Ethyl formate

Endpoint summary

Description of key information

Hydrolysis

The half-life and alkaline hydrolysis rate constant of the test chemical was determined at a temperature of 25°C (from handbook, authoritative databases and secondary source). The alkaline hydrolysis rate constant of test chemical was determined to be 25.7L/mol-sec with a corresponding half-lives of 3.1 days and 7.5 hr at pH 7 and 8, and temperature of 25°C, respectively.The hydrolysis products of test chemical were formic acid and ethanol, respectively. Based on the half-life values, it is concluded that the test chemical undergoes moderate to slow hydrolysis in water.

Biodegradation in water

28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item (Experimental study report, 2018). The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used for this study. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/l. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 76.5%. Degradation of Sodium Benzoate exceeds 45.18% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.17 mgO2/mg. ThOD was calculated as 1.51 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 77.48%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

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, 43.1% 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 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 test chemical 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 0.0856%), indicates that the 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, 29.4% 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 30 days (720 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

The bioaccumulation study in Salmon gairdneri (rainbow trout) was conducted for determining the BCF (bioaccumulation factor) value of test chemical (from peer reviewed journal, handbook and secondary source).Salmon gairdneri (rainbow trout) was used as a test organisms for the study. BCF value of test chemical was measured using a logKow value of 0.23. The study was performed at a temperature of 12°C for 2-6 hrs. Radiolabeled test chemical was used for the study.All radiolabeled chemicals (purity > 98%) used in these experiments were supplied by Pathfinder Laboratories. Specific activities were confirmed by liquid scintillation counting (LSC) then gas chromatographic (GC). Analyses were done on a Hewlett-Packard 5730A automatic CC with Model 3552A data system. Test chemical was chromatographed on a Tenax-CC 60/80 mesh 3-ft X 2-mm column after direct aqueous injection. Rainbow Trout used in the study weighed 660 to 840 g. Fishes were fed with Glencoe mills trout feed for upto 24 hr before experimentation. The fish were on a 12-hr photoperiod (incandescent) at an intensity of 11.0 Ix at the air-water interface. All of the trout were acclimated to a temperature of 1 I to 12°C for several months prior to experimental use. Plexiglass respirometer metabolism chamber was used as a test vessel for the study. Chemicals were individually introduced into the respirometer-metabolism chambers at water concentrations 10 to 100 times lower than reported 96-hr LC50 values and lower than solubility value. The duration of exposure to each chemical was 2 to 6 hr during which the inspired and expired water of each fish was monitored three to six times to determine the amount of each chemical removed by a fish after flowing once across its gills (extraction efficiency). At the end of each 3- to 6-hr period, chemical dosing was stopped and the chambers were flushed with control water for 1 hr followed by initiation of dosing with the next chemical to be tested. Two separate experiments were conducted utilizing two fish per experiment. Two fish out of the four were reexposed with selected chemical near the end of each 2 to 4 day experiment to see if changes in uptake efficiency has occurred for a given chemical over the duration of the experiment. Uptake efficiency values for the two reexposed chemicals were then measured. A t test was used to analyze all of the respiratory physiology data whereas regression analysis was applied to the uptake efficiency vs time data. The extraction efficiency of test chemical was determined to be very low (approximately 7%), indicating that this chemical is not bioconcentratedin aquatic organisms.

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 (Experimental study report, 2016). The solutions of the test substance and reference substances were prepared in appropriate solvents. A test item solution was prepared by accurately weighing 50mg of test item and diluted with mobile phase up to 100ml. Thus, the test solution concentration was 500mg/l. The pH of test substance was 4.61. 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(Annex - 2).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 structural similarity with the test substance and calibration graph was prepared. The reference substances were2 Nitrobenzamide, p Toluamide, aniline, n methyl aniline, nitrobenzene, 2 nitro phenol and 2,5 Dichloroanilinehaving Koc value ranging from 1.45 to 2.58.The Log Koc value of test chemical was determined to be 1.963 ± 0.000 at 25°C. This log Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

Additional information

Hydrolysis

Experimental study and various predicted data of the test chemical were reviewed for the hydrolysis end point which are summarized as below:

 

In an experimental key study from handbook, authoritative databases and secondary source,the half-life and alkaline hydrolysis rate constant of the test chemical was determined at a temperature of 25°C. The alkaline hydrolysis rate constant of test chemical was determined to be 25.7L/mol-sec with a corresponding half-lives of 3.1 days and 7.5 hr at pH 7 and 8, and temperature of 25°C, respectively. The hydrolysis products of test chemical were formic acid and ethanol, respectively. Based on the half-life values, it is concluded that the test chemical undergoes moderate to slow hydrolysis in water.

 

In an another study (E. Rorije et. al., 1997), hydrolysis half-life value of test chemical was estimated using the HYDROWIN model. The models have been applied are Quantitative Structure-Activity Relationships. This model yields the second order alkaline hydrolysis reaction rate constant of chemical at pH 7.0. To arrive at an environmental half-life, this reaction rate constant should be multiplied by the concentration of hydroxyl ions in water. The hydrolysis half-live value of test chemical was determined to be 6.34 days at pH 7, respectively. The hydrolysis products of test chemical were formic acid and ethanol, respectively. Based on the half-life value, it is concluded that the test chemical undergoes slow hydrolysis in water.

 

HYDROWIN v2.00 program of Estimation Programs Interface prediction model was used to predict the hydrolysis half-life of test chemical (2018). The estimated half-life of test chemical was determined to be 5.411 days at pH 7.0 and 12.987 hrs at pH 8.0 (at 25ᵒC) respectively with a hydrolysis rate constant of 14.83 L/mol-sec. Thus, based on the half-life value, it indicates that test chemical undergoes moderate to slow hydrolysis in water.

 

On the basis of the above results of test chemical(fromhandbook, authoritative databases and secondary source,2017), it can be concluded that the hydrolysis half-life value of test chemical ranges from 7.5 hr to 6.34 days, indicating that the test chemical undergoes moderate to slow hydrolysis in water.

Hydrolysis endpoint can also be considered for waiver as per in accordance with column 2 of Annex VIII of the REACH regulation, testing for this endpoint is scientifically not necessary and does not need to be conducted since the test chemical is readily biodegradable in water.

Biodegradation in water

Various experimental key and supporting studies for the test chemical and supporting study for its structurally and functionally similar read across substance were reviewed for the biodegradation end point which are summarized as below:

 

In an experimental key study from study report (2018), 28-days Closed Bottle test following the OECD guideline 301 D to determine the ready biodegradability of the test item (Experimental study report, 2018). The study was performed at a temperature of 20°C. The test system included control, test item and reference item. Polyseed were used for this study. The concentration of test and reference item (Sodium Benzoate) chosen for both the study was 4 mg/L, while that of inoculum was 32 ml/l. OECD mineral medium was used for the study. ThOD (Theoretical oxygen demand) of test and reference item was determined by calculation. % degradation was calculated using the values of BOD and ThOD for test item and reference item. The % degradation of procedure control (reference item) was also calculated using BOD & ThOD and was determined to be 76.5%. Degradation of Sodium Benzoate exceeds 45.18% on 7 days & 70.48% on 14th day. The activity of the inoculum was thus verified and the test can be considered as valid. The BOD28 value of test chemical was observed to be 1.17 mgO2/mg. ThOD was calculated as 1.51 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to Closed Bottle test was determined to be 77.48%. Based on the results, the test item, under the test conditions, was considered to be readily biodegradable in nature.

In a supporting study, biodegradation experiment was conducted according to respiromteric test for evaluating the percentage biodegradability of test chemical (Study report, 1987). Activated sludge (adapted) obtained from biological sewage treatment plants was used as a test inoculum. The concentration of test item used for the study was 395 mg/L based on org. C. % degradation was calculated using the values of BOD and COD for test item. The BOD5 value of test chemical was observed to be 760 mgO2/mg. COD was calculated as 1090 mgO2/mg. Accordingly, The % degradation of the test item after 8 days of incubation according to respiromteric test was determined to be 69 and 86% degradation by BOD and TOC removal parameter. Based on the results, the test chemical, under the test conditions, was considered to be readily biodegradable in nature.

In an another supporting study (from peer reviewed journal, handbook, authoritative databases and secondary source), biodegradation experiment was conducted for 10 days for evaluating the percentage biodegradability of test chemical. The study was performed under aerobic conditions at a temperature of 20°C, respectively. The inoculum used for the study was sewage seed which has been acclimated for one year to the tested substance. Initial test substance conc. used in the study was 200-1000 mg/L, respectively. The biodegradation is measured after one day in an oxidation unit with non-flocculants growth activated sludge. The percentage degradation of test chemical was determined to be 30% by BOD parameter after 10 days. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

 

Another biodegradability of test chemical was estimated using the BIODEG linear and non-linear model (E. Rorije et. al., 1997). The models have been applied are Quantitative Structure-Activity Relationships. Two models are fitted to the judgement of an evaluation of various different biodegradation rates of chemical. This include the one using linear regression and other using a form of non-linear fitting. These models used 36 fragments as descriptors with the molecular weight of the molecule as an added descriptor, and are fitted on the evaluated biodegradation data of a series of 295 compounds. The output of the models, x, is the number that should be interpreted as x < 0.5 (=0) (Chemical biodegrades slowly or not at all) or x > 0.5 (=1) (Chemical biodegrades fast), respectively. These tests typically produce ‘biodegradable’ (1) or ‘non-biodegradable’ (0) as a result. The application of the models has been automated, the BIODEG models are incorporated in the PC-based program. As the biodegradability prediction of test chemical by the BIODEG models comes out to be 1, test chemical is estimated to be readily biodegradable in nature.

 

For the test chemical, biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of test substance. The study was performed according to OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I) under aerobic conditions. Activated sludge was used as a test inoculums for the study. 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 test substance was determined to be 94, 100 and 97% by BOD, GC and TOC removal parameter in 28 days. Thus, based on percentage degradation, test chemical is considered to be readily biodegradable in nature.

 

On the basis of above results for test chemical, it can be concluded that the test chemical can be considered to be readily biodegradable in nature.

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, 43.1% 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 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 test chemical 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 0.0856%), indicates that the 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, 29.4% 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 30 days (720 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.

On the basis of available information, the test chemical can be considered to be readily biodegradable in nature.

Bioaccumulation: aquatic / sediment

Various experimental studies for the test chemical and supporting study for its structurally and functionally similar read across substance were reviewed for the bioaccumulation end point which are summarized as below:

 

In an experimental key study from peer reviewed journal (J. MCKIM, et. al., 1985), handbook and secondary source, bioaccumulation experiment in Salmon gairdneri (rainbow trout) was conducted for determining the BCF (bioaccumulation factor) value of test chemical. Salmon gairdneri (rainbow trout) was used as a test organisms for the study. BCF value of test chemical was measured using a logKow value of 0.23. The study was performed at a temperature of 12°C for 2-6 hrs. Radiolabeled test chemical was used for the study.All radiolabeled chemicals (purity > 98%) used in these experiments were supplied by Pathfinder Laboratories. Specific activities were confirmed by liquid scintillation counting (LSC) then gas chromatographic (GC). Analyses were done on a Hewlett-Packard 5730A automatic CC with Model 3552A data system. Test chemical was chromatographed on a Tenax-CC 60/80 mesh 3-ft X 2-mm column after direct aqueous injection. Rainbow Trout used in the study weighed 660 to 840 g. Fishes were fed with Glencoe mills trout feed for upto 24 hr before experimentation. The fish were on a 12-hr photoperiod (incandescent) at an intensity of 11.0 Ix at the air-water interface. All of the trout were acclimated to a temperature of 1 I to 12°C for several months prior to experimental use. Plexiglass respirometer metabolism chamber was used as a test vessel for the study. Chemicals were individually introduced into the respirometer-metabolism chambers at water concentrations 10 to 100 times lower than reported 96-hr LC50 values and lower than solubility value. The duration of exposure to each chemical was 2 to 6 hr during which the inspired and expired water of each fish was monitored three to six times to determine the amount of each chemical removed by a fish after flowing once across its gills (extraction efficiency). At the end of each 3- to 6-hr period, chemical dosing was stopped and the chambers were flushed with control water for 1 hr followed by initiation of dosing with the next chemical to be tested. Two separate experiments were conducted utilizing two fish per experiment. Two fish out of the four were reexposed with selected chemical near the end of each 2 to 4 day experiment to see if changes in uptake efficiency has occurred for a given chemical over the duration of the experiment. Uptake efficiency values for the two reexposed chemicals were then measured. A t test was used to analyze all of the respiratory physiology data whereas regression analysis was applied to the uptake efficiency vs time data. The extraction efficiency of test chemical was determined to be very low (approximately 7%), indicating that this chemical is not bioconcentratedin aquatic organisms.

 

In a supporting study, bioaccumulation experiment in rainbow trout was conducted for 1 hr for determining the BCF (bioaccumulation factor) value of test chemical (Wolfgang Larisch, et. al., 2017). Rainbow trout of an average weight of 750 g was used as a test organisms for the study. BCF value of test chemical was measured using a logKow value of 0.2. Rainbow trout has a ventilation rate of 117 ml/min. The ventilated water volume that actually is in contact with the gills, the respiratory volume, is approximately 70% of the ventilation rate. The uptake efficiency is defined as the substance mass that is taken up, Nupt (mol/min) over the substance mass that is delivered into the gills by ventilation Nresp (mol/min). This leads to a natural upper limit of 70% if the respiratory volume is 70% of the ventilation rate. The extraction efficiency of test chemical was determined to be very low (approximately 5%), indicating that this chemical is not bioconcentrated in aquatic organisms.

 

Another bioaccumulation study was conducted for estimating the BCF (bioaccumulation factor) value of test chemical (authoritative databases, 2017). The bioaccumulation factor (BCF) value was calculated using a logKow of 0.23 and a regression-derived equation. The estimated BCF (bioaccumulation factor) value of test chemical was determined to be 0.88 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that the test chemical is considered to be non-accumulative in aquatic organisms.

 

For the test chemical fromauthoritative databases (2017),the bioaccumulation study in fish was conducted for estimating the BCF (bioaccumulation factor) value of test chemical. The bioaccumulation factor (BCF) value was calculated using a logKow of 0.88 and a regression-derived equation. The estimated BCF (bioaccumulation factor) value of test substance was determined to be 3 dimensionless, which does not exceed the bioconcentration threshold of 2000, indicating that the test chemical is considered to be non-accumulative in aquatic organisms.

 

On the basis of above overall results for test chemical, it can be concluded that the BCF value of test chemical was determined to be 0.88which does not exceed the bioconcentration threshold of 2000, indicating that the test chemicalis not expected to bioaccumulate in the food chain.

Adsorption / desorption

Various experimental studies of the test chemical were reviewed for the adsorption end point which are summarized as below:

 

In an experimental key study from study report (2016), 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 item solution was prepared by accurately weighing 50mg of test item and diluted with mobile phase up to 100ml. Thus, the test solution concentration was 500mg/l. The pH of test substance was 4.61. 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(Annex - 2).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 structural similarity with the test substance and calibration graph was prepared. The reference substances were2 Nitrobenzamide, p Toluamide, aniline, n methyl aniline, nitrobenzene, 2 nitro phenol and 2,5 Dichloroanilinehaving Koc value ranging from 1.45 to 2.58.The Log Koc value of test chemical was determined to be 1.963 ± 0.000 at 25°C. This log Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

Another adsorption study in soil was conducted for estimating the adsorption coefficient (Koc) value of test chemical (from handbook, 1999). The adsorption coefficient (Koc) value of test chemical was calculated to be 32 (Log Koc = 1.5051). This Koc value indicates that the test chemical has a low sorption to soil and sediment and therefore have moderate migration potential to ground water.

 

In a supporting study from authoritative database (2018), adsorption experiment was conducted for estimating the adsorption coefficient (Koc) value of test chemical. The adsorption coefficient (Koc) value was calculated using a water solubility of 88.25 g/l & a regression derived equation and from molecular structure. The adsorption coefficient (Koc) value of test chemical was estimated to be 8 (Log Koc = 0. 903) and 4 (Log Koc = 0. 602), respectively. This Koc value indicates that the test chemical has a negligible sorption tosoil and sediment and therefore have rapid migration potential to ground water.

 

On the basis of above overall results for test chemical (from study report, handbook and authoritative databases), it can be concluded that the logKoc value of test chemicalranges from0.602–1.963indicating that the test chemicalhas a negligible to lowsorption to soil and sediment and therefore have rapid to moderate migration potential to ground water.