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Toxicity to microorganisms

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Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
supporting study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
test procedure in accordance with national standard methods with acceptable restrictions
Qualifier:
no guideline followed
Principles of method if other than guideline:
Lumistox - luminescent bacteria test
GLP compliance:
not specified
Remarks:
Test before implementation of GLP
Test organisms (species):
Photobacterium phosphoreum
pH:
7.0
Key result
Duration:
30 min
Dose descriptor:
EC50
Effect conc.:
ca. 1 380 mg/L
Nominal / measured:
nominal
Conc. based on:
test mat.
Basis for effect:
other: bioluminescence
Validity criteria fulfilled:
not specified
Conclusions:
The EC50 of Guanidine Thiocyanate was determined to be 1380 mg/L (nominal).
Executive summary:

The acute toxicity to bacteria of Guanidine Thiocyanate was tested in a Bacterial Luminescence Assay (LUMIStox (Dr. Lange GmbH, Dusseldorf, Germany)).Cultures ofPhotobacterium phosphoreumwere exposed to 5 different concentrations for 30 min.The EC50 was determined to be 1380 mg/L (nominal) by bioluminescence measurement.

 

Results Synopsis

Test Organism:Photobacterium phosphoreum

Test Type:Bacterial Luminescence Assay (LUMIStox)

EC50:1380 mg/l (nominal)

Endpoint:
toxicity to microorganisms, other
Type of information:
experimental study
Adequacy of study:
key study
Study period:
2000-04-04 to 2000-05-02
Reliability:
1 (reliable without restriction)
Rationale for reliability incl. deficiencies:
guideline study
Reason / purpose:
reference to same study
Qualifier:
according to
Guideline:
other: OECD 302B guideline
GLP compliance:
yes
Specific details on test material used for the study:
Batch 1210.9225
Details on test solutions:
The test substance was dissolved at a concentration of 343 mg/I, in aerobic mineral salts medium according to OECD guideline 302 B equivalent to 70.9 mg/l DOC
Test organisms (species):
activated sludge of a predominantly domestic sewage
Details on inoculum:
Activated sludge from the aeration tank of a municipal biological waste water treatment plant, not adapted, not pre-conditioned. 0.2 g/L dry matter in the final mixture.
Prior to the test the sludge was washed twice with tap water.
Test type:
static
Water media type:
other: mineral salts medium according to OECD guideline 302 B
Total exposure duration:
28 d
Details on test conditions:
For each test series the following number of test flasks was set up:
Test suspension (T) 2 replicates: containing activated sludge + test medium + test substance
Inoculum blank (B), 2 replicas: containing activated sludge + test medium
Procedure control (R), 1 replicate: containing activated sludge + test medium + diethyleneglycol as ready biodegradable reference compound

The test vessels were stirred (100 r.p.m.) and aerated with synthetic CO2-free air for a maximum test period of 28 days.
The air leaving the individual vessels was passed through gas-absorption bottles filled with NaOH.
It was assured that during the test the oxygen concentration was > 6 mg/l.
The pHvalue was checked periodically and adjusted to pH 6.5-8.0 with NaOH or H2S04, if necessary.
The elimination of the test material was followed by DOC determinations at regular intervals.
First samples were analyzed at the beginning of and 3 h after starting the test.
The trapped CO2 was determined as inorganic carbon (IC).
Duration:
28 d
Dose descriptor:
EC50
Effect conc.:
> 185 mg/L
Conc. based on:
test mat.
Basis for effect:
other:
Remarks:
inhibition of degradation
Remarks on result:
other:
Remarks:
inocculum stayed active until day 28 with a remaining test material concentration of 185mg/L
Key result
Duration:
10 d
Dose descriptor:
EC10
Effect conc.:
200 mg/L
Nominal / measured:
estimated
Conc. based on:
test mat.
Basis for effect:
other: no inhibition of degradation
Details on results:
Based on the data of the individual DOC determinations the test substance reached a biodegradation of 46 % after 28 days, therefore the test substance is considered non-toxic to the activated sludge.
With an initial concentration of 343mg/L, 42% degradation was reached at day 10 (remaining concentration at day 10 ca. 200mg/L). It can be concluded that the activity of inocclum was not inhibited in a relevant way until day 10. This coresponds to a worst case EC10 effect concentration of 200mg/L.
Degradation continued until day 28 according to degradation curve. Based on the data of the individual DOC determinations the test substance reached a biodegradation of 46 % after 28 days, therefore the test substance is considered non-toxic to the activated sludge.
Validity criteria fulfilled:
not applicable
Conclusions:
Based on the data of the individual DOC determinations the test substance reached a biodegradation of 46 % after 28 days, therefore the test substance is considered non-toxic to the activated sludge. According to degradation curve, the inocculum was active until the end of test (28d). As most of degradation occured until day10 (42% degradation), 10d-EC10, as a worst case assumption, was estimated to be 200mg/L.

Description of key information

The acute toxicity to bacteria of Guanidine Thiocyanate was tested in a Bacterial Luminescence Assay (LUMIStox (Dr. Lange GmbH, Dusseldorf, Germany)).Cultures of Photobacterium phosphoreum were exposed to 5 different concentrations for 30 min. The EC50 was determined to be 1380 mg/L (nominal) by bioluminescence measurement.

 Based on a degradation test according to OECD302, 10d-EC10 was estimated to be 200 mg/L (based on test material concentration).

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:
200 mg/L

Additional information