2-(6-methoxybenzofuran-2-yl)-1,3-dimethyl-5-(methylsulphonyl)1H-benzimidazolium acetate

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:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

other: Internal Method "Nr. 58"

Principles of method if other than guideline:

The acute toxicity testing on microorganisms in sewage sludge was performed according to published methods, which were adapted and standardized for the specific needs of the sponsor company, well before Test Guidelines for these methods were established by the OECD beginning 1981.

GLP compliance:

no

Test organisms (species):

activated sludge

Details on inoculum:

- Source: isolated suspended bacteria from sewage sludge, taken from the aerated compartment of an Husmann apparatus and has to be prepared freshly on a weekly basis.
- Culturing: once per week a pre-culture is prepared taking one inoculation loop of bacteria from an agar plate (BHI-agar) to be cultivated in Nutrient-Broth medium. Each day one inoculation loop from the pre-culture is used to inoculate 5 ml of Nutrient-Broth which is then cultured at 22 °C.
- Pretreatment: sludge is directly used from the Husmann apparatus on day 3 to 5. 100 ml of underrun is taken on a daily basis and filtered through a Whatman GF/A filter. The filtrate is used as inoculation suspension.

Test type:

static

Water media type:

not specified

Limit test:

no

Nominal and measured concentrations:

1, 5, 10, 20, 50, 100, 200 and 300 ppm

Details on test conditions:

TEST SYSTEM
- Plates: 0.2 ml of the dilution is mixed with 15 ml of liquid nutrient agar (tempered to 45 °C) and plated on sterile petri dishes (agar incorporation test).
- Control: solvent and growth controls were used in parallel. In case of the suspension test 0.1 ml of dilutions are mixed with 4.5 ml of Nutrient broth in a test tube.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Nutrient Broth.

EFFECT PARAMETERS MEASURED
KST is the lowest concentration which clearly inhibits bacterial growth, based on visible opacity of the test solution. The KST is given in relation to the growth control.

Dose descriptor:

IC50

Effect conc.:

> 300 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other: duration not specified

Conclusions:

IC50 > 300 mg/l

Executive summary:

The acute toxicity testing on microorganisms in sewage sludge was performed according to published methods, which were adapted and standardized for the specific needs of the sponsor company, well before Test Guidelines for these methods were established by the OECD beginning 1981. The method is designed to evaluate the acute bacteriotoxicity to sewage sludge.

The lowest concentration which clearly inhibits bacterial growth (i.e. reported as KST), based on visible opacity of the test solution, was indicated to be higher than 300 mg/l.

Conclusion

IC50 > 300 mg/l

Reference 2

Endpoint:

toxicity to microorganisms, other

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

study well documented, meets generally accepted scientific principles, acceptable for assessment

Qualifier:

according to guideline

Guideline:

other: Internal Method "Nr. 58"

Principles of method if other than guideline:

The acute toxicity testing on microorganisms in sewage sludge was performed according to published methods, which were adapted and standardized for the specific needs of the sponsor company, well before Test Guidelines for these methods were established by the OECD beginning 1981.

GLP compliance:

no

Test organisms (species):

activated sludge

Details on inoculum:

- Source: bacteria used were isolated from sewage sludge, taken from the aerated compartment of an Husmann apparatus and has to be prepared freshly on a weekly basis.
- Culturing: once per week a pre-culture is prepared taking one inoculation loop of bacteria from an agar plate (BHI-agar) to be cultivated in Nutrient-Broth medium. Each day one inoculation loop from the pre-culture is used to inoculate 5 ml of Nutrient-Broth which is then cultured at 22 °C.
- Pretreatment: bacteria, the over-night culture is used as such.

Test type:

static

Water media type:

not specified

Limit test:

no

Nominal and measured concentrations:

1, 5, 10, 20, 50, 100, 200 and 300 ppm

Details on test conditions:

TEST SYSTEM
- Plates: 0.2 ml of the dilution is mixed with 15 ml of liquid nutrient agar (tempered to 45 °C) and plated on sterile petri dishes (agar incorporation test).
- Control: solvent and growth controls were used in parallel. In case of the suspension test 0.1 ml of dilutions are mixed with 4.5 ml of Nutrient broth in a test tube.

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: Nutrient Broth.

EFFECT PARAMETERS MEASURED
BST is the lowest concentration which clearly inhibits bacterial growth, based on visible opacity of the test solution.

Dose descriptor:

IC50

Effect conc.:

200 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

not specified

Remarks on result:

other: duration not specified

Conclusions:

IC50: 200 mg/l

Executive summary:

The acute toxicity testing on microorganisms in sewage sludge was performed according to published methods, which were adapted and standardized for the specific needs of the sponsor company, well before Test Guidelines for these methods were established by the OECD beginning 1981. The method was designedto evaluate the acute bacteriotoxicity to isolated suspended bacteria.

The lowest concentration which clearly inhibits bacterial growth (i.e. reported as BST), based on visible opacity of the test solution, was indicated to be 200 mg/l.

Conclusion

IC50: 200 mg/l

Description of key information

Non harmful/toxic to microorganisms.

Additional information

Several studies, conducted on batches characterized by different purity degrees of Fluorescent Brightener 363 and investigating the potential toxicity to microorganisms, are available.

Almost all the experiments here reported were performed according to published methods, which were adapted and standardized for the specific needs of the sponsor company, well before Test Guidelines for these methods were established by the OECD beginning 1981; the methods are comparable to current standard testing procedures.

In the two studies conducted with test batches at highest purity degrees among all the experiments, the lowest concentration which clearly inhibits bacterial growth, i.e. reported as BST and KST, was found to be 200 mg/l and higher than 300 mg/l, respectively.

Adverse effects were not recorded in none of all the other available experiments.