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Environmental fate & pathways

Biodegradation in soil

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Reference
Endpoint:
biodegradation in soil, other
Type of information:
experimental study
Adequacy of study:
key study
Reliability:
2 (reliable with restrictions)
Rationale for reliability incl. deficiencies:
other: Data is from peer reviewed journal
Justification for type of information:
Data is from peer reviewed journal
Qualifier:
according to guideline
Guideline:
other: as mentioned below
Principles of method if other than guideline:
Biodegradation study was conducted for 64 days for evaluating the percentage biodegradability of test substance 2,4-Pyridinedicarboxylic acid.
GLP compliance:
not specified
Test type:
not specified
Specific details on test material used for the study:
- Name of test material (IUPAC name): 2,4-Pyridinedicarboxylic acid
- Molecular formula: C7H5NO4
- Molecular weight: 167.12 g/mol
- Smiles notation: c1(cc(ncc1)C(O)=O)C(O)=O
- InChl: 1S/C7H5NO4/c9-6(10)4-1-2-8-5(3-4)7(11)12/h1-3H,(H,9,10)(H,11,12)
- Substance type: Organic
- Physical state: Solid
- Other: Test chemical 2,4-Pyridinedicarboxylic acid was purchased from Aldrich Chemical Co., Inc.
Radiolabelling:
not specified
Oxygen conditions:
not specified
Soil no.:
#1
Soil type:
silt loam
% Clay:
0.25
% Org. C:
12
pH:
6.7
CEC:
0.15 other: mol (+)/kg
Details on soil characteristics:
Total N content: 1300 mg/kg
Soil No.:
#1
Duration:
64 d
Soil No.:
#1
Initial conc.:
2 other: mmol/kg
Based on:
test mat.
Parameter followed for biodegradation estimation:
test mat. analysis
Soil No.:
#1
Temp.:
25°C
Details on experimental conditions:
EXPERIMENTAL DESIGN
- Test apparatus (Type/material/volume): 100 ml glass vials was used as a test vessel for the study.
- Details of traps for CO2 and organic volatile, if any: The incubation vessels were plugged with 4.5-cm diam by 2.5-cm thick polyurethane foam stoppers.
Soil No.:
#1
% Recovery:
49.1
Remarks on result:
other: at day 1
Soil No.:
#1
% Recovery:
23.9
Remarks on result:
other: at day 2
Soil No.:
#1
% Recovery:
15.1
Remarks on result:
other: at day 4
Soil No.:
#1
Remarks on result:
other: from day 8 upto 64 days, no recovery of test chemical was determined
Key result
Soil No.:
#1
% Degr.:
100
Parameter:
test mat. analysis
Sampling time:
8 d
Remarks on result:
other: Other details not known
Transformation products:
not specified
Evaporation of parent compound:
not specified
Volatile metabolites:
not specified
Residues:
not specified
Details on results:
Pyridinecarboxylic acids were not recovered in KCl-HCl extracts after 4 to 16 d of incubation.Most of the N (> 90%) accumulating in soil treated with pyridine derivatives was in the ammonium form, indicating very little nitrification.
Loss of pyridine derivatives from soil by volatilization was 5% or less for all pyridine derivatives i.e, for test chemical2,4-Pyridinedicarboxylic acid.
 
The result suggest that test chemical wasextensively degraded during 64 d of incubation. This conclusion is based on:
(i) the compounds were no longer recovered by extraction of soil
with 2 M KC1 + 0.01 M HC1 and
(ii) inorganic N released by decomposition was from 60 to 80% of the N added.

Table: Recovery of pyridine derivatives from soil.

 

Functional group

Position

Incubated in sterile soil for 7 days (% of added)

 

Recovery of pyridine after incubation, d(% of added)

0 (% of added)

1

2

4

8

16

32

64

NF

F

-COOH

2,4

84.5

81.1

82.3

49.1

23.9

15.1

ND

ND

ND

ND

 

Where,

NF = samples analyzed on day 0

F = samples frozen on day 0 and analyzed on day 64.

ND = not detected.

 

Table: Accumulationof inorganic N in soil treated with pyridine derivatives.

 

Functional group

Position

Inorganic N+ extracted after

incubation time, d(% degraded)

0

16

32

64

-COOH

2,4

2.1

11.2

65.2

51.4

 

Where,

+ = Inorganic N, NH4+, NO2- and NO3- - N.

 

Conclusions:
The percentage degradation of test substance 2,4-Pyridinedicarboxylic acid was determined to be 100% by test material analysis and UV analysis after 8 days. Test chemical was not recovered in KCl-HCl extracts after 4 to 16 d of incubation. Thus, based on percentage degradation, 2,4-Pyridinedicarboxylic acid is considered to be readily biodegradable in soil.
Executive summary:

Biodegradation study was conducted for 64 days for evaluating the percentage biodegradability of test substance 2,4-Pyridinedicarboxylic acid.Soil was incubated with a pyridine

derivative i.e, 2,4-Pyridinedicarboxylic acid (2 mmol/kg) in 100-mLgl ass vials at 25°C for 0 to 64 d.The soil was a Fincastle silt loam (Aerie Ochraqualfs) which had water pH of 6.7 (1:2 soil-water ratio), organic carbon content of 12 /kg, total N content of 1300 mg/kg, CEC of 0.15 mol ( +) /kg, and contained 0.25 kg H20 kg dry soil-1 at -0.03 MPa.The incubation vessels were plugged with 4.5-cm diam by 2.5-cm thick polyurethane foam stoppers. At 3- to 4-d intervals, incubation vessels were adjusted for loss of 0.3 to 0.4 g H20. After 0, 1, 2, 4, 8, 16, 32, and 64 d of incubation, the foam stopper and soil from replicate containers were extracted separately and analysed.Since processing of samples from each date required more than a day to complete, samples were stored at -20°C for a few days prior to extraction. To assess the effect of storage on N content and recovery of pyridine derivatives, a second set of replicate samples was taken at 0 days of incubation and stored at -20°C for the duration of the experiment before analysis. A preliminary experiment was conducted to evaluate 2 M KCI, 0.01 M HCI, and 2 M KCI + 0.01 M HCI as extractants for pyridine derivatives in soil. The extraction and analysis procedure was: 40 mL of 2 M KC1 + 0.01 M HC1 were added to the incubation bottle and the bottle was sealed and shaken (180 oscillations min-1) for 30 min at 23°C. After allowing the soil to settle for 60 min, 6 mL subsamples were removed and centrifuged for 20 min at 20 000 x g. Pyridine derivatives were analyzed in the supernatant from UV spectra (340-240 nm). Nitrogen was measured at 0, 16, 32 and 64 d.Pyridined-2,4-dicarboxylic acids were not recovered in KCl-HCl extracts after 4 to 16 d of incubation.Most of the N (> 90%) accumulating in soil treated with pyridine derivatives was in the ammonium form, indicating very little nitrification.Loss of pyridine derivatives from soil by volatilization was 5% or less for all pyridine derivatives i.e, for test chemical 2,4-Pyridinedicarboxylic acid.The percentage degradation of test substance 2,4-Pyridinedicarboxylic acid was determined to be 100% by test material analysis and UV analysis after 8 days. Thus, based on percentage degradation, 2,4-Pyridinedicarboxylic acid is considered to be readily biodegradable in soil. Based on this value of test chemical, it is concluded that the chemical 2,4-Pyridinedicarboxylic acid is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Description of key information

Biodegradation study in soil was conducted for 64 days for evaluating the percentage biodegradability of test substance 2,4-Pyridinedicarboxylic acid (CAS no. 499 -80 -9)

(Gerald K. Sims and Lee E. Sommers, 1985). Soil was incubated with a pyridine derivative i.e, 2,4-Pyridinedicarboxylic acid (2 mmol/kg) in 100-mLgl ass vials at 25°C for 0 to 64 d.The soil was a Fincastle silt loam (Aerie Ochraqualfs) which had water pH of 6.7 (1:2 soil-water ratio), organic carbon content of 12 /kg, total N content of 1300 mg/kg, CEC of 0.15 mol ( +) /kg, and contained 0.25 kg H20 kg dry soil-1 at -0.03 MPa.The incubation vessels were plugged with 4.5-cm diam by 2.5-cm thick polyurethane foam stoppers. At 3- to 4-d intervals, incubation vessels were adjusted for loss of 0.3 to 0.4 g H20. After 0, 1, 2, 4, 8, 16, 32, and 64 d of incubation, the foam stopper and soil from replicate containers were extracted separately and analysed.Since processing of samples from each date required more than a day to complete, samples were stored at -20°C for a few days prior to extraction. To assess the effect of storage on N content and recovery of pyridine derivatives, a second set of replicate samples was taken at 0 days of incubation and stored at -20°C for the duration of the experiment before analysis. A preliminary experiment was conducted to evaluate 2 M KCI, 0.01 M HCI, and 2 M KCI + 0.01 M HCI as extractants for pyridine derivatives in soil. The extraction and analysis procedure was: 40 mL of 2 M KC1 + 0.01 M HC1 were added to the incubation bottle and the bottle was sealed and shaken (180 oscillations min-1) for 30 min at 23°C. After allowing the soil to settle for 60 min, 6 mL subsamples were removed and centrifuged for 20 min at 20 000 x g. Pyridine derivatives were analyzed in the supernatant from UV spectra (340-240 nm). Nitrogen was measured at 0, 16, 32 and 64 d.Pyridined-2,4-dicarboxylic acids were not recovered in KCl-HCl extracts after 4 to 16 d of incubation.Most of the N (> 90%) accumulating in soil treated with pyridine derivatives was in the ammonium form, indicating very little nitrification.Loss of pyridine derivatives from soil by volatilization was 5% or less for all pyridine derivatives i.e, for test chemical 2,4-Pyridinedicarboxylic acid.The percentage degradation of test substance 2,4-Pyridinedicarboxylic acid was determined to be 100% by test material analysis and UV analysis after 8 days. Thus, based on percentage degradation, 2,4-Pyridinedicarboxylic acid is considered to be readily biodegradable in soil. Based on this value of test chemical, it is concluded that the chemical 2,4-Pyridinedicarboxylic acid is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

Key value for chemical safety assessment

Additional information

Various experimental studies and predicted data for the target compound 2,4-Pyridinedicarboxylic acid (CAS No. 499-80-9) were reviewed for the biodegradation in soil end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (Gerald K. Sims and Lee E. Sommers, 1985), biodegradation study in soil was conducted for 64 days for evaluating the percentage biodegradability of test substance 2,4-Pyridinedicarboxylic acid. Soil was incubated with a pyridine derivative i.e, 2,4-Pyridinedicarboxylic acid (2 mmol/kg) in 100-mLgl ass vials at 25°C for 0 to 64 d. The soil was a Fincastle silt loam (Aerie Ochraqualfs) which had water pH of 6.7 (1:2 soil-water ratio), organic carbon content of 12 /kg, total N content of 1300 mg/kg, CEC of 0.15 mol ( +) /kg, and contained 0.25 kg H20 kg dry soil-1 at -0.03 MPa. The incubation vessels were plugged with 4.5-cm diam by 2.5-cm thick polyurethane foam stoppers. At 3- to 4-d intervals, incubation vessels were adjusted for loss of 0.3 to 0.4 g H20. After 0, 1, 2, 4, 8, 16, 32, and 64 d of incubation, the foam stopper and soil from replicate containers were extracted separately and analysed. Since processing of samples from each date required more than a day to complete, samples were stored at -20°C for a few days prior to extraction. To assess the effect of storage on N content and recovery of pyridine derivatives, a second set of replicate samples was taken at 0 days of incubation and stored at -20°C for the duration of the experiment before analysis. A preliminary experiment was conducted to evaluate 2 M KCI, 0.01 M HCI, and 2 M KCI + 0.01 M HCI as extractants for pyridine derivatives in soil. The extraction and analysis procedure was: 40 mL of 2 M KC1 + 0.01 M HC1 were added to the incubation bottle and the bottle was sealed and shaken (180 oscillations min-1) for 30 min at 23°C. After allowing the soil to settle for 60 min, 6 mL subsamples were removed and centrifuged for 20 min at 20 000 x g. Pyridine derivatives were analyzed in the supernatant from UV spectra (340-240 nm). Nitrogen was measured at 0, 16, 32 and 64 d.Pyridined-2,4-dicarboxylic acids were not recovered in KCl-HCl extracts after 4 to 16 d of incubation. Most of the N (> 90%) accumulating in soil treated with pyridine derivatives was in the ammonium form, indicating very little nitrification. Loss of pyridine derivatives from soil by volatilization was 5% or less for all pyridine derivatives i.e, for test chemical 2,4-Pyridinedicarboxylic acid. The percentage degradation of test substance 2,4-Pyridinedicarboxylic acid was determined to be 100% by test material analysis and UV analysis after 8 days. Thus, based on percentage degradation, 2,4-Pyridinedicarboxylic acid is considered to be readily biodegradable in soil. Based on this value of test chemical, it is concluded that the chemical 2,4-Pyridinedicarboxylic acid is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

 

Another biodegradation study in soil was conducted for 30 days for evaluating the percentage biodegradability of test substance 2,4-Pyridinedicarboxylic acid (CAS no. 499-80-9) (Gerald K. Sims, et. al, 1986). Fincastle silt loam was used as a test inoculum for the study. Initial test substance conc. used for the study was 1671.2 mg/l.Erlenmeyer flask of 500 ml volume was used as a test vessel for the study. The test vessel was plugged with polyurethane foam stoppers (4.5 cm in diameter and 2.5 cm thick) to trap the volatile pyridine compounds. Pyridine derivative i.e 2,4-Pyridinedicarboxylic acid was sterilised and solubilized by adding 2.25 mmol of each compound to a sterile screw-top tube containing 5 g 95% ethanol and diluting with 5 g sterile water. The solution was adjusted to pH 6 to 8 with 1M KOH and brought to a total weight of 15 g (150 mmol pyridine kg/solution) with sterile water. One milliliter (approx. 1 g) of each pyridine solution was added to replicate flasks of nutrient medium to give a final substrate concentration of approx. 1mM. Thus, the test system contains mineral salts, yeast extract, a pyridine derivative as a substrate and ethanol (7 mM) as a cosubstrate. The flasks were inoculated with 1 ml of a dilute soil suspension prepared by suspending 15 g Fincastle silt loam in 1 lt of mineral salts medium and continuously stirring the suspension as 1 ml subsamples were removed. Flasks were incubated with continuous shaking at 24°C for 30 days. Subsamples were removed from each flask before and after inoculations and periodically throughout the incubation. Samples were centrifuged for 20 mins at 20,000 g and the supernatant was diluted with 33 mM KH2PO4 buffer (pH 5.0) for analysis. Test chemical was measured spectrophotometrically by scanning solutions at from 340 to 240 nm with a Cary 17D spectrophotometer. The compound was quantified by comparing of the absorbance values obtained with a calibration curve. Interference from UV-absorbing soil components in the extract was eliminated by placing a sample of nutrient medium incubated with soil in the absence of a test chemical 2,4-Pyridinedicarboxylic acid in the reference beam. The disappearance of the 2,4-Pyridinedicarboxylic acid from solution plus the mineralization of pyridine N was taken as evidence of degradation. 3.0% of the chemical2,4-Pyridinedicarboxylic acid was sorbed by soil.Test chemical 2,4-Pyridinedicarboxylic acid was disappeared after 24 days. The accumulation of inorganic N (NH4+ plus NO2- plus NO3-) was used as an independent indicator of the degradation of pyridine derivative i.e. 2,4-Pyridinedicarboxylic acid. The percentage degradation of test substance 2,4-Pyridinedicarboxylic acid was determined to be 77 and 100% by test material analysis and UV analysis after 24 days. Thus, based on percentage degradation, 2,4-Pyridinedicarboxylic acid is considered to be readily biodegradable in soil. Based on this value of test chemical, it is concluded that the chemical 2,4-Pyridinedicarboxylic acid is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

 

In a supporting study from peer reviewed journal (Gerald K. Sims, et. al; 1989), biodegradation experiment in soil was conducted for evaluating the percentage biodegradability of test substance 2,4-Pyridinedicarboxylic acid (CAS no. 499-80-9).The percentage degradation of test substance 2,4-Pyridinedicarboxylic acid was determined to be 100% after 24 days. Thus, based on percentage degradation, 2,4-Pyridinedicarboxylic acid is considered to be readily biodegradable in soil. Based on this value of test chemical, it is concluded that the chemical 2,4-Pyridinedicarboxylic acid is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

 

In a supporting data from EPI Suite, the half-life period of 2,4-Pyridinedicarboxylic acid (CAS No. 499 -80 -9) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2017). If released into the environment, 76.9% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 2,4-Pyridinedicarboxylic acid in soil is estimated to be 30 days (720 hrs). Based on this half-life value of 2,4-Pyridinedicarboxylic acid, it is concluded that the chemical is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.

 

On the basis of above results for target chemical 2,4-Pyridinedicarboxylic acid (from peer reviewed journals and EPI suite, 2017), it can be concluded that the test substance 2,4-Pyridinedicarboxylic acid is not persistent in the soil environment and the exposure risk to soil dwelling animals is moderate to low.