long chain alkyl thio carbamide metal complex

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

29 June 1999 to 2 July 1999

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

guideline study with acceptable restrictions

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Deviations:

yes

Remarks:

only 3 concentrations used due to poor solubility

Qualifier:

according to guideline

Guideline:

EU Method C.11 (Biodegradation: Activated Sludge Respiration Inhibition Test)

Deviations:

yes

Remarks:

only 3 concentrations used due to poor solubility

GLP compliance:

yes

Specific details on test material used for the study:

Details on properties of test surrogate or analogue material (migrated information):

PHYSICO-CHEMICAL PROPERTIES
- Water solubility (under test conditions): poor

Analytical monitoring:

no

Details on sampling:

no data

Vehicle:

yes

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: dissolved in tetrahydrofuran and coated on the inside surfaces of the beakers, then the solvent evaporated off using nitrogen gas.
- Eluate: no data
- Differential loading: no data
- Controls: without test material
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): tetrahydrofuran
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)): not applicable, the vehicle was evaporated to leave the test substance coating the walls of the test beaker
- Evidence of undissolved material (e.g. precipitate, surface film, etc): not applicable

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

- Laboratory culture: activated sludge maintained under aerobic conditions
- Method of cultivation: none
- Preparation of inoculum for exposure: mixed liquor suspended solids concentration was adjusted to 4 g/L and 200 ml (0.8 g) added to each beaker (1.6 mg/ml).
- Initial biomass concentration: Final concentration in a total volume of 500 ml mixture was 1.6 mg/ml of mixed liquor suspended solids.

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

No

Hardness:

Softened tap water

Test temperature:

20-22oC

pH:

7.2-8.1

Dissolved oxygen:

no data

Salinity:

not applicable

Nominal and measured concentrations:

Nominal concentrations were 0, 1, 10, and 100 mg/L. "At the Sponsor request allowance for a purity of less than 100% was made during formulation." Bearing in mind the insoluble nature of the test material, it is unlikely that the aqueous phase achieved these levels

Details on test conditions:

TEST SYSTEM
- Test vessel: beaker
- Type (delete if not applicable): open
- Material, size, headspace, fill volume: glass beaker of unspecified size but >500 ml, since this was the total volume used
- Aeration: oil-free compressed air
- Type of flow-through (e.g. peristaltic or proportional diluter): none
- Renewal rate of test solution (frequency/flow rate): not renewed
- No. of organisms per vessel: no data
- No. of vessels per concentration (replicates): one each for 1 and 10 mg/L, in triplicate for 100 mg/L
- No. of vessels per control (replicates): 2
- Biomass loading rate: 1.6 mg/ml of mixed liquor suspended solids

TEST MEDIUM / WATER PARAMETERS
- Source/preparation of dilution water: tap water, dechlorinated. Ultrapure water used for the synthetic sewage feed.
- Total organic carbon: no data
- Particulate matter: no data
- Metals: no data
- Pesticides: no data
- Chlorine: no data
- Alkalinity: no data
- Ca/mg ratio: no data
- Conductivity: no data
- Culture medium different from test medium: no culture medium used
- Intervals of water quality measurement: no data

OTHER TEST CONDITIONS
- Adjustment of pH: no
- Photoperiod: no data
- Light intensity: no data

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : temperature, pH and rate of oxygen consumption measured at 3 hr

TEST CONCENTRATIONS
- Spacing factor for test concentrations: x 10
- Justification for using less concentrations than requested by guideline: no data
- Range finding study: no

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol at 3, 10 and 32 mg/litre

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

- Any observations (e.g. precipitation) that might cause a difference between measured and nominal values: no data, but test material was intentionally deposited on sides of vessel as only poorly soluble
- Effect concentrations exceeding solubility of substance in test medium: no data

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 calculated as 8.3 mg/litre (95% confidence limits 6.4-10.6 mg/litre)

Reported statistics and error estimates:

Not applicable. The test material had no inhibitory effect

Table 1. Parameters measured

Test concentration (mg/L)	Temperature (^oC)		pH		Respiration rate mgO2/g/hr	% inhibition
	Initial	Final	Initial	Final
0	21.8	20.2	7.2	8.0	28.3	-
0	21.7	20.5	7.2	8.0	31.3	-
1	21.9	20.3	7.3	8.0	29.4	1
10	21.9	20.7	7.2	8.0	29.4	1
100	21.9	20.7	7.3	8.0	29.4	1
100	21.8	20.7	7.3	8.0	31.9	0
100	21.8	20.5	7.3	8.0	31.9	0
3,5-DCP
3	21.3	21.4	7.2	8.1	22.4	25
10	21.6	20.6	7.4	8.1	13.3	55
32	21.7	20.6	7.3	8.1	5.5	81

 

Validity criteria fulfilled:

yes

Conclusions:

In a GLP study conducted according to OECD guideline 209, there was no evidence of a significant inhibitory effect on the respiration rate when activated sludge was treated with EC# 434-650-5 at concentrations of up to 100 mg/L for 3 h.

Executive summary:

In a GLP study conducted according to OECD guideline 209, EC# 434-650-5 was assessed for its ability to inhibit the respiration rate of activated sludge in a static freshwater system for 3 h.

Since the test material was poorly soluble in aqueous media, aliquots calculated to nominally provide concentrations of 1, 10 or 100 mg/L were dissolved in tetrahydrofuran, coated over the inside surfaces of glass beakers and the solvent evaporated under nitrogen. Single beakers were prepared for the low- and mid-doses and three beakers for the high-dose. The final volume of the incubation mixture was: 200 ml activated sludge, 16 ml synthetic sewage and 284 ml dechlorinated tap water. Duplicate beakers were prepared for the negative control and one each for the three concentrations of a positive control, 3,5-dichlorophenol. The prepared mixtures were then aerated for 3 h using compressed air. Following exposure, samples were removed and the rate of oxygen consumption measured; pH and temperature were measured at the start and end of the study.

There was no evidence of an inhibitory effect of the test material on the respiration rate, therefore an EC50 could not be established. The positive control reduced the respiration rate in a dose-related manner, demonstrating the validity of the test.

In conclusion, no evidence of a significant inhibitory effect on the respiration rate was seen when activated sludge was treated with EC# 434-650-5 at concentrations of up to 100 mg/L for 3 h. In view of the structural and chemical similarities, it is considered that the results of this study can be used for read-across to EC# 457-320-2.

Reference 2

Endpoint:

activated sludge respiration inhibition testing

Type of information:

read-across from supporting substance (structural analogue or surrogate)

Adequacy of study:

key study

Reason / purpose for cross-reference:

read-across source

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

> 100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

100 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Validity criteria fulfilled:

yes

Conclusions:

In a GLP study conducted according to OECD guideline 209, there was no evidence of a significant inhibitory effect on the respiration rate when activated sludge was treated with EC# 434-650-5 at concentrations of up to 100 mg/L for 3 h.

Executive summary:

In a GLP study conducted according to OECD guideline 209, EC# 434-650-5 was assessed for its ability to inhibit the respiration rate of activated sludge in a static freshwater system for 3 h.

Since the test material was poorly soluble in aqueous media, aliquots calculated to nominally provide concentrations of 1, 10 or 100 mg/L were dissolved in tetrahydrofuran, coated over the inside surfaces of glass beakers and the solvent evaporated under nitrogen. Single beakers were prepared for the low- and mid-doses and three beakers for the high-dose. The final volume of the incubation mixture was: 200 ml activated sludge, 16 ml synthetic sewage and 284 ml dechlorinated tap water. Duplicate beakers were prepared for the negative control and one each for the three concentrations of a positive control, 3,5-dichlorophenol. The prepared mixtures were then aerated for 3 h using compressed air. Following exposure, samples were removed and the rate of oxygen consumption measured; pH and temperature were measured at the start and end of the study.

There was no evidence of an inhibitory effect of the test material on the respiration rate, therefore an EC50 could not be established. The positive control reduced the respiration rate in a dose-related manner, demonstrating the validity of the test.

In conclusion, no evidence of a significant inhibitory effect on the respiration rate was seen when activated sludge was treated with EC# 434-650-5 at concentrations of up to 100 mg/L for 3 h. In view of the structural and chemical similarities, it is considered that the results of this study can be used for read-across to EC# 457-320-2.

Description of key information

In an activated sludge respiration inhibition test, the NOELR was 100 mg/L (nominal loading rate), the highest concentration tested.

Key value for chemical safety assessment

EC10 or NOEC for microorganisms:

100 mg/L

Additional information

No toxicity to microorganisms studies are available for EC# 457-320-2; however, one is available for the structurally and chemically similar substance, EC# 434-650-5: an activated sludge respiration inhibition test, conducted to GLP and in accordance with OECD Test Guideline 209.

Due to the poor water solubility of the test substance, aliquots calculated to nominally provide concentrations of 1, 10 or 100 mg/L were dissolved in tetrahydrofuran, coated over the inside surfaces of glass beakers and the solvent evaporated under nitrogen. The final volume of the incubation mixture was: 200 ml activated sludge, 16 ml synthetic sewage and 284 ml dechlorinated tap water.

There was no evidence of an inhibitory effect of the test material on the respiration rate, therefore an EC50 could not be established. The positive control reduced the respiration rate in a dose-related manner, demonstrating the validity of the test.

In view of the structural and chemical similarities, it is considered that the results of this study can be used for read-across to EC# 457-320-2.