2-vinylpyridine

Toxicity to microorganisms

Administrative data

Endpoint:

activated sludge respiration inhibition testing

Type of information:

experimental study

Adequacy of study:

key study

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: Guideline study according to GLP

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2010

Report date:

2010

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 209 (Activated Sludge, Respiration Inhibition Test

GLP compliance:

yes (incl. QA statement)

Test material

Test material information

Constituent 1

Reference substance name:

2-vinylpyridine

EC Number:

202-879-8

EC Name:

2-vinylpyridine

Cas Number:

100-69-6

Molecular formula:

C7H7N

IUPAC Name:

2-ethenylpyridine

Details on test material:

2-vinylpyridine, Batch 0000101324, Certificate of Analysis date: 01/28/2010
Purity: 98.5%, lower limit 98.0%
Inhibitor (t-butyl catechol) 0.100%, (0.090-0.110)

Sampling and analysis

Analytical monitoring:

no

Test solutions

Vehicle:

no

Details on test solutions:

PREPARATION AND APPLICATION OF TEST SOLUTION (especially for difficult test substances)
- Method: 2000 mg of the test item, a liquid, was dissolved in water up to 1 L, as a stock solution.
- Differential loading: 10 mg/L
- Controls: 3,5-dichlorophenol. Stock solutions of 50 and 160 mg/l were prepared in water using ultrasonication for 15 minutes. These were dispersed with activated sewage sludge and water, at a final concentration of 3.2 and 32 mg/L
- Chemical name of vehicle (organic solvent, emulsifier or dispersant): water
- Concentration of vehicle in test medium (stock solution and final test solution(s) including control(s)):
- Evidence of undissolved material (e.g. precipitate, surface film, etc): no undissolved test item by visual observation; a clear colourless water column was observed.
The test item (2000 mg) was dissolved in water and volume adjusted to 1 liter, to give a 2000 mg/l stock solution, with additional stocks of 200 and 20 mg/l stocks. An aliquot (250 ml) of the 20 mg/l stock solution was dispersed with synthetic sewage (16 ml), activated sludge (200 ml) and water, to a final volume of 500 ml for a required concentration of 10 mg/l. Additional test concentrations were 32, 100, 320 and 1000 mg/l. The volumetric flasks were inverted several times to mix. The control group was maintained under identical conditions but not exposed to the test item.

Test organisms

Test organisms (species):

activated sludge of a predominantly domestic sewage

Details on inoculum:

A mixed population of sewage sludge micro-organisms was obtained fromt he Severn Trent Water Plc sewage treatment plant at Loughborough, Leicestershire, UK, (domestic sewage). The test was performed on the day of collection of the sample. Suspended solids were determined by weighing multiple paper-filtered samples which were dried; concentration was determined to 4.0 g/l prior to use.

Study design

Test type:

static

Water media type:

freshwater

Total exposure duration:

30 min

Remarks on exposure duration:

Due to the volatile nature of 2VP, the test duration was selected at 30 minutes, as allowed in the protocol

Test conditions

Test temperature:

21.1 degrees C.

pH:

7.06

Salinity:

0

Details on test conditions:

Test systems were prepared as follows: 16 ml of synthetic sewage was diluted to 300 ml with water and 200 ml of inoculum, and added to a 1 liter beaker, stirring with a magnetic stirrer. At 15 min intervals, the procedure was repeated with reference item or test item added. At 30 min contact time, an aliquot was transferred to a darkened Biological Oxygen Demand (BOD) bottle, and the rate of respiration measured using a dissolved oxygen meter (Yellow Springs). The test was conducted under normal laboratory lighting in a temperature controlled room at 21 ± 1 oC. Observations were made on the test preparations at o hours (prior to addition of activated sludge and sewage) and throughout the test period. The pH of the control, reference item and test item preparations were measured using a WTW pH/Oxi 3401 pH and dissolved oxygen meter at 0 hour and prior to measurement of the oxygen consumption rate.

Reference substance (positive control):

yes

Remarks:

3,5-dichlorophenol

Results and discussion

Effect concentrations

Effect concentrations 1

Duration:

30 min

Dose descriptor:

EC50

Effect conc.:

260 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Effect concentrations 2

Duration:

30 min

Dose descriptor:

NOEC

Effect conc.:

32 mg/L

Nominal / measured:

nominal

Conc. based on:

test mat.

Basis for effect:

inhibition of total respiration

Remarks:

respiration rate

Details on results:

The test item did not result in greater than 80% inhibition at any concentration tested. It was not possible to obtain 95% confidence limits for the item EC50 value, as the data did not fit the models available for calculation.

Results with reference substance (positive control):

The reference item gave a 30-min EC50 value of 11 mg/l, 95% confidence limits 8.9-14 mg/l.

Reported statistics and error estimates:

Variation in control respiration rates after 30 minutes of contact time was +/- 2%. The reference item displayed inhibition of sludge respiration, EC50 of 11 mg/l, as expected.

Any other information on results incl. tables

In some instances, the initial and final dissolved O₂concentrations were below those recommended by the guideline (6.5 mg O₂/l and 2.5 mg O₂/l, respectively). This was considered to have had no adverse effect on the results of the study given that the oxygen consumption rate was determined over the linear portion of the oxygen consumption trace.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Remarks:

control respiration rates and reference item EC50 values are satisfied.

Conclusions:

The potential inhibitory effect of 2-vinylpyridine on respiration of activate sewage sludge was investigated using an OECD 209 guideline. The 30 minute EC50 was 260 mg/l, and the NOEC after 30 minutes was 32 mg/l.