Registration Dossier

Ecotoxicological information

Endpoint summary

Administrative data

Description of key information

Additional information

Acute toxicity

- The acute toxicity of Imidazolidine-2-thione (ETU) was evaluated with Poecilia reticulata in a study performed in accordance with OECD testing guideline 203 (GLP study : no data). The fish were exposed to nominal test concentrations under semi-static conditions during 96 hours. The LC50-96h was estimated using measured concentrations as being equal to 7500 mg/L.

- The acute toxicity of ETU was evaluated with Daphnia magna in a study performed in accordance with OECD testing guideline 202 (GLP study : no data). The young daphnids were exposed to nominal test concentrations under semi-static conditions during 48 hours. The LC50-48h was estimated using measured concentrations as being equal to 26.4 mg/L.

-The acute toxicity of ETU was evaluated with P.subcapitata in a study performed in accordance with OECD testing guideline 201 and GLP requirements. As no effect was observed during the preliminary test, a limit test was performed. The algae were exposed to nominal test concentration of 100 mg/L under static conditions during 72 hours. EC50 -72h was estimated using measured concentrations as being > 100 mg/L.

Chronic toxicity

The chronic toxicity of ETU was firstly evaluated with Daphnia magna in a study performed with no guideline. The effects of prolonged exposure (21 days) to ETU were examined on survival, fecondity and growth of Daphnia magna. The EC50 -21d was estimated equal to 18 mg/L. Inhibition of population growth was observed at levels below those which caused a significant reduction in survival.

A significant reduction in mean carapace length of 21-day-old daphnids was generally detected at levels comparable with LC50 value. With ETU, the carapace length was 1x10^4. However no NOEC was estimated during this study.

In order to refine the PNECs, a 21-day Daphnia magna reproduction study was conducted to determine the effects of exposure to Ethylenethiourea (CAS 96-45-7) on Daphnia magna reproduction and survival in accordance with the OECD Chemicals Testing Guideline No.211 Daphnia magna Reproduction Test (adopted October 2012). The definitive test was conducted at nominal concentrations of 0.10, 0.32, 1.0, 3.2 and 10 mg/L. Actual concentrations did not differ by more than 20% of the nominal concentrations. The test was conducted using a semi-static design with renewal of the test media three times a week. The NOEC for reproduction was considered to be 3.2 mg/L.