Registration Dossier
Registration Dossier
Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.
The new ECHA CHEM database has been released by ECHA, and it now contains all REACH registration data. There are more details on the transition of ECHA's published data to ECHA CHEM here.
Use of this information is subject to copyright laws and may require the permission of the owner of the information, as described in the ECHA Legal Notice.
EC number: 225-863-2 | CAS number: 5124-30-1
Adsorption / desorption
Administrative data
Link to relevant study record(s)
- Endpoint:
- adsorption / desorption: screening
- Type of information:
- calculation (if not (Q)SAR)
- Adequacy of study:
- key study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- accepted calculation method
- Principles of method if other than guideline:
- Calculated usind PCKOC Program v1.66 of EPI-Suite software as well as according to Sabljic (1995) and Gerstl (1990).
The calculation of PCKOC program is based upon the molecule structure using the molecular connectivity method.
The calculation according to Sabljic (1995, QASR Modelling of Soil Sorption. Improvements and Systematics of logKoc vs. logKow Correlations. Chemosphere, Vol. 31, pp. 4498-4514) is based on a statistical relationships between Koc and the octanol/water partition coefficient.
The calculation according to Gerstl (1990, Estimation of Organic Chemical Sorption by Soils, Journal of Contaminant Hydrology, 6, pp. 357-375) is based on a statistical relationships between Koc and the octanol/water partition coefficient. - GLP compliance:
- no
- Type of method:
- other: estimation
- Media:
- soil
- Radiolabelling:
- no
- Type:
- Koc
- Value:
- 43 471 - 375 837
- Executive summary:
4,4-methylenedicyclohexyl diisocyanate is characterized by a Koc 375837 of being calculated with PCKOCWIN v. 1.66 (Currenta, 2009).
According to the method of Sabljic (1995) the Koc of 4,4-methylenedicyclohexyl diisocyanate accounts for 43471 (Currenta, 2009).
According to the method of Gerstl (1999) the Koc of 4,4-methylenedicyclohexyl diisocyanate accounts for 64817 (Currenta, 2009).
- Endpoint:
- adsorption / desorption: screening
- Type of information:
- calculation (if not (Q)SAR)
- Adequacy of study:
- supporting study
- Reliability:
- 2 (reliable with restrictions)
- Rationale for reliability incl. deficiencies:
- accepted calculation method
- Principles of method if other than guideline:
- Calculated usind PCKOC Program v1.66 of EPI-Suite software as well as according to Sabljic (1995) and Gerstl (1990).
The calculation of PCKOC program is based upon the molecule structure using the molecular connectivity method.
The calculation according to Sabljic (1995, QASR Modelling of Soil Sorption. Improvements and Systematics of logKoc vs. logKow Correlations. Chemosphere, Vol. 31, pp. 4498-4514) is based on a statistical relationships between Koc and the octanol/water partition coefficient.
The calculation according to Gerstl (1990, Estimation of Organic Chemical Sorption by Soils, Journal of Contaminant Hydrology, 6, pp. 357-375) is based on a statistical relationships between Koc and the octanol/water partition coefficient. - GLP compliance:
- no
- Type of method:
- other: estimation
- Media:
- soil
- Radiolabelling:
- no
- Type:
- Koc
- Value:
- >= 110 - <= 672
- Executive summary:
The hydrolysis product of Desmodur W is characterized by a Koc of 672 being calculated with PCKOCWIN v. 1.66 (Currenta, 2009).
According to the method of Sabljic (1995) the Koc of the hydrolysis product accounts for 128 (Currenta, 2009).
According to the method of Gerstl (1999) the Koc of the hydrolysis product accounts for 110 (Currenta, 2009).
Referenceopen allclose all
|
||||||||||||||||||||||
|
|||||||||||||||||||||
Description of key information
There are no experimental data on the geoaccumulation potential of 4,4’-methylenedicyclohexyl diisocyanate, because the substance hydrolyses rapidly in aqueous environment. The distribution of 4,4’-methylene-dicyclohexyl diisocyanate between the organic phase of soil or sediments and the pore water was calculated using EPI-Suite software and two other QSARs.
4,4’-methylenedicyclohexyl diisocyanate should be regarded as a substance with very high geoaccumulation properties with a Koc-value in the range between 4.3*1004 and 3.8*1005. The calculated Koc values indicate that of 4,4’-methylenedicyclohexyl diisocyanate may strongly adsorb to soil but due to its rapid hydrolysis any emission to the terrestrial compartment would be affected by humidity.
It is therefore concluded that geoaccumulation of 4,4’-methylenedicyclohexyl diisocyanate is unlikely to occur. The hydrolysis product has only a small to medium tendency for geoaccumulation (log Koc <3).
Key value for chemical safety assessment
- Koc at 20 °C:
- 380 000
Additional information
Adsorption properties of substances are an essential input to environmental exposure assessment as the main compartments to which the substances are partitioned are identified and then tests strategies may be adapted to the behaviour of these substances. However, adsorption may be of minor importance for compounds with specific chemical properties and can be considered as not relevant for the assessment of the environmental behaviour.
According to REACH Regulation, Annex VIII adsorption / desorption studies can be waived, if one of the following circumstances applies:
– based on the physicochemical properties the substance can be expected to have a low potential for adsorption (e. g. the substance has a low octanol water partition coefficient); or
– the substance and its relevant degradation products decompose rapidly.
Methods for adsorption/desorption tests:
The adsorption of a substance to sewage sludge, sediment and/or soil can be measured using several methods.
In the OECD 106 “batch equilibrium method” adsorption coefficients are determined on various soils as a function of soil characteristics (e. g. organic carbon content). The use of a range of actual soils allows to predict realistic conditions. However, as a direct measurement of the adsorption, this method requires a quantitative analytical method for the substance, reliable over the range of the test concentrations.
The other commonly used adsorption method is an HPLC method referred as the “OECD 121 guideline”. It is an indirect estimation method based on the calibration of HPLC retention times for reference substances. In contrast to the OECD 106 method, the HPLC method does not require a quantitative analytical method. It is also independent from any choice of soils that might impair the results. However, the reference substances should be selected with known adsorption coefficients encompassing the expected value of the test chemical. In addition, the detection method does not guarantee that the parent substance or its degradation products are all detected implying some uncertainty on the results.
Instability of 4,4’-methylenedicyclohexyl diisocyanate:
Whatever method may have been chosen they all require the test substance to be sufficiently stable during the experiment. It may not apply to substances and relevant degradation products that decompose rapidly. Therefore, among others, information on the water solubility, the octanol/water partition coefficient and the stability of the substance is useful.
In water, 4,4'-methylenedicyclohexyl diisocyanate hydrolyses with a half-life of approximately 2 h (Bayer AG, 1999). The behaviour of 4,4’-methylenedicyclohexyl diisocyanate in soil will be affected by humidity due to its rapid hydrolysis. Therefore, an experimental study with 4,4’-methylenedicyclohexyl diisocyanate is scientifically unjustified.
The hydrolysis product is a complex mixture of water-insoluble oligomeric and polymeric ureas and of compounds derived from the corresponding diamine, where the isocyanate groups have been transformed to amino or urethane groups.
The diamine was considered in order to get an estimate on the adsorption behaviour of the hydrolysed product. For both, the unreacted diisocyanate as well as for the corresponding diamine, calculated values with three estimation methods are presented. For the polymers, no surrogate structure can be identified. However, negligible mobility and therefore insignificant adsorption is expected.
It is therefore concluded that adsorption of 4,4’-methylenedicyclohexyl diisocyanate to soil is unlikely to occur. The hydrolysis product methylene bis(4-cyclohexyl diamine) has only a small to medium tendency for adsorption.
Hydrolysis tests have been conducted and concluded rapid hydrolysis (half life <2h):
The 12 hours hydrolytical half-life value is considered as a threshold value below which this qualitative screening information is sufficient to evaluate the behaviour of the substance and its partition in the main compartments without conducting a full adsorption/desorption test (ECHA 2008: Guidance on information requirements and chemical safety assessment; chapter R.7. a: Endpoints specific guidance;4,4’-methylenedicyclohexyl diisocyanate is unlikely to adsorb to sediment, sludge or soil due to rapid hydrolysis processes which will prevail over adsorption mechanisms. Both components can be considered as unstable with a hydrolysis half life far below 12 hours (see above). Therefore adsorption/desorption tests cannot be performed without extended adaptations or deviations to the OECD standardised methods.
Conclusions:
Due to the instability of 4,4’-methylenedicyclohexyl diisocyanate, none of the OECD 106 or OECD 121 method seems to be relevant as the rapid hydrolysis of the components (half lives below 12 hours) will prevent them from adsorption to soil, sludge or sediments. Experimental determination of adsorption / desorption of 4,4’-methylenedicyclohexyl diisocyanate is not feasible. Instead of an experimental study QSAR predictions on adsorption/desorption are available and summarised.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
