Guanidinium thiocyanate

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

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)

Reference 2

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 for cross-reference:

reference to same study

Qualifier:

according to guideline

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