2-Butanol, 2-methyl-, lithium salt (1:1)

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Study period:

2007-11-23

Reliability:

1 (reliable without restriction)

Cross-reference

Cross-reference 1

Reason / purpose for cross-reference:

reference to same study

Cross-reference 2

Reason / purpose for cross-reference:

reference to other study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2007

Report date:

2007

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

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

Version / remarks:

88/303/EC

Deviations:

no

Principles of method if other than guideline:

no other principles

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Specific details on test material used for the study:

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

Sampling and analysis

Analytical monitoring:

not required

Details on sampling:

NA

Test solutions

Vehicle:

no

Details on test solutions:

In the main test an aqueous stock solution of Lithium-tert-amoxide (LTA) was prepared with a test item concentration of 200 mg/L, and during the performance of the test the test solutions were mixed by mechanical stirring to ensure a good dispersion.
Because the test item reacts violently with water a complementary experiment was carried out to repeat and confirm the 0-7 day results of the main test.
During the performance of the complementary experiment defined amounts of test item were directly weighed into the large glass bottles with valve to reach the planned nominal concentrations (2 mg/L). The nominal test item concentrations were prepared by mechanical dispersion (intensive stirring). These test solutions were freshly prepared at the beginning of the experiment, in the testing laboratory.

Test organisms

Test organisms (species):

activated sludge, domestic

Details on inoculum:

The activated sludge used for this study was washed by centrifugation 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. An aliquot of the final sludge suspension was weighed, dried and the ratio of wet sludge to its dry weight was determined. Based on this ratio, calculated aliquots of washed sludge suspension, corresponding to 4 g dry material per litre were mixed with test water (see below) and then aerated until use. Before use the sludge was filtered through cotton wool.

Study design

Test type:

static

Water media type:

freshwater

Limit test:

no

Total exposure duration:

3 h

Post exposure observation period:

NA

Test conditions

Hardness:

NA

Test temperature:

19.4 – 20.3 °C (during the incubation) and
19.2 – 22.0 °C (during oxygen measurement)

pH:

The pH of the activated sludge inoculum was determined to be pH 7.43.

Dissolved oxygen:

The concentration of dissolved oxygen did not drop below 2.5 mg O2/L during the incubation period, and just before the measurements of the respiration rates the oxygen concentrations were at least 7.3 mg O2/L.

Salinity:

NA

Nominal and measured concentrations:

nominal: 10, 31, 100, 313 and 1000 mg/L
no concentrations measured

Details on test conditions:

aerobic incubation

Reference substance (positive control):

yes

Remarks:

3,5-Dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

3 h

Dose descriptor:

EC50

Effect conc.:

185.7 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% conf. limit 156.8–219.9

Effect concentrations 2

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:

The NOEC for respiration rates was not based on the results of a statistical analysis, but biologically justified. The respiration rates were inhibited and influenced dose dependently in the whole concentration range, however the observed slight inhibitions (4.7 % and 6.5 %) at the concentration levels of 10 and 31 mg/L were evaluated as reflecting the biological variability in the test. At the concentration of 100 mg/L the calculated respiration rate (0.470) was in the historical control data range (0.490 - 0.089), and the acceptable range of controls of +/- 15 %. Thus, the observed inhibition at 100 mg/L of < 15% can be considered as a biological variability of the test system.

Results with reference substance (positive control):

The 3-hour EC50 of the reference item 3,5-Dichlorophenol for the used activated sludge batch was determined to be 8.20 mg/L and thus the EC50 was in the acceptable range of 5 to 30 mg/L.

Reported statistics and error estimates:

NA

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Conclusions:

EC50 (3h) = 185.7 mg/l

Executive summary:

In comparison to the inoculum controls the respiration rate of the activated sludge was inhibited dose-dependently in the whole examined concentration range, displaying inhibition rates from 4.7 up to 98.1 %.

NOEC (3h) = 100 mg/l. EC50 (3h) = 185.7 mg/l.