2-butyl-6-(butylamino)-1H-benz[de]isoquinoline-1,3(2H)-dione

Endpoint summary

Description of key information

Short term toxicity to fish:
The Lethal concentration (LC50) value for 2-butyl-6-(butylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione on Danio rerio (previous name: Brachydanio rerio) in a 96 hrs. study was estimated to be 172.24 mg/L on the basis of effects on mortality in static freshwater by OECD QSAR toolbox.

Short term toxicity to Aquatic Invertebrates:
The median effective concentration (EC50) for the test substance, 2-butyl-6-(butylamino)-1H-benz[de]isoquinoline-1,3(2H)-dione, in Daphnia magna was determined to be 0.17 mg/L on the basis of mobility inhibition effects in a 48 hour study.

Toxicity to Aquatic Algae and Cyanobacteria:
The median effective concentration (ErC50) for the test substance, 2-butyl-6-(butylamino)-1H-benz[de]isoquinoline-1,3(2H)-dione, in a freshwater algae Desmodesmus subspicatus was determined to be 381.3 mg/L on the basis of effects on growth rate in a 72 hour study.

Toxicity to microorganism:
The study does not need to be conducted because the substance is highly insoluble in water, hence indicating that aquatic toxicity is unlikely to occur.

Additional information

Short term toxicity to fish:
Predicted data for the substance 2-butyl-6-(butylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione and its read across substance were reviewed for short term toxicity to fish endpoint and are represented here as weight of evidence approach:

The toxic effects of the test compound 2-butyl-6-(butylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione were predicted using QSAR toolbox version 3.4. The prediction was based on the effects of the test compound on Danio rerio (previous name: Brachydanio rerio) in a static fresh water system during a 96 hour exposure. The Lethal concentration (LC50) value was estimated to be 172.24 mg/L on the basis of effects on mortality.

96 hour short term toxicity to fish was carried for the substance 2-methyl-1H-isoindole-1,3(2H)-dione (CAS 550-77-4)according to OECD guideline 203 (HPVIS database, 2017). The test species used was fresh water Oncorhynchus mykiss in static condition. Nominal concentrations used were 0, 40, 68,116, 200, 293.3 mg/L while measured concentrations were 0, 34.6, 58.7, 100.3, 174.6, 293.3 mg/L. LC50 were calculated at 24, 48, 72, and 96 h. At test termination (96-hour exposure), all fish appeared normal in the control.  As per the observations made, the 50% Lethal concentration value of the substance 2-methyl-1H-isoindole-1,3(2H)-dione to Oncorhynchus mykiss is determined to be 110 mg/L.

Considering above data and by applying weight of evidence approach it can be concluded that the substance 2-butyl-6-(butylamino)-1H-benzo[de]isoquinoline-1,3(2H)-dione is not toxic to fish and is considered to not classified as per CLP regulation.

Short term toxicity to Aquatic Invertebrates:
Determination of the inhibition of the mobility of daphnids was carried out with the substance, 2-butyl-6-(butylamino)-1H-benz[de]isoquinoline-1,3(2H)-dione according to OECD Guideline 202. The test substance was tested at the concentrations 0, 0, 0.025, 0.05, 0.10, 0.25 and 0.50 mg/L. Effects on immobilisation were observed for 48 hours. The median effective concentration (EC50) for the test substance, 2-butyl-6-(butylamino)-1H-benz[de]isoquinoline-1,3(2H)-dione, in Daphnia magna was determined to be 0.17 mg/L. Thus considering the above value, it can be concluded that 2-butyl-6-(butylamino)- 1H-benz[de]isoquinoline-1,3(2H)-dione exhibits toxicity to aquatic invertebrate (Daphnia magna) in the acute 1 classification category. Also since long term toxicity data is not available and the substance is not readily biodegradable, the final classification for aquatic invertebrate is considered to be Aquatic Acute 1 as well as Chronic category 1 as per CLP criteria.

Toxicity to Aquatic Algae and Cyanobacteria:
Freshwater algal growth inhibition test was carried out on Desmodesmus subspicatus with the substance 2-butyl-6-(butylamino)-1H-benz[de]isoquinoline -1,3(2H)-dione according to OECD Guideline 201. The test substance was dissolved in DMSO and tested at the concentrations 0, 0, 5, 10, 20, 40 and 50 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (ErC50) for the test substance, 2-butyl-6-(butylamino)-1H-benz[de]isoquinoline-1,3(2H)-dione, in Desmodesmus subspicatus was determined to be 381.3 mg/L. Based on this ErC50 value and after comparing with CLP criteria for aquatic classification of the substance it is concluded that the substance 2-butyl-6-(butylamino)-1H-benz[de]isoquinoline-1,3(2H)-dione does not exhibit toxicity to aquatic algae (Desmodesmus subspicatus).

Toxicity to microorganism:
The study does not need to be conducted because the substance is highly insoluble in water, hence indicating that aquatic toxicity is unlikely to occur.