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Environmental fate & pathways

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Description of key information

N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine is biodegraded by73% biodegradation at day 28 in the Closed Bottle test (AkzoNobel 2016a) hence N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine is classified as readily biodegradable.

Additional information

Biodegradation

 

N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamineis biodegraded by 73% biodegradation at day 28 in the Closed Bottle test (AkzoNobel 2016a) Hence N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine should be classified as readily biodegradable. The Table below summarizes half-life values derived by default using the ready biodegradability test result and cross reading.

 

Table:Summary of degradation rate constants in various (eco)systems based the ready biodegradability of N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine and a Kdsoil/sedof 1763 L/kg.

(Eco)system

Method

 

Surface water (fresh)

TGD default value

15 days half-life

Surface water sediment (aerobic)

TGD default value

3000 days half-lifea

Marine water

TGD default value

50 days half-life

Soil

TGD default value

3000 days half-lifea

Removal from wastewater in sewage treatment plants

Determined through read across

>98.8%

Biological degradation in sewage treatment plants

Determined through read across

>94.2%

aHalf-life of the fraction present in the aqueous phase is expected to in the order of a few days.

 

  • AkzoNobel (2016a) Biodegradability of N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine in the Closed Bottle test (OECD TG 301D) Report no F16034 CG GLP study no T16018 C.
  • AkzoNobel 2016b) Evaluation of the biodegradability of N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine using both the Closed Bottle test and SCAS test. Report no. F 16031 CG.

 

Biodegradation in water; screening tests

Ready biodegradability was found in Closed Bottle tests inocculated with river water. Biodegradation percentages in excess of 60% were also achieved in Closed Bottle tests inoculated with activated sludge. The longer test period required with activated sludge should be attributed to the slight biocidal properties of the fatty amine (AkzoNobel 2016b). 

For N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine, a result of 73% at day 28 was obtained in a Closed Bottle test (OECD TG 301 D). The time window criterion was not be applied for classification because of the poor water solubility of the substance, the composition of the substance (UVCB) and the nature of the substance (two moieties linked covalently).                 

Poor water solubility of organic compoundsaffects the biodegradation kinetics because of slow desorption and dissolution rates of the test substance present at high concentrations. The biodegradation curves of poorly-water soluble substances are linear as found forN-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamineinstead of the anticipated S-shape. The poor water solubilityofN-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamineistherefore a reason for not applying the time window as pass/fail criterion(Battersby, 2000; Richterich and Steber, 2001).

Surfactants are chemicals in which a hydrophilic group is linked to a hydrophobic moiety. Biodegradation of both moieties of surfactants requires the concerted action of at least two microorganisms as a single organism usually lacks the full complement of enzymatic capabilities (van Ginkel, 1996). Biodegradation of fatty amine derivatives is achieved initially through one main pathway, namely cleavage of the Calkyl-N bonds (van Ginkel, 1996). Growth on the alkyl chain(s) of fatty amine derivatives is accompanied by the excretion of hydrophilic moieties. Another microorganism usually degrades the hydrophilic moiety (van Ginkel 1996). In ready biodegradability tests,the two moieties offatty amine derivatives are as a consequence degraded sequentially. The biodegradation of the two moieties may be fully in line with the time window criterion when judged as separate chemicals.The sequential degradation of both moieties is therefore another important reason for not applying the time window criterion as pass/fail criterion forN-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine

Finally,N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diaminebeing an UVCB consisting of homoloques is a reason for ignoring the time window.The time window concept assumes that biodegradation of a single organic compound in a ready biodegradability test is a growth-linked process which should follow an S-shaped growth curve. The biodegradation kinetics (lag period, growth rate, yield etc.) of the individual compounds in a UVCB are not necessarily same. It is thus possible that individual compounds meet the time window criterion whereas the biodegradability curve of the mixture of homologues suggests that the surfactant is not readily biodegradable (Richterich and Steber, 2001).

The >60% biodegradation obtained at day 28 in a ready biodegradability test and the scientific arguments allowing to ignore the time window concept lead to the conclusion thatN-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine should be classified asreadily biodegradable.

 

  • Battersby NS (2000) The biodegradability and microbiological toxicity testing of lubricants some recommendations. Chemosphere 41 1011-1027.
  • Ginkel CG van (1996) Complete degradation of xenobiotic surfactants by consortia of aerobic microorganisms. Biodegradation 7 151-164.
  • Richterich K and Steber J (2001) The time-window – an inadequate criterion for the ready biodegradability assessment of technical surfactants. Chemosphere 44 1649-1654.

 

 

Biodegradation in water and sediment; simulation tests

 

A mean Kpsed of 1763 L/kg was observed. The half-life at 12 ºC for a readily degradable substance with a Kpsed in the range >1000 and < 10000 L/kg is 3000 days. This value is considered as conservative but in the absence of measured data will be used in the exposure assessment. The half-life of the bioavailable fraction ofN-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diaminein the water phase of sediments is expected to be in the order of a few days, which is based on experiments with dialkyldimethylammonium salts (van Ginkel et al, 2003).

Accurate assessment of the removal of surfactants in biological treatment plants of fatty amine derivatives is possible in continuously-fed activated sludge (CAS) units (Geerts et al, 2015). Results found with readily biodegradable alkylamines having varying log Ko/c values allow assessment of the removal other readily biodegradable cationic surfactants from wastewater by biodegradation in treatment systems through read across (Table). The mean observed log Ko/c of N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine is 5.12. Read across using this log Ko/c results in a removal percentage of >98.8 fromthe wastewater in biological wastewater treatment plants. This high percentage is in line with the 95%(organic carbon)removal ofN-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine found in a SCAS unit.N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine is primarily removed by biodegradation i.e.>94.5% (Table).

 

Table:Removal offive cationic surfactantsfrom the wastewater and the percentages removed by biodegradation and adsorption in Continuously-fed Activated Sludge (CAS) units(Geerts et al, 2015).

 

Biodegradability

Log Koc

Removal (%)

From wastewater

By biodegradation

Measured

SimpleTreat

Measured

SimpleTreat

Decylamine

Ready

1.23

99.998

91.52

99.998

91.50

Tetradecylamine

Ready

2.32

99.968

91.52

99.960

91.40

Octadecylamine

Ready

3.41

99.754

91.38

98.197

90.00

Dioctadecylmethyl-amine

Ready

8.59

98.822

84.60

94.538

0.03

Dioctadecyldimethyl-amine

Inherent fulfilling criteria

7.76

99.348

84.60

69.003

0.03

logKoc values were estimated from log Kow values based on the protonated form of the alkylamines using KOCWIN v2.00 (EPISUITE). Simpletreat removals were calculated using the six-box model and the estimated Koc values (EUSES 2.1).

 

  • R Geerts, CG van Ginkel, CM Plugge, (2015) Accurate assessment of the biodegradation of cationic surfactants in activated sludge reactors (OECD 303A) Ecotoxicology and Environmental Safety 118 83-89.
  • AkzoNobel 2016b) Evaluation of the biodegradability of N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine using both the Closed Bottle test and SCAS test. Report no. F 16031 CG.

 

 

Soil

 

The mean observed Kpsoil ofN-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamineis 1763 L/kg. The half-life for a ready biodegradable substance with a Kpsoil in the range >1000 and < 10000 L/kg is 3000 days at 12 ºC. This value is considered as conservative but in the absence of measured data will be used in the exposure assessment as a worst-case. The half-life of the bioavailable fraction of other fatty amine derivatives in the aqueous phase of soils is expected to be in the order of only a few days, which is based on experiments with dialkyldimethylammonium salts (van Ginkel et al, 2003).

 

 

  • CG van Ginkel, A Hoenderboom AM van Haperen and MGJ Geurts (2003) Assessment of the biodegradability of dialkyldimethylammonium salts in flow through systems. Environmental Science and Health (Part A) / 38(9) 1825-1835
  • R Geerts, CG van Ginkel, CM Plugge, (2015) Accurate assessment of the biodegradation of cationic surfactants in activated sludge reactors (OECD 303A) Ecotoxicology and Environmental Safety 118 83-89.
  • AkzoNobel 2016b) Evaluation of the biodegradability of N-C16-18-alkyl-(even numbered, C18 unsaturated) trimethylpropane-1,3-diamine using both the Closed Bottle test and SCAS test. Report no. F 16031 CG.