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Environmental fate & pathways

Biodegradation in water: screening tests

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Description of key information

The substance is not readily biodegradable, but can be rapidly degraded after adaptation of the inoculum to the substance.

Key value for chemical safety assessment

Biodegradation in water:
inherently biodegradable

Additional information

Parent compound (1-methylpiperazine):


The ready biodegradability of 1-methylpiperazine was studied in a closed bottle test according to OECD 301D under GLP (Ginkel, 2011; report no. F11080CG). Activated sludge of a wastewater treatment plant treating predominantly municipal sewage was the inoculum. After 28 d, the degradation was 5% based on oxygen consumption. The degradation did not increase after prolonged incubation for 60 d.


In another closed bottle test (OECD 301D, non-GLP; Ginkel et al., 2013; report no. F12023 CG), the activated sludge was adapted to the substance prior to the exposure. The substance was degraded to 74% after 28 d.


These two studies were selected as key studies.


Further studies support the conclusion that the substance can be rapidly degraded when the microorganisms are adapted to the substance.


Another closed bottle test used an inoculum derived from river water and activated sludge which was adapted to environmental concentrations of 1-methylpiperazine (OECD 301D, non-GLP; Ginkel et al., 2013; report no. F13043 CG). The substance  was degraded to more than 70% based on oxygen consumption after 28 d.


Metabolites:


In addition, the model CATALOGIC 301C v11.16 (OASIS Catalogic v5.14.1.5) was used to predict potential metabolites of 1-methylpiperazine. In agreement with the experimental data, the model predicted the substance to be not readily biodegradable (0% removal in 28 d, based on BOD; BASF SE, 2020). The substance was completely within the applicability domain of the model. The model predicted four metabolites, identifying one metabolite as a relevant degradation product in terms of PBT/vPvB assessment, with an estimated quantity of ≥ 0.1% (for details see the respective Endpoint Study Record). The relevant metabolite was calculated to be not readily biodegradable (1% after 28 d, based on BOD).


 


Table 1: QSAR prediction for CAS 109-01-3 using CATALOGIC 301C v11.16 – December 2019 (OASIS CATALOGIC v5.14.1.5); metabolites with a quantity > 0.001 mol/mol parent after 28 d are highlighted by grey background and bold type






















































#



Name (CAS no., SMILES)



Quantity
(mol/mol parent)



LogKow



BOD prediction
(% after 28 d)



PBT-Assessment
(ECHA-disseminated substances) 



parent



N-methyl-piperazine (109-01-3; CN1CCNCC1)



0.963



-0.57



0



 



1



1-Piperazinemethanol (90324-69-9; OCN1CCNCC1)



0.0359



-2.05



1



not listed



2



1-(hydroxymethyl)piperazin-2-ol (OCN1CCNCC1O)



0.000493



-3.18



34



not listed



3



OC(O)N1CCNCC1



0.000329



-2.28



10



not listed



4



OCN1CCNC(O)C1



0.000164



-3.18



22



not listed



 


Conclusion:


Summing up the available experimental and calculated data, 1-methylpiperazine (CAS 109-01-3) is concluded to be not readily biodegradable from a precautionary point of view.

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