Registration Dossier

Diss Factsheets

Environmental fate & pathways

Endpoint summary

Currently viewing:

Administrative data

Description of key information

Additional information

No experimental data on aquatic bioaccumulation are available for MDIPA-Esterquat C16-18 and C18 unsatd. According to REACH regulation (Annex XI, 1.5), a study on aquatic bioaccumulation does not need to be conducted for the substance under investigation if data from structurally closely related material are available. A justification for read-across is attached in the target record.

Measured BCF data are available for the structurally related substance Dimethyldioctadecyl ammonium chloride (DODMAC). The registration substance differs from DODMAC by the ester linking groups between the alkyl chains and the headgroup (effectively the dimethyl ammonium group); details are given below in the justification for read-across.

Regarding the BCF of MDIPA-Esterquat C16-18 and C18 unsatd., the BCF is expected to be lower than that of DODMAC:

The chemical structure of MDIPA-Esterquat C16-18 and C18 unsatd. includes, in contrast to DODMAC, two polar ester moieties that lower BCF and which are susceptible to biodegradation and/or hydrolysis which also will result in a lower BCF of MDIPA-Esterquat C16-18 and C18 unsatd. DODMAC is poorly biodegradable and much more stable than MDIPA-Esterquat C16-18 and C18 unsatd. For DODMAC no abiotic degradation is to be expected, for biotic degradation in water the degradation rate is very low (1.4 x 10E-4/d) (EU 2002).

The BCF of DODMAC was determined in a study in which juvenile fish (Pimephales promelas) were exposed for 24 h under flow-through conditions, followed by a depuration period of 72 h. A BCF of 104 L/kg was calculated based on the uptake rate constant (k1) of 1.35 mg/g x h and the depuration rate constant (k2) of 0.013 mg/g x h.

The measured BCF values for similar substances (DODMAC, DHTDMAC=dihydrogenated tallow alkyl dimethyl ammonium chloride) are 12 -32 L/kg (BUA-Report 191, 1995) and 13 - 256 L/kg (EU RAR, 2002). The EU RAR (2002) concluded 'bioaccumulation is indicated, but is assumed that it is low under environmental conditions. A BCF of 13 L/kg is used in the risk assessment... '

This is further supported by a QSAR calculation that yielded a calculated BCF value for MDIPA-Esterquat C16-18 and C18 unsatd. of 70.8 L/kg (EPIWIN v3.20, BCFWIN v2.17). As this QSAR model does not include metabolism, it can be considered a conservative estimate of BCF.

The low bioavailability of the substance (due to rapid and strong sorption to negatively charged surfaces in the aquatic environment) in combination with the rapid (bio) degradation of the bioavailable fraction (mainly due to the hydrolysis of the ester bond), make high bioconcentration factors for MDIPA-Esterquat C16-18 and C18 unsatd. even more improbable.

For the target substance MDIPA-Esterquat C16-18 and C18 unsatd. a BCF of the same order of magnitude and not higher than DODMAC is to be expected. The above information is considered as sufficient to support the conclusion that the bioaccumulation potential of MDIPA-Esterquat C16-18 and C18 unsatd. is expected to be low.