Reaction mass of carbon tetrachloride and chloroform and 1,2-dichloroethane

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Reference 1

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

experimental study

Adequacy of study:

weight of evidence

Reliability:

3 (not reliable)

Rationale for reliability incl. deficiencies:

other: Only secondary source (http://www.safe.nite.go.jp/english/kizon/KIZON_start_hazkizon.html and IUCLID 4 file) but according to the protocol used a test concentration being toxic to the microorganisms was applied and the result constitutes an artifact.

Qualifier:

according to guideline

Guideline:

OECD Guideline 301 C (Ready Biodegradability: Modified MITI Test (I))

Principles of method if other than guideline:

Test Equipment: Improved type for a volatile substance

GLP compliance:

not specified

Oxygen conditions:

aerobic

Inoculum or test system:

activated sludge (adaptation not specified)

Details on inoculum:

Concentration of inoculum 30 ppm (mg/l)

Duration of test (contact time):

2 wk

Initial conc.:

100 mg/L

Based on:

test mat.

Parameter followed for biodegradation estimation:

other: BOD

Parameter followed for biodegradation estimation:

TOC removal

Parameter followed for biodegradation estimation:

test mat. analysis

Remarks:

GC

Parameter:

other: BOD

Value:

0

Sampling time:

14 d

Parameter:

% degradation (TOC removal)

Value:

0

Sampling time:

14 d

Parameter:

% degradation (test mat. analysis)

Value:

0

Remarks on result:

other: GC "negative value of the biodegradation"

Interpretation of results:

under test conditions no biodegradation observed

Conclusions:

No biodegradation reported in this ready biodegradability test, but test conditions are not suitable for this substance.

Executive summary:

The test substance concentration in the MITI (I) / OECD 301C method: 100 mg/L as test substance is likely to be toxic to microorganisms, as reported in studies of carbon tetrachloride toxicity to aerobic bacteria. Therefore, no definitive conclusion can be deduced from absence of aerobic biodegradation in this study.

Reference 2

Endpoint:

biodegradation in water: screening tests

Type of information:

(Q)SAR

Adequacy of study:

weight of evidence

Study period:

Not applicable

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

results derived from a valid (Q)SAR model and falling into its applicability domain, with adequate and reliable documentation / justification

Remarks:

The value is not an experimental result, however the QSAR model is recommended by the ECHA guidance document on information requirements, is well documented with regard to validation parameters according to OECD principles. Moreover, the substance is fully characterised towards the applicability domain.

Justification for type of information:

1. SOFTWARE
EPISUITE v4.1

2. MODEL (incl. version number)
BIOWIN v4.10

3. SMILES OR OTHER IDENTIFIERS USED AS INPUT FOR THE MODEL
C(Cl)(Cl)(Cl)Cl

4. SCIENTIFIC VALIDITY OF THE (Q)SAR MODEL
See attached QMRF

5. APPLICABILITY DOMAIN
See attached QMRF

6. ADEQUACY OF THE RESULT
See attached QPRF

Qualifier:

according to guideline

Guideline:

other: Reach Guidance on QSAR - R.6

Deviations:

no

Principles of method if other than guideline:

QSAR, Biowin v4.10. More details are given in QMRF/QPRF attached to the dossier.

GLP compliance:

no

Specific details on test material used for the study:

No additional information

Details on inoculum:

not applicable

Details on study design:

not applicable

Preliminary study:

not applicable

Test performance:

not applicable

Key result

Parameter:

probability of ready biodegradability (QSAR/QSPR)

Remarks on result:

not readily biodegradable based on QSAR/QSPR prediction

Details on results:

Biowin 1 (linear model prediction) = Does not Biodegrade Fast
Biowin 2 (non-linear model prediction) = Does not Biodegrade Fast
Biowin 3 (ultimate biodegradation timeframe) = Months
Biowin 4 (Primary biodegradation timeframe) = Weeks
Biowin 5 (MITI linear model prediction) = Not Readily Degradable
Biowin 6 (MITI non-linear model prediction) = Not Readily Degradable
Biowin 7 (Anaerobic model prediction) = Does Not biodegrade Fast
Ready Biodegradability Prediction: NO

See details in "Any other information on results incl. tables".

Results with reference substance:

not applicable

Table 5.2.1/1: Biowin 1 result

TYPE	NUM	Biowin 1 FRAGMENT DESCRIPTION	COEFF	VALUE
Frag Frag MolWt Const	4 1 * *	Aliphatic chloride [-CL] Carbon with 4 single bonds & no hydrogens Molecular weight parameter Equation constant	-0.1114 -0.1839	-0.4456 -0.1839 -0.0732 0.7475
RESULT		Biowin 1 (linear biodeg probability)		0.0448

The fragments present in the molecule are within the applicability domain of the model.

For Biowin 1: a probability lower than 0.5 indicates -> Does not Biodegrade Fast

Table 5.2.1/2: Biowin 2 result

TYPE	NUM	Biowin 1 FRAGMENT DESCRIPTION	COEFF	VALUE
Frag Frag MolWt	4 1 *	Aliphatic chloride [-CL] Carbon with 4 single bonds & no hydrogens Molecular weight parameter	-1.0528 -1.7232	-7.4112 -1.7232 -2.1843
RESULT		Biowin 2 (Non-linear biodeg probability)		0.0002

The fragments present in the molecule are within the applicability domain of the model.

For Biowin 2: a probability lower than 0.5 indicates -> Does not biodegrade Fast

Table 5.2.1/3: Biowin 3 result

TYPE	NUM	Biowin 1 FRAGMENT DESCRIPTION	COEFF	VALUE
Frag Frag MolWt Const	4 1 * *	Aliphatic chloride [-CL] Carbon with 4 single bonds & no hydrogens Molecular weight parameter Equation constant	-0.1732 -0.2121	-0.6927 -0.2121 -0.3399 3.1992
RESULT		Biowin 3 (Survey Model -Ultimate Biodeg)		1.9544

The fragments present in the molecule are within the applicability domain of the model. 

For Biowin 3: 2.0 = months; 3.0 = weeks; 4.0 = days

Table 5.2.1/4: Biowin 4 result

TYPE	NUM	Biowin 1 FRAGMENT DESCRIPTION	COEFF	VALUE
Frag Frag MolWt Const	4 1 * *	Aliphatic chloride [-CL] Carbon with 4 single bonds & no hydrogens Molecular weight parameter Equation constant	-0.1006 -0.1534	-0.4024 -0.1534 -0.2219 3.8477
RESULT		Biowin 4 (Survey Model - Primary Biodeg)		3.0699

The fragments present in the molecule are within the applicability domain of the model. 

For Biowin 4: 2.0 = months; 3.0 = weeks; 4.0 = days

Table 5.2.1/5: Biowin 5 result

TYPE	NUM	Biowin 1 FRAGMENT DESCRIPTION	COEFF	VALUE
Frag Frag MolWt Const	4 1 * *	Aliphatic chloride [-CL] Carbon with 4 single bonds & no hydrogens Molecular weight parameter Equation constant	-0.0011 -0.0676	0.0044 0.0676 -0.4576 0.7121
RESULT		Biowin 5 (MITI Linear biodeg probability)		0.3265

The fragments presents in the molecule are within the applicability domain of the model. 

For Biowin 5: a probability less than 0.5 indicates -> Not Readily degradable.

Table 5.2.1/6: Biowin 6 result

TYPE	NUM	Biowin 1 FRAGMENT DESCRIPTION	COEFF	VALUE
Frag Frag MolWt	4 1 *	Aliphatic chloride [-CL] Carbon with 4 single bonds & no hydrogens Molecular weight parameter	-0.6391 0.3990	-2.5565 0.3990 -4.4407
RESULT		Biowin 6 (MITI non-linear biodeg probability)		0.0167

The fragments presents in the molecule are within the applicability domain of the model.

For Biowin 6: a probability less than 0.5 indicates -> Not Readily degradable.

Table 5.2.1/7: Biowin 7 result

TYPE	NUM	Biowin 1 FRAGMENT DESCRIPTION	COEFF	VALUE
Frag Frag Const	4 1 *	Aliphatic chloride [-CL] Carbon with 4 single bonds & no hydrogens Equation Constant	-0.0147 -0.3342	-0.0586 -0.3342 -0.8361
RESULT		Biowin 7 (Anaerobic linear biodeg probability)		0.4432

The fragments presents in the molecule are within the applicability domain of the model.

For Biowin 7: a probability less than 0.5 indicates -> Does Not Biodegrade Fast.

Ready biodegradability prediction (YES or NO):

Criteria for the YES or NO prediction: if the Biowin 3 result is "weeks" or faster (i.e. "days", "days to weeks", or "weeks") AND the Biowin 5 probability is >= 0.5, then the prediction is YES (readily biodegradable). If this condition is not satisfied, the prediction is NO (not readily biodegradable). This method is based on application of Bayesian analysis to ready biodegradation data. Biowin 5 and 6 also predict ready biodegradability, but for degradation in the OECD 301C test only; using data from the Chemicals Evaluation and Research Institute Japan (CERIJ) database.

Validity criteria fulfilled:

not applicable

Interpretation of results:

not readily biodegradable

Conclusions:

It is expected that the substance is not readily biodegradable.

Executive summary:

The substance ready biodegradation property was investigated using QSAR approach with Biowin v4.10 plug-in from EPISUITE v4.1 from US EPA.

The Biowin 3 result is " months" and the Biowin 5 probability is less than 0.5, therefore the prediction is not readily biodegradable. In conclusion, it's expected that the substance is not readily biodegradable.

Description of key information

Based on MITI study (Japan, 1992) and QSAR prediction, CTC is considered as not readily biodegradable and fulfils P criterion of PBT assessment.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

No experimental study was conducted on the multiconstituent substance (Flux1). Instead, a constituent-based, Weigh-of-Evidence approach, was performed.

The three major constituents were targeted, representing ca 95% of a typical composition (carbon tetrachloride (CAS n° 56-23-5),1,2-Dichloroethane (CAS n°107 -06 -2) and chloroform (CAS n° 67-66 -3)). Numerous published data were available, and a single consensus value was selected for each, from a reliable source.

No average key value was derived for the multiconstituent substance: as the Risk Assessment is conducted per constituent, individual values are the key data.

One OECD 301C study has been perfomed on carbon tetrachloride or CTC (CAS n° 56-23-5) by MITI (Japan, 1992). No biodegradation reported in this ready biodegradability test, but test conditions are not suitable for this substance. The study is scored as klimish 3 because the test substance at 100 mg/L is likely to be toxic to microorganisms, as reported in studies of carbon tetrachloride toxicity to aerobic bacteria.

Another biodegradation study is available on carbon tetrachloride (Tabak, 1981). The author states carbon tetratchloride to be primarily biodegradable (loss measured by GC specific analysis) in a static aerobic culture based on domestic sewage in an essay utilizing BOD water added with small amounts of yeast extract as culture medium. However, this study is scored as klimish 4 because details are missing such as controls, methods (TOC or DOC) and ethanol concentration.

A QSAR prediction was performed on CTC with the model used is Biowin v4.10, plug-in from EPISUITE v4.1 from US EPA (K2). This model is recommended by the ECHA guidance document on information requirements and is well documented with regard to validation parameters according to OECD principles. Moreover, the substance is fully characterised for the applicability domain. The Biowin 3 result is "months" and the Biowin 5 probability is less than 0.5, therefore the prediction is not readily biodegradable.

In conclusion, CTC is considered as not readily biodegradable (MITI Japan study, 1992; QSAR Biowin).