(±)-menthone

Endpoint summary

Description of key information

Short-term toxicity to fish:

The short-term toxicity of the 2-isopropyl-5-methylcyclohexanone (CAS no. 1074-95-9) to Danio rerio (previous name: Brachydanio rerio) was predicted using QSAR toolbox version. 3.4, based on the effects observed in a static freshwater system during a 96 hr exposure. The lethal concentration (LC50) for the substance is estimated to be 28.2 mg/L. Based on this value, it can be concluded that the test chemical 2-isopropyl-5-methylcyclohexanone can be considered as toxic to fish at environmentally relevant concentrations and can be classified in aquatic chronic category 3 as per the CLP classification criteria

Short term toxicity to aquatic invertebrates

The median effective concentration (EC50) for the test substance,(±)-menthone, in Daphnia magna was determined to be 74.7mg/L on the basis of mobiity inhibition effects in a 48 hour study.

Toxicity to aquatic algae and cyanobacteria

The median effective concentration (EC50) for the test substance, (±)-menthone, in Desmodesmus subspicatus was determined to be 172.9 mg/L on the basis of effects on growth rate in a 72 hour study.

Toxicity to microorganisms:

In experiment the test substance Menthone (Cas no.1074-95-9) showed inhibitory effects (MIC) on growth of the 4 bacterial strains (Clavibacter michiganense, Xanthomonas campestrispv.Rhapontici,Klebsiella trevisanii,Pseudomonas aeruginosa ATCC 9027)out of 63 strains at a concenttration of 10μl..

Additional information

Short-term toxicity to fish:

Two studies including validated Predicted data source for short term fish endpoint of target chemical 2-isopropyl-5-methylcyclohexanone (Cas no. 1074-95-9) were reviewed to summarize as follows:  

 

First study of 96 hrs aquatic toxicity was estimated to assess toxic effects of the test compound 2 -isopropyl-5 -methylcyclohexanone (CAS no. 1074 -95 -9) using the OECD QSAR toolbox (ver.3.4; 2017). The study was based on the effects of the test compound on fish species Danio rerio (previous name: Brachydanio rerio) in a static fresh water system. The predicted data suggests the median lethal concentration (LC50) for the test compound 2 -isopropyl-5 -methylcyclohexanone (CAS no. 1074 -95 -9) was estimated to be 28.221 mg/l on the basis of mortality effect.

Another prediction for toxicity to fish is done using the EPI Suite ECOSAR version 1.10, which indicated the 96 hours LC50 to be 20.973 mg/l for substance 2-isopropyl-5-methylcyclohexanone (CAS no. 1074-95-9) on the basis of mortality effects.

Based on both predicted lethal concentration (LC50) it can be concluded that the target substance 2-isopropyl-5-methylcyclohexanone is likely to be toxic to aquatic organisms at environmentally relevant concentrationa and thus can be classified in aquatic chronic category 3 as per the CLP criteria.

Short term toxicity to aquatic invertebrates

Various studies, used as key and supporting, for short term toxicity to aquatic invertebrates was reviewed for 2-isopropyl-5-methylcyclohexanone (CAS no 1074-95-9) and two read across, 2-(4-chlorophenoxy)-2-methylpropanoic acid (882-09-7) and (R)-2-(4-Chloro-2-methylphenoxy) propionic acid (16484-77-8). The results are summarised as follows:

In a key study conducted by SSS, determination of the inhibition of the mobility of daphnids was carried out with the substance(±)-menthoneaccording to OECD Guideline 202. The test substance was tested at the concentrations0, 5, 10, 20, 40, 80 and 160 mg/L. Effects on immobilisation were observed for 48 hours.The median effective concentration (EC50) for the test substance,(±)-menthone, in Daphnia magna was determined to be 74.7mg/L for immobilisation effects.

This value indicates that the substance is likely to be hazardousto aquatic invertebrates and can be classified as Aquatic Chronic 3 as per the CLP criteria.

Above experimental data is supported by the prediction done using the OECD QSAR toolbox version 3.4 with log kow as the primary descriptor and considering the five closest read across substances, the short term toxicity on aquatic invertebrates was predicted for 2-isopropyl-5-methylcyclohexanone (CAS no 1074-95-9). EC50 value was estimated to be 55.84mg/L on the basis of mobility for Daphnia magna for 48 hrs duration.

Another prediction on short-term toxicity to invertebrate is predicted using EPI suite, ECOSAR version 1.1, 2017, based on the effects observed in 48 hr exposure. The lethal concentration (LC50) for the substance is estimated to be 12.90 mg/L.

A study was performed for read across chemical 2-(4-chlorophenoxy)-2-methylpropanoic acid (882-09-7) (Toxicology Letters 142 (2003) 185-194) using Daphnia magna strauss for 48 hrs at different concentrations. The Daphnids was bred in ADaM, a culture medium imitating natural fresh water. Experiment was performed at temperature 20±1ᵒC and 16:8 photoperiod. Twenty daphnids younger than 24 h were used for the controls and each treatment subdivided in four replicates each containing five daphnids. Culture volume was 50 ml. After experiments, the EC 50 value for 2-(4-chlorophenoxy)-2-methylpropanoic acid (882-09-7) for short term toxicity to aquatic invertebrates was determined to be 72 mg/l on the basis of mobility.

Further, another study was performed for read across (R)-2-(4-Chloro-2-methylphenoxy) propionic acid (16484-77-8)(Ecotox database,2017)in Daphnia magna for 48 hr using freshwater in static condition. 5 daphnia magna were used having age of <24 hrs. After experiment the EC 50 value for (R)-2-(4-Chloro-2-methylphenoxy) propionic acid (16484-77-8) for Daphnia magna was determined to be 90.94 mg/l on the basis of intoxication.

Thus, based on the experimental key results of EC50= 74.7mg/L for 2-isopropyl-5-methylcyclohexanone (CAS no 1074-95-9), it can be considered that the substance isopropyl-5-methylcyclohexanone (CAS no 1074-95-9) was likely to be toxic to aquatic invertebrates at environmentally relevant concentrations and can be considered to be classified as aquatic chronic 3 as per the criteria of CLP regulation.

Toxicity to aquatic algae and cyanobacteria

In a study conducted by SSS, Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance(±)-menthoneaccording to OECD Guideline 201.The test substance was dissolved in DMSO/ OECD growth medium and tested at the concentrations0, 30, 45, 67, 100 and 150 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (EC50) for the test substance,(±)-menthone, in Desmodesmus subspicatus was determined to be 172.9 mg/L.

This value indicates that the substance is likely to be non-hazardous to aquatic algae and can be considered as not classified as per the CLP criteria.

Toxicity to microorganisms:

The objective of this study was to evaluate the inhibitory effects of 21 pure oxygenated monoterpenes, obtained commercially including test chemicalMenthone(Cas no.1074-95-9) on the growth of 63 bacterial strains (plant, food and clinic origins).

 

In experiment Suspensions (100μl) of the bacteria, adjusted to 108 cfu/ml final cell concentration, were added to flasks containing 25 ml sterile NA medium and then poured into Petri dishes and spread by a sterile swab (9 cm). 30 mg of each of the compounds were dissolved in 1 ml of methanol and these solutions were sterilized in 0.45μm milipore filters. Sterilized discs (5 mm) were soaked with 10μl of each compound solution. These discs were put in the middle of plates containing NA medium.Penicillin was used as a positive control.For this purpose, 1 mg of penicillin was added

into 1 ml sterilized water, and a sterilized disc was soaked with 10μl of this solution. Bacterial cultures of plant origins were incubated at (27 ± 2) °C, whereas the bacterial cultures of clinic and food origins were incubated at (35 ± 2) °C for 6 d. At the end of six-day-periods, inhibition zones were measured in mm. All the tests were made in triplicate.

 

At end of the experiment the test substanceMenthone showed inhibitory effects on growth of the 4 bacterial strains (Clavibacter michiganense, Xanthomonas campestrispv.Rhapontici, Klebsiella trevisanii, Pseudomonas aeruginosa ATCC 9027)out of 63 strains at a concenttration of 10μl.