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Ecotoxicological information

Toxicity to aquatic algae and cyanobacteria

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Administrative data

toxicity to aquatic algae and cyanobacteria
Type of information:
experimental study
Adequacy of study:
key study
Study period:
72 h
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study

Data source

Reference Type:
study report
Report date:

Materials and methods

Test guideline
according to guideline
OECD Guideline 201 (Alga, Growth Inhibition Test)
GLP compliance:
yes (incl. QA statement)

Test material

Constituent 1
Chemical structure
Reference substance name:
{[(2-carbamimidamido-1,3-thiazol-4-yl)methyl]sulfanyl}methanimidamide dihydrochloride
EC Number:
Cas Number:
Molecular formula:
{[(2-carbamimidamido-1,3-thiazol-4-yl)methyl]sulfanyl}methanimidamide dihydrochloride

Sampling and analysis

Analytical monitoring:

Test solutions

Details on test solutions:
The stock solution was prepared by measuring 300.36 mg of test item into 2 000 ml OECD growth medium. The suspension was stirred till complete dilution. The measured concentration of stock solution was 148.98 mg/L.

Test organisms

Test organisms (species):
Pseudokirchneriella subcapitata (previous names: Raphidocelis subcapitata, Selenastrum capricornutum)
Details on test organisms:
Test species: Pseudokirchneriella subcapitata (Korshikov) F.Hindák (formerly known as Selenastrum capricornutum and Raphidocelis subcapitata)
Source: Culture Collection of Algae and Protozoa, Scottish Marine Institute (
Batch: CCAP 278/4
Date of arriving: 27 October 2017

Study design

Test type:
Water media type:
Limit test:
Total exposure duration:
72 h

Test conditions

Test temperature:
The vessels were kept in incubator at 21 ± 2 °C with continuous illumination.
Nominal and measured concentrations:
The concentration of test item was measured at each concentration level at start and at the end of the test by a validated HPLC method. The geometric means of measured concentrations were determined. The following concentrations were measured: 147.53; 98.06; 45.96; 21.93; 6.15 and 11.87 mg/L. The test item concentrations of the abiotic controls were 149.25 (in light) and 149.74 (in darkness) mg/L.
At the end of the test the concentrations of the test item in the dilution levels No 5 and 6 were out of the validated concentration range, so these values were omitted from the statistical evaluation. The following concentrations were applied for the statistical evaluation in the test: 147.53; 98.06; 45.96 and 21.93 mg/L.
Details on test conditions:
Preparation and breeding of inoculum culture:
The inoculum culture was prepared four days before starting the test and it was bred in incubator at 21 ± 2 °C. At the end of incubation the cell density of the inoculum culture was determined with a Bürker chamber. The cell concentration was 944 444 cell/ml
Preparation of stock solution:
The preparation of stock and test solutions was based on the preliminary non GLP range finding test [9]. As the Range Finding Test was not performed in compliance with the GLP-Regulations it is excluded from the Statement of Compliance in the final report, but the raw data of this test are archived under the study code of present study. The stock solution was prepared by measuring 300.36 mg of test item into 2 000 ml OECD growth medium. The suspension was stirred till complete dilution. The measured concentration of the stock solution was 148.98 mg/L.
Preparation of test solutions:
Six test solutions of different concentration were prepared by mixing appropriate volume of OECD medium and stock solution of the test item. The maximum separation factor between of test vessels was 2.0. Two additional replicates were prepared for controlling the abiotic degradation of the test substance. These test vessels were not inoculated with alga inoculum culture. The following table shows the preparation of test solutions. The volume of the prepared
dilution levels was 300 ml except the control solution which was 600 ml. The alga inoculum culture was diluted 189.87 times so the initial alga cell concentration in every dilution and the control levels were 4 974 cells/ml.
Preparation of test vessels:
Three replicates were prepared at every test, two at the abiotic control and six at the control level. The vessels contained 75 ml test media.
Test procedure:
The test vessels were closed with silicone stopper and kept in the Binder KBW 400 incubator. For the proper mass transfer of carbon dioxide glass tubes with filter were placed through silicone stoppers. The test was maintained under static conditions for a period of 72 hours. The temperature during the test remained in the 21 ± 2 °C range. The temperature data were harvested by Extech SD200 datalogger. The vessels were shaken and illuminated continuously in the incubator. The vessels were placed randomly into the incubator and were repositioned daily after sampling. One of the vessels of abiotic controls was taken into the incubator with a complete aluminium foil cover to check the stability of test item in the absence of light. This vessel was signed as 7/B (vessel No: 20). The abiotic control on light were signed as 7/A (vessel No: 19).

Results and discussion

Effect concentrationsopen allclose all
72 h
Dose descriptor:
Effect conc.:
45.98 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
growth rate
72 h
Dose descriptor:
Effect conc.:
45.99 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
growth rate
Key result
72 h
Dose descriptor:
Effect conc.:
46.03 mg/L
Nominal / measured:
Conc. based on:
test mat.
Basis for effect:
growth rate

Applicant's summary and conclusion

Validity criteria fulfilled:
According to the Council Regulation (EC) 440/2008 Methyl-guanidyl-thiazole dihydrochloride monohydrate is hazardous to the aquatic environment and classified into the third acute toxic hazardous category [GHS Acute aquatic hazard Category Acute III. – 72 h EC50 (for algae or other aquatic plants) > 10 mg/L but ≤ 100 mg/L].