2,3,5-trimethylphenol

Endpoint summary

Description of key information

Short-term toxicity to fish

Based on the EPI Suite ECOSAR version 1.10 prediction model, the 96 hours LC50 was estimated to be 10.274 mg/l on Fish for substance 2,3,5-trimethylphenol (CAS no.697-82-5) on the basis of mortality effects using neutral organics class for prediction.Based on this value it can be concluded that the substance 2,3,5-trimethylphenol is considered to be toxic to Fish. 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 to aquatic invertebrates

Short term toxicity test was performed in Daphnia magna byJames devillers, 1988 to study the immobilization study of < 72 h old daphnids in test tubes which is filled with 8ml with test chemical and make up to 10ml for 24 hrs. Range finding test was conducted and a concentration was decided with specific test conditions. From experiment it was concluded that the IC 50 value for short term toxicity to aquatic invertebrates for 2,3,5Trimethylphenol (687-82-5) was determined to be 26.69 mg/l. Based on the value, the chemical was considered to be toxic in nature but as it was readily biodegradable in nature , thus the 2,3,5Trimethylphenol was considered to be not classified as per the CLP regulations.

Toxicity to aquatic algae and cyanobacteria

Long term toxicity toChlorella autofrophica studywas carried out for 3-7 daysKenneth 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.

Toxicity to microorganisms:

The toxicity of test substance 2,3,5-trimethylphenol was determined with a Microtox model 500 toxicity autoanalyzer (Microbics Corp., Carlsbad, Calif.)

Microbial inoculum was prepared by mixing 25 g of creosote-contaminated surface soil freshly obtained from the American Creosote Works site with 100 ml of 2.5 mM phosphate buffer (pH 7). After being mixed well, the suspension was centrifuged (2,500 rpm, 10 min) to remove larger soil particles. The resultant supernatant was decanted and used as a source of indigenous, "creosote-adapted"microorganisms for the groundwater medium (GWM).Each flask containing 25 ml of GWM was inoculated with 1.0 ml (27 pLg of bacterial protein) of the soil microbial suspension.The Microtox assays demonstrated a 50% effective concentration (EC50) of 0.72 (a solution containing 0.72% parent material killed 50% of the test organisms) this 0.72% concentration equivalent to 7000 mg/l of test substance 2,3,5-trimethylphenol.

Additional information

Short-term toxicity to fish

Two predicted models represents the data for short term fish toxicity of test chemical 2,3,5-trimethylphenol (Cas no. 697-82-5) were summarize as follows:

First model from EPI Suite ECOSAR version 1.10 prediction indicate the 96 hours LC50 was estimated to be 10.274 mg/l on Fish for substance 2,3,5-trimethylphenol (CAS no.697-82-5) on the basis of mortality effects using neutral organics class for prediction.Based on this value it can be concluded that the substance 2,3,5-trimethylphenol is considered to be toxic to Fish. 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.

And another prediction suggest the estimated 96 hrs LC50 value of test substance 2,3,5-trimethylphenol on Fathead minnow was determined by three different models i.e, Battery, Leadscope and SciQSAR used within Danish QSAR database. Based on mortality, the estimated 96 hrs LC50 value was predicted to be 14.22226 mg/l.

Thus based on both prediction for target 2,3,5-trimethylphenol (Cas no. 697-82-5) give the lethal concentration is in the range of 10.274- 14.22226 mg/l but the chemical is readily biodegradable in nature, thus considered as non-toxic to aquatic environment and can be considered to be not classified as per the CLP classification criteria.

Short term toxicity to aquatic invertebrates

Short term toxicity to aquatic invertebrates for 2,3,5Trimethylphenol (CAS:687-82-5)was summaries with one experimental study and two experimental studies with one read across substances 2,3-dimethylphenol are as follows:

Short term toxicity test was performed in Daphnia magna byJames devillers, 1988 to study the immobilization study of < 72 h old daphnids in test tubes which is filled with 8ml with test chemical and make up to 10ml for 24 hrs. Range finding test was conducted and a concentration was decided with specific test conditions. From experiment it was concluded that the IC 50 value for short term toxicity to aquatic invertebrates for 2,3,5Trimethylphenol (687-82-5) was determined to be 26.69 mg/l. Based on the value, the chemical was considered to be toxic in nature but as it was readily biodegradable in nature , thus the 2,3,5Trimethylphenol was considered to be not classified as per the CLP regulations.

From the same reference, study was performed on read across 2,3 –dimethylphenol in Daphnia magna when they were exposed for 24h.They were found to be immobilized at the concentration of 13.615mg/l .Therefore the IC50 was considered to be 13.615mg/l for 2,3 –dimethylphenol when Daphnia magna  were exposed for 24h under static condition.

For same read across 2,3 –dimethylphenol study was conducted by A. Kahru, 2000 to find out the toxicity of 2, 3-dimethyl phenol to Daphnia magna. Test plates with Daphnia magna neonates (Daphtoxkit Fᵀᴹ manga) were incubated for 48 h at 20 deg C in the dark. Immobilization of the organism was observed after exposure to 2, 3-dimethyl phenol. The LC50 value of 2,3-dimethylphenol was considered to be 11 mg/l for Daphnia magna. Based on the value, the chemical was considered to be toxic in nature but as it was readily biodegradable in nature , thus the 2,3,dimethylphenol was considered to be not classified as per the CLP regulations.

Based on the above experimental study for target and studies of read across chemicals it can be considered that all the above studies supported the target classification, so based on the results it was considered that 2,3,5Trimethylphenol (687-82-5) was not hazardous to aquatic invertebrates and can be considered to be not classified as per the CLP regulations.

Toxicity to aquatic algae and cyanobacteria

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.

Toxicity to microorganisms:

Three studies including experimental data from peer reviewed journals for toxicity to micro organism endpoint of test chemical 2, 3, 5-trimethylphenol (Cas no. 697-82-5) with relevant read across which is structurally similar to target were summarized as followed:

First experimental study (APPLIED AND ENVIRONMENTAL MICROBIOLOGY, May 1991, p. 1277-1285)suggest the toxicity of test substance 2,3,5-trimethylphenol was determined with a Microtox model 500 toxicity autoanalyzer (Microbics Corp., Carlsbad, Calif.) Microbial inoculum was prepared by mixing 25 g of creosote-contaminated surface soil freshly obtained from the American Creosote Works site with 100 ml of 2.5 mM phosphate buffer (pH 7). After being mixed well, the suspension was centrifuged (2,500 rpm, 10 min) to remove larger soil particles. The resultant supernatant was decanted and used as a source of indigenous, "creosote-adapted"microorganisms for the groundwater medium (GWM).Each flask containing 25 ml of GWM was inoculated with 1.0 ml (27 pLg of bacterial protein) of the soil microbial suspension. The Microtox assays demonstrated a 50% effective concentration (EC50) of 0.72 (a solution containing 0.72% parent material killed 50% of the test organisms) this 0.72% concentration equivalent to 7000 mg/l of test substance 2,3,5-trimethylphenol.

And one another peer reviewed journal Chemical Research in Toxicology; vol. 12; nb. 12; (1999); p. 1262 – 1267 for target chemical indicate Population growth impairment testing with the ciliate T. pyriformis (strain GL-C) was conducted following the protocol described by Schultz of test substance 2,3,5-trimethylphenol.

The test protocol allows for eight to nine cell cycles in controls. Following range finding, each chemical was tested in three replicate tests (or assays). Two controls were used to provide a measure of the acceptability of the test by indicating the suitability of the medium and test conditions as well as a basis for interpreting data from other treatments. The first control had no test material and was inoculated with T. pyriformis. The other, a blank, had neither test material nor ciliates. Test replicate consisted of six to eight different concentrations.The IGC50 is calculated by Structure-toxicity models using the regression procedure of MINITAB version 12.1.

A test on growth impairment with Tetrahymena pyriformis results in an inhibitory growth concentration (IGC50) of 1/log IGC50=0.36 which is equivalent to 599.48 (dimensionless) after 40 hours.

Whereas read across chemical 2,3,6 Trimethylphenol (CAS no. 2416-94-6) suggest Inhibition concentration to 50% of test organisms (IGC50) for the substance 2,3,6Trimethylphenol (CAS no. 2416-94-6) was determine to be 52.05 mgl/L on micro organism species Tetrahymena pyriformis (Ciliate) on the basis of effect on Population growth rate in static fresh water.( ECOTOX DATABASE; 2017)

On the basis of available effects values on micro organism from above three studies give the common conclusion as test chemical 2, 3, 5-trimethylphenol (Cas no. 697-82-5) have no concern to micro organism for toxicity in acute exposure period.