Registration Dossier

Environmental fate & pathways

Endpoint summary

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.

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.

 

Justification for read-across

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 C16-18 and C18 unsatd. is a UVCB substance composed of diesters of mainly saturated C16 and C18 fatty acids with MDIPA (Methyldiisopropanol amine) as amine backbone.

The source substances DODMAC (Dimethyldioctadecyl ammonium chloride) and DHTDMAC (dihydrogenated tallow alkyl dimethyl ammonium chloride) 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. The justification of the proposed read-across approach is elaborated in the next chapters.

 

Substance Identities

Table 1: Substance identities

 

Source substance

DODMAC (EU, 2009)

Source substance

DHTDMAC (EU, 2009)

Target substance MDIPA-Esterquat C16-18 and C18 unsatd.

CAS number

 61789-80-8

61789-80-8

NA

EC number

 263-090-2

263-090-2

 941-174-6

Chain length distribution

C12: </=2 %

C14: 1 - 5 %

 C16: 25 - 35 %

 C18: ca. 65 %

 C 20: </=2 %

C12: </=2 %

C14: 1 - 5 %

C16: 25 - 35 %

C18: ca. 65 %

C 20: </=2 %

< C16: <= 6%

C16 - < C18: 20-65%

C18: 4-60%

C18 unsatd.: 10-43%

> C18: <= 5%

Amine

 ---

---

MDIPA

Anion

 Chloride

Chloride

Methyl sulphate

 

Structural similarity

a. Structural similarity and functional groups

Figure 1 (see attachment): Structures of source substance (DODMAC) and target substance (MDIPA Esterquat C16-18 and C18 unsatd.)

 

The target substance, MDIPA-Esterquat C16-18 and C18 unsatd., consists of an amine backbone (MDIPA = Methyldiisopropanol amine) esterified with long chain fatty acids C16, C18 and C18 unsaturated. The main reaction product is the dialkylester compound, besides that, small amounts of the monoalkylester may also be formed. The amine function is quaternised with two methyl groups. The counter ion is Methosulfate.

 

DODMAC is one of the active components of the technical product DHTDMAC. DHTDMAC is produced of tallow fatty acid via the nitrile to result in the amine, which is then methylated twice to the quaternised amine. The counter ion is Chloride.

Both, source and target substances have similar chain length distribution and contain a quaternised and dimethylated amine function.

 

b. Differences

The chemical structure of the target substance MDIPA-Esterquat C16-18 and C18 unsatd. contains, in contrast to the source substance, two polar ester moieties which are susceptible to hydrolysis and /or /degradation.

 

Physicochemical properties

Table 2: Physicochemical properties

 

Endpoints

Source substance

DODMAC (EU, 2009)

Source substance

DHTDMAC (EU, 2009)

Target substance MDIPA-Esterquat C16-18 and C18 unsatd.

 

Molecular weight

586.52 g/mol

567 - 573 g/mol

ca. 761 g/mol

Physical state at 20°C / 1013 hPa

Solid

Solid

solid (waxy)

Melting point

72-122 °C

60 - 65 °C

OECD Guideline 102; RL1; GLP

 

36°C 

Boiling point

decomposition at 135°C

decomposition at 120°C

OECD Guideline 103; RL1; GLP

 

Decomposition at > 250°C 

Surface tension

11 mN/m at 20 °C (saturated solution; method: filmbalance)

No data, read-across from DODMAC

OECD Guideline 115; RL2, GLP

 

73.9 mN/m at 20°C - not in line with the expected surface active behaviour of the substance

Water solubility

2.7 mg/L

Insoluble

ASTM International E 1148 – 02; RL1, GLP

 

1.01 mg/L at 20°C

ASTM International E 1148 – 02, RL1; ISO17025

 

7.4 mg/L at 20±0.3°C

ASTM International E 1148 – 02, RL1; ISO17025

 

1.9 mg/L at 20±0.3°C

Log Kow

3.8

No data, read-across from DODMAC

Determination technically not feasible due to the surface-active properties; calculationbased on Koc

 

4.43

Vapour pressure

negligible because of the salt character

negligible because of the salt character

OECD Guideline 104, RL1, GLP

 

< 8.4E-07 Pa at 20°C

 

All three substances are solid at room temperature with slightly differing melting ranges. The vapour pressure is negligible. The water solubility and log Kow of the source substances and the target substance are similar.

The results from the study on surface tension with the target substance MDIPA-Esterquat C16-18 and C18 unsatd. were not in line with the expected surface tension behaviour of the substance. Cationic surfactants carrying two C16/C18 alkyl chains, such as MDIPA-Esterquat C16-18 and C18 unsatd., are designed to possess surface active properties and typically exhibit surface tension values as low as 27 mN/m (depending on the area per molecule) when studied on a Langmuir film balance. Therefore due to the intrinsic properties (crystallisation) of this double-chain cationic amphiphiles at temperatures below the melting point no reliable results were obtained using the ring method.

 

Conclusion

The purpose of determining the bioconcentration factor is to assess whether there is any potential for the chemical to accumulate in organisms to a high degree and for further transfer up the food chain.

As demonstrated above, the physicochemical properties and structures of source and target substances are similar enough to support the read-across approach.

The main difference is the fact that the chemical structure of the target substance MDIPA-Esterquat C16-18 and C18 unsatd. includes, in contrast to the source substances, two polar ester moieties that would lower the BCF. Moreover these ester moieties are also susceptible to biodegradation and/or hydrolysis. DODMAC on the contrary is poorly biodegradable (EU, 2009) and much more stable than MDIPA-Esterquat C16-18 and C18 unsatd.

In HERA (2008) it is concluded that: “Based on the measured Log BCF value of DODMAC (also considered to be a conservative estimate for esterquats, the esterquats have a relatively low bioaccumulation potential. The low bioavailability of the esterquats (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 high probability of hydrolysis of the ester bond), make high bioaccumulation factors of esterquats even more improbable. Hydrolysis will lead to production of the more soluble degradation products and hence rapid elimination. ”

Thus, the results from the source substances can also be applied for the target substance MDIPA-Esterquat C16-18 and C18 unsatd. as a conservative estimation.

 

References

EU, 2009: European Union Summary Risk Assessment Report - dimethyldioctadecylammonium chloride (DODMAC) - with addendum, available online: http: //publications. jrc. ec. europa. eu/repository/handle/111111111/5276

HERA, 2008: Esterquats Environmental Risk Assessment Report, available online: http: //www. heraproject. com/files/17-E-01-03-2008%20%20HERA%20EQ%20Environment%20Final%20Draft. pdf