Pyridine-2-carbaldehyde

Biodegradation in water: screening tests

Administrative data

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

key study

Study period:

17 August - 14 September 2001

Reliability:

1 (reliable without restriction)

Rationale for reliability incl. deficiencies:

other: GLP - guideline study

Data source

Reference

Reference Type:

study report

Title:

Unnamed

Year:

2001

Report date:

2001

Materials and methods

Test guideline

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 D (Ready Biodegradability: Closed Bottle Test)

Deviations:

no

GLP compliance:

yes (incl. QA statement)

Remarks:

(The Department of Health of the Government of the United Kingdom)

Test material

Test material information

Constituent 1

Reference substance name:

Pyridine-2-carbaldehyde

EC Number:

214-333-6

EC Name:

Pyridine-2-carbaldehyde

Cas Number:

1121-60-4

Molecular formula:

C6H5NO

IUPAC Name:

pyridine-2-carbaldehyde

Test material form:

other: liquid

Details on test material:

- Name of test material (as cited in study report): Pyridine-2-aldehyde
- Physical state: light yellow liquid
- Storage condition of test material: room temperature , in the dark until 31 July 2001 , thereafter approximately 4°C , under nitrogen , in the dark

Study design

Oxygen conditions:

aerobic

Inoculum or test system:

sewage, domestic, non-adapted

Details on inoculum:

- Source of inoculum/activated sludge : Final effluent of Severn Trent Water Plc sewage treatment plant at Loughborough,Leicestershire, UK , obtained on 17 August 2001
- Pretreatment: The effluent was filtered through coarse filter paper (first approximate 200 ml discarded) and the filtrate maintained on continuous aeration in a temperature controlled room at 21°C prior to use.

Duration of test (contact time):

28 d

Initial test substance concentration

Initial conc.:

2 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation

Parameter followed for biodegradation estimation:

O2 consumption

Details on study design:

TEST CONDITIONS
- Composition of medium:
For the purpose of the definitive study the test material was dissolved directly in culture medium.
An amount of test material (100 mg) was dissolved in culture medium with the aid of ultrasonication (approximately 5 minutes) and the volume adjusted to 100 ml to give a 1000 mg/l stock solution. An aliquot (12 ml) of this stock solution was dispersed in a final volume of 6 litres of inoculated culture medium to give a concentration of 2 mg/l.
The volumetric flask containing the stock solution was inverted several times to ensure homogeneity of the solution.
All preparations were carried out under laboratory safety lighting as data supplied by the Sponsor indicated that the test material was unstable in natural or artificial day light.
A test concentration of 2 mg/l was employed in the study as the Theoretical Oxygen Demand (ThOD) of the test material was calculated to be 1.79 mg 02/mg . Hence, if complete degradation of the test material occurred, the oxygen depletion in the. test vessels would be 3.58 mg 02/l and as such de-oxygenation of the test media would not occur.
- Test temperature: 20°C
- pH adjusted: no

TEST SYSTEM
- The following test solutions were prepared and inoculated in 250-300 ml Biological Oxygen Demand (BOD) bottles (darkened glass) with ground glass stoppers:
a) A control consisting of inoculated culture medium.
b) The standard material in inoculated culture medium to give a concentration of 3 mg/I.
c) The test material in inoculated culture medium to give a concentration of 2 mg/l.
d) The test material (2 mg/l) plus the standard material (1.5 mg/l) in inoculated culture medium to act as a toxicity control.
Test media a-d were inoculated with sewage treatment micro-organisms at a rate of 1 drop of inoculum per litre . The test media were transferred by siphon to BOD bottles, which were firmly stoppered to exclude all air bubbles. Sufficient bottles were prepared to allow a single oxygen determination per bottle with duplicate bottles for each test medium at each sampling occasion.
The BOD bottles were incubated in a temperature controlled water bath at 20°C.

SAMPLING
- Sampling frequency: Dissolved oxygen concentrations for each test medium were determined, in duplicate on Days 0,3, 6, 9, 12, 15, 18, 21, 24 and 28 by means of a Yellow Springs oxygen meter and BOD Probe.
- Other:
Nitrate analysis:
The test material contained nitrogen and therefore on each sampling occasion water samples were taken for the analysis of nitrate concentration from the inoculated control, standard material, test material and toxicity control vessels in order to enable correction of the oxygen depletion values for any nitrification that may have occurred. The nitrate concentration was determined spectrophotometrically by measuring absorbance values at 220 nm and 275 nm. These absorbance values were corrected for any organic matter present by subtracting twice the absorbance of the test solutions at 275 nm from those measured at 220 nm.
A calibration curve was prepared by measuring absorbance values at 220 nm and 275 nm of standard solutions of sodium nitrate at the following concentrations: 0.010, 0.020, 0.040, 0.060,0.080, 0.10, 0.20, 0.40, 0.60, 0.80 and 1.0 mg NO3-N/l. Linear regression analysis of the standard curve data produced an equation for the best fit line into which the corrected test solution absorbance values were substituted to determine the nitrate concentration.
Nitrite analysis
On each sampling occasion water samples were also taken for the analysis of nitrite concentration from the inoculated control, standard material, test material and toxicity control vessels in order to enable correction of the oxygen depletion values for any nitrification that may have occurred.
The nitrite concentration was determined using a spectrophotometric method measuring absorbance values at 543 nm.
A calibration curve was prepared by measuring the absorbance values at 543 nm of standard solutions of sodium nitrite at the following concentrations : 0.0010, 0.0020, 0.0040, 0.0060,0.0080, 0.010, 0.020, 0.040, 0.060, 0.080 and 0.10 mg NO2- N/l. Linear regression analysis of the standard curve data produced an equation for the best fit line into which the test solution absorbance values were substituted to determine the nitrite concentration

CONTROL AND BLANK SYSTEM
- Inoculum blank: yes
- Abiotic sterile control: -
- Toxicity control: yes , the test material (2 mg/l) plus the standard material (1.5 mg/l) in inoculated culture medium

Reference substance

Reference substance:

benzoic acid, sodium salt

Remarks:

3 mg/l

Results and discussion

% Degradation

Parameter:

% degradation (O2 consumption)

Value:

82

Sampling time:

28 d

Details on results:

The test material attained 82% degradation after 28 days. Under the strict terms and conditions of OECD Guideline No 301D the test material cannot be considered to be readily biodegradable as the test material failed to satisfy the 10-Day window validation criterion, whereby 60% degradation must be attained within 10 days of the degradation rate exceeding 10%. However, the test material has exhibited the potential for rapid degradation. In terms of the classification and labelling requirements (EU Directive for Dangerous Substances, L110A) the test material may be considered as readily biodegradable as evidence of >70% degradation has been shown over a 28-Day period in a standard biodegradation study.

BOD5 / COD results

Results with reference substance:

The standard material, sodium benzoate, attained 74% degradation after 28 days thereby confirming the suitability of the test method and culture conditions.

Applicant's summary and conclusion

Validity criteria fulfilled:

yes

Interpretation of results:

other: readily & rapidly biodegradable

Conclusions:

The study was conducted under GLP compliance and a well documented study report is available.
The test material attained 82% degradation after 28 days. Under the strict terms and conditions of OECD Guideline No. 301D the test material cannot be considered to be readily biodegradable as the test material failed to satisfy the 10-Day window validation criterion, whereby 60% degradation must be attained within 10 days of the degradation rate exceeding 10%. However, the test material has exhibited the potential for rapid degradation. In terms of the classification and labelling requirements (EU Directive for Dangerous Substances, L110A) the test material may be considered as readily and rapidly biodegradable as evidence of >70% degradation has been shown over a 28-Day period in a standard biodegradation study.

Executive summary:

The biodegradability of the substance Pyridine-2-aldehyde was investigated according to OECD Guidelines for Testing of Chemicals (1992) No 301 D, "Ready Biodegradability; Closed Bottle Test" referenced as Method C.4-E of Commission Directive 92/69/EEC (which constitutes Annex V of Council Directive 67/548/EEC).. The study was conducted in compliance with the Principles of Good Laboratory Practice (GLP). The test material was exposed to sewage treatment micro-organisms at a concentration of 2 mg/I with culture medium in sealed culture vessels in the dark at 20°C for 28 days. The degradation of the test material was assessed by the determination of the amount of oxygen consumed. Control solutions with inoculum and the standard material, sodium benzoate, together with a toxicity control were used for validation purposes. Sodium benzoate attained 74 % degradation after 28 days thereby confirming the suitability of the inoculum and test conditions.Examination of the degradation curve for the toxicity control showed that the toxicity control attained in excess of 25% degradation by Day 14 of the study thereby confirming that the test material was not toxic to the sewage treatment micro-organisms used in the study. After 28 days the toxicity control had attained 75% degradation.

The test material attained 82% degradation after 28 days. Under the strict terms and conditions of OECD Guideline No. 301D the test material cannot be considered to be readily biodegradable as the test material failed to satisfy the 10-Day window validation criterion, whereby 60% degradation must be attained within 10 days of the degradation rate exceeding 10%. However, the test material has exhibited the potential for rapid degradation. In terms of the classification and labelling requirements (EU Directive for Dangerous Substances, L110A) the test material may be considered as readily and rapidly biodegradable as evidence of >70% degradation has been shown over a 28-Day period in a standard biodegradation study.