2,3,5-trimethylphenol

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:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data is from peer reviewed journal

Justification for type of information:

Data is from peer reviewed journal

Qualifier:

according to guideline

Guideline:

other: as mentioned below

Principles of method if other than guideline:

Long term toxicity to Chlorella autofrophica study was carried out for 3-7 days.

GLP compliance:

not specified

Specific details on test material used for the study:

- Name of test material (as cited in study report): 2,3,5Trimethylphenol
- Molecular formula (if other than submission substance): C9H12O
- Molecular weight (if other than submission substance): 136.193 g/mol
- Smiles notation (if other than submission substance): c1(c(cc(C)cc1O)C)C
- InChl (if other than submission substance): 1S/C9H12O/c1647(
2)8(3)9(10)56/h45,10H,13H3
- Substance type: Organic
- Physical state: Solid
- Analytical purity: >95%

Analytical monitoring:

not specified

Details on sampling:

- Concentrations: Test chemical conc. used for the study were 0.001, 0.01, 0.05, 0.1, 0.5, 1, 2 and 10 mg (1, 10, 50, 100, 500, 1000, 2000, 10,000 µg), respectively.
- Sampling method: Test solutions were prepared in absolute ethanol.

Vehicle:

yes

Remarks:

absolute ethanol was used as a vehicle in the study.

Test organisms (species):

other: Chlorella autofrophica

Details on test organisms:

TEST ORGANISM
- Common name: Green Algae
- Strain: Strain 580
- Source (laboratory, culture collection): Test organism Chlorella autofrophica strain 580 was obtained from R. L. Guillard, Woods Hole.
- Method of cultivation: Chlorella autofrophica was grown on medium ASP-2 plus 8 µg/l. vitamin Blz and 1 mg/l. vitamin B1
- Other: The inoculum was preconditioned to the test conditions.

Test type:

static

Water media type:

freshwater

Total exposure duration:

7 d

Remarks on exposure duration:

Exposure duration is 3-7 days

Test temperature:

28 - 30°C

Nominal and measured concentrations:

nominal concentration

Details on test conditions:

TEST SYSTEM
- Test vessel: Petridish
- Initial cells density: 105 cells/ml
- Final cell conc: 5000-10000
cell/ml

GROWTH MEDIUM
- Standard medium used: No
- Detailed composition if non-standard medium was used: 1% Difco agar, 0140

OTHER TEST CONDITIONS
- Photoperiod: continuous illumination
- Light intensity and quality: continuous illumination from Sylvania F20T12-D Daylight fluorescent lamps

EFFECT PARAMETERS MEASURED (with observation intervals if applicable): The experimental endpoint was the zone size of growth inhibition around the pad, judged visually and microscopically.

TEST CONCENTRATIONS
- Test concentrations: Test chemical conc. used for the study were 0.001, 0.01, 0.05, 0.1, 0.5, 1, 2 and 10 mg (1, 10, 50, 100, 500, 1000, 2000, 10,000 µg), respectively.

Key result

Duration:

7 d

Dose descriptor:

EC100

Effect conc.:

10 other: mg

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

other: Growth inhibition

Table: Effect of test chemical on growth, as a lawn, of green alga,Chlorella autofrophicaStrain 580.

 

Amount on pad,µg	Zone of inhibition (mm)
1	0
10	0
50	0
100	0
500	2 (10)
1000	20 (36)
2000	36
10000	36

 

Note: Number indicates zone of inhibition of growth around pad in mm; 36 mm means no growth in Petri dish.Numbers in parentheses are zone sizes of reduced colony size indicative of some but not complete inhibition.

Validity criteria fulfilled:

not specified

Conclusions:

Based on growth inhibition of test organism, the EC100 value for chemical 2,3,5-Trimethylphenol was determined to be 10 mg.

Executive summary:

Long term toxicity to Chlorella autofrophica study was carried out for 3-7 days.Chlorella autofrophica was used as a test organism. Test organismChlorella autofrophicastrain 580was obtained fromR. L. Guillard, Woods Hole.Chlorella autofrophicawas grown onmedium ASP-2 plus 8µg/l. vitamin Blz and 1 mg/l. vitamin B1. An algal lawn technique was used to test pure compounds. Exponentially growing cells (final concentration 5000-10000 cell/ml) were added to agarized medium (1% Difco agar, 0140) held at 42°C ;20 ml was then immediately distributed to plastic Petri dishes. The test materials, with absolute ethanol as solvent, were presented to the algal cells embedded in the agar by absorbing them on antibiotic sensitivity discs (12.7 mm) and placing the discs directly on the agar surface. The plates were then sealed with Scotch tape and incubated in the light for 3-7 days, 28-30°C. The experimental endpoint was the zone size of growth inhibition around the pad, judged visually and microscopically. No inhibition was observed with appropriate ethanol controls.Based on growth inhibition of test organism, the EC100 value for chemical 2,3,5-Trimethylphenol was determined to be 10 mg. Based on this value it can be concluded that the substance 2,3,5-trimethylphenol is considered to be toxic to aquatic environment. Since the test chemical is readily biodegradable in nature, chemical 2,3,5-trimethylphenol can be considered as non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

Description of key information

Long term toxicity to Chlorella autofrophica study was carried out for 3-7 days Kenneth Winters et. al; 1977). Chlorella autofrophicawas used as a test organism. Test organismChlorella autofrophicastrain 580was obtained fromR. L. Guillard, Woods Hole.Chlorella autofrophicawas grown onmedium ASP-2 plus 8µg/l. vitamin Blz and 1 mg/l. vitamin B1. An algal lawn technique was used to test pure compounds. Exponentially growing cells (final concentration 5000-10000 cell/ml) were added to agarized medium (1% Difco agar, 0140) held at 42°C ;20 ml was then immediately distributed to plastic Petri dishes. The test materials, with absolute ethanol as solvent, were presented to the algal cells embedded in the agar by absorbing them on antibiotic sensitivity discs (12.7 mm) and placing the discs directly on the agar surface. The plates were then sealed with Scotch tape and incubated in the light for 3-7 days, 28-30°C. The experimental endpoint was the zone size of growth inhibition around the pad, judged visually and microscopically. No inhibition was observed with appropriate ethanol controls.Based on growth inhibition of test organism, the EC100 value for chemical 2,3,5-Trimethylphenol was determined to be 10 mg. Based on this value it can be concluded that the substance 2,3,5-trimethylphenol is considered to be toxic to aquatic environment. Since the test chemical is readily biodegradable in nature, chemical 2,3,5-trimethylphenol can be considered as non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

Additional information

Various experimental key study and predicted data for the target compound2,3,5-trimethylphenol(CAS no. 697-82-5) which is supported further by 1 study (from peer reviewed journal) for its closest read across substance with logKow as the primary descriptor were reviewed for the toxicity to aquatic algae and cyanobacteria end point which are summarized as below:

 

In an experimental key study for test chemical 2,3,5-trimethylphenol(CAS no. 697-82-5), long term toxicity to Chlorella autofrophica study was carried out for 3-7 days (Kenneth Winters et. al; 1977). Chlorella autofrophica was used as a test organism. Test organism Chlorella autofrophica strain 580 was obtained from R. L. Guillard, Woods Hole.Chlorella autofrophicawas grown onmedium ASP-2 plus 8µg/l. vitamin Blz and 1 mg/l. vitamin B1. An algal lawn technique was used to test pure compounds. Exponentially growing cells (final concentration 5000-10000 cell/ml) were added to agarized medium (1% Difco agar, 0140) held at 42°C ;20 ml was then immediately distributed to plastic Petri dishes. The test materials, with absolute ethanol as solvent, were presented to the algal cells embedded in the agar by absorbing them on antibiotic sensitivity discs (12.7 mm) and placing the discs directly on the agar surface. The plates were then sealed with Scotch tape and incubated in the light for 3-7 days, 28-30°C. The experimental endpoint was the zone size of growth inhibition around the pad, judged visually and microscopically. No inhibition was observed with appropriate ethanol controls.Based on growth inhibition of test organism, the EC100 value for chemical 2,3,5-Trimethylphenol was determined to be 10 mg. Based on this value it can be concluded that the substance 2,3,5-trimethylphenol is considered to be toxic to aquatic environment. Since the test chemical is readily biodegradable in nature, chemical 2,3,5-trimethylphenol can be considered as non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

 

Short term toxicity on aquatic algae and cyanobacteria of target chemical 2,3,5-trimethylphenol(CAS no. 697-82-5)is predicted using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the five closest read across substances (2017). EC50 value was estimated to be 17.71 mg/l for Pseudokirchneriella subcapitata for 72 h duration. Based on this value it can be concluded that the substance 2,3,5-trimethylphenol is considered to be toxic to aquatic environment. Since the test chemical is readily biodegradable in nature, chemical 2,3,5-trimethylphenol can be considered as non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

 

Another short term toxicity study to Selenastrum capricornutum (algae) of the read across chemical 2, 3-dimethyl phenol (CAS no. 526-75-0) was carried out for 72 hrs (A. Kahru et. al; 2000). The initial algal culture was prepared from the immobilized algal beads and the deimmobilized cells were pregrown in the sterile growth medium (25 °C, 6000-8000 lux). Before the experiment the culture was diluted to OD670=0.001 corresponds to ~10⁴ cells/ml. and cultivated further for 4 days. The activated culture was used as the inoculum for the toxicity experiments. Algae were incubated with 2, 3-dimethyl phenol at 25°C for 72 h. The EC50 value of 2, 3-dimethyl phenol is considered to be 50mg/L in Selenastrum capricornutum. Based on this value it can be concluded that the substance 2,3 -dimethylphenol is considered to be toxic to aquatic environment. Since the test chemical is readily biodegradable in nature, chemical 2, 3-dimethyl phenol can be considered as non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

 

Thus, based on the overall reported results for target chemical2,3,5-trimethylphenol(from peer reviewed journal and OECD QSAR toolbox version 3.3) and for its read across chemical (from peer reviewed journal) , it can be concluded that the test substance2,3,5-trimethylphenolcan be considered as non-toxic to aquatic environment and thus can be considered to be not classified as per the CLP classification criteria.