Methyl 3-mercaptopropionate

Toxicity to aquatic algae and cyanobacteria

Administrative data

Endpoint:

toxicity to aquatic algae and cyanobacteria

Type of information:

migrated information: read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Study period:

2008-02-29 to 2008-10-23

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP study conducted according to OECD Guideline 201 "Alga, Growth Inhibition Test" and EU Commission Directive 92/69/EEC, C.3 "Algal Inhibition test".

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2008

Report date:

2008

Materials and methods

Test guideline

Test guideline 1

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Deviations:

no

Test guideline 2

Qualifier:

according to guideline

Guideline:

EU Method C.3 (Algal Inhibition test)

Deviations:

no

Principles of method if other than guideline:

N/A

GLP compliance:

yes (incl. QA statement)

Remarks:

The Swiss GLP Monitoring Authorities, Bern, Switzerland

Test material

Test material information

Constituent 1

Reference substance name:

3-mercaptopropionic acid

EC Number:

203-537-0

EC Name:

3-mercaptopropionic acid

Cas Number:

107-96-0

IUPAC Name:

3-sulfanylpropanoic acid

Details on test material:

- Name of test material (as cited in study report): 3-mercaptopropionic acid
- Molecular formula (if other than submission substance): N/A
- Molecular weight (if other than submission substance): N/A
- Smiles notation (if other than submission substance): N/A
- InChl (if other than submission substance): N/A
- Structural formula attached as image file (if other than submission substance): N/A
- Substance type: active
- Physical state: liquid

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):
N/A

Sampling and analysis

Analytical monitoring:

yes

Details on sampling:

- Concentrations: All test concentrations and control, duplicate samples at the start of the test (without algae), and at the end of the test (with algae). At the end of the test, replicates were pooled prior to sampling.
- Sampling method: N/A
- Sample storage conditions before analysis: Immediately after sampling, all samples were buffered to pH 5 for stabilization, and stored deep-frozen at -20 deg. C until analysis.

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: The 100 mg/L concentration was prepared by dissolving 100.7 mg of the test substance in 1000 mL of the test water using intense stirring for 15 minutes at room temperature. The lower concentrations were made by dilution with test water.
- Eluate: N/A
- Differential loading: N/A
- Controls: Test water only
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): N/A
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): N/A
- Evidence of undissolved material (e.g. precipitate, surface film, etc): N/A

Test organisms

Test organisms (species):

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

Details on test organisms:

TEST ORGANISM
- Common name: Pseudokirchneriella subcapitata
- Strain: 61.81 SAG
- Source (laboratory, culture collection): Collection of Algal Cultures, Institute for Plant Physiology, University of Gottingen, Gottingen, Germany
- Age of inoculum (at test initiation): 3 days
- Method of cultivation: N/A


ACCLIMATION
- Acclimation period: 3 days
- Culturing media and conditions (same as test or not): same as test
- Any deformed or abnormal cells observed: N/A

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Post exposure observation period:

N/A

Test conditions

Hardness:

24 mg/L CaCO3

Test temperature:

22 deg. C

pH:

Initial-5.4-8.4
Final-6.2-9.3

Dissolved oxygen:

N/A

Salinity:

N/A

Nominal and measured concentrations:

Nominal- Control, 2.2, 4.6, 10, 22, 46, and 100 mg/L.
Measured- Control, not tested, 4.1, 8.0, 19, 30, and 78. These values represent 65-90% of the nominal concentrations (initial measured concentrations).

Details on test conditions:

TEST SYSTEM
- Test vessel: 50 mL Erlenmeyer flasks
- Type (delete if not applicable): closed-covered with a glass dish
- Material, size, headspace, fill volume: glass, 15 mL test volume
- Aeration: no, but continuously stirred with magnetic stirrers
- Type of flow-through (e.g. peristaltic or proportional diluter): N/A
- Renewal rate of test solution (frequency/flow rate): N/A
- Initial cells density: 10,000 cells/mL (1.4 relative fluorescence units)
- Control end cells density: 176 relative fluorescence units
- No. of organisms per vessel: N/A
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): 6
- No. of vessels per vehicle control (replicates): N/A


GROWTH MEDIUM
- Standard medium used: yes
- Detailed composition if non-standard medium was used: N/A


TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: reconstituted test water per guideline
- Total organic carbon: N/A
- Particulate matter: N/A
- Metals: N/A
- Pesticides: N/A
- Chlorine: N/A
- Alkalinity: N/A
- Ca/mg ratio: N/A
- Conductivity: N/A
- Culture medium different from test medium: no
- Intervals of water quality measurement: daily


OTHER TEST CONDITIONS
- Sterile test conditions: no
- Adjustment of pH: no
- Photoperiod: continuous light
- Light intensity and quality: 5800-7000 Lux, white fluorescent tubes
- Salinity (for marine algae): N/A


EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: electronic particle counter - Coulter Counter Model ZM
- Chlorophyll measurement: no
- Other: N/A


TEST CONCENTRATIONS
- Spacing factor for test concentrations: 2.2
- Justification for using less concentrations than requested by guideline: N/A
- Range finding study
- Test concentrations: N/A
- Results used to determine the conditions for the definitive study: N/A

Reference substance (positive control):

yes

Remarks:

potassium dichromate

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

17 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI is 6.0-21 mg/L

Effect concentrations 2

Duration:

72 h

Dose descriptor:

EC10

Effect conc.:

6.8 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

yield

Remarks on result:

other: 95% CI is 0.00-12 mg/L

Effect concentrations 3

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

19 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI is 9.8-23 mg/L

Effect concentrations 4

Duration:

72 h

Dose descriptor:

EC20

Effect conc.:

9 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

yield

Remarks on result:

other: 95% CI is 0.01-14 mg/L

Effect concentrations 5

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

26 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CI is 21-34 mg/L

Effect concentrations 6

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

16 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

biomass

Remarks:

yield

Remarks on result:

other: 95% CI is 2.5-30 mg/L

Effect concentrations 7

Duration:

72 h

Dose descriptor:

NOEC

Effect conc.:

4.1 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

other: growth rate and yield

Effect concentrations 8

Duration:

72 h

Dose descriptor:

LOEC

Effect conc.:

8 mg/L

Nominal / measured:

meas. (initial)

Conc. based on:

test mat.

Basis for effect:

other: growth rate and yield

Details on results:

- Exponential growth in the control (for algal test): yes. In the control, the biomass increased by a factor of 124 over 72 hours. The validity criterion of increase of biomass by at least a factor of 16 within 3 days was fulfilled.
- Observation of abnormalities (for algal test): yes
- Unusual cell shape: no
- Colour differences: N/A
- Flocculation: N/A
- Adherence to test vessels: N/A
- Aggregation of algal cells: N/A
- Other: N/A
- Any stimulation of growth found in any treatment: N/A
- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: N/A
- Effect concentrations exceeding solubility of substance in test medium: N/A

Results with reference substance (positive control):

N/A

Reported statistics and error estimates:

The 72h EC10, EC20, and EC50 values for the inhibition of growth and yield, and their 95% confidence intervals were calculated by Probit Analysis. For the LOEC and NOEC, the average growth rate and yield at each test concentration was compared to the control via Dunnett's tests.

Any other information on results incl. tables

 

Table 1. Nominal vs. Measured Concentrations

Nominal Conc. (mg/L)	Mean Measured Conc. (mg/L)	% of Nominal Conc.
2.2	n.d.	--
4.6	4.1	90
10	8.0	80
22	19	88
46	30	65
100	78	78

n.d.: not determined

Table 2. Results summary

Parameter	Growth rate	Yield
EC10 (mg/L) 95% confidence interval	17 6.0-21	6.8 0.00-12
EC20 (mg/L) 95% confidence interval	19 9.8-23	9.0 0.01-14
EC50 (mg/L) 95% confidence interval	26 21-34	16 2.5-30
NOEC (mg/L)	4.1	4.1
LOEC (mg/L)	8.0	8.0

 

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

All Guideline validity criteria met for this test.

Conclusions:

The 72h EC50 for 3-mercaptopropionic acid to P.subcapitata based on growth was found to be 26 mg/L, with a 95% confidence interval of 21-34 mg/L. The 72h EC50 based on yield was found to be 16 mg/L, with a 95% confidence interval of 2.5-30 mg/L. The overall NOEC was 4.1 mg/L, and the LOEC was 8.0 mg/L.

Executive summary:

N/A