Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 200-543-5 | CAS number: 62-56-6
Endpoint summary
Administrative data
Description of key information
For the assessment of the short-term toxicity of thiourea to fish five different studies are available. Species tested werePimephales promelas,Leuciscus idus(L.), Hong Kong guppy,Danio rerio,andOryzias latipes. In none of the studies could an LC50value be obtained that would be close to the regulatory cut-off value of 100 mg/L for classification. Therefore, classification of thiourea for acute toxicity to fish is not warranted.
The 14-d subchronic NOEC of thiourea to fish was determined to be 5000 mg/L.
The 96-hr effect concentrations of thiourea to the green algaScenedesmus subspicatusChodat used in the risk assessment of the substance are as follows: EC10= 0.3 mg/L, and EC50= 3.8 mg/L.
Conflicting results are available regarding the short-term toxicity of thiourea to daphnia. Several non-standard data of low reliability are available that provide information on the acute toxicity of thiourea towards daphnia. Reported EC50values were determined after 24 to 96 hours exposure and range between 1.8 mg/L and 4000-6000 mg/L. However, consistent results are reported with regard to the long-term toxicity to daphnia. All 21-d NOEC values (reproduction) are in the range of 0.1 to 1 mg/L. Following the precautionary principle, the lowest reported result of NOEC (21-d) of 0.1 mg/L is used in the assessment of thiourea.
Regarding the toxicity of thiourea to microorganisms, it could be demonstrated in several studies that thiourea is toxic to microorganisms, with nitrification being the most sensitive process. Toxic effects (75 % nitrification inhibition) were reported at thiourea concentrations ranging from 0.76 mg/L to 0.076 mg/L. However, acclimatisation to thiourea occurs over time, resulting in the microorganism's capability of degrading thiourea. In a study conducted by Tomlinson et al. (1966) incremental increase of thiourea concentrations up to 76 mg/l correlated with a gradual increase of the degradation products nitrate and sulphate, indicating complete mineralisation of thiourea. An EC50of 0.35 mg/l could be established with respect to the inhibitory effect of thiourea to STP microorganisms. This value was chosen for the risk assessment as it is the only result obtained making use of a (modified) standard guideline (ISO 9509).
For details on the information referenced above please refer to the individual sections.
Additional information
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
