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EC number: 202-039-0 | CAS number: 91-08-7
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Administrative data
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Additional information
Biodegradation in water: screening tests
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 substance 2,6-Toluene diisocyanate can be expected to be not readily biodegradable in nature.
Biodegradation in water and sediment
Estimation Programs Interface (EPI) Suite (2016) prediction model was run to predict the half-life in water and sediment for the test compound 2,6-Toluene diisocyanate (CAS No. 91 -08 -7). If released in to the environment, 15.6% of the chemical will partition into water according to the Mackay fugacity model level III and the half-life period of 2,6-Toluene diisocyanate 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 2,6-Toluene diisocyanate in sediment is estimated to be 337.5 days (8100 hrs). Based on this half-life value (337.5 days), it indicates that the chemical 2,6-Toluene diisocyanate is highly persistent in sediment.
Biodegradation in soil
The half-life period of 2,6-Toluene diisocyanate (CAS No. 91 -08 -7) in soil was estimated using Level III Fugacity Model by EPI Suite version 4.1 estimation database (EPI suite, 2016). If released into the environment, 76.5% of the chemical will partition into soil according to the Mackay fugacity model level III. The half-life period of 2,6-Toluene diisocyanate in soil is estimated to be 75 days (1800 hrs). Based on this half-life value of 2,6-Toluene diisocyanate, 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 substance 2,6-Toluene diisocyanate can be considered to be not readily biodegradable in nature.
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