Registration Dossier

Ecotoxicological information

Endpoint summary

Currently viewing:

Administrative data

Description of key information

Short-term toxicity to fish

In a Short-term toxicity to fish study (Inger-Britt Falk-Petersen et al; Sarsia, 29 May 1985, Vol. 70, Issue 1, pages 11 – 16) for 2, 3 Dimethylphenol in Gadus morhua L (egg and larva).When they were exposed for 96 h at concentration of 13 mg /l mortality were observed. Therefore EC50 was considered to be 13 mg/l for 2, 3 Dimethylphenol when Gadus morhua L (egg and larva) were exposed for 96h under static condition.

Mentioned effect concentration (EC50) for 96 hrs exposure period suggest that the test chemical2, 3 Dimethylphenol was toxic to fish and thus consider for aquatic category 3 as per the CLP criteria.

Short-term toxicity to aquatic invertebrates:

Short-term toxicity test was conducted to 2, 3-Dimethylphenol (526-75-0) by Kahruet,al(Environ Toxicol 15: 431-442, 2000) to determined 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.

Toxicity to aquatic algae and cyanobacteria

The study was designed to assess the toxic effects of the test compound 2,3-dimethylphenol (526-75-0) on the green alga Chlorella vulgaris. Test was conducted in compliance with the OECD guideline 201 (Alga, Growth Inhibition Test).Test was carried out in 100mL conical flasks which were carefully autoclaved and sterilized. The test solution in each of these test vessels was kept constant which is 60 ml so that a sufficient amount of head space was left. The test substance 2,3-dimethylphenol (526-75-0) was prepared by adding 4 mg of test item in 250 ml of BBM to get the final concentration of 16 mg/L. This stock solution was kept for stirring for 05 minutes to obtain a homogenous solution for the experiment. The test concentrations >0.5 mg/L, 1 mg/L, 2 mg/L, 4 mg/L, 8 mg/L, 16 mg/L were chosen according to the available data of the test item. The concentrations chosen were set up to the water solubility limit. The remaining test solutions were prepared by dilution from the above stock solution.For the assessment of algal growth, the test was conducted in replicates. The control flask was maintained in triplicates as recommended in the OECD guideline and the test concentration were selected in geometric series which were maintained in duplicates. To obtain a quantitative concentration-response relationship by regression analysis, a linearizing transformation of the response data into probit was performed. Using the same, effective concentration (EC) were determined.Algal growth was calculated daily by counting the cells microscopically with the help of haemocytometer. For microscopic observations the cultures were observed daily with the help of a microscope to verify a normal and healthy appearance of the algal culture and also to observe any abnormal appearance of the algae (as may be caused by the exposure of the test item). Apart from this, the cell count of each test vessel was also noted with the help of a microscope and haemocytometer. By spectrophotometer the absorbance values of each test vessel and control vessel was noted at 680nm.The BBM was taken as blank for both control and test vessels. The absorbance value of each vessel was in line with the average specific growth rate.As per OECD 201, the biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72 hr test period. This corresponds to a specific growth rate of 0.92 per day. Thus, the observed specific growth rate in the control cultures during the experiment was 0.358 per day. Secondly the mean coefficient of variation for section by section specific growth rates (days 0-1, 1-2 & 2-3, for 72 hr tests) in the control cultures must not exceed 35%. Thus, the observed mean coefficient of variation in the control cultures during the experiment was 33.42%. Thirdly the coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 10%. Thus, the observed coefficient of variation of average specific growth rates during the experiment in control cultures was 8.26%. Hence, the test is considered valid as per OECD guideline, 201.After 72 hours of exposure to test item 2,3-dimethylphenol (526-75-0) to various nominal test concentrations, EC50 was determine to be 2.726 mg/l graphically and through probit analysis. Based on the EC50, it can be concluded that the chemical was hazardous and can be consider to be classified aq aquatic chronic 2 as per the CLP classification criteria.

Toxicity to microorganisms

Toxicity test was performed with Laboratory-prepared freeze-dried photobacterial reagent (Photobacterium phosphoreum strain FEI 162095) registered in the Finnish Environment Institute. The freeze-dried bacteria were reconstituted by adding 12.5-ml 2% NaCl into the reagent bottle and incubating it at +4°C for 20 min before use. The concentration of 2, 3-dimethyl phenol in the test (mg/L) which caused a 50% reduction in light after exposure of 2,3dimethyl phenol for 15 min. The EC50 value of 2, 3-dimethyl phenol is considered to be 28 mg/l for Photobacterium phosphoreum bacteria.

Additional information

Short-term toxicity to fish

Four studies including experimental data and predicted data from validated model for short term fish toxicity endpoint of target chemical 2,3-dimethylphenol (Cas no. 526-75-0) were summarized as follows:

 

First experimental study suggest short-term toxicity to fish study (Inger-Britt Falk-Petersen, et al. 1985) for 2, 3 Dimethylphenol in Gadus morhua L (egg and larva) was conduct, When they were exposed for 96 h at concentration of 13 mg /l mortality were observed. Therefore EC50 was considered to be 13 mg/l for 2, 3 Dimethylphenol when Gadus morhua L (egg and larva) were exposed for 96h under static condition. Mentioned effect concentration (EC50) for 96 hrs exposure period suggest that the test chemical2, 3 Dimethylphenol was toxic to fish and thus consider for aquatic category 3 as per the CLP criteria.

 

Above aquatic classification supported by other evidence i.e short term toxicity study was conducted by Devillers,J., T. Meunier, and P. Chambon (1985) to determine the effects of test chemical 2,3 Dimethylphenol on Danio rerio for 24 hours under static condition. The study indicates LC50 was considered to be 10-35mg/l for Danio rerio based on mortality effect. Thus based on the lethal concentration it is concluded that the test substance 2, 3 Dimethylphenol was toxic to fish for acute exposure period.

 

Another experimental study from same data source i.e Devillers,J., et al; Tech. Sci. Munic.80:329-334, (1985) suggest Short term toxicity study was conducted to test the effects 2, 3 Dimethylphenol on Danio rerio for 6 hours under static condition. The LC50 at 2 hours was considered to be 35-100 mg/L for Danio rerio based on mortality effects.

 

Last data from Danish QSAR database using three different models i.e, Battery, Leadscope and SciQSAR indicate estimated 96 hrs LC50 value of test substance 2,3-Dimethylphenol on Fathead minnow was determined to be 20.21 mg/l.

Thus above all studies indicate that the target chemical 2, 3 Dimethylphenol (Cas no.526-75-0) is likely to be toxic to fish. Since the test chemical is readily biodegradable in nature, chemical can be considered as not hazardous to aquatic organisms and thus 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-Dimethylphenol (526-75-0) is summaries with key and supporting studies are as follows:

Short-term toxicity test was conducted to 2, 3-Dimethylphenol (526-75-0) by Kahruet,al(Environ Toxicol 15: 431-442, 2000) to determined 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.

Supporting study by James Devillers (Science of The Total Environment Volume 76, Issue 1, 15 September 1988, Pages 79-83) short-term toxicity to aquatic invertebrates for 2, 3-dimethyl phenol, in Daphnia magna when exposed for 24h.Daphnia magna were found to be immobilized at the concentration of 13.615 mg/l .Therefore the IC50 was considered to be 13.615 mg/l for 2, 3-dimethyl phenol when Daphnia magna were exposed for 24h under static condition.

Another supporting study by Kahruet, al(Environ Toxicol 15: 431-442, 2000) was conducted to find out the toxicity of 2, 3-dimethyl phenol to Thamnocephalus platyurus. Test plates with Thamnocephalus platyurus larvae (Thamnotoxkit F) was incubated at 25°C for 24 h in the dark. Mortality was observed after exposure to 2, 3-dimethyl phenol. The LC50 value of 2, 3-dimethylphenol was considered to be 6 mg/l for Thamnocephalus platyurus.

Study of Daphnia magna was carried out for 48 hrs from HSDB, 2011 to determine the effect of test substance 2, 3-Dimethylphenol on test organism. After the experiment the LC50 value was determined to be 16.0 mg/l.

Based on the above key and supporting studies it was considered that 2, 3-Dimethylphenol was considered to be hazardous to aquatic invertebrates but as it was readily biodegradable hence, it can be considered to be not classified as per the CLP regulations.

Toxicity to aquatic algae and cyanobacteria

Various studies for the target chemical 2,3-Dimethylphenol (CAS No. 526-75-0) were reviewed to summarize the following information:

In an experimental study, the study was designed to assess the toxic effects of the test compound 2,3-dimethylphenol (526-75-0) on the green alga Chlorella vulgaris. Test was conducted in compliance with the OECD guideline 201 (Alga, Growth Inhibition Test).Test was carried out in 100mL conical flasks which were carefully autoclaved and sterilized. The test solution in each of these test vessels was kept constant which is 60 ml so that a sufficient amount of head space was left. The test substance 2,3-dimethylphenol (526-75-0) was prepared by adding 4 mg of test item in 250 ml of BBM to get the final concentration of 16 mg/L. This stock solution was kept for stirring for 05 minutes to obtain a homogenous solution for the experiment. The test concentrations >0.5 mg/L, 1 mg/L, 2 mg/L, 4 mg/L, 8 mg/L, 16 mg/L were chosen according to the available data of the test item. The concentrations chosen were set up to the water solubility limit. The remaining test solutions were prepared by dilution from the above stock solution.For the assessment of algal growth, the test was conducted in replicates. The control flask was maintained in triplicates as recommended in the OECD guideline and the test concentration were selected in geometric series which were maintained in duplicates. To obtain a quantitative concentration-response relationship by regression analysis, a linearizing transformation of the response data into probit was performed. Using the same, effective concentration (EC) were determined.Algal growth was calculated daily by counting the cells microscopically with the help of haemocytometer. For microscopic observations the cultures were observed daily with the help of a microscope to verify a normal and healthy appearance of the algal culture and also to observe any abnormal appearance of the algae (as may be caused by the exposure of the test item). Apart from this, the cell count of each test vessel was also noted with the help of a microscope and haemocytometer. By spectrophotometer the absorbance values of each test vessel and control vessel was noted at 680nm.The BBM was taken as blank for both control and test vessels. The absorbance value of each vessel was in line with the average specific growth rate.As per OECD 201, the biomass in the control cultures should have increased exponentially by a factor of at least 16 within the 72 hr test period. This corresponds to a specific growth rate of 0.92 per day. Thus, the observed specific growth rate in the control cultures during the experiment was 0.358 per day. Secondly the mean coefficient of variation for section by section specific growth rates (days 0-1, 1-2 & 2-3, for 72 hr tests) in the control cultures must not exceed 35%. Thus, the observed mean coefficient of variation in the control cultures during the experiment was 33.42%. Thirdly the coefficient of variation of average specific growth rates during the whole test period in replicate control cultures must not exceed 10%. Thus, the observed coefficient of variation of average specific growth rates during the experiment in control cultures was 8.26%. Hence, the test is considered valid as per OECD guideline, 201After 72 hours of exposure to test item 2,3-dimethylphenol (526-75-0) to various nominal test concentrations, EC50 was determine to be 2.726 mg/l graphically and through probit analysis. Based on the EC50, it can be concluded that the chemical was hazardous and can be consider to be classified aq aquatic chronic 2 as per the CLP classification criteria.

In another CRO lab experimental study report,aim of this study was to evaluate the nature of chemical test chemical 2,3-dimethylphenol (526-75-0) when comes in contact with the test organism Desmodesmus subspicatus (previous name: Scenedesmus subspicatus). The stock solution 100.0 mg/l was prepared by dissolving dark orange 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.0,10,18,32,58,100 mg/l concentration were used.With the test substance one positive control Potassium dichromate (K2Cr2O7) was also run simultaneously. After the exposure of chemical, effect concentration EC50 was calculated using nonlinear regression by the software Prism 4.0. Effect on the growth of algae was determine after an exposure period of 72 hrs.The median effective concentration (EC50) for the test substance 2,3-dimethylphenol (526-75-0), in algae was determined to be 92.3 mg/l(95% CI:73.1-116.5) on the basis of growth rate inhibition effects in a 72 hour study. Based on the EC50 value, which indicates that the substance is likely to be hazardous to aquatic algae and can be classified as aquatic chronic 3 category as per the CLP classification criteria.

In an experimental study, toxicity of substance 2, 3-dimethyl phenol (CAS no. 526 -75 -0) to aquatic algae Selenastrum capricornutum assay was carried out using standard procedure for Algaltoxkit Fᵀᴹ(A. Kahru et. al; 2000). Selenastrum capricornutum was used as a test organism. The study was based on the effect on the test compound 2, 3-dimethyl phenol to Selenastrum capricornutum under static conditions at a temperature of 25°C for 72 hrs. 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 toapprox.104cells/ml)and cultivated further for 4 days.The EC50 value of 2, 3-dimethyl phenol is determined to be 50mg/L in Selenastrum capricornutum. Thus, based on the EC50 value, substance 2, 3-dimethyl phenol can be considered as toxic to aquatic organisms. Since the chemical is readily biodegradable in nature, chemical 2, 3-dimethyl phenol can be considered as non-toxic to aquatic organisms and thus can be considered to be not classified as per the CLP classification criteria.

Thus above all studies indicate that the target chemical 2, 3 Dimethylphenol (Cas no.526-75-0) is likely to be toxic to aquatic algae.Since the test chemical is readily biodegradable in nature, chemical can be considered as not hazardous to aquatic organisms and thus can be considered to be not classified as per the CLP classification criteria.

 

Toxicity to microorganisms

Four studies including experimental data from peer reviewed journals for micro organism toxicity endpoint of target chemical 2,3-dimethylphenol (Cas no. 526-75-0) were summarized as follows:

 First experimental study suggest toxicity test was performed by Kahru et. al (2000) with Laboratory-prepared freeze-dried photobacterial reagent (Photobacterium phosphoreum strain FEI 162095) registered in the Finnish Environment Institute. The freeze-dried bacteria were reconstituted by adding 12.5-ml 2% NaCl into the reagent bottle and incubating it at +4°C for 20 min before use. The concentration of 2, 3-dimethyl phenol in the test (mg/L) which caused a 50% reduction in light after exposure of 2,3dimethyl phenol for 15 min. The EC50 value of 2, 3-dimethyl phenol is considered to be 28 mg/l for Photobacterium phosphoreum bacteria.

Another experiment indicates Mirotox test was performed with Vibrio fischeri to find toxicity of 2, 3-dimethyl phenol. MicrotoxTM Reagent (Vibrio fischeri NRRL-B 11177). (AZUR Environmental, Carlsbad, California, USA). The freeze-dried reagent was reconstituted and bacteria cultivated, harvested, and frozen in cryoprotectant as described in paper (Kahru et al., 1996). The thawed bacterial suspension was used for the toxicity tests. The amount of viable bacteria in the case of all photo bacterial tests was ~10⁶ bacteria per ml test solution. The concentration of 2, 3-dimethyl phenol in the test (mg/L) which caused a 50% reduction in light after exposure of 2, 3-dimethyl phenol for 15 min. The EC50 value of 2, 3-dimethyl phenol is considered to be 5.3 mg/l in Vibrio fischeri NRRL-B 11177. (A. Kahru et al;Environ Toxicol 15: 431-442, 2000)

Same data source (i.e A. Kahru et al;Environ Toxicol 15: 431-442, 2000) also suggest Biotox test was performed with Vibrio fisheri to find toxicity of 2, 3-dimethyl phenol. Vibrio fisheri 1500 Reagent (Vibrio fischeri NRRL-B11177). from the BioTox test (Labsystems, Helsinki, Finland). The freeze-dried reagent was reconstituted with 12.5-ml 2% NaCl, incubated at +4°C for 20 min and, prior to the assay, further diluted five-fold with 2% NaCl. The concentration of 2, 3-dimethyl phenol in the test (mg/L) which caused a 50% reduction in light after exposure of 2, 3-dimethyl phenol for 15 min. The EC50 value of 2, 3-dimethyl phenol is considered to be 5.2 mg/l in Vibrio fischeri NRRL-B 11177.

And last study from another peer reviewed journal Water Pollution Research Journal Canada; Volume 26, No. 3, 361-431, 1991 indicate toxicity study of micro-organism to the test substance was conducted using Photobacterium phosphoreum, strain NRRL-B-11177 (also referred to as Vibrio fischerii, strain NRRL-B-11177).When test bacteria was exposed to the test substance 2,3-dimethylphenol with exposure duration of 5, 15 and 30 mins, reduction in light output was observed. Thus, based on reduction in light output by the test organism, the EC50 value during 30 mins exposure period was found to be 3.36 mg/l.

Thus all aquatic micro organism studies available for 15-30 min. exposure period indicate the effect concentration is in the range of 3.36 to 28 mg/l. And all EC50 values on the basis of reduction in light output effect. Based on the EC50 values it is concluded that target chemical 2,3-dimethylphenol (Cas no. 526-75-0) may have toxicity concern to micro organism for acute exposure period.