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
The objective of this study was to assess the effects of test item Thiourea on the growth ofPseudokirchneriella subcapitata over a period of 72 hours according to OECD 201 Guideline (March2006, corrected July 2011). Pseudokirchneriella subcapitata is a freshwater green algae that isrecommended by the OECD Guideline 201.The test item is a soluble product under the test conditions and the test solutions were prepared in thetest medium by dilution of a primary stock solution of test item.The effects of test item at the definitive nominal concentrations of 0; 6.25; 12.5; 25; 50 and 100 mg testitem/L to Pseudokirchneriella subcapitata were investigated under laboratory conditions.According to the results of the test, the NOErC and the NOEyC were both observed to be at 100 mg/L(nominal).The analytical samples were taken at the beginning of the test and at the end of the test (72 hours) withthe content of the vessels pooled and homogenized.Since the deviation between the measured concentrations and the nominal concentrations was withinthe range of ± 20 %, analysis of the results was based in the nominal concentrations.
In a 96 hour acute toxicity study, the cultures of Scendedesmus subspicatus Chodat were exposed to thiourea at several concentrations (4 replicates per concentration, 2 parallel measurements) under static conditions in accordance with the Guideline of the German Environmental Protection Agnecy (UBA) of May 1982 (Hemmung der Zellvermehrung bei der Grünalge Scenedesmus subspicatus Chod.").
The EC10 and EC50 values based on cell density were 0.3 -0.6 mg/L and 4.8 -10 mg/L, respectively.
Test Organism: Scenedesmus subspicatus Chodat
Test Type: Static
96 -hr EC10: 0.3 -0.6 mg/L
96 -hr EC50: 4.8 -10 mg/L
Endpoint effected: cell growth
In a 96 hour acute toxicity study, the cultures of Scendedesmus subspicatus Chodat were exposed to thiourea at several concentrations (6 replicates per concentration, 3 parallel measurements) under static conditions in accordance with the Guideline of the German Environmental Protection Agnecy (UBA) of May 1982 (Hemmung der Zellvermehrung bei der Grünalge Scenedesmus subspicatus Chod.").
The EC10 and EC50 values based on cell density were 0.5 -0.7 mg/L and 3.8 -5.4 mg/L, respectively.
This toxicity study is classified as acceptable.
96-hr EC10: 0.5 -0.7 mg/L
96-hr EC50: 3.8 -5.4 mg/L
Endpoint effected: cell number
A new study on toxitity to algae and cyanobacteria (OECD No. 201) is available.
The 72 h ECr50 is > 100 mg/L
The 72 h NOErC is 100 mg/L
Two publications are available that are reporting 96-hr effect concentrations for the green algae Scenedesmus subspicatus Chodat:- Geyer et al. (1985): EC10 = 0.3 - 0.6 mg/L, EC50 = 4.8 - 10 mg/L- Friesel et al. (1984): EC10 = 0.5 - 0.7 mg/L, EC50 = 3.8 - 5.4 mg/LBoth publications report values that are within in the same range. Due to precautionary principles, the lowest reported value for the EC10 and EC50, respectively, is used as key value in the risk assessment for thiourea.
Friesel at al. (1984) and Geyer et al. (1985) both report 96 -hr EC50 and EC10 values of thiourea for the green algae Scenedesmus subspicatus Chodat. In both cases results were determined in test according to the guideline "Hemmung der Zellvermehrung bei der Grünalge Scenedesmus subspicatus Chod." of the German Environmental Protection Agency (UBA; May 1982). But as the documentation of both experiments, especially with regard to the results, is insufficient for assessment, the publications are rated as Klimisch III.
According to current guidelines, the standard test duration for testing of algae toxicity is 72 hours instead of 96 hours. But as the test duration in the reported experiments is longer than in standard tests, the results are considered to rather overestimate the toxicity of thiourea to algae. Thererfore, the results are deemed sufficiently precautionary to be used in the risk assessment of the substance.
In addition, as both publications report results that are within the same range, the results are used in a weight-of-evidence approach to assess the environmental risk of thiourea:
- Geyer et al. (1985): EC10 = 0.3–0.6 mg/L, EC50 = 4.8–10 mg/L
- Friesel et al. (1984): EC10 = 0.5–0.7 mg/L, EC50 = 3.8–5.4 mg/L
Due to precautionary principles, the lowest reported value for the EC10 and EC50, respectively, is used as key value in the risk assessment for thiourea.
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.
Welcome to the ECHA website. This site is not fully supported in Internet Explorer 7 (and earlier versions). Please upgrade your Internet Explorer to a newer version.
Do not show this message again