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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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.

Diss Factsheets

Administrative data

Link to relevant study record(s)

Description of key information

A theoretical assessment of the toxicokinetic properites of the substance is made, based on exisiting toxicity data and physicochemical properties.

Key value for chemical safety assessment

Bioaccumulation potential:
no bioaccumulation potential
Absorption rate - oral (%):
Absorption rate - dermal (%):
Absorption rate - inhalation (%):

Additional information

Theoretical assessment of the toxicokinetic properties of DBU

1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) is a non-volatile liquid with a moderate LogP value of ~2.7 and which is hydrolytically stable and miscible with water.



Absorption following oral exposure


The molecular weight, LogP value and high water solubility favour the oral absorption of DBU.  Oral bioavailability is predicted for DBU according to Lipinski’s rules.  Theoretical assessment indicates that the substance is hydrolytically stable; therefore is likely to be absorbed intact. DBU is demonstrated to be corrosive to skin; therefore toxicity testing in vivo is limited. Mortality in the acute toxicity study is associated with severe local effects on the stomach. A 14-day range-finding study and a longer-term screening study (OECD 422) performed in the rat report some toxicity, however the effects seen in these studies are almost entirely associated with local effects on the gastric mucosa.  A suggestion of increased kidney weight in the OECD 422 study may indicate the urinary excretion of DBU. Studies do not conclusively demonstrate systemic exposure; a default assumption of 50% oral absorption is therefore made for the purposes of risk assessment.


Absorption following dermal exposure


No studies of toxicity following dermal administration are available. The molecular weight, LogP value and high water solubility favour the dermal absorption of DBU.  The substance is shown to be corrosive to skin; local irritation or damage caused by dermal exposure may act to facilitate dermal absorption. A default assumption of 50% dermal absorption is made for the purposes of risk assessment.


Absorption following inhalation exposure


Inhalation absorption is only relevant for substances which are gases, volatile liquids or which are used in a manner which generates small droplets or particles (e.g. by spraying).  The physicochemical properties of DBU indicate that significant inhalation exposure is unlikely.  The extent of absorption following the inhalation of DBU is likely to be extensive. An assumption of 100% inhalation absorption is therefore made for the purposes of risk assessment.




The available toxicity data do not provide any indication of the systemic distribution of DBU with the possible exception of the kidney; however the water solubility and low molecular weight of the substance indicates that any systemically absorbed substance would be rapidly distributed in the systemic circulation.




OECD QSAR Toolbox (3.0) does not predict any hepatic or dermal metabolites for DBU. 




Data indicate that DBU will be rapidly excreted in the urine. Biliary excretion is unlikely based on the low molecular weight of the substance.




The physicochemical properties and predicted toxicokinetic properties of DBU do not indicate any potential for bioaccumulation.