2-(chloromethyl)-4-methylquinazoline

Toxicity to microorganisms

Link to relevant study record(s)

Reference

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2007-01-29 to 2007-03-01

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

guideline study

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

1988

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

Version / remarks:

1984

Qualifier:

according to guideline

Guideline:

EPA OPPTS 850.6800 (Modified Activated Sludge, Respiration Inhibition Test for Sparingly Soluble Chemicals)

Version / remarks:

1996

GLP compliance:

yes (incl. QA statement)

Analytical monitoring:

no

Vehicle:

no

Details on test solutions:

-Preparation of Test Flask: One test solution with a final volume of 330 mL was tested per treatment in a glass flask. 10.56 mL synthetic sewage and an adequate amount of the stock solution of the test item or an adequate volume of the stock solution of the reference item were added to a flask and then the flask was filled up with deionised water to 198 mL before the start of the test. At the start of the test 132 mL activated sludge inoculum with a sludge concentration of 4 g/L (dry weight) was added, first to the first control, then in time intervals of approximately 15 minutes (an optional but convenient interval) to the test solutions of the reference item and the test item and finally to a second control.

Test organisms (species):

activated sludge, domestic

Details on inoculum:

- Source: sewage plant for domestic sewage in Veszprém, Hungary
- Pretreatment: activated sludge was washed and centrifuged and the supernatant liquid phase was decanted. The solid material was re-suspended in isotonic saline solution and again centrifuged. This procedure was repeated twice. Based on dry weight determinations, calculated amounts of wet sludge were suspended in isotonic saline solution to yield a concentration equivalent to 4 g per litre (on dry weight basis). The activated sludge inoculum was determined to have a pH of 7.51. The activated sludge was used directly after conditioning.
- Initial biomass concentration: 1.6 g/L

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Hardness:

no data

Test temperature:

18.4 – 20.9 °C (during the incubation) and
18.6 – 20.5 °C (during oxygen measurement)

pH:

7.05 - 7.78

Dissolved oxygen:

6.7 - 9.0

Salinity:

not applicable

Nominal and measured concentrations:

- Nominal: 3, 10, 31, 98, 313 and 1000 mg test item/L

Details on test conditions:

TEST SYSTEM
- Test vessel: Erlenmeyer bottles of approximately 350 ml volume, and BOD bottles with special neck of 300 ml volume
- Material, fill volume: 330 mL test media
- Aeration: yes, compressed air (approximately 1 litre per minute)
- No. of organisms per vessel: 132 mL activated sludge (with 4 g dw/L)
- No. of vessels per concentration (replicates): 1
- No. of vessels per control (replicates): 2
- Biomass loading rate: 132 mL activated sludge inoculum with a sludge concentration of 4 g/L (dry weight) (start of the test)

OTHER TEST CONDITIONS
- Other: Climate chamber (during the incubation) and controlled environment room (during the formulation and oxygen measuring)

EFFECT PARAMETERS MEASURED (with observation intervals if applicable) : respiration rate and pH, Dissolved Oxygen, Water Temperature

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol (nominal test concentrations of 5, 16 and 32 mg/L)

Key result

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

316.8 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% CL = 245.4 - 408.9 mg/L

Duration:

3 h

Dose descriptor:

other: EC20

Effect conc.:

71.3 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% CL = 54.6 - 92.9 mg/L

Duration:

3 h

Dose descriptor:

other: EC80

Effect conc.:

1 408.2 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Remarks on result:

other: 95% CL = 939.2 - 2111.5 mg/L

Key result

Duration:

3 h

Dose descriptor:

NOEC

Effect conc.:

31 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Results with reference substance (positive control):

- Results with reference substance valid? yes
- Relevant effect levels: EC50 (3 h, 3,5-Dichlorophenol) = 7.3 mg/L (95% CL 5.2 - 10.4 mg/L).

Reported statistics and error estimates:

Based on measured inhibition rates, the 3-h EC20, EC50 and EC80 and their 95%-confidence limits were calculated by Probit analysis using TOXSTAT software.

Toxicity of test item:

In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited by 5.3 % at the lowest nominal concentration of 3 mg/L. At the nominal concentrations of 10, 31 and 98 mg/L, the respiration rate was inhibited by -8.8 %*, -1.8 %* and 29.8 %, respectively. At the nominal concentrations of 313 and 1000 mg test item/L, the respiration rate was inhibited by 50.9 % and 77.2 %, respectively.

Toxicity of 3,5 -Dichlorophenol

In comparison to the controls the respiration rate of the activated sludge was inhibited by 42.1 % at the lowest nominal concentration of 5 mg/L. At the nominal concentrations of 16 and 32 mg/L, the respiration rate was inhibited by 66.7 % and 78.9 %, respectively. The 3-hour EC50 of 3,5-Dichlorophenol was calculated to be 7.3 mg/L with 95 % confidence limits of 5.2 to 10.4 mg/L.

* the negative value was interpreted biologically as zero inhibition (slight stimulation)

Validity criteria fulfilled:

yes

Conclusions:

A 3-h EC50 value of 316.8 mg/L and a NOEC of 31 mg/L were determined for the test item under the conditions of the test.

Executive summary:

In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited between –8.8 % (the negative value was interpreted biologically as zero inhibition (slight stimulation)) and 77.2 % up to the highest nominal test concentration of 1000 mg/L. Concentrations exceeding 1000 mg/L nominal were not tested.

Based on measured inhibition rates, the 3-hour EC20, EC50 and EC80 and their 95 %-confidence limits were calculated by

Probit analysis using TOXSTAT software: EC20: 71.3 mg/L (54.6–92.9); EC50: 316.8 mg/L (245.4–408.9); EC80: 1408.2 mg/L (939.2–2111.5). The EC50 value is in the range of 100 to 1000 mg/L.

The NOEC was determined to be 31 mg/L The NOEC for respiration rates was not based on the results of a statistical analysis, but it is biologically justified. At the lower concentration values the respiration inhibition was not influenced dose dependently and additionally the respiration rates at 3.1, 10 and 31 mg/L concentrations were in/above the historical control data range (0.490 ± 0.090).

Description of key information

A 3 -h EC50 of 316.8 mg/L and a NOEC of 31 mg/L for activated sludge were determined for the substance according to OECD 209.

Key value for chemical safety assessment

EC50 for microorganisms:

316.8 mg/L

EC10 or NOEC for microorganisms:

31 mg/L