o-anisic 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

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

comparable to guideline study

Justification for type of information:

Data is from Abitec report

Qualifier:

according to guideline

Guideline:

OECD Guideline 201 (Alga, Growth Inhibition Test)

Principles of method if other than guideline:

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus according to OECD Guideline 201.

GLP compliance:

no

Specific details on test material used for the study:

- Name of test material: 2-methoxybenzoic acid (2-MBA)
- Molecular formula: C8H8O3
- Molecular weight: 152.1482 g/mol
- Smiles notation: COc1ccccc1C(=O)O
- InChl:1S/C8H8O3/c1-11-7-5-3-2-4-6(7)8(9)10/h2-5H,1H3,(H,9,10)
- Substance type: Organic
- Physical state: Solid

Analytical monitoring:

not specified

Vehicle:

yes

Details on test solutions:

The stock solution (100 mg/L) was prepared by dissolving white powder in OECD growth medium. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture.

Test organisms (species):

Desmodesmus subspicatus (previous name: Scenedesmus subspicatus)

Details on test organisms:

TEST ORGANISM
- Common name:
- Strain: 86.81 SAG
- Source (laboratory, culture collection): Institute of botany of the ASCR
- Initial biomass concentration: 5x10(3) cells /ml
- Method of cultivation: No data available

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

72 h

Remarks on exposure duration:

±1 hour

Test temperature:

23±2°C

pH:

Sample concentrations 35 46 59 77 100
Start of the test 7.4 7.4 7.2 6.8 5.6
The end of the test 7.7 6.7 5.9 5.7 5.7
control pH=8.1 changed to pH =7.4 during the test

Nominal and measured concentrations:

0, 35, 46, 59, 77 and 100 mg/L

Details on test conditions:

TEST SYSTEM
- Test vessel: 50/ 100 ml Glass vessel
- Type (delete if not applicable): closed (with air permeable stopper)
- Sample volume: 7.5/ 30 ml
- Initial cells density: 5x10(3) cells/ml
- No. of vessels per concentration (replicates): 3

GROWTH MEDIUM
- Standard medium used: yes

OTHER TEST CONDITIONS
- Adjustment of pH: No
- Photoperiod: Continuous
- Light intensity and quality: 6000-8000 lx

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) :
- Determination of cell concentrations: microscope with counting chamber Cyrus I or electronic particle counter.
- 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.:

78.8 mg/L

Nominal / measured:

meas. (not specified)

Conc. based on:

test mat.

Basis for effect:

growth rate

Remarks on result:

other: 95% CL: 77.7-80.0

Results with reference substance (positive control):

Results with reference substance valid
- EC50: 0.75 mg/L

Reported statistics and error estimates:

ErC50 was calculated using non-linear regression by the software Prism 4.0.

Validity criteria fulfilled:

not specified

Conclusions:

The median effective concentration (EC50) for the test substance 2-methoxybenzoic acid (2-MBA) in Desmodesmus subspicatus was determined to be 78.8 mg/L on the basis of effects on growth rate in a 72 hour study.Based on the value the2-methoxybenzoic acid (2-MBA)was considered as toxic to aquatic organism but as it was readily biodegradable in nature, hence can be considered as not classified as per the CLP regulations.

Executive summary:

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus using OECD Guideline 201. The stock solution (100 mg/L) was prepared by dissolving white powder in OECD growth medium. The solution was kept in ultrasonic bath for 20 mins. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Conc. of test chemical used for the study was 0, 35, 46, 59, 77 and 100 mg/L, respectively. 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 (EC50) for the test substance 2-methoxybenzoic acid (2-MBA) in Desmodesmus subspicatus was determined to be 78.8 mg/L on the basis of effects on growth rate in a 72 hour study.Based on the value the2-methoxybenzoic acid (2-MBA)was considered as toxic to aquatic organism but as it was readily biodegradable in nature, hence can be considered as not classified as per the CLP regulations.

Description of key information

Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus using OECD Guideline 201. The stock solution (100 mg/L) was prepared by dissolving white powder in OECD growth medium. The solution was kept in ultrasonic bath for 20 mins. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Conc. of test chemical used for the study was 0, 35, 46, 59, 77 and 100 mg/L, respectively. 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 (EC50) for the test substance 2-methoxybenzoic acid (2-MBA) in Desmodesmus subspicatus was determined to be 78.8 mg/L on the basis of effects on growth rate in a 72 hour study.Based on the value the2-methoxybenzoic acid (2-MBA)was considered as toxic to aquatic organism but as it was readily biodegradable in nature, hence can be considered as not classified as per the CLP regulations.

Key value for chemical safety assessment

EC50 for freshwater algae:

78.8 mg/L

Additional information

Toxicity to algae for 2-methoxybenzoic acid (579-75-9) was summarised with data for target and by using functional read across studies was summaries as follows:

Freshwater algal growth inhibition test (Abitec , Freshwater algal growth inhibition test, report number 185/17,2017) was carried out on Desmodesmus subspicatus using OECD Guideline 201. The stock solution (100 mg/L) was prepared by dissolving white powder in OECD growth medium. The solution was kept in ultrasonic bath for 20 mins. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with OECD growth medium and inoculum culture. Concentration of test chemical used for the study were 0, 35, 46, 59, 77 and 100 mg/L, respectively. 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 (EC50) for the test substance 2-methoxybenzoic acid (2-MBA) in Desmodesmus subspicatus was determined to be 78.8 mg/L on the basis of effects on growth rate in a 72 hour study.Based on the value the 2-methoxybenzoic acid (2-MBA)was considered as toxic to aquatic organism but as it was readily biodegradable in nature, hence can be considered as not classified as per the CLP regulations.

Study for read across Benzoic acid from Environmental Pollution (Series A), Vol. 29, Pg. no. 71-80, 1982 was carried out using cyanobacteria (blue-green algae) Anabaena inaequalis, A. cylindrica,and A.variabilis, and the green algae Chlorella pyrenoidosa and Scenedesmus quadricauda as test organisms. The study was based on the effects of the test compound Benzoic acid on algae in a static fresh water system. Stock solutions of test chemical were prepared in pesticide grade acetone.The proper level of acetone (0.1 %v/v) to use in each bioassay system was determined using the solvent-pesticide interaction analysis technique.Chemical was tested at a minimum of five concentrations ranging from 0 to 100 mg/l (nominal concentration). Test organisms used for the study include (blue-green algae) Anabaena inaequalis, A. cylindrica, and A.variabilis, and the green algae Chlorella pyrenoidosa and Scenedesmus quadricauda, respectively.

Cultures of Anabaena inaequalis and A. cylindrica were maintained in a liquid nitrogen-free medium at a temperature of 20°C and a light intensity of 7000 lux on a 12 h light-dark cycle whereas the other cultures such as A.variabilis, Chlorella pyrenoidosa and Scenedesmus quadricauda were maintained under the same conditions except the growth medium was supplemented with 1.5 g NaNO3/l. Photosynthesis was assayed by following the uptake of 14CO2 from NaH14CO3. Plastic tissue culture flasks with a total internal volume of 74 ml were employed as assay chambers. Each contained 9.9ml of cell suspension (containing 6-5 × 104cyanobacterial or 1.0 × 105green algal cells/ml), 0.1 ml of radioisotope (to give a final activity of 0.1µCi/ml) and 0.01 ml of test chemical. The flasks were incubated for 3 h and photosynthetic activity was assayed. Per cent inhibition values were calculated relative to photosynthetic activity in control systems (solvent only) and EC50 values determined by probit or regression analysis, where applicable. Analyses for significant differences (p = 0.05) were performed using Dunnett's testand Duncan's multiple range test.

Based on the effect of Benzoic acid on the photosynthesis of the test organisms, the EC50 value was determined to be 5, 60, 55, 60 and 75 mg/l for Anabaena inaequalis, A. cylindrical, A.variabilis, Chlorella pyrenoidosa and Scenedesmus quadricauda respectively. Thus, based on this value, it can be concluded that the test chemical Benzoic acid can be considered as toxic to aquatic organisms. Since the chemical is readily biodegradable in nature, Benzoic acid can be considered as non-toxic to aquatic organisms and thus cannot be classified as hazardous as per the CLP criteria.

Short term toxicity to Pseudokirchneriella subcapitata (green algae) study was carried out on same read across benzoic acid for 48 hrs from Ecotox database, 2016 .The study was based on the effects of the test compound on Pseudokirchneriella subcapitata in a static fresh water system. On the basis of population of the test organism Pseudokirchneriella subcapitata (green algae), the 48 hr EC50 value was determined to be 207.5 mg/l.

Based on the results of target and result of read across chemical, it was considered that 2-methoxybenzoic acid (579-75-9) was likely to be non-toxic to aquatic algae and can be considered to be not classified as per the CLP regulations.