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Biodegradation in water

Biodegradation study was conducted for evaluating the percentage biodegradability of test substance 2,4-Pyridinedicarboxylic acid (CAS no. 499-80-9) (Gerald K. Sims, et. al; 1986).

The study was carried out usingMicrococcus luteus as the test inoculum isolated from Chalmers silt loam soil, not previously exposed to pyridine, using enrichment culture techniques. A Chalmers silt loam soil, not previously exposed to pyridine, was used as an inoculum for enrichment cultures. The medium contained basal salts, yeast extract (150 mg/liter), and pyridine (0.01 M).The soil was perfused with pyridine enrichment medium in a rotary perfusion device. Perfusion of the soil resulted in enrichment of a gram-positive, aerobic, furazolidone-resistant coccus which was identified as a Micrococcus species.Cells were maintained on pyridine agar slants at 4°C. Growth was measured as optical density at 540 nm and expressed as cell density (dry weight) based on standard curves. Measurement at 540 nm avoided interference from a soluble yellow pigment produced by M. luteus when grown on pyridine. The test medium contained basal salts, yeast extract (150 mg/liter), and pyridine (0.01 M).Media containing substituted pyridines were filter sterilized.Defined media used in enzyme induction experiments thus contained thiamine (2 µM), arginine (0.3 mM), valine (0.4 mM), leucine (0.4 mM), and methionine (0.2 mM) to satisfy growth factor requirements and produce a high yield of cells. M. luteus required thiamine for growth on pyridine or succinate, and growth was enhanced by the addition of arginine, valine, leucine, and methionine.Cells were cultured in the salt medium with yeast extract and various carbon sources at 24°C.Degradation of substituted pyridines was measured as the decrease in absorbance at an appropriate wavelength in the UV, and samples were periodically scanned from 300 to 200 nm to detect the formation of UV-absorbing intermediates. Scans were performed with a Cary 17-D spectrophotometer, whereas measurements at fixed wavelengths were made with a Gilford 250.M. luteus was unable to grow at the expense of the substituted pyridine tested i.e.2,4-Pyridinedicarboxylic acid. Thus,no degradation of test substance 2,4-Pyridinedicarboxylic acidwas determined by M. luteus. Based on percentage degradation (0%), 2,4-Pyridinedicarboxylic acid is considered to be not readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound 2,4-Pyridinedicarboxylic acid (CAS No. 499 -80 -9). If released in to the environment, 23% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 2,4-Pyridinedicarboxylic acid in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 2,4-Pyridinedicarboxylic acid in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.0794%), indicates that 2,4-Pyridinedicarboxylic acid is not persistent in sediment.

Biodegradation in soil

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.

Bioaccumulation: aquatic / sediment

BCFBAF model (v3.01) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the bioconcentration factor (BCF) of test chemical 2,4-Pyridinedicarboxylic acid (CAS No. 499 -80 -9). The bioconcentration factor (BCF) of 2,4-Pyridinedicarboxylic acid was estimated to be 3.162 L/kg whole body w.w (at 25 deg C) which does not exceed the bio concentration threshold of 2000, indicating that the chemical 2,4-Pyridinedicarboxylic acid is not expected to bioaccumulate in the food chain.

Adsorption / desorption

KOCWIN model (v2.00) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the soil adsorption coefficient i.e Koc value of test chemical2,4-Pyridinedicarboxylic acid(CAS No. 499 -80 -9).The soil adsorption coefficient i.e Koc value of 2,4-Pyridinedicarboxylic acid was estimated to be 38.98 L/kg (log Koc=1.5909)  by means of MCI method (at 25 deg C). This Koc value indicates that the substance 2,4-Pyridinedicarboxylic acid has a low sorption to soil and sediment and therefore have moderate migration potential to ground water

Additional information

Biodegradation in water

Various experimental studies for the target compound 2,4-Pyridinedicarboxylic acid (CAS No. 499-80-9) and supporting weight of evidence study for its structurally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (Gerald K. Sims, et. al; 1986),biodegradation experimemt was conducted for evaluating the percentage biodegradability of test substance 2,4-Pyridinedicarboxylic acid (CAS no. 499-80-9). The study was carried out using Micrococcus luteus as the test inoculum isolated from Chalmers silt loam soil, not previously exposed to pyridine, using enrichment culture techniques. A Chalmers silt loam soil, not previously exposed to pyridine, was used as an inoculum for enrichment cultures. The medium contained basal salts, yeast extract (150 mg/liter), and pyridine (0.01 M).The soil was perfused with pyridine enrichment medium in a rotary perfusion device. Perfusion of the soil resulted in enrichment of a gram-positive, aerobic, furazolidone-resistant coccus which was identified as a Micrococcus species. Cells were maintained on pyridine agar slants at 4°C. Growth was measured as optical density at 540 nm and expressed as cell density (dry weight) based on standard curves. Measurement at 540 nm avoided interference from a soluble yellow pigment produced by M. luteus when grown on pyridine. The test medium contained basal salts, yeast extract (150 mg/liter), and pyridine (0.01 M).Media containing substituted pyridines were filter sterilized. Defined media used in enzyme induction experiments thus contained thiamine (2 µM), arginine (0.3 mM), valine (0.4 mM), leucine (0.4 mM), and methionine (0.2 mM) to satisfy growth factor requirements and produce a high yield of cells. M. luteus required thiamine for growth on pyridine or succinate, and growth was enhanced by the addition of arginine, valine, leucine, and methionine. Cells were cultured in the salt medium with yeast extract and various carbon sources at 24°C.Degradation of substituted pyridines was measured as the decrease in absorbance at an appropriate wavelength in the UV, and samples were periodically scanned from 300 to 200 nm to detect the formation of UV-absorbing intermediates. Scans were performed with a Cary 17-D spectrophotometer, whereas measurements at fixed wavelengths were made with a Gilford 250.M. luteus was unable to grow at the expense of the substituted pyridine tested i.e.2,4-Pyridinedicarboxylic acid. Thus, no degradation of test substance 2,4-Pyridinedicarboxylic acid was determined by M. luteus. Based on percentage degradation (0%), 2,4-Pyridinedicarboxylic acid is considered to be not readily biodegradable in nature.

 

In a supporting study, biodegradability of test substance 2,4-Pyridinedicarboxylic acid (CAS no. 499-80-9) was estimated using the MULTICASE method which involve the use of two QSAR models (Bodo Phillip, et. al; 2007). The models have been applied are Quantitative Structure-Activity Relationships.QSAR models for biodegradation are created with experimental biodegradation data and structures of the corresponding chemicals. The MULTICASE method has been described.This software is designed to automatically perform statistical analysis of learning sets containing structures and biological activity data of organic compounds, detect the molecular fragments significantly linked to a biological endpoint, and derive predictive QSAR models there from.The MULTICASE method has been described.This software is designed to automatically perform statistical analysis of learning sets containing structures and biological activity data of organic compounds, detect the molecular fragments significantly linked to a biological endpoint, and derive predictive QSAR models there from. Order to run statistical algorithms on the learning set, the program calculates all the possible fragments for each molecule, ranging from 2 to 10 non-hydrogen atoms along with their associated hydrogen atoms. Each of these fragments as well as automatically calculated 2-dimensional distance descriptors (based upon the presence of lipophilic centers and heteroatoms in the molecule) is associated with a confidence level and a probability of activity that is derived from its distribution among biological active and inactive molecules. Molecules containing the same activating fragments but having slightly different activity values are then searched for modulators of activity. These modulators may be chemical properties (eg. Structural fragments), physicochemical properties (eg. logPow), or quantum chemical parameters (eg. HOMO and LUMO energies), which are calculated by the program. Provided that the learning set contained sufficient data on potential SAR, a QSAR-model is established which enables the program to run in a predictive mode and evaluate untested molecules. Experimental biodegradation data were taken from different databases.On the basis of this evaluation, we classified the N-heterocycles into three categories, namely readily/inherently, moderately, and poorly degradable, according to OECD Standards. MULTICASE analysis was performed with the 194 data set to determine fragments that activate (QSAR1) or inactivate (QSAR 2) the aerobic biodegradation of N-heterocycles. In QSAR1, biodegradable compounds were considered as active and were assumed to contain biodegradation-related structural fragments (activating fragments). Poorly biodegradable compounds were considered as inactive and were assumed not to contain structural fragments activating biodegradation or containing inactivating fragments. To identify inactivating fragments (QSAR 2), the scale of activity was inversed, labelling biodegradable molecules as inactive and poorly biodegradable molecules as active before analysis with MULTICASE. If MULTICASE detects unknown fragments, or fragments with a low confidence level or with a low probability, the respective molecules are rejected as inconclusive and no prediction is made. Test chemical was estimated to contain fragment 4 and 9, respectively. Molecules carrying activating fragment 4 are aromatic N-heterocycles, mainly pyridines and quinolines.Molecules with activating fragment 9 overlap largely with aromatic compounds carrying fragment 4 (68%) or with nonaromatic molecules carrying fragments 1 or 2. Chemical biodegradability was reported as (+) readily/inherently biodegradable, (0) moderately biodegradable or (-) poorly biodegradable. As the biodegradability prediction of chemical 2,4-Pyridinedicarboxylic acid by the two QSAR models (used within MULTICASE analysis) comes out to be +, test chemical 2,4-Pyridinedicarboxylic acid is estimated to be readily biodegradable in water.

 

For the read across chemical 2,5-Pyridinedicarboxylic acid (CAS no. 100-26-5) from authoritative database (J-CHECK, 2017), biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance 2,5-Pyridinedicarboxylic acid. Concentration of inoculum i.e, sludge used was 30 mg/l and initial test substance conc. used in the study was 100 mg/l, respectively. The percentage degradation of substance 2,5-Pyridinedicarboxylic acid was determined to be 0, 1 and 9% by O2 consumption, BOD, TOC removal, Test mat. analysis and HPLC parameter in 28 days.. Thus, based on percentage degradation, 2,5-Pyridinedicarboxylic acid is considered to be not readily biodegradable in nature.

 

Although one study frompeer reviewed journalwhich is the estimated result indicates that the test chemical 2,4-Pyridinedicarboxylic acid is readily biodegradable, but based on the other experimental study from peer reviewed journal (K2) and on the basis ofread across substance (from authoritative database J-CHECK), it can be concluded that the test substance 2,4-Pyridinedicarboxylic acid can be expected to be not readily biodegradable in nature.

Biodegradation in water and sediment

Estimation Programs Interface (EPI Suite, 2017) prediction model was run to predict the half-life in water and sediment for the test compound 2,4-Pyridinedicarboxylic acid (CAS No. 499 -80 -9). If released in to the environment, 23% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 2,4-Pyridinedicarboxylic acid in water is estimated to be 15 days (360 hrs). The half-life (15 days estimated by EPI suite) indicates that the chemical is not persistent in water and the exposure risk to aquatic animals is moderate to low whereas the half-life period of 2,4-Pyridinedicarboxylic acid in sediment is estimated to be 135 days (3240 hrs). However, as the percentage release of test chemical into the sediment is less than 1% (i.e, reported as 0.0794%), indicates that 2,4-Pyridinedicarboxylic acid is not persistent in sediment.

Biodegradation in soil

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.

On the basis of available information, the test substance 4'-Cyanoacetophenone can be considered to be readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

Various predicted data for the target compound 2,4-Pyridinedicarboxylic acid(CAS No. 499-80-9) and supporting weight of evidence study for its structurally similar read across substance were reviewed for the bioaccumulation end point which are summarized as below:

 

In aprediction done using theBCFBAF Program(v3.01)of Estimation Programs Interface (EPI Suite, 2017) was used to predict the bioconcentration factor (BCF) of test chemical 2,4-Pyridinedicarboxylic acid (CAS No. 499 -80 -9). The bioconcentration factor (BCF) of 2,4-Pyridinedicarboxylic acid was estimated to be 3.162 L/kg whole body w.w (at 25 deg C).

 

In an another prediction done by using Bio-concentration Factor (v12.1.0.50374) moduleACD (Advanced Chemistry Development)/I-Lab predictive module, 2017), theBCFover the entire pH scale (pH 1 -14) of the test substance 2,4-Pyridinedicarboxylic acid (CAS no. 499 -80 -9) was estimated to be 1.

 

Bioconcentration Factor (BCF) of test chemical 2,4-Pyridinedicarboxylic acid was estimated using Chemspider database(ChemSpider, 2017). The bioconcentration factor of test substance 2,4-Pyridinedicarboxylic acid was estimated to be 1 at both pH 5.5 and 7.4, respectively.

 

Another predicted data was estimated usingSciFinder database (American Chemical Society (ACS), 2017) was used for predicting the bioconcentration factor (BCF) of test chemical2,4-Pyridinedicarboxylic acid (CAS No. 499 -80 -9).The bioconcentration factor (BCF) of 2,4-Pyridinedicarboxylic acid was estimated to be 1 (at 25 deg C).

 

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application)  V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical), the bioaccumulation i.e BCF for test substance 2,4-Pyridinedicarboxylic acid was estimated to be 5.52 dimensionless . The predicted BCF result based on the 5 OECD principles. Thus based on the result it is concluded that the test substance 2,4-Pyridinedicarboxylic acid is non-bioaccumulative in nature.

 

In a supporting weight of evidence study from authoritative database (J-CHECK, 2017 and EnviChem, 2014) for the read across chemical 2,5-Pyridinedicarboxylic acid (CAS no. 100-26-5),bioaccumulation experiment was conducted on test organism Cyprinus carpiofor 6 weeks for evaluating the bioconcentration factor (BCF value) of 2,5-Pyridinedicarboxylic acid. Cyprinus carpio was used as a test organism for the study. Test chemical nominal conc. used for the study were2mg/land 0.2mg/l, respectively. Range finding study involve the TLm (48 hr) ˃ 1000 mg/l (w/v) on Rice fish (Oryzias latipes). Lipid content of the test organism Cyprinus carpio was determined to be4.1%. The bioconcentration factor (BCF value) of substance 2,5-Pyridinedicarboxylic acid on Cyprinus carpio was determined to be in the range of 0.3-0.9 L/Kg at a conc. of 2 mg/l and 2.9-8.6 L/Kg at a conc. of 0.2 mg/l, respectively.

 

For the read across chemical 2,3-Pyridinedicarboxylic acid (CAS no. 89-00-9),bioaccumulation study in fish was conducted for estimating the BCF (bioaccumulation factor) value of read across chemical 2,3-Pyridinedicarboxylic acid (HSDB, 2017). The bioaccumulation factor (BCF) value was calculated using a water solubility of 11000 mg/l and a regression-derived equation. The estimated BCF (bioaccumulation factor) value of 2,3-Pyridinedicarboxylic acid in fish was determined to be 3 dimensionless.

 

On the basis of above results for target chemical2,4-Pyridinedicarboxylic acid(from EPI suite, ACD labs,ChemSpider and CompTox Chemistry Dashboard,  2017) and for its read across substance from authoritative database (HSDB, J-CHECK and EnviChem), it can be concluded that the BCF value of test substance2,4-Pyridinedicarboxylic acidranges from 1 – 5.52 which does not exceed the bioconcentration threshold of 2000, indicating that the chemical2,4-Pyridinedicarboxylic acidis not expected to bioaccumulate in the food chain.

Adsorption / desorption

Various predicted data for the target compound 2,4-Pyridinedicarboxylic acid (CAS No. 499-80-9) and supporting weight of evidence study for its structurally similar read across substance were reviewed for the adsorption end point which are summarized as below:

 

In aprediction done using theKOCWIN Program(v2.00) of Estimation Programs Interface (EPI Suite, 2017) was used to predict the soil adsorption coefficient i.e Koc value of test chemical 2,4-Pyridinedicarboxylic acid (CAS No. 499 -80 -9). The soil adsorption coefficient i.e Koc value of 2,4-Pyridinedicarboxylic acid was estimated to be 38.98 L/kg (log Koc=1.5909)  by means of MCI method (at 25 deg C). This Koc value indicates that the substance 2,4-Pyridinedicarboxylic acid has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

The Soil Adsorption Coefficient i.e Koc value of test substance 2,4-Pyridinedicarboxylic acid was estimated using Adsorption Coefficient module (v12.1.0.50374) program as Koc 9.89, 14.3, 11.2, 3.16 and 1 at pH range 0, 1, 2, 3 and 4-14 respectively (log Koc ranges from  0 to 1.2 ± 1.0)(ACD (Advanced Chemistry Development)/I-Lab predictive module, 2017). This Koc value indicates that the test substance 2,4-Pyridinedicarboxylic acid has a negligible sorption to soil and therefore have rapid migration potential to groundwater.

 

In an another prediction done by using ChemSpider Database (2017),the Soil Adsorption Coefficient i.e Koc value of test substance 2,4-Pyridinedicarboxylic acid (CAS no. 499 -80 -9) was estimated using ChemSpider Database. The adsorption coefficient (Koc) value of substance 2,4-Pyridinedicarboxylic acid was estimated to be 1 (Log Koc = 0) at pH 5.5 and 7.4, respectively. This Koc value indicates that the test substance 2,4-Pyridinedicarboxylic acid has a negligible sorption to soil and therefore have rapid migration potential to groundwater.

 

Additional soil adsorption coefficient i.e Koc value of test chemical2,4-Pyridinedicarboxylic acid (CAS No. 499 -80 -9)was estimated using the SciFinder database (American Chemical Society (ACS), 2017). The soil adsorption coefficient i.e Koc value of 2,4-Pyridinedicarboxylic acid was estimated to be 9.42, 7.39, 2.08 and 1 at pH range 1, 2, 3 and 4-10, respectively (log Koc value ranges from 0 to 0.974) (at 25 deg C). This Koc value indicates that the substance  2,4-Pyridinedicarboxylic acid has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

 

From CompTox Chemistry Dashboard using OPERA (OPEn (quantitative) structure-activity Relationship Application)  V1.02 model in which calculation based on PaDEL descriptors (calculate molecular descriptors and fingerprints of chemical), the adsorption coefficient i.e KOC for test substance 2,4-Pyridinedicarboxylic acid was estimated to be 117 L/kg (log Koc = 2.068).The predicted KOC result based on the 5 OECD principles. This Koc value indicates that the substance 2,4-Pyridinedicarboxylic acid has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

In a supporting weight of evidence study from authoritative database (HSDB, 2017) for the read across chemical 2,3-Pyridinedicarboxylic acid (CAS no. 89-00-9),adsorption study was conducted for estimating the adsorption coefficient (Koc) value of read across chemical 2,3-Pyridinedicarboxylic acid. The adsorption coefficient (Koc) value was calculated using a water solubility of 11000 mg/l and a regression derived equation. The adsorption coefficient (Koc) value of test substance 2,3-Pyridinedicarboxylic acid was estimated to be 26 (Log Koc = 1.414). This Koc value indicates that the substance 2,3-Pyridinedicarboxylic acid has a negligible sorption to soil and sediment and therefore have rapid migration potential to ground water.

 

For the read across chemical 1,3-benzenedicarboxylic acid (CAS no. 121-91-5),adsorption study was conducted for estimating the adsorption coefficient (Koc) value of read across chemical 1,3-benzenedicarboxylic acid (HSDB, 2017). The adsorption coefficient (Koc) value was calculated using astructure estimation method based on molecular connectivity indices. The adsorption coefficient (Koc) value of test substance 1,3-benzenedicarboxylic acid was estimated to be 79 (Log Koc = 1.897). This Koc value indicates that the substance 1,3-benzenedicarboxylic acid has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

On the basis of above overall results for target chemical2,4-Pyridinedicarboxylic acid(from EPI suite, ACD labs,ChemSpider and CompTox Chemistry Dashboard,2017) and for its read across substance from authoritative database (HSDB, 2017), it can be concluded that the Koc value of test substance2,4-Pyridinedicarboxylic acidranges from 1–117,indicating that the test chemical2,4-Pyridinedicarboxylic acidhas a negligible to low sorption to soil and sediment and therefore have rapid to moderate migration potential to ground water.