2-methyl-m-phenylene diisocyanate

Biodegradation in water: screening tests

Link to relevant study record(s)

Reference

Endpoint:

biodegradation in water: ready biodegradability

Type of information:

calculation (if not (Q)SAR)

Remarks:

Migrated phrase: estimated by calculation

Adequacy of study:

weight of evidence

Reliability:

2 (reliable with restrictions)

Rationale for reliability incl. deficiencies:

other: Data is from computational model developed by USEPA

Qualifier:

according to guideline

Guideline:

other: Modeling database

Principles of method if other than guideline:

The Biodegradation Probability Program (BIOWIN) estimates the probability for the rapid aerobic biodegradation of an organic chemical in the presence of mixed populations of environmental microorganisms .The model is part of the EpiSuite program of the US-EPA. Estimations are made with BIOWIN version 4.10Estimates are based upon fragment constants that were developed using multiple linear and non-linear regression analyses. Experimental biodegradation data for the multiple linear and non-linear regressions were obtained from Syracuse Research Corporation's (SRC) data base of evaluated biodegradation data (Howard et. al., 1987). This version (v4.10) designates the models as follows (see also Boethling et al. 2003):
Biowin1 = linear probability model
Biowin2 = nonlinear probability model
Biowin3 = expert survey ultimate biodegradation model
Biowin4 = expert survey primary biodegradation model
Biowin5 = MITI linear model
Biowin6 = MITI nonlinear model
Biowin7 = anaerobic biodegradation model

GLP compliance:

not specified

Oxygen conditions:

other: aerobic (Biowin 1-6) and anaerobic (Biowin 7)

Inoculum or test system:

other: mixed populations of environmental microorganisms

Duration of test (contact time):

2.739 mo

Details on study design:

Using the computer tool BIOWIN v4.10 by US-EPA (EPIWIN) the aerobic as well as the anaerobic biodegradability of the test material can be estimated. The follwoing seven different models are used by the tool: Linear Model, Non-Linear Model, Ultimate Biodegradation Timeframe, Primary Biodegradation Timeframe, MITI LInear Model, MITI Non-Linear Model and Anaerobic Model (calles Biowin 1-7, respectively). Due to this results the overall prediction of readily biodegradability is done for the desired chemical.

Parameter:

other: Half-life

Value:

50

Sampling time:

2.739 mo

Remarks on result:

other: Other details not known

Details on results:

Biowin1 (Linear Model Prediction) : 0.7193: Biodegrades Fast
Biowin2 (Non-Linear Model Prediction): 0.7526: Biodegrades Fast
Biowin3 (Ultimate Biodegradation Timeframe):2.7394: Weeks-Months
Biowin4 (Primary Biodegradation Timeframe): 3.5279: Days-Weeks
Biowin5 (MITI Linear Model Prediction) : 0.2601: Does Not Biodegrade Fast
Biowin6 (MITI Non-Linear Model Prediction): 0.1377: Does Not Biodegrade Fast
Biowin7 (Anaerobic Model Prediction): 0.1780: Does Not Biodegrade Fast
Ready Biodegradability Prediction: NO

BIOWIN (v4.10) Program Results:

==============================

SMILES : O=C=Nc(c(c(N=C(=O))cc1)C)c1

CHEM : Benzene, 1,3-diisocyanato-2-methyl-

MOL FOR: C9 H6 N2 O2

MOL WT : 174.16

--------------------------- BIOWIN v4.10 Results ----------------------------

Biowin1 (Linear Model Prediction) : Biodegrades Fast

Biowin2 (Non-Linear Model Prediction): Biodegrades Fast

Biowin3 (Ultimate Biodegradation Timeframe): Weeks-Months

Biowin4 (Primary Biodegradation Timeframe): Days-Weeks

Biowin5 (MITI Linear Model Prediction) : Does Not Biodegrade Fast

Biowin6 (MITI Non-Linear Model Prediction): Does Not Biodegrade Fast

Biowin7 (Anaerobic Model Prediction): Does Not Biodegrade Fast

Ready Biodegradability Prediction: NO

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin1 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Alkyl substituent on aromatic ring | 0.0547 | 0.0547

MolWt| * | Molecular Weight Parameter | | -0.0829

Const| * | Equation Constant | | 0.7475

============+============================================+=========+=========

RESULT | Biowin1 (Linear Biodeg Probability) | | 0.7193

============+============================================+=========+=========

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin2 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Alkyl substituent on aromatic ring | 0.5771 | 0.5771

MolWt| * | Molecular Weight Parameter | | -2.4731

============+============================================+=========+=========

RESULT | Biowin2 (Non-Linear Biodeg Probability) | | 0.7526

============+============================================+=========+=========

A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast

A Probability Less Than 0.5 indicates --> Does NOT Biodegrade Fast

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin3 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Alkyl substituent on aromatic ring | -0.0749 | -0.0749

MolWt| * | Molecular Weight Parameter | | -0.3849

Const| * | Equation Constant | | 3.1992

============+============================================+=========+=========

RESULT | Biowin3 (Survey Model - Ultimate Biodeg) | | 2.7394

============+============================================+=========+=========

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin4 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Alkyl substituent on aromatic ring | -0.0685 | -0.0685

MolWt| * | Molecular Weight Parameter | | -0.2513

Const| * | Equation Constant | | 3.8477

============+============================================+=========+=========

RESULT | Biowin4 (Survey Model - Primary Biodeg) | | 3.5279

============+============================================+=========+=========

Result Classification: 5.00 -> hours 4.00 -> days 3.00 -> weeks

(Primary & Ultimate) 2.00 -> months 1.00 -> longer

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin5 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Aromatic-CH3 | 0.0415 | 0.0415

Frag | 3 | Aromatic-H | 0.0082 | 0.0247

MolWt| * | Molecular Weight Parameter | | -0.5181

Const| * | Equation Constant | | 0.7121

============+============================================+=========+=========

RESULT | Biowin5 (MITI Linear Biodeg Probability) | | 0.2601

============+============================================+=========+=========

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin6 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Aromatic-CH3 | 0.3072 | 0.3072

Frag | 3 | Aromatic-H | 0.1201 | 0.3604

MolWt| * | Molecular Weight Parameter | | -5.0278

============+============================================+=========+=========

RESULT |Biowin6 (MITI Non-Linear Biodeg Probability)| | 0.1377

============+============================================+=========+=========

A Probability Greater Than or Equal to 0.5 indicates --> Readily Degradable

A Probability Less Than 0.5 indicates --> NOT Readily Degradable

------+-----+--------------------------------------------+---------+---------

TYPE | NUM | Biowin7 FRAGMENT DESCRIPTION | COEFF | VALUE

------+-----+--------------------------------------------+---------+---------

Frag | 1 | Alkyl substituent on aromatic ring | -0.1145 | -0.1145

Frag | 1 | Aromatic-CH3 | -0.2573 | -0.2573

Frag | 3 | Aromatic-H | -0.0954 | -0.2863

Const| * | Equation Constant | | 0.8361

============+============================================+=========+=========

RESULT | Biowin7 (Anaerobic Linear Biodeg Prob) | | 0.1780

============+============================================+=========+=========

A Probability Greater Than or Equal to 0.5 indicates --> Biodegrades Fast

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 Biowin3 (ultimate survey

model) result is "weeks" or faster (i.e. "days", "days to weeks", or

"weeks" AND the Biowin5 (MITI linear model) 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

(see Help). Biowin5 and 6 also predict ready biodegradability, but for

degradation in the OECD301C test only; using data from the Chemicals

Evaluation and Research Institute Japan (CERIJ) database.

Validity criteria fulfilled:

not specified

Interpretation of results:

other: not readily biodegradable

Conclusions:

The biodegradability of the substance was calculated using seven different Biowin 1-7 models of the BIOWIN v4.10 software. The results indicate that 2,6-Toluene diisocyanate is not expected to be readily biodegradable.

Executive summary:

Estimation Programs Interface Suite (EPI suite, 2016) was run to predict the biodegradation potential of the test compound 2,6-Toluene diisocyanate (CAS no. 91 -08 -7) 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 2,6-Toluene diisocyanate is not expected to be readily biodegradable.

Description of key information

Estimation Programs Interface Suite (EPI suite, 2016) was run to predict the biodegradation potential of the test compound 2,6-Toluene diisocyanate (CAS no. 91 -08 -7) 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 2,6-Toluene diisocyanate is not expected to be readily biodegradable.

Key value for chemical safety assessment

Biodegradation in water:

under test conditions no biodegradation observed

Additional information

Predicted data for the test compound 2,6-Toluene diisocyanate (CAS No. 91-08-7) and the study for its read across substance were reviewed for the biodegradation end point which are summarized as below:

 

Estimation Programs Interface Suite (EPI suite, 2016) was run to predict the biodegradation potential of the test compound 2,6-Toluene diisocyanate (CAS no. 91 -08 -7) 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 2,6-Toluene diisocyanate is not expected to be readily biodegradable.

 

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance Toluene 2,4-diisocyanate (CAS no. 584-84-9) (HSDB, U. S. National Library of Medicine, 2016). Conc. of inoculum used for the study was 30 mg/l and initial substance conc. used in the study was 100 mg/l. No degradation of read across substance was observed in 28 days by BOD parameter. Thus, the substance Toluene 2,4 -diisocyanate is considered to be not readily biodegradable in water.

 

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance Bitolylene diisocyanate (CAS no. 91-97-4) (J-CHECK, 2016). The percentage degradation of read across substance was determined to be 4% by O2 consumption and 0% by both Test mat. analysis and GC in 28 days. Most of the substance Bitolylene diisocyanate remained in (Activated sludge + substance) system, while little part changed and polymerized the substance, then small amount of insoluble polymerized transformation products were formed. Thus, based on percentage degradation, Bitolylene diisocyanate was considered to be not readily biodegradable in water.

 

Biodegradation study was conducted for 28 days for evaluating the percentage biodegradability of read across substance1,5-Naphthylene di-isocyanate (CAS no. 3173-72-6) (J-CHECK, 2016). The percentage degradation of read across substance was determined to be 0% by O2 consumption in 28 days. Some of the substance degraded and formed 1,5-Diaminonaphthalene (not readily biodegradable, not high bioaccumulation) and high poly merized transformation products were formed by polymerizing 1,5-Diaminonaphthalene (transformation product) and remaining(average 37%) substance. It was considered that the reason of loss of material balance is caused by generation of high polymerized transformation products. It was considered that the reason of BOD value in (Activated sludge + read across substance) system being lower than sludge blank was caused by inhibition of substance being isocyanate against activated sludge. Thus, based on percentage degradation,1,5-Naphthylene di-isocyanate was considered to be not readily biodegradable in water.

 

On the basis of above results for target and read across substance, it can be concluded that the test substance2,6-Toluene diisocyanatecan be expected to be not readily biodegradable in nature.