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Diss Factsheets

Environmental fate & pathways

Adsorption / desorption

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Link to relevant study record(s)

adsorption / desorption, other
Type of information:
read-across from supporting substance (structural analogue or surrogate)
Adequacy of study:
supporting study
Justification for type of information:

This read-across is based on the hypothesis that source and target substance have similar environmental fate properties based on similar physicochemical properties, common functional groups and structural similarities.
The target substance MDIPA-Esterquat C18 unsatd. is a UVCB substance consisting of diesters of mainly unsaturated C18 fatty acids with MDIPA as amine backbone.
The source substances DODMAC and DHTDMAC exhibit large structural similarities with the target substance. Details are described below.
Therefore, read-across from the existing bioaccumulation data on the source substance is considered as an appropriate adaptation to the standard information requirements of Annex IX, 9.3 of the REACH Regulation for the target substance, in accordance with the provisions of Annex XI, 1.5 of the REACH Regulation.

See justification for read-across attached to chapter 13 of this IUCLID file.

See justification for read-across attached to chapter 13 of this IUCLID file.

See justification for read-across attached to chapter 13 of this IUCLID file.
Reason / purpose for cross-reference:
read-across: supporting information
Reason / purpose for cross-reference:
read-across source
other: Kp(sediment), Kp(soil)
10 000 L/kg

Description of key information

Koc = 10000 L/kg dw; read-across from DODMAC

Key value for chemical safety assessment

Koc at 20 °C:
10 000

Additional information

No data on adsorption/desorption is available for MDIPA Esterquat C18 unsatd. However, data from the structurally related substance DODMAC (Dimethyldioctadecylammonium chloride) are provided. A justification for read-across is attached to Iuclid section 13.


According to HERA, 2008, the “predictive power of the log Kow for the partitioning to soil, sediment and sludge or its bioaccumulation potential is considered to be limited, because the common Koc derivations are not valid for surface active substances like the esterquats. Therefore the log Kow values can not be used to derive the environmental distribution constants. Instead as a more reliable basis, the experimentally determined sorption and bioaccumulation figures of DODMAC are used. […]When esterquats enter the aquatic environment, it is likely that a large amount of the esterquats is not truly dissolved but is adsorbed onto suspended matter or included in vesicles together with other organics (e.g. humic acids, surfactants). The sorption behaviour of the esterquats in soils, sediment and sludge will be governed by two processes; partitioning to organic matter and ionic interaction with negatively charged particles. Under environmental conditions, sorption due to ionic interaction is expected to be the predominant process for cationic surfactants. The higher the cationic exchange capacity (CEC) of the sorbent, the higher the sorption will be. Under these conditions, the chain length of the esterquats is expected to be of minor importance for sorption/desorption behaviour onto soil, sediment or sludge. The sorption behaviour of esterquats is expected to be comparable to that of DHTDMAC or DODMAC, due to structural similarities. Therefore, the value reported for DODMAC [DODMAC, EU 2002] of 10,000 l/kg dw is assumed to be a realistic estimate for the estimation of both Kp-sed and Kp-soil and has been taken in the absence of measured data”.


DODMAC has a chemical structure similar to that of MDIPA Esterquat C18 unsatd. The chemical structure of the registration substance includes, in contrast to DODMAC, two polar ester moieties, which will lower adsorption potential. Thus, DODMAC could be considered as a worst case. No calculated Koc is provided for MDIPA Esterquat C18 unsatd., but instead the value obtained with the structurally closely related substance DODMAC is used for chemical safety assessment.


The reviewed investigations demonstrated that DODMAC can be bound very strongly by some minerals, while in others relatively small distribution constants were estimated. Under environmental conditions, the sorption properties of DODMAC probably vary in a wide range depending on the nature of the adsorbant. The authors chose a value of 10,000 L/kg dw for both Kp(sed) and Kp(soil).