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Environmental fate & pathways

Endpoint summary

Administrative data

Description of key information

Hydrolysis:

At an initial concentration of 88 and 84.8 uM hydrolysis rate constants for chloral hydrate was determined to be 1.0X10-3/hr and 1.8X10-3/hr using MOPS buffer and carbonate buffers respectively in the presence of carbonate green rust; GR(CO32-).

Chloral hydrate were transformed via parallel pathways of hydrolysis and sequential hydrogenolysis in the presence of GR(CO32-).

Chloral hydarte was degraded to TCM (Tricholormethane) via hydrolysis (31%) and to DCAh (Dichloro acetaldehyde hydrate) via hydrogenolysis (69%).

Biodegradation in water: screening tests:

The test item 2, 2, 2 trichloroethane-1, 1-diol (CAS No. 302-17-0) undergoes 44.04%biodegradation after 28 days in the test condition. Thus, the test item can be considered as inherently biodegradable.

Biodegradation in water and sediment:

Estimated half life of test chemical in water was (37.5) days (900 h) and in sediment estimated to be (337.5) days (8100 h).

Biodegradation in soil:

Biodegradation half-life of test substance in soil was estimated to be (75) days (1800 hrs).

Bioaccumulation: aquatic/sediment

The estimated bioconcentration factor (BCF) for 2,2,2-trichloroethane-1,1-diol is 3.162 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000. Thus it is concluded that 2,2,2-trichloroethane-1,1-diol is not expected to bioaccumulate in the food chain.

Adsorption / desorption:

The Adsorption Coefficient of test substance 2,2,2-trichloroethane-1,1-diol (CAS No.302-17-0)was determined as per the HPLC method (OECD Guideline-121). The Log Koc value was found to be 1.645 ± 0.003 (Koc=45.81) at 25°C.

Additional information

Hydrolysis:

The study was performed to investigate the kinetics and pathways of the degradation of selected halogenated DBPs (Disinfection byproducts), i.e. cholral hydrate in the presence of carbonate green rust; GR(CO32-). DBP degradation experiments were carried out in 123 mL serum bottles containing a 2.4 g/L GR(CO32-) suspension buffered at pH 7.5 with Ar-sparged 25 mM MOPS buffer or 50 mM carbonate buffer at 22±3 °C. All batch experiments were conducted in duplicate. The overall loss and individual hydrolysis and reductive dehalogenation pseudo-first-order rate constants of the DBPs were determined by fitting the experimental data using Scientist for Windows (v. 2.01, Micromath Research).

At an initial concentration of 88 and 84.8 uM hydrolysis rate constants for chloral hydrate was determined to be 1.0X10-3/hr and 1.8X10-3/hr using MOPS buffer and carbonate buffers respectively in the presence of GR(CO32-). Chloral hydrate were transformed via parallel pathways of hydrolysis and sequential hydrogenolysis in the presence of GR(CO32-). Chloral hydarte was degraded to TCM (Tricholormethane) via hydrolysis (31%) and to DCAh (Dichloro acetaldehyde hydrate) via hydrogenolysis (69%). Thus, from above study it can be considered that the substance chloral hydrate is very slowly hydrolysable.

Biodegradation in water: screening tests:

Experimental key and predicted supporting data for the test substance chloral hydarte is reviewed for biodegradation in water which is summarised as follows:

In experimental key study, 28-days Manometric respirometry test following the OECD guideline 301F to determine the ready biodegradability of the test item2, 2, 2 -trichloroethane-1, 1 -diol(CAS No. 302 -17 -0) was conducted. The test system included control, test item and reference item. The concentration of test and reference item (Sodium Benzoate) chosen for the study was 100 mg/L, while that of inoculum was 10ml/l. 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 BOD28value of 2,2,2 -trichloroethane-1, 1 -diol(CAS No. 302 -17 -0) was observed to be 0.085 mgO2/mg. ThOD was calculatedas 0.193 mgO2/mg. Accordingly, the % degradation of the test item after 28 days of incubation at 20 ± 1°C according to manometric respirometry test was found to be 44.04%.Based on the results, the test item, under the test conditions, was found to be inherently biodegradable at 20 ± 1°C over a period of 28 days.

Supporting above data, Estimation Programs Interface Suite (EPI suite, 2018) was run to predict the biodegradation potential of the test compound  2,2,2-trichloroethane-1,1-diol (Chloral hydrate)(CAS no. 302 -17 -0) in the presence of mixed populations of environmental microorganisms. The biodegradability of the substance 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 2,2,2-trichloroethane-1,1-diol (Chloral hydrate) is expected to be not readily biodegradable.

Thus based on the above data it can be observed that substance is likely to be inherently biodegradable or not readily biodegradable. However considering the experimental key value the substance chloral hydrate is concluded to be inherently biodegradable in water.

Biodegradation in water and sediment:

Estimation Programs Interface (EPI Suite, 2018) prediction model was run to predict the half-life in water and sediment for the test compound2,2,2-trichloroethane-1,1-diol (Chloral hydrate)(CAS No.302 -17 -0). If released in to the environment, 45% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of chloral hydrate 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 waterand the exposure risk to aquatic animals is moderate to low whereas the half-life period of chloral hydrate 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 1% (i.e, reported as 0.0885%), indicates that chloral hydrate is not persistent in sediment.

Biodegradation in soil:

The half-life period of2,2,2-Trichloroethane-1,1-diol (Chloral hydrate)(CAS No.302 -17 -0) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2018). If released into the environment, 54.8% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of chloral hydrate in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of chloral hydrate, 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 estimated bioconcentration factor (BCF) for 2,2,2-trichloroethane-1,1-diol is 3.162 L/kg wet-wt which does not exceed the bioconcentration threshold of 2000. Thus it is concluded that 2,2,2-trichloroethane-1,1-diol is not expected to bioaccumulate in the food chain.

Adsorption / desorption:

The adsorption coefficient Koc in soil and in sewage sludge2,2,2-trichloroethane-1,1-diol (CAS No. 302-17-0)was determined by the Reverse Phase High Performance Liquid Chromatographic method according to OECD Guideline No. 121 for testing of Chemicals. The reference substances were chosen according to structural similarity with the test substance and calibration graph was prepared. The reference substances were 2- Nitrobenzamide, p – Toluamide, 4 – methyl aniline, Aniline, N – methyl aniline, 2,5 Dichloroaniline having Kocvalue ranging from 1.45 to 2.58. TheLog Kocvalue was found to be1.645 ± 0.003at 25°C.

This value indicates that the substance has low sorption to soil and sediment, moderate migration to ground water.