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Description of key information

Short term toxicity to fish:
Based on nominal concentrations, experimental median lethal Concentrations [LC-50 (96 h)] for CAS No.509-34-2 on Zebra Fish (Danio rerio) was found to be 50 mg/L. This value indicates that the substance 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one is toxic to fish and can be classified as Aquatic chronic category 3.

Short term toxicity to aquatic invertebrate:
The median effective concentration (EC50) for the test substance, 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one , in Daphnia magna was determined to be 3.4 mg/L on the basis of mobiity inhibition effects in a 48 hour study.This value indicates that the substance is likely to be hazardous to aquatic invertebrates and can be classified as Aquatic Chronic 2 as per the CLP criteria.

Toxicity to aquatic algae and cynobacteria:
The median effective concentration (EC50) for the test substance, 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one, in Desmodesmus subspicatus was determined to be 13.4 mg/L on the basis of effects on growth rate in a 72 hour study. This value indicates that the substance is likely to be hazardous to aquatic algae and can be classified as Aquatic Chronic 3 as per the CLP criteria.

Toxicity to microorganism:

The IC50 value (concentration for 50% inhibition of respiration rate) for the test chemical 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one on activated sludge (aerobic bacteria) is determined to be >100 mg/1 after 3 hrs of exposure.

Additional information

Short term toxicity to fish:
Various studies, considering its adequacy as one key and other supporting, were reviewed for the endpoint short term toxicity to fish of the substance 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one and same are summarized as below:

In a key study, 96 h study was conducted by SSS for CAS No. 509-34-2 on Zebra fish (Danio rerio), at a test concentrations of 6.25mg/L,12.5mg/L, 25mg/L, 50mg/L and 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

This value indicates that the substance 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one is toxic to fish and can be classified as Aquatic chronic category 3.

In supporting study for read across Rhodamine B (Cas no. 81-88-9) from Experimental data (J. Toxicol. Sci. 7: 193; 1982) indicated that fish toxicity study was conducted for 48 hrs for evaluating the lethal concentration of test substance Rhodamine B on fish Oryzias latipes on the basis of mortality effect. During experiment the lethal concentration (LC50) for test substance Rhodamine B was found to be 17 mg/l for 24 hrs. and 12 mg/l for 48 hrs. This LC50 value indicate that the test substance Rhodamine B is toxic to fish and classified in aquatic chronic 3 category as per the CLP criteria.

For the same read across substance, i.e Rhodamine B (Cas no. 81-88-9); Fish toxicity study (Japan chemicals collborative knowledge database (J-check); 2017) was conducted for 48 hrs for evaluating the lethal concentration of test substance Rhodamine B on fish Oryzias latipes on the basis of mortality effect. During experiment the lethal concentration (LC50) for test substance Rhodamine B was determined to be 33.9 mg/l. This LC50 value indicate that the test substance Rhodamine B is toxic to fish and classified in aquatic chronic 3 category as per the CLP criteria.

Both studies for read across chemical give assistance to experimental result of target chemical.

Thus, based on experimental study conducted by SSS with EC50= 50 mg/l, it can be concluded that the target chemical 3',6'-Bis(N,N-diethylamino)-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one (CAS no. 509-34-2) is toxic to fish and thus can be classified in Aquatic Chronic 3 category as per the CLP criteria.

Short term toxicity to aquatic invertebrate:
Determination of the inhibition of the mobility of daphnids was carried out by SSS with the substance 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one according to OECD Guideline 202.

 

The test substance was tested at the concentrations 0, 0.5, 1, 2, 3, 4 and 8 mg/L. Effects on immobilisation were observed for 48 hours. The median effective concentration (EC50) for the test substance, 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one, in Daphnia magna was determined to be 3.4 mg/L for immobilisation effects.

This value indicates that the substance is likely to be hazardous to aquatic invertebrates and can be classified as Aquatic Chronic 2 as per the CLP criteria.

Toxicity to aquatic algae and cyanobacteria:
Various studies, considering its adequacy as one key and other supporting, were reviewed for the endpoint short term toxicity to aquatic algae of the substance 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one and same are summarized as below:

In key study, Freshwater algal growth inhibition test was carried out by SSS on Desmodesmus subspicatus with the substance 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one according to OECD Guideline 201. The test substance was dissolved in DMSO/ OECD growth medium and tested at the concentrations 0, 2.5, 5, 10, 20 and 40 mg/L. Effects on the growth rate of the organism were studied. The median effective concentration (EC50) for the test substance, 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one, in Desmodesmus subspicatus was determined to be 13.4 mg/L. This value indicates that the substance is likely to be hazardous to aquatic algae and can be classified as Aquatic Chronic 3 as per the CLP criteria.

The above experimental result was supported by yet another study carried out by SSS in which the effect of test item 3',6'-bis(diethylamino)spiro[isobenzofuran-1(3H),9'-[9H]xanthene]-3-one, CAS No. 509-34-2 was studied on the growth of fresh water green alga Chlorella vulgaris. The study was conducted following OECD guideline 201- Alga, growth inhibition test. The test concentration chosen for the study were 6.2 5 mg/L,12.5 mg/L,25 mg/L,50 mg/L,100 mg/L,200 mg/L. The test concentrations were prepared using stock solution of the test item using mineral media. The green alga was exposed to the test concentration for a period of 72 hours to observe average specific growth rate and % growth inhibition under the effect of the test item. EC50 calculated graphically through probit analysis was observed to be 98.169 mg/L. This value indicates that the substance 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one is toxic to algae and can be classified as Aquatic chronic category 3 as per the CLP criteria.

Thus, based on experimental study conducted by SSS with EC50=13.4 mg/L , it can be concluded that the target chemical 3',6'-Bis(N,N-diethylamino)-3H-spiro[isobenzofuran-1,9'-xanthen]-3-one (CAS no. 509-34-2) is toxic to aquatic algae and thus can be classified in Aquatic Chronic 3 category as per the CLP criteria.

Toxicity to microorganism:

A screening method based on the measurement of the respiration rate of activated sludge for assessing the possible inhibitory effect of dyestuffs on aerobic waste-water bacteria. The test principle involves measuring the respiration rate of an activated sludge and comparing it with the respiration rate of the same activated sludge under identical conditions, but in the presence of the chemical under test. The test was carried out in activated sludge respiration rate apparatus with constant 20 ± 2°C and pH about 7-8. The test concentration used was 100 mg/l. OECD recommended synthetic sewage was used as feed, while activated sludge was obtained from a sewage works treating predominantly domestic sewage or from a sewage works treating predominantly industrial waste water. The respiration rate of an activated sludge and the respiration rate of activated sludge with test chemical were noted down. In order to calculate the inhibitory effect of a particular chemical at 100 mg/l test concentration its respiration rate is expressed as a percentage of the mean of the two control respiration rates. For those chemicals whose respiration rate is at least 80% of the control, the IC50 (concentration for 50% inhibition of respiration rate) is recorded as >100 mg/l.

Thus, IC50 value (concentration for 50% inhibition of respiration rate) for the test chemical 3',6'-bis(diethylamino)-3H-spiro[2-benzofuran-1,9'-xanthen]-3-one on activated sludge (aerobic bacteria) is determined to be >100 mg/1 after 3 hrs of exposure.