2-methyl-m-phenylene diisocyanate

PBT assessment

PBT assessment: overall result

PBT status:

the substance is not PBT / vPvB

Justification:

Classification of for 2-methyl-m-phenylene diisocyanate effects in the environment:

 

2-methyl-m-phenylene diisocyanate(CAS no. 91-08-7) has a wide variety of uses such as: intermediate for chemical synthesis and as a laboratory agent. The aim was to assess whether the PBT criterion within Annex XIII was fulfilled for2-methyl-m-phenylene diisocyanate. The PBT criterion was herein assessed based on experimental data in conjunction with standardized environmental fate models. Here follows a description of the PBT assessment.

 

 

Persistence assessment

The tested substance fulfils the P criterion within Annex XIII based on the assessment that here follows:

 

Biotic degradation

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. (Biowin 2= 0.7526, BIOWIN 3= 2.7394, BIOWIN 6= 0.1377).

 

The experimental data for various read-across substances also indicate that they are not readily biodegradable.

 

Environmental fate

According to the fugacity model levels III, the most likely environmental fate for this test chemical is soil (i.e.estimated to 76.5%). The Koc-value was estimated to 7580 at 25ºC (KOCWIN program) indicating negligible mobility and strong adsorption potential.

The tested chemical is therefore not expected to leach from soil. The half-life in soil (75 days estimated by EPI suite) indicates that the substance is not persistent in soil and hence the exposure risk to soil-dwelling organism should therefore be moderate to low.

 

If released in to the environment, 15.6 and 6.85 % of the chemical will partition into water and sediment respectively, according to the Mackay fugacity model level III in EPI suite version 4.1 (2016). However, the half-life (37.5 days in water and 337.5 days in sediment estimated by EPI suite) indicates that the substance is not persistent in water but persistent in sediment and the exposure risk to sediment dwelling animals is moderate.

 

On the basis of the above mentioned half-life values, the chemical is classified as a persistent chemical (P) but not very persistent (not vP) since only estimated half-life values for the same are available.

                                                                                                      

Bioaccumulation assessment

The tested substance does not fulfil the B criterion within Annex XIII based on the assessment that here follows:

 

The octanol-water partition coefficient (Log Kow) is estimated as 3.74 (calculated by EPI suite version 4.1, 2016 and Danish EPA QSAR, 2016 respectively). If this chemical is released into the aquatic environment, there should be a low risk for the chemical to bioaccumulate in fish and food chains.

 

In addition, 2,6-Toluene diisocyanate decomposes in water and therefore, bioconcentration in aquatic organisms is not expected to be an important environmental fate process (HSDB, 2016).

 

Toxicity assessment

The tested substance fulfils the T criterion within Annex XIII based on the assessment that here follows:

 

Mammals

The tested chemical is regarded to be classified for Carcinogenicity in Category 2 as per the Harmonised classification - Annex VI of Regulation (EC) No 1272/2008 (CLP Regulation).

The tested chemical is regarded to be not classified for mutagenicity, and reprotoxicity, Further, there is no evidence of chronic toxicity, as identified by the classifications STOT (repeated exposure), category 1 (oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume) or category 2 (oral, dermal, inhalation of gases/vapours, inhalation of dust/mist/fume).

 

 

Aquatic organisms

All of the available short-term eco-toxicity estimation for fish, invertebrates and algae for the substance indicates the LC50/EC50 value to be in the range 33.38 – 37.10 mg/L. These value suggest classification in Aquatic chronic category 3 as per the CLP regulation.

There are no available long-term toxicity evaluations for2-methyl-m-phenylene diisocyanate. NOEC values for the read-across substances Isophorone diisocyanate and 1,6-Hexamethylene diisocyanate in a 72 hour study on algae is reported as 4.4 mg/L and 77.4 mg/L respectively.

By speculation, adverse effects at environmentally relevant concentrations in freshwater species were not expected for 2-methyl-m-phenylene diisocyanate based on the determined acute EC50/LC50 above 10 mg/L (from all 3 trophic levels).

The chemical was therefore not considered as hazardous to aquatic environments as per the criteria set out in Annex XIII.

 

Conclusion

Based on critical, independent and collective evaluation of information summarized herein, the tested compound fulfils the P and T criterion within Annex XIII. The tested chemical does not fulfil the B criterion and has therefore not been classified as a PBT compound within Annex XIII.