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Please be aware that this old REACH registration data factsheet is no longer maintained; it remains frozen as of 19th May 2023.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

Short description of key information on bioaccumulation potential result: 
MBTester is predicted to be bioavailable via the oral route but is very poorly absorbed via skin.
MBTester is expected to undergo stepwise hydrolysis of the ester bonds yielding 2,2'-(methylenebis(thio))bisacetic acid (MBTAA; CAS: 2068-24-8) and 1-butananol (1-Bu; CAS: 71-36-3). Both substances are very polar and thus subject to renal elimination. Tissue accumulation can be excluded.

Key value for chemical safety assessment

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

Additional information


Oral absorptionof MBTester is predicted to be high. The Danish EPA (% G.I. abs. for 1 mg dose) predicts an oral absorption of 100% following an administered dose of 1 mg.

The EpiSuite DermWin v2.02 program predicts a very lowdermal absorptionof 0.00025 mg/cm²/event.

Theinhalative absorptioncan be neglected due to the very low vapour pressure of the substance.


The substance will be hydrolyzed; the hydrolysis products are water soluble and are predicted to have no accumulation potential. They are expected to enter the urine shortly after systemic absorption.


MBTester will undergo enzymatic and non-enzymatic ester hydrolysis. This is a stepwise process and mixed hydrolysis and oxidation products are likely to occur at least as intermediate metabolites.

The resulting molecules 2,2'-(methylenebis(thio))bisacetic acid (MBTAA; CAS: 2068-24-8) and 1-butananol (1-Bu; CAS: 71-36-3), are soluble in water. Both substances can be further oxidized [R2S to R2S(=O)2; -CH2OH to -COOH]. Carboxylic acids can be subject to sulphation and glucuronidation mediated by sulfotransferases and UGT-isozymes prior to urinary excretion.


The hydrolysis products of MBTester as well as the oxidized metabolites are soluble in water (MBTAA: ca. 200 g/L; 1-Bu: ca. 70 g/L; calculated with EPI Suite, WSKOW v1.42) and will be excreted rapidly via urine, either as such or as conjugates with glucuronic acid or suphate. Significant faecal excretion is not expected.