4,7-dichloroquinoline

Endpoint summary

Description of key information

Hydrolysis:

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be ranges from 75 days to >879 yr, at pH range 4 and 7, respectively. Thus, based on this half-life value, it can be concluded that the test chemical is expected to be stable in water.

Biodegradation in water:

Estimation Programs Interface Suite (EPI suite) was run to predict the biodegradation potential of the test compound  in the presence of mixed populations of environmental microorganisms. The biodegradability of the test chemical was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical was expected to be not readily biodegradable.

Biodegradation in water and sediment:

Estimation Programs Interface prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 15.9% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemical in water is estimated to be 37.5 days (900 hrs). The half-life (37.5 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 test chemical in sediment is estimated to be 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 5% (i.e, reported as 3.72%), indicates that test chemical is not persistent in sediment.

Biodegradation in soil:

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database. If released into the environment, 78.9% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of test chemical, 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.

Bioaccumulation: aquatic / sediment

From BCFBAF (v3.00) model of EPI suite Program, the estimated bio concentration factor (BCF) for test chemical was 105.3 L/kg on the basis of whole body w.w which does not exceed the bio concentration threshold of 2000. Thus it is concluded that test chemical was not expected to bioaccumulate in the food chain.

Adsorption/desorption:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test chemical solution was prepared by accurately weighing 4 mg of test chemical and diluted with 5 ml Acetonitrile and made up with water up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 4.1. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k.The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, phenanthrene having Koc value ranging from 2.369 to 4.09. The Log Koc value of test chemical was determined to be 2.270 ± 0.006 dimensionless at 25°C. This log Koc value indicates that the substance has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

Additional information

Hydrolysis:

Data available for the test chemical and structually and functionally similar read across chemicals has been reviewed to determine the half-life of hydrolysis as a function of pH. The studies are as mentioned below:

The half-life of the test chemical was determined at different. The study was performed at pH 7 & at a temperature of 25°C, respectively. The pseudo first order hydrolysis rate constant of test chemical was determined to be < 0.9 m/hr with a corresponding half-lives of >879 years at pH 7 and a temperature of 25°C, respectively. Based on the half-life values, it is concluded that the chemical was not hydrolysable.

Above study further supported by the third weight of evidence study from authoritative database. The half-life of the test chemical was determined at different pH range. The study was performed at pH of 4, 7 and 9. The half-life period of test chemical was determined to be 75 days at pH 4 and thus test chemical was reported to be hydrolytically stable at pH 7 and 9. On the basis of this, test chemical was considered to be not hydrolysable.

On the basis of the experimental studies of the test chemical and applying the weight of evidence approach, the hydrolysis half-life value of the test chemical can be expected to be ranges from 75 days to >879 yr, at pH range 4 and 7, respectively. Thus, based on this half-life value, it can be concluded that the test chemical is expected to be stable in water.

Biodegradation in water:

Predicted data and experimental studies for the test chemical and structurally and functionally similar read across chemical have been reviewed and their results are summarized as below for biodegradation in water endpoint.

Estimation Programs Interface Suite (EPI suite) was run to predict the biodegradation potential of the test compound  in the presence of mixed populations of environmental microorganisms. The biodegradability of the test chemical was calculated using seven different models such as Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI Linear Model, MITI Non-Linear Model and Anaerobic Model (called as Biowin 1-7, respectively) of the BIOWIN v4.10 software. The results indicate that chemical was expected to be not readily biodegradable.

Above study further supported by the second weight of evidence study from authoritative database. Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance.  Test conducted in accordance with the "Biodegradation test of a chemical substance using a microorganism etc." provided in "the Notice on the Test Method Concerning New Chemical Substances" for 28 hours. The percentage degradation of test substance was determined 0% degradation by O2 consumption, DOC removal, Test mat. analysis and HPLC parameter in 28 days. Thus, based on percentage degradation, test chemical was considered to be not readily biodegradable in water.

Similar biodegradation study was conducted for 4 weeks for evaluating the percentage biodegradability of test substance. 30ppm sludge concentration was used in th study. 100 ppm initial test substance concentration was used. The percentage degradation of test substance was determined to be 0%, 1 % and 9% degradation by BOD, TOC removal and HPLC parameter respectively in 4 weeks. Thus, based on percentage degradation, test chemical was considered to be not readily biodegradable in water.

Thus based on the above all studes from various sources, it was concluded that the test chemical was not readily biodegradable in water.

Biodegradation in water and sediment:

Estimation Programs Interface prediction model was run to predict the half-life in water and sediment for the test chemical. If released in to the environment, 15.9% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of test chemical in water is estimated to be 37.5 days (900 hrs). The half-life (37.5 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 test chemical in sediment is estimated to be 337.5 days (8100 hrs). However, as the percentage release of test chemical into the sediment is less than 5% (i.e, reported as 3.72%), indicates that test chemical is not persistent in sediment.

Biodegradation in soil:

The half-life period of test chemical in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database. If released into the environment, 78.9% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of test chemical in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of test chemical, 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.

Bioaccumulation: aquatic / sediment

Various predicted data for the test chemical were reviewed for the bioaccumulation end point which are summarized as below:

From BCFBAF (v3.00) model of EPI suite Program, the estimated bio concentration factor (BCF) for test chemical was 105.3 L/kg on the basis of whole body w.w which does not exceed the bio concentration threshold of 2000. Thus it is concluded that test chemical was not expected to bioaccumulate in the food chain.

Based on available data from authoritative database, the bio concentration factor (BCF) for test chemical was estimated as 224.44 at pH 5.5 and 224.51 at pH 7.4 which does not exceed the bio concentration threshold of 2000. Thus it is concluded that test chemical was not expected to bioaccumulate in the food chain.

Above data further supported by the third weight of evidence study 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 chemical was estimated to be 7.05 dimensionless the predicted BCF result based on the 5 OECD principles. Thus based on the result it is concluded that the test chemical was non-bioaccumulative in nature, because the bioconcentration factor in fish is less than 2000.

Thus based on the above information for bioaccumulation endpoint, it can be concluded that the BCF of the test substance was expected to be non Bioaccumulative in aquatic environment as per their BCF values does not exceeds the threshold of 2000.

Adsorption/desorption:

The adsorption coefficient Koc in soil and in sewage sludge of test chemical was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The solutions of the test substance and reference substances were prepared in appropriate solvents. A test chemical solution was prepared by accurately weighing 4 mg of test chemical and diluted with 5 ml Acetonitrile and made up with water up to 10 ml. Thus, the test solution concentration was 400 mg/l. The pH of test substance was 4.1. Each of the reference substance and test substance were analysed by HPLC at 210 nm. After equilibration of the HPLC system, Urea was injected first, the reference substances were injected in duplicate, followed by the test chemical solution in duplicate. Reference substances were injected again after test sample, no change in retention time of reference substances was observed. Retention time tR were measured, averaged and the decimal logarithms of the capacity factors k were calculated. The graph was plotted between log Koc versus log k.The linear regression parameter of the relationship log Koc vs log k were also calculated from the data obtained with calibration samples and therewith, log Koc of the test substance was determined from its measured capacity factor. The reference substances were chosen according to estimated Koc range of the test substance and generalized calibration graph was prepared. The reference substances were Xylene, Ethylbenzene, Toluene, Naphthalene, 1,2,3-trichlorobenzene, phenanthrene having Koc value ranging from 2.369 to 4.09. The Log Koc value of test chemical was determined to be 2.270 ± 0.006 dimensionless at 25°C. This log Koc value indicates that the substance has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.