1,3-dihydro-5-methoxy-2H-benzimidazole-2-thione

Short-term toxicity to aquatic invertebrates

Link to relevant study record(s)

Reference

Endpoint:

short-term toxicity to aquatic invertebrates

Type of information:

calculation (if not (Q)SAR)

Remarks:

Migrated phrase: estimated by calculation

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: estimated by calculation

Justification for type of information:

estimated by calculation

Qualifier:

according to guideline

Guideline:

other: Modeling database

Principles of method if other than guideline:

Estimation of 96 hr EC50 value of test chemical by modelling Database - ECOSAR v.1.11. The ECOSAR Class Program is a computerized version of the ECOSAR analysis procedures as currently practiced by the Office of Pollution Prevention and Toxics (OPPT).  It has been developed within the regulatory constraints of the Toxic Substances Control Act (TSCA).  It is a pragmatic approach to SAR. The structure-activity relationships (SARs) presented in this program are used to predict the aquatic toxicity of chemicals based on their similarity of structure to chemicals for which the aquatic toxicity has been previously measured.  Most SAR calculations in the ECOSAR Class Program are based upon the octanol/water partition coefficient (Kow).  Various surfactant SAR calculations are based upon the average length of carbon chains or the number of ethoxylate units.

GLP compliance:

no

Analytical monitoring:

not specified

Vehicle:

not specified

Test organisms (species):

Daphnia magna

Test type:

not specified

Water media type:

not specified

Total exposure duration:

48 h

Duration:

48 h

Dose descriptor:

LC50

Effect conc.:

82.747 mg/L

Nominal / measured:

estimated

Conc. based on:

test mat.

Basis for effect:

mortality

Validity criteria fulfilled:

not specified

Conclusions:

The Lethal concentration (LC50) value of test material in aquatic invertebrate (Daphnia Magna) in a 48 hr study based on mortality effect was estimated to be 82.747 mg/L.

Executive summary:

The Lethal concentration (LC50) value of test material in aquatic invertebrate (Daphnia Magna) in a 48 hr study based on mortality effect was estimated to be 82.747 mg/L. Thus considering the value from CLP Criteria for aquatic classification of the substance , it is concluded that test material exhibit short term toxicity aquatic invertebrate (Daphnia Magna) and can be classified aquatic chronic 3 .

Description of key information

Short term toxicity to aquatic invertebrate:

The Lethal concentration (LC50) value of test material in aquatic invertebrate (Daphnia Magna) in a 48 hr study based on mortality effect was estimated to be 82.747 mg/L. Thus considering the value from CLP Criteria for aquatic classification of the substance , it is concluded that test material exhibit short term toxicity aquatic invertebrate (Daphnia Magna) and can be classified aquatic chronic 3 .

Key value for chemical safety assessment

Fresh water invertebrates

Fresh water invertebrates

Effect concentration:

82.7 mg/L

Additional information

Short term toxicity to aquatic invertebrate:

The short term toxicity of test material on aquatic invertebrate was evaluated using prediction along with data for functionally and structurally similar read across substance:

The Lethal concentration (LC50) value of test material in aquatic invertebrate (Daphnia Magna) in a 48 hr study based on mortality effect was estimated to be 82.747 mg/L. Thus considering the value from CLP Criteria for aquatic classification of the substance , it is concluded that test material exhibit short term toxicity aquatic invertebrate (Daphnia Magna) and can be classified aquatic chronic 3 .

The above prediction was supported by data for structurally similar read across substance, determination of the inhibition of the mobility of daphnids was carried out with the test substance according to OECD Guideline 202. The stock solution (200 g/L) was prepared by dissolving white powder in DMSO. Test solutions of required concentrations were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 5, 10, 20, 30, 40, 80 mg/L and the immobilisation effects were observed for 48 hours. Effects on immobilisation were observed for 48 hours. 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. The median effective concentration (EC50) for the test substance, in Daphnia magna was determined to be 26 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 can can be classified as Aquatic chronic category 3 as per the CLP criteria.

The above study was further supported by data for functionally similar read accross substance, experimental study for inhibition of the mobility of daphnids was carried out with the benzimidazole according to OECD Guideline 202. The animals used for the test shall be less than 24 h old and should not be of first brood progeny. Test solutions of required concentration were prepared by mixing the stock solution of the test sample with reconstituted test water. The test substance was tested at the concentrations 0, 7.5, 15, 30, 60 and 120 mg/L. The test was performed under static conditions in a static fresh water system at 20±1°C temperature. Effects on immobilisation were observed for 48 hours. EC50 was calculated using non linear regression by the software Prism 4.0. After the experiment, the median effective concentration (EC50) for the test substance, benzimidazole, in Daphnia magna was determined to be 55.5 mg/L on the basis of immobilisation effects. Based on the EC50 value chemical consider to be toxic and classified as aquatic chronic 3 as per the CLP classification criteria.