4-methoxyphenylacetic acid

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:

21.03.2017 – 31.03.2017

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Justification for type of information:

Experimental test result using OECD guidelines

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Principles of method if other than guideline:

The freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance 4-methoxyphenylacetic acid (CAS No.- 104-01-8) according to OECD Guideline 201.

GLP compliance:

no

Specific details on test material used for the study:

SOURCE OF TEST MATERIAL
- Source and lot/batch No.of test material: No data
- Expiration date of the lot/batch: No data
- Purity test date: No data

RADIOLABELLING INFORMATION (if applicable)
- Radiochemical purity: No data
- Specific activity: No data
- Locations of the label: No data
- Expiration date of radiochemical substance: No data

STABILITY AND STORAGE CONDITIONS OF TEST MATERIAL
- Storage condition of test material: No data
- Stability under test conditions: No data
- Solubility and stability of the test substance in the solvent/vehicle: No data
- Reactivity of the test substance with the solvent/vehicle of the cell culture medium: No data

TREATMENT OF TEST MATERIAL PRIOR TO TESTING
- Treatment of test material prior to testing: No data
- Preliminary purification step (if any): No data
- Final dilution of a dissolved solid, stock liquid or gel: No data
- Final preparation of a solid: No data

FORM AS APPLIED IN THE TEST (if different from that of starting material) No data

OTHER SPECIFICS: No

Analytical monitoring:

no

Details on sampling:

No data

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION
The stock solution 150.0 mg/L was prepared by dissolving white powder in OECD growth medium. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.

- Controls: OECD medium as specified in OECD 201, used as a control and for dilution of the stock solution.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Strain: 86.81 SAG
- Source (laboratory, culture collection): Institute of botany of the ASCR
- Age of inoculum (at test initiation): 5x103 cells/ml
- Method of cultivation: No data

ACCLIMATION
- Acclimation period: No data
- Culturing media and conditions (same as test or not): No data
- Any deformed or abnormal cells observed: No data

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Remarks on exposure duration:

±1 hour

Post exposure observation period:

No data

Hardness:

No data

Test temperature:

23°C ± 2°C

pH:

Sample concentration [mg/l]: 30.0, 45.0, 67.5, 100.0 and 150.0 mg/L
Start of the test: 7.7, 7.4, 7.3, 5.5, 5.2
The end of the test: 7.4, 7.2, 6.0. 5.2, 4.9
Control 1: pH= 8.3 changed to pH = 7.8 during the test.
Control 2: pH = 8.0 changed to pH = 7.8 during the test.

Dissolved oxygen:

No data

Salinity:

No data

Conductivity:

No data

Nominal and measured concentrations:

0, 0, 30.0, 45.0, 67.5, 100.0 and 150.0 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 50ml glass vessel
- Type : closed (with air-permeable stopper)
- Material, size, headspace, fill volume: 15 ml
- Aeration: No data
- Type of flow-through (e.g. peristaltic or proportional diluter): No data
- Renewal rate of test solution (frequency/flow rate): No data
- Initial cells density: 5x103 cells/mL
- Control end cells density: No data
- No. of organisms per vessel: No data
- No. of vessels per concentration (replicates): 3
- No. of vessels per control (replicates): No data
- No. of vessels per vehicle control (replicates): No data

GROWTH MEDIUM
- Standard medium used: Yes

OTHER TEST CONDITIONS
- Adjustment of pH: Without adjustment
- Photoperiod: Continuous
- Light intensity and quality: 6000 lx - 8000 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell counting: microscope with counting chamber Cyrus I or electronic particle counter.
- Chlorophyll measurement: No
- Other: ErC50 was calculated using non-linear regression by the software Prism 4.0

Reference substance (positive control):

yes

Remarks:

Potassium dichromate (K2Cr2O7)

Key result

Duration:

72 h

Dose descriptor:

EC50

Effect conc.:

106.9 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 83.2 - 137.3 mg/L

Results with reference substance (positive control):

- Results with reference substance valid
- ErC50: 0.75 mg/L K2Cr2O7

Reported statistics and error estimates:

No data

Control Solution: OECD growth medium without the sample, the coefficient of variation of average growth rate in replicates during the whole test period was 0.6 % in control 1 and 0.9 % in control 2.

Validity criteria fulfilled:

yes

Conclusions:

The median effective concentration (ErC50) for the test substance, 4-methoxyphenylacetic acid, in a freshwater algae Desmodesmus subspicatus was determined to be 106.9 mg/L on the basis of effects on growth rate in a 72 hour study with 95% Cl of 83.2 - 137.3 mg/L.

Executive summary:

The freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance 4-methoxyphenylacetic acid (CAS No.- 104 -01 -8) according to OECD Guideline 201.

The stock solution 150.0 mg/L was prepared by dissolving white powder in OECD growth medium. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture and tested at the concentrations 0, 0, 30.0, 45.0, 67.5, 100.0 and 150.0 mg/L.Effects on the growth rate of the organism were studied. The test was performed under static conditions in a static fresh water system at a temperature of 23± 2°C. Initial cell density of test organism used was 5x10(3) cells/ml. Determination of cell counting involve the use of microscope with counting chamber Cyrus I or electronic particle counter. ErC50 was calculated using non-linear regression by the software Prism 4.0.

The median effective concentration (ErC50) for the test substance, 4-methoxyphenylacetic acid , in a freshwater algae Desmodesmus subspicatus was determined to be 106.9 mg/L on the basis of effects on growth rate in a 72 hour study with 95% Cl of 83.2 - 137.3 mg/L. Thus, based on this ErC50 value and according to CLP Criteria for aquatic classification of the substance, it is concluded that 4-methoxyphenylacetic acid (CAS No.- 104 -01 -8) does not exhibits toxicity to aquatic algae (Desmodesmus subspicatus).

Description of key information

The freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance4-methoxyphenylacetic acid(CAS No.- 104 -01 -8) according to OECD Guideline 201.

The stock solution 150.0 mg/L was prepared by dissolving white powder in OECD growth medium. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture and tested at the concentrations 0, 0, 30.0, 45.0, 67.5, 100.0 and 150.0 mg/L.Effects on the growth rate of the organism were studied. The test was performed under static conditions in a static fresh water system at a temperature of 23± 2°C. Initial cell density of test organism used was 5x10(3) cells/ml. Determination of cell counting involve the use of microscope with counting chamber Cyrus I or electronic particle counter. ErC50 was calculated using non-linear regression by the software Prism 4.0.

The median effective concentration (ErC50) for the test substance,4-methoxyphenylacetic acid, in a freshwater algae Desmodesmus subspicatus was determined to be 106.9 mg/L on the basis of effects on growth rate in a 72 hour study with 95% Cl of 83.2 - 137.3 mg/L. Thus, based on this ErC50 value and according to CLP Criteria for aquatic classification of the substance, it is concluded that4-methoxyphenylacetic acid(CAS No.- 104 -01 -8) does not exhibits toxicity to aquatic algae (Desmodesmus subspicatus).

Key value for chemical safety assessment

EC50 for freshwater algae:

106.9 mg/L

Additional information

Various experimental studies following OECD guideline for toxicity to aquatic algae with the target substance 4-methoxyphenylacetic acid (CAS No. 104-01-8) and the relevant read across substance 2-(2,4-dichlorophenoxy)propanoic acid (CAS No. 120-36-5) by considering its structure-activity relationships, were summarized as follows:

 

The freshwater algal growth inhibition test was carried out by SSS (2017) on Desmodesmus subspicatus with the substance 4-methoxyphenylacetic acid (CAS No.- 104 -01 -8) according to OECD Guideline 201. The stock solution 150.0 mg/L was prepared by dissolving white powder in OECD growth medium. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture and tested at the concentrations 0, 0, 30.0, 45.0, 67.5, 100.0 and 150.0 mg/L. Effects on the growth rate of the organism were studied. The test was performed under static conditions in a static fresh water system at a temperature of 23± 2°C. Initial cell density of test organism used was 5x10(3) cells/ml. Determination of cell counting involve the use of microscope with counting chamber Cyrus I or electronic particle counter. ErC50 was calculated using non-linear regression by the software Prism 4.0.

The median effective concentration (ErC50) for the test substance, 4-methoxyphenylacetic acid , in a freshwater algae Desmodesmus subspicatus was determined to be 106.9 mg/L on the basis of effects on growth rate in a 72 hour study with 95% Cl of 83.2 - 137.3 mg/L.

 

The above study is supported by another experimental study conducted by UERL (2017). The effect of test item 4-methoxyphenylacetic acid, CAS No. 104-01-8 was studied on the growth of fresh water green alga Chlorella vulgaris. The study was conducted following OECD guideline 201- Alga, growth inhibition test. The test concentration chosen for the study were 0.9 mg/L,2.7 mg/L,8.1 mg/L,24.3 mg/L,72.9 mg/L,218.7 mg/L. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be >200 mg/L.

 

Moreover, the short term toxicity to Selenastrum capricornutum strain NIVA-CHL 1(green algae) study for read across substance 2-(2,4-dichlorophenoxy)prop anoic acid (CAS No. 120-36-5) was carried out by Mohammad I. Abdel-Hamid (Water Science and Technology, Vol. 33, No. 6, Pg. no. 129-138, 1996) using the microplate test for 96 hrs. The study was based on the effects of the test compound 2-(2,4-dichlorophenoxy)propanoic acid on Selenastrum capricornutum(green algae) in a static fresh water system. The chlorococcal alga Selenastrum capricomutum strain NIV A-CHL. 1 (nowRaphidocelis subcapitala) was obtained from the culture collection of the Norwegian Institute for Water Research, Oslo, Norway.The alga was cultivated in standard AAM medium. The culture flasks were placed on a shaking table at 22±2 'C under continuous illumination (approx.70µE m-2s-I) provided by white fluorescent tubes. Test chemical conc. used for the study were 320, 100, 32, 10, 3.2, 1.0, 0.32, 0.1, 0.032, 0.01,&0.0032 mg/I, respectively. To each well on the polystyrene microplates, 1.8 ml of algal inoculum was added. Stock solutions containing 3.2 g I-I (stock A) and 1.0 g I-I (stock B) were prepared for each pesticide. To the first and to the second wells on the plate, a volume of 0.2 ml was added from stock A and stock B, respectively. The contents of each well were, then, thoroughly mixed and 0.2ml was transferred from the well I to 3 and from 2 to 4. The serial dilutions were repeated down the row of wells on two successive plates to give 11 concentrations (320, 100, 32, 10, 3.2, 1.0, 0.32, 0.1, 0.032, 0.01,&0.0032 mg I-I) and one left as control.The test plates were incubated at 22±2 'C under continuous illumination (approx.70µE m-2s-I)provided by white fluorescent tubes. The test was terminated after an incubation period of four days.Cell density of the free cultures 10 each well was counted using a Coulter Multisizer(Software Level 1.8).At the same time the corresponding mean cell volume (MCV,µm3cell-1) was also determined. Algal dry weight was calculated from cell density and MCV. EC50 is the effective median concentration that inhibits algal growth by 50%, compared with control culture. Values of the toxicity-response parameter (algal dry weight) were plotted, as relative percent’s of the Control (control=100%), against the logarithm of the corresponding pesticide concentration. A curve was fitted to the points by third level pesticide polynomial. This allowed the calculation of EC50 by the straight line graphical interpolation method. The lowest concentrations giving no observable algal growths (EC 100) were visually detected. On the basis of effect on growth rate of the test organism Selenastrum capricornutum(green algae),the 96 hr EC50 and EC100 value was determined to be 190 and >320 mg/l, respectively.

 

So, based on the above experimental studies for target substance 4-methoxyphenylacetic acid (CAS No. 104-01-8) and to its relevant read across substa nce, the effective concentration (EC50) value was found to be in the range of 106.9 mg/L to >200 mg/L and EC100 value to be >320 mg/L.

Therefore, according to the CLP Criteria for aquatic classification of the substance, it is concluded that 4-methoxyphenylacetic acid (CAS No. 104-01-8) does not exhibit toxicity to aquatic algae.