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Environmental fate & pathways

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No measured BCF fish is available for the primary fatty amine ethoxylates.

Standard OECD 305 tests are technically not feasible with these strongly sorbing easily degradable substances. In addition is the route of exposure in a standard OECD 305 test unrealistic for these substances because the substance will either be sorbed or biodegraded. The bioaccumulation potential of primary fatty amine ethoxylates was therefore assessed based on a measured log Kow. As indicated before, primary fatty amine ethoxylates are readily biodegradable and it is therefore unlikely that they will accumulate in the food chain. Since there is a measured log Kow value available this value is used to assess the bioaccumulation potential.

Three valid measured log Kow values are however available as presented in the table below.

 Primary fatty amines ethoxylates

CAS number

Measured log Kow 

2,2'-(C12-18 evennumbered alkyl imino) diethanol

71786-60-2

0.7

2,2'-(C16-18 (evennumbered) alkyl imino) diethanol

1218787-30-4

3.6

2,2’(octadec-9-enylimino) -bisethanol

25307-17-9

3.4

 

The highest log Kow is observed for 2,2'-(C16-18 (evennumbered) alkyl imino) diethanol (CAS no 1218787-30-4). For this product also the lowest CMC of 3.5 mg/L was observed. The measured log Kow value of 3.6 indicates a moderate bioaccumulation potential for narcotic substances. For polar narcotics like the primary fatty amine ethoxylates however there is only limited information on the relationship between log Kow and BCF.

Thein vitrobiotransformation of C12to C18alkyldiethanolamines was therefore tested according to a slightly adaptedCellzdirect/Invitrogen Hepatic Rainbow Trout S9 Incubation Protocol using testosterone as benchmark.

The results show thatC12– C18alkyldiethanol amines are quickly metabolized.

A summary of the mean observed biotransformation rates, the predicted whole body metabolism rate (Kmet) and BioConcentration Factor (BCF) are presented in the Table below. The Kmetand BCF values were estimated using a calculation spreadsheet obtained from John Nichols (USEPA, personal communication). The BCF is calculated assuming thatthe reduction in bioavailability in the test is functionally identical to the reduction in bioavailability in fish plasma (fu= 1).

 

Table: Summary of data in relation to the bioaccumulation potential of alkyl diethanolamines.

Alkyl chain length

Measured

Log Kow

using OECD 123*

Slope of log transformed substrate depletion curve**

Estimated Partitioning based BCF(L/kg)

Estimated

Kmet(1/day)

 

Estimated

BCF with biotransformation (L/kg)

C12

1.58

-0.119 ± 0.034

1.9

12.4

1.7

C14

2.79

-0.103 ± 0.017

31

4.05

25

C16

4.4

-0.051 ± 0.012

1256

0.82

465

C18

3.8

-0.011 ± 0.005

315

0.30

272

*Paulson, 2010a, b and c      

** Negative values represent the decrease of the test substance

 

The observed rapid biotransformation of the C12 to C18alkyldiethanol amines (RSS under 6.5) demonstrates that it will be very unlikely that these substances will accumulate in fish. This was confirmed by the calculated BCF values which where all below the CLP threshold value of 500 L/kg. It is therefore concluded that C12 to C18alkyldiethanolamines have a low bioaccumulation potential and that anin vivoevaluation of the bioaccumulation potential by e.g. performing an OECD 305 bioaccumulation test is not expected to result in BCF values > 500 L/kg.

The weight evidence of each of the fate points (log Kow, metabolism, biodegradability, bioavailability, BCF model) separately is limited but when considered together it is justified to concluded that primary alkyl amine ethoxylates (2EO) will not accumulate in the food chain and have a low bioaccumulation potential.