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Description of key information

Short-term toxicity to fish

A 96 h study was conducted for CAS No. 2244-16-8 on Zebra fish(Danio rerio), at a test concentrations of 6.25mg/L,12.5mg/L,25mg/L,50mg/L,100mg/L . The fishes were moving slowly as compared to control. No mortalities were found in the control aquaria. The lethal concentrations LC50 was found to be 50 mg/L

LC0 (96 hours) (highest loading at which no mortality was observed) = 25 mg/L

LC50 (96 hours) Experimental = 50 mg/L

LC100 (96 hours) (lowest loading at which 100% mortality was observed) = 100 mg/L.

Based on the above effect concentration (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one can be classified as aquatic chronic 3

Eventhough the experimental result is considered (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one is toxic for fish but

(5S)-2-methyl-5- (prop-1-en-2-yl)cyclohex-2-en-1-one is readily biodegradable . Hence it can be considered Not classified as per CLP classification.

Short-term toxicity to aquatic invertebrates

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic invertebrate was predicted (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8). EC50 Intoxication value was estimated to be 249.516 mg/l for Daphnia magna for 48 hrs duration. It was concluded that (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) was likely to be not toxic to aquatic invertebrate.

Toxicity to aquatic algae and cyanobacteria

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic invertebrate was predicted (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one. EC50 growth rate value was estimated to be 154.67 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) was likely to be not toxic to aquatic algae.

Toxicity to microorganisms

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to micro-organisms was predicted (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8). IGC50 Growth value was estimated to be 201.961 mg/l for Tetrahymena pyriformis for 48 hrs duration. It was concluded that (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) was likely to be not toxic to micro-organisms.

Additional information

Short-term toxicity to fish

The experimental study was conducted by NS Support Services to evaluate short teerm toxicity to fish of test chemical (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one

A 96 h study was conducted for CAS No. 2244-16-8 on Zebra fish(Danio rerio), at a test concentrations of 6.25mg/L,12.5mg/L,25mg/L,50mg/L,100mg/L . The fishes were moving slowly as compared to control. No mortalities were found in the control aquaria. The lethal concentrations LC50 was found to be 50 mg/L

LC0 (96 hours) (highest loading at which no mortality was observed) = 25 mg/L

LC50 (96 hours) Experimental = 50 mg/L

LC100 (96 hours) (lowest loading at which 100% mortality was observed) = 100 mg/L.

Based on the above effect concentration (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one can be classified as aquatic chronic 3 as per CLP classification.

Short-term toxicity to aquatic invertebrates

Following studies of target chemical and structurally similar read across includes predicted data and experimental data to conclude the toxicity extent of (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) towards aquatic invertebrate is summarized as follows:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic invertebrate was predicted (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8). EC50 Intoxication value was estimated to be 249.516 mg/l for Daphnia magna for 48 hrs duration. It was concluded that (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) was likely to be not toxic to aquatic invertebrate.

The above predicted data of target chemical is supported by the experimental study of structurally similar read across Isophorone (CAS: 78 -59 -1) from the publication Bulletin of Environmental Contamination and Toxicology 1980, suggests thatTo study the effects of 1,1,3-Trimethyl-3-cyclohexene-5-one on aquatic invertebrate acute toxicity test was carried out for 48 hr under static condition. The chemical to be tested was added to 500 mL of diluent water in 2-L jars to prepare each test solution. If the chemical was soluble in the diluent water, then the 500 mL volume of test solution was divided into three, 150 mL aliquots in 250-mL beakers to provide triplicate exposures.

Observations of test populations were made at 24 and 48 hours of exposure and any mortalities were recorded. Lethal concentration LC50 to 50% of Daphnia magna when exposed to 1,1,3-Trimethyl-3-cyclohexene-5-one of 48 h is 120 mg/L. It can be concluded from the mortality value that the 1,1,3-Trimethyl-3-cyclohexene-5-one (CAS:78 -59 -1)  is not toxic to the aquatic invertebrate and can be considered as “not classified” as per the classification criteria for aquatic environment.

Another supporting experimental study for the structurally similar read across 2-Hydroxyethyl methacrylate (CAS: 868-77-9) from the (J check) 2018, also suggests that To study the effcts of 2-Hydroxyethyl methacrylate on invertebrate test was carried out according to the OECD Guideline 202 (Daphnia sp., Acute Immobilisation Test and Reproduction Test). The test was carried out under static condition at nominal concentrations of1000, 556, 309, 171, 95.3 mg/L (geometric ratio 1.8), control. Immobilization was measured during the test.Results after 24-hour exposure:- 50 % Effective concentration (EC50) for immobilization: 598 mg/L (95 % CL: 309 - 1000 mg/L), Results after 48-hour exposure:

- No observed effect concentration (NOEC) for immobilization: 171 mg/L,

- Lowest concentration causing 100 % immobility: 556 mg/L,(All results were based on the nominal values.)

The effective concentration EC50 to 50% of Daphnia magna when exposed to 2-Hydroxyethyl methacrylate for 48 hr is 380 mg/L.It can be concluded from the value that the 2-Hydroxyethyl methacrylate (CAS: 868-77-9) is not toxic/toxic to the aquatic invertebrate and can be considered as “not classified” as per the classification criteria for aquatic environment.

Thus based on the effect concentrations which is in the range 120 mg/L to380 mg/lgive the conclusion that test substance (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) is likely to be not toxic to aquatic invertebrate at environmentally relevant concentrations and applying weight of evidence approach it can be considered to be “not classified” as per the CLP classification criteria.

Toxicity to aquatic algae and cyanobacteria

Following studies of target chemical and structurally similar read across includes predicted data and experimental data to conclude the toxicity extent of (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) towards aquatic algae is summarized as follows:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to aquatic invertebrate was predicted (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one. EC50 growth rate value was estimated to be 154.67 mg/l for Pseudokirchneriella subcapitata for 72 hrs duration. It was concluded that (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) was likely to be not toxic to aquatic algae.

The above predicted data of target chemical is supported by the experimental study of structurally similar read across 2-Hydroxyethyl methacrylate (CAS: 868 -77-9) from the (J check) 2018,, suggests that theToxicity to aquatic algae and cyanobacteria test was carried out to study the effects of 2-Hydroxyethyl methacrylate on algae for 72 hr.

The effective concentration EC50 to 50% of algae when exposed to 2-Hydroxyethyl methacrylate for 72 hr is 710 mg/L.It can be concluded from the value that the 2-Hydroxyethyl methacrylate is not toxic/toxic to the aquatic algae and can be considered as “not classified” as per the classification criteria for aquatic environment.

Another supporting experimental study for the structurally similar read across 1,1,3-Trimethyl-3-cyclohexene-5-one (CAS: 78-59-1) from the Environmental Protection Agency 1978, also suggests that the Toxicity to aquatic algae test was carried for 96 hr to study the effects of 1,1,3-Trimethyl-3-cyclohexene-5-one on aquatic algae.Decreasing trend of Population (Chlorophyll A concentration) was measured during the test.

Effective concentration EC50 to 50% of Skeletonema costatum when exposed to 1,1,3-Trimethyl-3-cyclohexene-5-one for 96 hr is 110 mg/L. It can be concluded from the value that the 1,1,3-Trimethyl-3-cyclohexene-5-one is not toxic to the aquatic algae and can be considered as “not classified” as per the classification criteria for aquatic environment.

Thus based on the effect concentrations which is in the range 110 mg/L to710 mg/lgive the conclusion that test substance (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) is likely to be not toxic to aquatic algae at environmentally relevant concentrations and applying weight of evidence approach it can be considered to be “not classified” as per the CLP classification criteria.

Toxicity to microorganisms

Following studies of target chemical and structurally similar read across includes predicted data and experimental data to conclude the toxicity extent of (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) towards microrganisms is summarized as follows:

Based on the prediction done using the OECD QSAR toolbox version 3.3 with log kow as the primary descriptor and considering the closest read across substances, the toxicity to micro-organisms was predicted (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8). IGC50 Growth value was estimated to be 201.961 mg/l for Tetrahymena pyriformis for 48 hrs duration. It was concluded that (5S)-2-methyl-5-(prop-1-en-2-yl)cyclohex-2-en-1-one (CAS: 2244-16-8) was likely to be not toxic to micro-organisms.

The above predicted data of target chemical is supported by the experimental study of structurally similar read across Isophorone (CAS: 78 -59 -1) from the publicationScience of The Total Environment1985, suggests that theToxicity to microorganisms test was carried out of 1,1,3-Trimethyl-3-cyclohexene-5-one for 24 H on Tetrahymena pyriformis uncder static condition to study the effects. Decreasing trend of population growth rate was measured during the test.

Effective concentration EC50 to 50% of Tetrahymena pyriformis when exposed to 1,1,3-Trimethyl-3-cyclohexene-5-one for 24 hr is 420 mg/L. It can be concluded from the value that the 1,1,3-Trimethyl-3-cyclohexene-5-one is not toxic to the microorgnaisms.