day	7	8	9	11	14	16	18	21	Total
Control^a	A	0(0)	68(0)	11(0)	122(0)	222(0)	153(0)	139(0)	301(0)	1016(0)
	B	0(0)	52(0)	26(0)	195(0)	211(0)	92(0)	201(0)	362(0)	1139(0)
	Total	0(0)	120(0)	37(0)	317(0)	433(0)	245(0)	340(0)	663(0)	2155(0)
14^b	A	24(0)	55(0)	37(0)	285(0)	294(0)	112(0)	205(0)	382	1397(0)
	B	0(0)	70(0)	15(0)	264(0)	249(0)	16(0)	196(0)	301	1141(0)
	Total	24(0)	125(0)	52(0)	549(0)	543(0)	158(0)	401(0)	686	2538(0)
30^ad	A	0(0)	0(0)	3(0)	0(0)	0(0)	0(0)	0(0)	6(0)	9(0)
	B	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	4(0)	4(0)
	Total	0(0)	0(0)	3(0)	0(0)	0(0)	0(0)	0(0)	10(0)	13(0)
53^b	A	0(0)	36(0)	43(0)	197(0)	168(0)	178(0)	146(0)	185(0)	953(0)
	B	0(0)	39(0)	23(0)	135(0)	148(0)	166(0)	153(0)	240(0)	904(0)
	Total	0(0)	75(0)	66(0)	332(0)	316(0)	344(0)	299(0)	425(0)	1857(0)
110^c	A	0(0)	0(0)	0(0)	1(0)	0(0)	0(0)	0(0)	0(0)	0(0)
	B	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)
	Total	0(0)	0(0)	0(0)	1(0)	0(0)	0(0)	0(0)	0(0)	0(0)
230	A	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)
	B	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)
	Total	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)	0(0)

 

a First brood release was observed on test day 8
b First brood release was observed on test day 7
c First brood release was observed on test day 11
d Due to the diluter system malfunction which resulted in the direct addition of test material to this test concentration, the biological-response data for this treatment level was not used in the statistical analysis to evaluate the toxicity of methacrylic acid to Daphnia magna

Validity criteria fulfilled:

yes

Remarks:

56 living offspring per female instead of >= 60 (guideline criteria) at the end of the test, produced per parent animal. This criteria is not completely fullfilled. TOC was ca. 06. mg/l (Guideline criteria: <=2 mg/l)

Conclusions:

In a guideline study acc. OECD 202 Part B Daphnia magna reproduction test (21 days) NOEC was 53 mg/l .

Executive summary:

Methacrylic acid was tested in a Daphnia magna reproduction toxicity test for 21 days under flow through conditions at mean measured test concentrations of 14, 30, 53, 110 and 230 mg/l. At test termination ( day 21 ), reproduction among organisms exposed to the 14 and 53 mg/l treatment levels was 70 and 50 offspring per female, respectively, and was not significantly different as compared to the performance of control organisms (56 offspring per female). Since organism survival was significantly affected by exposure to 110 and 230 mg/l methacrylic acid, reproduction data for these two exposure concentrations were not statistically analyzed to establish treatment effects on reproduction. Time to first brood release by organisms exposed to 14 and 53 mg/l methacrylic acid was day 7, which was similar to the time to first brood release by the control population.

The guideline criteria (>= 60 offspring per female at test end) were not completely fulfilled as the number of offspring per parent animal was little lower (56 instead of >= 60) than the guideline criteria. But up to 53 mg/l parent animals survived and reproduction was also not impaired up to this concentration. Taking into account low chronic toxicity at the given test conditions, the biodegradability and low log Kow of methacrylic acid a long term impact of methacrylic acid to the environment is not expected and classification due to chronic toxicity to aquatic invertebrtaes is not required as the trigger for methacrylic acid would be a NOEC > 1 mg/l, which is more than one order of magnitude lower than the determined NOEC of 53 mg/l in this study.

Result: NOEC Daphnia magna reproduction (21 d): 53 mg/l

Description of key information

 

Methacrylic acid was tested in a Daphnia magna reproduction toxicity test for 21 days under flow through conditions at mean measured test concentrations of 14, 30, 53, 110 and 230 mg a.i./L. At test termination ( day 21 ), reproduction among organisms exposed to the 14 and 53 mg A.I.IL treatment levels was 70 and 50 offspring per female, respectively, and was not significantly different as compared to the performance of control organisms (56 offspring perfemale). Since organism survival was significantly affected by exposure to 110 and 230 mgA.I.IL methacrylic acid, reproduction data for these two exposure concentrations were not statistically analyzed to establish treatment effects on reproduction. Time to first brood releaseby organisms exposed to 14 and 53 mg A.I.IL methacrylic acid was day 7, which was similar tothe time to first brood release by the control population.

The guideline criteria were not completely fulfilled as the number of offspring per parent animal was little lower than the guideline criteria. But up to 53 mg/l parent animals survived and reproduction was also not impaired up to this concentration. Taking into account the biodegradability and low log Kow of methacrylic acid a long term impact of methacrylic acid to the environment is not expected and classification due to chronic toxicity to aquatic invertebrtaes is not required as the trigger for methacrylic acid would be a NOEC > 1 mg/l, which is more than one order of magnitude lower than the determined NOEC of 53 mg/l in this study.

 

Result: NOEC Daphnia magna reproduction (21 d): 53 mg/l

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Dose descriptor:

NOEC

Remarks:

21 d

Effect concentration:

53 mg/L