methyl acrylate; methyl propenoate

Toxicity to aquatic algae and cyanobacteria

Link to relevant study record(s)

Reference

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 Nov 1994 - 26 Sep 1995

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP-guideline study

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

GLP compliance:

yes

Analytical monitoring:

yes

Details on sampling:

- Concentrations:
Measured concentrations were determined for samples of test solution collected from each treatment and control group at test initiation, 72 hours and 96 hours. A fourth replicate of test solution was prepared for concentration verification at 72 hours. Additionally, in an attempt to monitor the decline in test substance concentration over the exposure period, measured concentrations were determined for samples of test solution collected from a fifth replicate prepared for the negative control and the 0.60, 4.8 and 38 mg Methyl Acrylate/L treatment groups at 24 hours. The additional replicates included for concentration verification at 24 and 72 hours were inoculated with algae, but were not evaluated for effects upon algal growth due to the test substance.

- Sampling method:
Samples collected at 0 hours were taken from the individual batches of test solution prepared for each treatment and control group at test initiation. Samples collected at 24 and 72 hours were collected from additional replicates prepared specifically to provide test solution for those sampling intervals. Samples collected at 96 hours consisted of the composited test solution from the three replicate test chambers remaining at the end of the exposure period for each treatment and control group.

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The test concentrations were prepared by a serial dilution of a stock solution (1.3 mg/ml)

Test organisms (species):

Raphidocelis subcapitata (previous names: Pseudokirchneriella subcapitata, Selenastrum capricornutum)

Details on test organisms:

TEST ORGANISM
- Source (laboratory, culture collection): Algae were originially obtained from the Culture Collection of Algae at the University of Texas at Austin and have been maintained in culture medium at Wildlife International Ltd., Easton, Maryland.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

96 h

Post exposure observation period:

9 days recovery period.

Test temperature:

24 +/- 2 °C

pH:

7.4 - 9.0

Nominal and measured concentrations:

Nominal test concentrations (mg/L): 0.60, 1.2, 2.4, 4.8, 9.5, 19, 38, control
Mean measured test concentrations (mg/L): 0.225, 0.325, 0.625, 1.5, 2.52, 4.75, 12.08, control (arithmetical means)

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer flasks
- Fill volume: 100 ml
- Initial cells density: 10000 cells/ml
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 1


OTHER TEST CONDITIONS
- Light intensity and quality: 4310 ± 431 lux.


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: hemacytometer and microscope

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

3.55 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

growth rate

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

2.02 mg/L

Nominal / measured:

meas. (arithm. mean)

Conc. based on:

test mat.

Basis for effect:

biomass

Analytical Dose Verification:

Analytical measurements were performed to verify exposure concentrations of Methy Acrylate in the test medium. Nominal concentrations used in this study were 0.60, 1.2, 2.4, 4.8, 9.5, 19 and 38 mg methyl acrylate/L. Samples collected at 0 hours showed measured values of 0.62, 1.3, 2.5, 4.2, 9.5, 19 and 34 mg methyl acrylate/L, which represent 103, 108, 104, 88, 100, 100 and 89 % of nominal, respectively. Measured values for samples collected for the 0.60, 4.8 and 38 mg methyl acrylate/L, treatments at 24 hours showed measured values of 0.28, 1.8 and 12 mg methyl acrylate/L, representing 47, 38 and 32 % of nominal , respectively. Measured values for samples collected from the 0.60, 1.2, 2.4, 4.8, 19 and 38 mg methyl acrylate/L treatments were below the limit of quantification (LOQ) for the methodology (0.25 mg/L) at both 72 and 96 hours. The 9.5 mg methyl acrylate/L treatment showed a measured concentration of 0.58 mg methyl acrylate/L at 72 hours, representing 6.1% of nominal, and fell below the LOQ by 96 hours. Based upon the decline in test substance concentration over the 96-hour exposure period, the test results were presented based on 0-hour measured concentrations in the original report.

Thus, a recalculation of the more realistic effect values concerning growth rate was additionally performed taking the arithmetic means of the measured concentrations and the measured inhibition.

Arithmetical means of the concentrations were 0.225, 0.325, 0.625, 1.5, 2.52, 4.75, and 12.08 mg methyl acrylate/L for the nominal concentrations of 0.60, 1.2, 2.4, 4.8, 9.5, 19 and 38 mg methyl acrylate/L. Missing 24 h measurements were considered to be 0 mg/L as worst case scenario.

Growth rate:

Nom. Conc.	Arithm. Conc.	72 h	96 h
[mg/L]	[mg/L]	% inhibition	% inhibition
0	0
0.60	0.225	-4.5	4.7
1.2	0.325	-6.1	0
2.4	0.625	0	4.7
4.8	1.5	-1.5	6.2
9.5	2.52	30	25
19	4.75	67	50
38	12.08	100	99

The recalculated EC50 values for growth rate were:

72 h-EC50 = 3.55 mg methyl acrylate/L

96 h-EC50 = 4.75 mg methyl acrylate/L

The EC50 values for biomass were recalculated accordingly.

Biomass:

Nom. Conc.	Arithm. Conc.	72 h	96 h
[mg/L]	[mg/L]	% inhibition	% inhibition
0	0
0.60	0.225	-11	5.3
1.2	0.325	-14	-8.9
2.4	0.625	5	14
4.8	1.5	11	18
9.5	2.52	79	77
19	4.75	96	95
38	12.08	100	100

The recalculated EC50 values for biomass were:

72 h-EC50 = 2.02 mg methyl acrylate/L

96 h-EC50 = 1.99 mg methyl acrylate/L

Validity criteria fulfilled:

yes

Description of key information

Methyl acrylate is acutely toxic to freshwater algae.
EC50 (72 h, growth rate) = 3.55 mg/L (measured) (Selenastrum capricornutum, OECD TG 201). No NOEC could be determined.

As described in section 13.2 of IUCLID, testing information on acute toxicity to alga is consistent with six acrylic esters evaluated as a category. Thus, testing information on chronic algal toxicity for 2-ethylhexyl acrylate is selected as a conservative approach (lowest NOEC). The NOEC for 2-EHA on growth rate is 0.45 mg/L.

 

NOEC (72 h, growth rate) = 0.45 mg/L (measured) (Selenastrum capricornutum, OECD TG 201)

 

 

Key value for chemical safety assessment

EC50 for freshwater algae:

3.55 mg/L

EC10 or NOEC for freshwater algae:

0.45 mg/L

Additional information

An acute toxicity study was conducted with Selenastrum capricornutum (BAMM, 1995) according to OECD Guideline 201 using a static design. Nominal exposure concentrations were 0.60, 1.2, 2.4, 4.8, 9.5, 19, 38 mg/L. At time 0, the analyzed concentrations were 0.62, 1.3, 2.5, 4.2, 9.5, 19 and 34 mg/L. After 72 and 96 hours, analyses of the test media were all below the limit of quantification (LOQ) for the methodology (0.25 mg/L). Based upon the decline in test substance concentration over the 96-hour exposure period, the test results were presented based on 0-hour measured concentrations in the original report.

Thus, a recalculation of the more realistic effect values concerning growth rate was additionally performed taking the arithmetic means of the measured concentrations and the measured inhibition. Arithmetical means of the concentrations were 0.225, 0.325, 0.625, 1.5, 2.52, 4.75, and 12.08 mg methyl acrylate/L for the nominal concentrations of 0.60, 1.2, 2.4, 4.8, 9.5, 19 and 38 mg methyl acrylate/L. Missing 24 h measurements were considered to be 0 mg/L as worst case scenario. The recalculation provided 72 h-EC50 values for growth rate and biomass of 3.55 and 2.02 mg/L, respectively. These values indicate the toxicity of methyl acrylate to algae is similar to other aquatic species and the recalculated EC50 values were considered appropriate for the assessment.

 

In addition, there is an older study withScenedesmus subspicatus conducted according to Directive 87/302/EEC, part C.3 without analytical monitoring (BASF AG, 1989). EC50 values after 72 hrs exposure were recalculated and determined to be 18.3 mg/L (biomass) and 38.1 mg/L (growth rate), respectively. This study which does not take the possible decrease in test concentration by volatilisation of the substance into consideration and is therefore not suitable for the assessment.

 

In addition, a robust data set of acute studies is available from the other members of the acrylic ester category (2-ethylhexyl, ethyl, n-butyl, isobutyl, and tert-butyl acrylate).